Herpes Zoster (Shingles)

Topic Overview

Summary

Herpes zoster (shingles) results from reactivation of latent varicella zoster virus (VZV) from dorsal root, cranial nerve, or autonomic ganglia, manifesting as a painful dermatomal vesicular rash. [1] VZV, a neurotropic alphaherpesvirus, establishes lifelong latency following primary varicella (chickenpox) infection, with reactivation triggered by declining cell-mediated immunity. [2] The lifetime risk approaches 30%, with incidence increasing markedly after age 50 and among immunocompromised individuals. [3] Major complications include postherpetic neuralgia (PHN), ophthalmic zoster with vision-threatening sequelae, Ramsay Hunt syndrome, and rare but serious neurological complications including stroke and meningoencephalitis. [4,5] Early antiviral therapy within 72 hours of rash onset reduces disease severity and PHN risk. [6] The recombinant zoster vaccine (Shingrix) demonstrates over 90% efficacy in preventing herpes zoster and its complications, even in adults over 70. [7]

Key Facts

• Pathogenesis: Reactivation of latent VZV from sensory ganglia when cell-mediated immunity wanes
• Epidemiology: Lifetime risk 30%; incidence 3-5/1000 person-years, rising to 10/1000 in those > 80 years [3]
• Presentation: Prodromal dermatomal pain → unilateral vesicular rash that does not cross midline
• Complications: PHN (10-18% overall; up to 30% in > 80 years), ophthalmic zoster (10-25% of cases), Ramsay Hunt syndrome (less than 1% of zoster cases) [4,8]
• Treatment: Oral antivirals (valaciclovir 1g TDS, aciclovir 800mg 5x/day, or famciclovir 500mg TDS for 7 days) within 72 hours [6]
• Prevention: Recombinant zoster vaccine (Shingrix) for adults ≥50 years; 97.2% efficacy in preventing herpes zoster [7]

Clinical Pearls

Hutchinson's Sign = Ophthalmology Emergency Vesicles on the nose tip indicate nasociliary nerve involvement with approximately 76% risk of ocular complications. Urgent same-day ophthalmology referral mandatory. [9]

"72-Hour Window" for Antivirals Treatment initiation within 72 hours of rash onset significantly reduces acute pain severity, rash duration, and PHN incidence. Consider treatment beyond 72 hours if new lesions forming or high-risk patient. [6]

Zoster Sine Herpete Dermatomal pain without rash accounts for up to 30% of Ramsay Hunt cases and occurs in other presentations. Diagnosis via VZV PCR from CSF or elevated VZV antibodies. Consider in unexplained dermatomal pain. [8]

Bilateral/Disseminated Zoster = Immunodeficiency Disseminated zoster (> 20 lesions outside primary dermatome) indicates significant immunosuppression. Requires IV antivirals, investigation for underlying immunodeficiency (HIV, malignancy), and consideration of visceral involvement. [10]

Why This Matters Clinically

Herpes zoster affects 1 in 3 individuals during their lifetime, with over 1 million cases annually in the United States alone. [3] The disease burden extends far beyond the acute rash: postherpetic neuralgia causes debilitating chronic pain lasting months to years, ophthalmic zoster threatens permanent vision loss, and emerging evidence links herpes zoster to increased stroke risk through zoster-associated vasculopathy. [4,5] Early recognition and treatment within the critical 72-hour window substantially improves outcomes, while targeted vaccination of adults over 50 can prevent the majority of cases and complications. [6,7] Prompt identification of red flag presentations—particularly ophthalmic involvement and immunocompromised states—enables timely specialist intervention and prevents serious morbidity.

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Visual Summary

Visual assets to be added:

• Dermatomal distribution map (full body with dermatomes labeled)
• Evolution of herpes zoster rash (macules → papules → vesicles → pustules → crusts)
• Hutchinson's sign photograph (nasal tip vesicles)
• Ophthalmic zoster with V1 distribution
• Ramsay Hunt syndrome (ear vesicles + facial palsy)
• Disseminated zoster vs localized zoster comparison
• Herpes zoster management algorithm (decision tree)
• PHN pain distribution diagram

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Epidemiology

Global Burden

Incidence and Prevalence

Herpes zoster represents a substantial global health burden with increasing incidence paralleling aging populations. [3]

The lifetime risk approaches 30% in immunocompetent individuals, with over 90% of adults harboring latent VZV due to prior varicella infection. [3,7] Incidence rises exponentially with age, reflecting progressive decline in VZV-specific cell-mediated immunity (immunosenescence). [11]

Demographic Patterns

Age Distribution

• Peak incidence in adults ≥50 years
• Pediatric herpes zoster rare (less than 1/1000), usually associated with intrauterine VZV exposure or early-life varicella [12]
• Median age at diagnosis: 65-70 years in developed countries [3]

Sex Distribution

• Females have marginally higher incidence than males (1.2-1.3:1 ratio)
• Women more likely to develop PHN (adjusted OR 1.19, 95% CI 1.10-1.27) [4]
• Gender difference possibly related to immune response variations

Seasonal Variation

• Slight increased incidence in spring and autumn in some studies
• Less pronounced seasonality than primary varicella
• Regional variations exist [3]

Risk Factors

Age (Primary Risk Factor)

Progressive immunosenescence drives the age-related increase in herpes zoster incidence. VZV-specific cell-mediated immunity declines with aging, enabling viral reactivation from latently infected sensory ganglia. [11]

Immunocompromise (Major Risk Factor)

Immunocompromised patients face substantially elevated herpes zoster risk with higher complication rates. [10]

Specific Immunocompromised States

Biologic Therapy Considerations Recent large-scale studies demonstrate varied herpes zoster risk across biologic agents:

• Adalimumab (TNF-α inhibitor): increased risk (weighted HR 1.63, 95% CI 1.22-2.18)
• Ustekinumab (IL-12/23 inhibitor): possible protective effect (weighted HR 0.82, 95% CI 0.61-1.11)
• Guselkumab (IL-23 inhibitor): possible protective effect (weighted HR 0.48, 95% CI 0.22-1.02) [13]

Other Risk Factors

Protective Factors

• Vaccination (varicella/zoster): Childhood varicella vaccination may reduce lifetime zoster risk; recombinant zoster vaccine (RZV) reduces zoster incidence > 90% [7]
• Exogenous boosting: Historical hypothesis that re-exposure to varicella boosts VZV immunity; evidence mixed
• VZV antibody levels: Higher anti-VZV antibody titers may correlate with reduced PHN risk [4]

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Pathophysiology

Viral Biology

Varicella Zoster Virus Characteristics

VZV is a neurotropic alphaherpesvirus (human herpesvirus 3) with exclusive human host specificity. [1]

• Genome: Linear double-stranded DNA (~125 kilobase pairs)
• Virion structure: Nucleocapsid, protein tegument, lipid envelope with glycoproteins
• Transmission: Airborne droplets, direct contact with vesicle fluid
• Cell tropism: Epithelial cells, T-lymphocytes, sensory neurons

Primary Infection (Varicella)

1. Respiratory tract entry: Viral inoculation of oropharyngeal/respiratory mucosa
2. Primary viremia: Replication in regional lymph nodes → spread to reticuloendothelial system
3. Secondary viremia: Widespread dissemination (Days 10-14 post-exposure)
4. Cutaneous manifestation: Characteristic "dewdrop on a rose petal" vesicles
5. Neuronal spread: Viremic dissemination and retrograde axonal transport to sensory ganglia along entire neuraxis [2]

Establishment of Latency

Following primary varicella infection, VZV establishes lifelong latency in multiple ganglia:

Ganglia Infected [2,14]

• Dorsal root ganglia (all spinal levels)
• Cranial nerve ganglia (particularly trigeminal, geniculate)
• Autonomic ganglia
• Enteric nervous system ganglia (emerging evidence)

Molecular Mechanisms of Latency [2,14]

1. Viral genome configuration: Histone-associated circular episomal DNA in neuronal nuclei
2. Limited gene expression: Highly restricted transcription during latency
   • VZV gene 63 (ORF63): hallmark of latency, expressed in latently infected neurons
   • At least 5-6 other viral genes transcribed at low levels
   • Minimal to no viral protein production (unlike HSV-1 latency)
3. Epigenetic regulation: Chromatin modifications regulate viral gene silencing
4. Cellular localization: Predominantly in sensory neurons (> 95%), occasionally satellite cells
5. Viral load: Low viral genome copy number during latency (10^5-10^6 copies per 10^5 cells)

Differences from HSV-1 Latency [2]

• No latency-associated transcript (LAT) in VZV
• No detectable microRNA production during VZV latency
• Limited evidence for T-cell surveillance during VZV latency
• VZV latency occurs throughout neuraxis; HSV-1 predominantly trigeminal ganglia

Reactivation and Herpes Zoster

Triggers for Reactivation [11]

1. Immunosenescence (primary): Age-related decline in VZV-specific T-cell immunity
2. Immunosuppression: Medications, disease states, malignancy
3. Immune modulation: Stress, trauma, concurrent infections
4. Unknown factors: Majority of cases have no identifiable trigger

Molecular Process of Reactivation [1,2]

1. Loss of immune control: Decline in VZV-specific CD4+ and CD8+ T-cell responses
2. Viral gene activation: Transcriptional upregulation of viral genes
3. Productive replication: Virion assembly in neuronal cell bodies
4. Anterograde transport: Virus travels along sensory nerves to cutaneous dermatome
5. Dermal infection: Viral replication in skin produces characteristic vesicular rash
6. Immune response: Localized inflammation, pain, neural damage

VZV Immune Evasion Mechanisms [15]

• MHC class I downregulation: Impairs CD8+ T-cell recognition
• MHC class II interference: Reduces CD4+ T-cell activation
• Cell-to-cell spread: Direct transmission minimizes antibody exposure
• Neurotropism: Sanctuary site with limited immune surveillance

Dermatomal Distribution

Frequency by Site [3,16]

Unilateral Distribution

• Herpes zoster characteristically respects the midline due to dermatomal innervation patterns
• Bilateral involvement rare (less than 1%); suggests immunocompromise or separate reactivation events
• Adjacent dermatome involvement (2-3 contiguous dermatomes) occurs in ~20% of cases [16]

Disseminated Zoster

Definition: > 20 vesicles outside the primary affected dermatome(s) [10]

Pathogenesis

• Secondary viremia due to failure of immune containment
• Occurs almost exclusively in immunocompromised hosts
• Risk of visceral dissemination (lungs, liver, CNS)

Clinical Implications

• Requires IV antiviral therapy
• Isolation precautions (airborne + contact)
• Investigation for underlying immunodeficiency
• Higher morbidity and mortality risk

Complications Pathophysiology

Postherpetic Neuralgia (PHN)

Pathological Mechanisms [4,17]

1. Acute neural damage: VZV-induced inflammation and neuronal injury during reactivation
2. Dorsal horn sensitization: Aberrant central pain processing
3. Peripheral sensitization: Damaged primary afferent nociceptors
4. Nerve fiber loss: Permanent reduction in epidermal nerve fiber density
5. Chronic ganglionitis: Persistent low-level inflammation in affected ganglia
6. Neuropathic pain: Combination of peripheral and central mechanisms

Risk Factors for PHN [4,18]

• Advanced age (strongest predictor): 10-year increase OR 1.70 (95% CI 1.63-1.78)
• Severe acute pain during rash phase
• Severe or extensive rash
• Prodromal pain before rash
• Ophthalmic involvement
• Female sex
• Comorbidities: diabetes, immunosuppression, chronic diseases

Ophthalmic Zoster Complications [9,19]

Pathophysiology

• Reactivation from trigeminal ganglion affecting ophthalmic division (V1)
• Direct viral infection of ocular structures
• Inflammatory damage to cornea, uvea, retina, optic nerve
• Neurotrophic keratopathy from loss of corneal sensation

Ocular Structures Affected (see Complications section for details)

Ramsay Hunt Syndrome [8,20]

Pathophysiology

• Reactivation from geniculate ganglion (cranial nerve VII)
• Facial nerve inflammation and edema
• Potential extension to CN VIII (vestibulocochlear), CN V, CN IX-XII
• Neural ischemia from inflammatory compression in narrow bony canal

VZV Vasculopathy [5]

Pathological Process

• VZV infection of cerebral arteries (large and small vessels)
• Transmural arterial inflammation
• Intimal hyperplasia and luminal stenosis
• Thrombosis and ischemic stroke
• May occur weeks to months after acute zoster (or without rash)

Evidence

• VZV DNA detected in affected arterial walls
• Associated with both ischemic and hemorrhagic stroke
• Increased stroke risk in months following herpes zoster diagnosis [5]

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Clinical Presentation

Prodromal Phase (1-5 Days Before Rash)

Duration: Typically 2-4 days; may extend to 1 week in some patients

Symptoms [1,16]

• Dermatomal pain: Burning, sharp, stabbing, or aching pain in affected dermatome(s)
  • Quality: Often described as "burning," "electric," or "deep aching"
  • "Severity: Variable; may be mild discomfort to severe pain"
  • "Pattern: Constant or intermittent; may worsen with movement or light touch"
• Paresthesias: Tingling, numbness, itching, hypersensitivity (allodynia)
• Systemic symptoms: Low-grade fever, malaise, headache, fatigue (25-50% of patients)

Clinical Significance

• Prodromal pain without rash easily misdiagnosed (cardiac pain, renal colic, pleurisy depending on dermatome)
• Consider herpes zoster in differential for unexplained dermatomal pain, especially in at-risk populations
• Severe prodromal pain correlates with increased PHN risk [4,18]

Acute Rash Phase

Timeline and Evolution [1,16]

Day 0-1: Macules and Papules

• Erythematous macules appear in affected dermatome
• Rapidly evolve to papules within hours

Day 1-3: Vesicles (Diagnostic)

• Characteristic appearance: Grouped vesicles on erythematous base ("dewdrops on a rose petal")
• Distribution: Unilateral dermatomal; does not cross midline
• Vesicle fluid: Initially clear, becomes cloudy by day 3-4
• New lesion crops continue for 3-5 days (occasionally up to 7 days)

Day 3-7: Pustules

• Vesicle fluid becomes turbid/purulent
• Base remains erythematous
• Pain typically peaks during this phase

Day 7-10: Crusting

• Pustules dry and crust over
• Crusts typically brown or hemorrhagic in appearance
• Erythema begins to fade

Day 10-21: Healing

• Crusts gradually separate (typically by 2-3 weeks)
• Post-inflammatory hyperpigmentation or hypopigmentation may persist for months
• Scarring variable (more likely with secondary bacterial infection or severe cases)

Rash Characteristics

Distribution

• Unilateral: Hallmark feature; respects midline except rare exceptions
• Dermatomal: Follows specific sensory dermatome(s)
• Contiguous spread: May involve 1-3 adjacent dermatomes
• Density: Variable from scattered vesicles to confluent involvement

Morphology

• Grouped vesicles and pustules on erythematous base
• Vesicle size: 2-5mm diameter typically
• May become hemorrhagic in severe cases
• Confluence of lesions common in immunocompromised hosts [10]

Site-Specific Presentations

Thoracic Herpes Zoster (50-55%)

Presentation

• Band-like distribution wrapping from spine to sternum
• Typically single dermatome (T3-L2 most common)
• Pain may mimic cardiac, pleural, or abdominal pathology during prodrome

Clinical Pearls

• Consider herpes zoster in acute "chest pain" or "flank pain" presentations before rash appears
• Usually uncomplicated course
• PHN risk lower than cranial involvement but increases with age

Ophthalmic Zoster (10-20% of All Zoster) [9,19]

V1 (Ophthalmic Division) Involvement

Ophthalmic Complications (in approximately 50% of HZO cases) [9,19]

• Conjunctivitis (most common): injection, chemosis
• Keratitis (up to 65% of HZO): epithelial, stromal, neurotrophic
• Anterior uveitis (30-40%): may be granulomatous; risk of secondary glaucoma
• Episcleritis/scleritis (10-15%)
• Posterior segment (rare but serious):
  • Acute retinal necrosis (ARN)
  • Progressive outer retinal necrosis (PORN) in AIDS
  • Optic neuritis
• Neurotrophic keratopathy: corneal anesthesia → epithelial defects → scarring/perforation

Red Flags in Ophthalmic Zoster [9,19]

• Hutchinson's sign (nose tip vesicles)
• Any eye pain, photophobia, blurred vision, or conjunctival injection
• Reduced corneal sensation on testing
• Age > 60 years (worse outcomes)

Management Imperatives

• URGENT same-day ophthalmology referral for ALL V1 involvement
• IV antivirals in severe cases or immunocompromised patients
• Topical corticosteroids under ophthalmology guidance
• Long-term follow-up (complications may develop weeks to months later)

Trigeminal V2/V3 Distributions

V2 (Maxillary)

• Cheek, upper lip, palate, upper teeth
• Intraoral vesicles on hard palate
• May cause severe pain with eating

V3 (Mandibular)

• Lower jaw, lower lip, anterior tongue, lower teeth
• Intraoral involvement of buccal mucosa, tongue
• Difficulty with speech and eating

Ramsay Hunt Syndrome (Herpes Zoster Oticus) [8,20]

Classic Triad

1. Vesicular rash: External ear (pinna, external auditory canal), sometimes palate, anterior tongue
2. Facial nerve palsy: Ipsilateral peripheral facial weakness (House-Brackmann grades III-VI typically)
3. Otalgia: Severe ear pain

Additional Features (variable presence) [8,20]

• Vestibulocochlear nerve (CN VIII) involvement:
  • Hearing loss (sensorineural)
  • Tinnitus
  • Vertigo, nystagmus
• Other cranial nerve involvement: CN V, IX, X, XI, XII (15-20% of cases)
• Zoster sine herpete: Facial palsy and otalgia WITHOUT rash (up to 30% of Ramsay Hunt cases) [8]

Prognosis [20]

• Complete recovery of facial function: ~50-70% (worse than Bell's palsy)
• Earlier treatment (within 72 hours) improves outcome
• Hearing recovery variable (~50%)
• Age and severity of palsy predict outcome

Sacral Zoster (S2-S4) [16]

Clinical Features

• Perianal, perineal, buttock distribution
• May cause bladder dysfunction (urinary retention)
• Bowel dysfunction rare but described
• Sexual dysfunction

Red Flags

• Any urinary retention → neurology consult, consider catheterization
• Rule out cauda equina syndrome if bilateral or progressive

Motor Zoster (1-5% of Cases) [16]

Pathophysiology

• Extension of inflammation from dorsal root ganglion to anterior horn cells or motor nerve roots
• Segmental paresis corresponding to myotome of affected dermatome

Presentations

• Limb weakness (corresponding myotome to dermatomal rash)
• Diaphragmatic palsy (C3-C5 zoster; rare)
• Abdominal wall weakness (thoracic zoster)

Prognosis

• Variable recovery; partial improvement in ~50-70%
• May have permanent weakness
• Physical therapy beneficial

Special Populations

Immunocompromised Patients [10]

Atypical Features

• Prolonged new lesion formation (> 1 week)
• Delayed healing (> 3 weeks to crusting)
• Hemorrhagic or necrotic lesions
• Disseminated rash (> 20 lesions outside primary dermatome)
• Multidermatomal involvement
• Recurrent zoster (same or different dermatome)
• Visceral dissemination risk: pneumonitis, hepatitis, encephalitis

Clinical Approach

• Lower threshold for IV antiviral therapy
• Investigate for underlying immunodeficiency if not previously known
• Isolation precautions for disseminated disease
• Screen for visceral involvement if systemic symptoms

Pregnancy

Maternal and Fetal Considerations

• Herpes zoster in pregnancy uncommon due to young maternal age
• No evidence of fetal harm from maternal zoster (unlike varicella)
• Congenital varicella syndrome NOT associated with herpes zoster
• Aciclovir considered safe in pregnancy (category B)

Children [12]

Epidemiology

• Rare (less than 1 per 1,000 children)
• Risk factors: intrauterine VZV exposure, varicella in first year of life

Presentation

• Generally milder course than adults
• Lower PHN risk
• Good visual prognosis if ophthalmic involvement

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Clinical Examination

Skin Examination

Distribution Assessment

• Unilaterality: Confirm rash does not cross midline
• Dermatomal pattern: Identify specific dermatome(s) involved
• Contiguous involvement: Note if multiple adjacent dermatomes affected

Rash Morphology

• Primary lesions: Vesicles on erythematous base at different stages (polymorphic)
• Size and grouping: 2-5mm vesicles in clusters
• Lesion stages: Identify predominant stage (vesicular, pustular, crusting)
• Distribution density: Scattered vs. confluent
• Evidence of complications:
  • Hemorrhagic vesicles (may indicate severe inflammation)
  • Necrotic lesions (immunocompromise, bacterial superinfection)
  • Satellite lesions beyond main dermatome

Hutchinson's Sign Assessment [9]

• Examine nasal tip carefully for vesicles
• If present → urgent ophthalmology referral

Dissemination Assessment [10]

• Count lesions outside primary dermatome

• 20 lesions = disseminated zoster

Neurological Examination

Sensory Testing

• Light touch: Reduced sensation or allodynia in affected dermatome
• Pain sensation: Hyperalgesia common
• Temperature sensation: May be altered
• Corneal sensation (if V1 involvement): Use cotton wisp; reduced or absent sensation predicts complications [9,19]

Motor Examination

• Assess relevant myotomes if motor symptoms reported
• Facial nerve assessment if trigeminal or ear involvement:
  • Forehead wrinkling, eye closure, smile symmetry
  • House-Brackmann grading for Ramsay Hunt syndrome [8]

Cranial Nerve Examination (if cranial involvement)

• CN V: Sensation in all three divisions, corneal reflex, jaw movements
• CN VII: Facial movements, taste (anterior 2/3 tongue), hyperacusis
• CN VIII: Hearing (Rinne/Weber), nystagmus, balance
• CN IX/X: Palatal movement, gag reflex, phonation

Reflexes and Tone

• Generally normal unless motor zoster
• Assess if suspected motor involvement

Ophthalmic Examination (V1 Involvement) [9,19]

Essential Assessments

• Visual acuity: Baseline and monitor
• Pupillary reactions: Check for relative afferent pupillary defect (RAPD)
• Conjunctival examination: Injection, chemosis, vesicles
• Corneal examination: Epithelial defects (fluorescein staining), edema, infiltrates
• Anterior chamber: Cells/flare (uveitis), keratic precipitates, hypopyon
• Intraocular pressure: Elevated in 40-50% of HZO cases [19]
• Fundoscopy: Vitritis, retinitis, optic nerve involvement (perform or refer for dilated exam)

Red Flags Requiring Immediate Ophthalmology [9,19]

• Decreased visual acuity
• Eye pain
• Photophobia
• Corneal epithelial defect
• Anterior chamber inflammation
• Elevated intraocular pressure
• Posterior segment signs

Otologic Examination (Suspected Ramsay Hunt) [8,20]

Inspection

• Pinna: Vesicles on concha, tragus, antihelix
• External auditory canal: Vesicles; may require otoscopy
• Tympanic membrane: Usually normal; may see erythema

Hearing Assessment

• Whisper test: Gross hearing screen
• Tuning forks (Rinne and Weber): Sensorineural hearing loss pattern if CN VIII involved
• Formal audiometry if hearing loss suspected

Vestibular Assessment (if vertigo present)

• Nystagmus evaluation
• Gait assessment
• Consider formal vestibular testing

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Investigations

Clinical Diagnosis

Gold Standard: Clinical diagnosis based on characteristic presentation [1,16]

• Dermatomal vesicular rash
• Unilateral distribution
• Typical evolution (macules → vesicles → pustules → crusts)
• Appropriate epidemiological context (age, immunosuppression)

Laboratory confirmation NOT routinely required for typical presentations

Laboratory Confirmation (When Indicated)

Indications for Laboratory Testing

• Atypical presentation (e.g., zoster sine herpete)
• Immunocompromised patient (guide treatment duration, assess for dissemination)
• Diagnostic uncertainty (differentiating from HSV, other vesicular eruptions)
• Medicolegal documentation
• CNS involvement suspected
• Research purposes

Direct Viral Detection

Preferred Approach: VZV PCR from vesicle fluid or unroofed vesicle base (highest yield in vesicular stage)

Serological Testing

Limited Role in Acute Diagnosis

• IgM anti-VZV: May be positive in reactivation but unreliable; false negatives common
• IgG anti-VZV: Demonstrates prior VZV exposure but doesn't confirm acute zoster
• Paired acute/convalescent titers: 4-fold rise may support diagnosis retrospectively; impractical

Clinical Use

• Assessing VZV immunity status (pre-vaccination, immunocompromised patients)
• Not recommended for acute herpes zoster diagnosis

Imaging

Not Routinely Indicated

Specific Indications

MRI Brain with Contrast [5]

• Suspected VZV vasculopathy (stroke in setting of recent or concurrent zoster)
• CNS complications (encephalitis, myelitis, cerebellitis)
• Findings: Arterial narrowing, enhancement, infarcts

CT Head (Non-Contrast)

• Acute stroke presentation
• Altered mental status

MRI Spine

• Suspected myelitis
• Cauda equina syndrome (sacral zoster)

Chest X-Ray

• Suspected VZV pneumonitis (disseminated zoster with respiratory symptoms)
• Immunocompromised patient with dyspnea

Specialized Testing

Lumbar Puncture (CSF Analysis)

Indications [5]

• Suspected VZV meningitis/encephalitis
• Zoster sine herpete with CNS symptoms
• Suspected VZV vasculopathy

CSF Findings

• VZV PCR: Confirmatory test for CNS VZV infection
• Cell count: Lymphocytic pleocytosis (10-1000 cells/μL)
• Protein: Mildly elevated
• Glucose: Typically normal
• VZV IgG/IgM: Anti-VZV antibody production in CSF

Ophthalmology Investigations (V1 Involvement) [9,19]

Slit-Lamp Biomicroscopy

• Detailed corneal examination
• Anterior chamber assessment
• Grading of uveitis

Corneal Sensitivity Testing

• Cotton wisp test
• Cochet-Bonnet aesthesiometry (quantitative)

Intraocular Pressure Measurement

• Goldmann applanation tonometry
• Non-contact tonometry

Fundoscopy (Dilated)

• Rule out posterior segment involvement
• Assess optic nerve

Optical Coherence Tomography (OCT)

• Corneal thickness and structure
• Retinal imaging if posterior involvement

In Vivo Confocal Microscopy (specialized centers)

• Assess corneal nerve changes
• Bilateral corneal nerve plexus alteration documented even in acute unilateral HZO without apparent keratitis [21]

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Differential Diagnosis

Vesiculobullous Eruptions

Dermatomal Pain Syndromes (Prodromal or Zoster Sine Herpete)

Site-Specific Differentials

Ophthalmic Presentations [9]

• Bacterial/viral conjunctivitis: Bilateral, no vesicles, discharge
• Anterior uveitis (other causes): Systemic disease associations; bilateral often
• Acute angle-closure glaucoma: Severe eye pain, fixed mid-dilated pupil, corneal edema, very high IOP

Ramsay Hunt Syndrome [8,20]

• Bell's palsy: Peripheral facial palsy WITHOUT vesicles or ear pain; may have hyperacusis; better prognosis than Ramsay Hunt
• Acute otitis media: Ear pain and erythema; TM bulging/erythema; no facial palsy; younger age typically
• Cerebellopontine angle tumor: Gradual facial weakness; CN VIII involvement; imaging shows mass
• Lyme disease (facial palsy): Bilateral in 30%; history of tick exposure/erythema migrans; positive Lyme serology

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Classification & Staging

By Anatomical Distribution

By Clinical Presentation

Localized Herpes Zoster

• Single or adjacent dermatomes
• Unilateral
• No systemic complications
• Most common presentation (~95% immunocompetent patients)

Disseminated Herpes Zoster [10]

• Definition: > 20 vesicles outside primary dermatome
• Mechanism: Viremia from inadequate immune control
• Population: Almost exclusively immunocompromised
• Risk: Visceral dissemination (pneumonitis, hepatitis, encephalitis)
• Management: IV antivirals, isolation, investigate for immunodeficiency

Complicated Herpes Zoster

Ophthalmic Zoster [9,19]

• V1 involvement
• Ocular complications in ~50% of cases
• Vision-threatening

Ramsay Hunt Syndrome [8,20]

• Geniculate ganglion involvement
• Facial palsy + ear vesicles + otalgia
• Hearing loss, vertigo possible

Motor Zoster

• Segmental paresis
• 1-5% of herpes zoster cases
• Variable recovery

CNS Complications [5]

• Meningoencephalitis
• Myelitis
• Cerebellitis
• Vasculopathy (stroke)

Disseminated with Visceral Involvement

• Pneumonitis
• Hepatitis
• CNS infection

Zoster Sine Herpete

• Dermatomal pain WITHOUT rash
• Confirmed by VZV PCR (CSF) or serological evidence
• Up to 30% of Ramsay Hunt cases [8]
• Challenging diagnosis; requires high index of suspicion

By Severity (Proposed Staging for PHN Risk)

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Management

Goals of Treatment

1. Reduce acute pain severity and duration
2. Accelerate rash healing
3. Prevent or reduce complications (especially PHN)
4. Prevent viral transmission
5. Minimize functional impairment

Antiviral Therapy

Indications for Antiviral Treatment [6]

Standard Indications (Oral Antivirals)

• All patients presenting within 72 hours of rash onset
• Consider beyond 72 hours if:
  • New lesions still forming
  • Immunocompromised host
  • Ophthalmic, facial, or genital involvement
  • Moderate-severe pain
  • Age > 50 years

Absolute Indications (Often IV Antivirals)

• Ophthalmic zoster (V1 involvement)
• Disseminated zoster
• Severe immunocompromise
• CNS complications (meningoencephalitis, myelitis)
• Visceral involvement
• Ramsay Hunt syndrome (IV or high-dose oral)

First-Line Oral Antivirals [6]

Efficacy

• All three agents are nucleoside analogues with comparable clinical efficacy [6]
• Benefits (when started within 72 hours):
  • Reduces duration of viral shedding
  • Accelerates rash healing (by ~1-2 days)
  • Reduces acute pain severity and duration
  • May reduce PHN incidence (evidence modest)
  • Greatest benefit in patients > 50 years

Pharmacokinetics

• Valaciclovir: Prodrug of aciclovir; 54% bioavailability (vs. 15-20% for aciclovir)
• Famciclovir: Prodrug of penciclovir; 77% bioavailability
• Aciclovir: Requires intracellular phosphorylation by viral thymidine kinase; selectively active in infected cells

Intravenous Antivirals

Aciclovir IV: 10mg/kg every 8 hours (or 5-10mg/kg TDS based on renal function) [6]

Indications

• Ophthalmic zoster (especially severe or immunocompromised)
• Disseminated zoster
• Severe immunosuppression (HIV with CD4 less than 200, transplant recipients, hematological malignancy)
• CNS involvement (meningoencephalitis, myelitis)
• Visceral dissemination (pneumonitis, hepatitis)
• Ramsay Hunt syndrome (some centers; alternatively high-dose oral)
• Inability to tolerate oral medications

Duration

• Typically 7-10 days IV
• May transition to oral once clinical improvement and patient able to tolerate PO
• Immunocompromised: often longer courses (10-14 days total)

Adverse Effects

• Nephrotoxicity: Ensure adequate hydration; dose adjust for renal impairment
• Neurotoxicity: Encephalopathy, tremor (especially elderly, renal impairment)
• Local: Phlebitis at infusion site

Dose Adjustments for Renal Impairment

All antivirals require dose reduction in renal insufficiency.

Valaciclovir Dose Adjustment

Aciclovir IV Dose Adjustment: Consult renal dosing guidelines; typically extend interval or reduce dose

Analgesia

Pain management is essential for acute herpes zoster and prevention of chronic pain. [17]

Acute Pain (During Rash Phase)

Mild-Moderate Pain

1. Paracetamol: 1g four times daily (maximum 4g/24h)
2. NSAIDs: Ibuprofen 400-600mg TDS-QDS or naproxen 500mg BD
   • Caution: Elderly, renal impairment, cardiovascular disease, GI bleeding risk

Moderate-Severe Pain

• Opioids: Consider for severe acute pain
  • Codeine 30-60mg QDS, tramadol 50-100mg QDS, or stronger opioids if needed
  • Short-term use; avoid prolonged opioids due to PHN chronicity risk

Neuropathic Pain (If Prominent) Even during acute phase, neuropathic agents may be beneficial: [17]

• Gabapentin: Start 300mg nocte, increase to 300mg TDS over 3-5 days, then escalate (max 3600mg/day in divided doses)
• Pregabalin: Start 75mg BD, increase to 150mg BD after 3-7 days (max 300mg BD)
• Tricyclic antidepressants (TCAs): Amitriptyline 10-25mg nocte, increase gradually (max 75-100mg)
  • "Caution: Elderly (falls, confusion, urinary retention, cardiac effects)"

Topical Agents

• Capsaicin cream: Limited use in acute phase (may increase pain initially)
• Lidocaine patches/gel: May provide localized pain relief
• Calamine lotion: Soothing; mild antipruritic

Postherpetic Neuralgia (PHN) Pain Management

See Complications section for detailed PHN management.

Corticosteroids

Role in Acute Herpes Zoster

Evidence: Controversial; randomized controlled trials show modest benefits in acute pain reduction but NO clear benefit in preventing PHN. [6]

Potential Use

• Adjunct to antivirals in select cases:
  • Severe acute pain
  • Ramsay Hunt syndrome (combined with antivirals) [20]
  • Ophthalmic zoster with significant inflammation (under ophthalmology guidance) [9]

Typical Regimen (if used)

• Prednisolone 60mg PO daily for 7 days, then taper over 7-14 days
• Must always combine with antivirals (never steroids alone)

Contraindications

• Immunocompromise (relative contraindication)
• Disseminated zoster
• Diabetes mellitus (relative; monitor glucose closely)
• Active infection, peptic ulcer disease

Current Recommendations [6]

• Routine use NOT recommended
• Consider in select cases after risk-benefit assessment
• Always combine with antivirals

Ophthalmic Zoster Management [9,19]

Emergency Management

All V1 Involvement = URGENT Ophthalmology Referral (Same Day)

Initial Measures

1. Systemic antivirals:

   • Oral: Valaciclovir 1g TDS or aciclovir 800mg 5x/day for 7-10 days
   • IV aciclovir 10mg/kg TDS if:
     • Severe presentation
     • Immunocompromised
     • Posterior segment involvement
     • Delayed presentation with active disease

2. Ophthalmology assessment (arrange urgently):

   • Slit-lamp examination
   • IOP measurement
   • Corneal sensation testing
   • Dilated fundoscopy

Specific Ophthalmic Treatments (Under Ophthalmology Guidance) [9,19]

Topical Antivirals

• Limited role (poor corneal penetration)
• May use aciclovir 3% ointment five times daily if epithelial keratitis

Topical Corticosteroids

• Indications: Stromal keratitis, anterior uveitis, scleritis
• Contraindication: Active epithelial keratitis (risk of corneal perforation)
• Regimen: Prednisolone acetate 1% or dexamethasone 0.1% (frequency based on severity)
• Monitoring: IOP (risk of steroid-induced glaucoma)

Cycloplegics

• For anterior uveitis: Cyclopentolate 1% BD-TDS or atropine 1% BD
• Reduces ciliary spasm pain, prevents posterior synechiae

IOP-Lowering Agents

• If elevated IOP: Timolol 0.5%, dorzolamide, brimonidine, prostaglandin analogues
• May require systemic acetazolamide if severe

Neurotrophic Keratopathy Management

• Preservative-free lubricants
• Autologous serum eye drops
• Punctal plugs
• Tarsorrhaphy (severe cases)
• Amniotic membrane transplantation
• Corneal neurotization (specialized centers)

Long-Term Follow-Up

• Ophthalmic zoster complications may develop weeks to months after initial presentation
• Regular ophthalmology review recommended for 6-12 months

Ramsay Hunt Syndrome Management [8,20]

Antiviral Therapy

• Preferred: IV aciclovir 10mg/kg TDS for 7 days, then switch to oral if improving
• Alternative: High-dose oral valaciclovir 1g TDS for 7-10 days
• Early treatment critical (within 72 hours for best facial nerve recovery)

Corticosteroids

• Prednisolone 60mg PO daily for 7 days, taper over 7 days
• Evidence limited but commonly used (extrapolated from Bell's palsy)
• Always combine with antivirals [20]

Supportive Care

• Eye care (if incomplete eye closure):
  • Lubricating eye drops (hourly during day)
  • Lacrilube ointment at night
  • Eye patch or moisture chamber
  • Ophthalmology review if exposure keratopathy develops
• Facial physiotherapy: May reduce synkinesis risk; start after acute phase
• Psychological support: Facial palsy has significant psychosocial impact

Specialist Referrals

• ENT: Audiology, vestibular testing
• Ophthalmology: If eye complications
• Neurology: If multiple cranial nerve involvement or severe disease
• Physiotherapy: Facial rehabilitation

Immunocompromised Patients [10]

Treatment Modifications

Antivirals

• Lower threshold for IV therapy
• Extended duration: Often 10-14 days (until lesions fully crusted and no new lesions for 48-72 hours)
• Disseminated zoster: IV aciclovir 10mg/kg TDS for 10-14 days

Monitoring

• Close follow-up: Risk of prolonged viral shedding, delayed healing, complications
• Screen for visceral involvement if systemic symptoms (CXR, LFTs, CNS examination)
• Isolation precautions: Airborne + contact isolation for disseminated disease

Specific Populations

Infection Control

Infectivity [1,16]

• Contagious period: From rash onset until ALL lesions are crusted (typically 7-10 days)
• Transmission route: Direct contact with vesicle fluid (contains infectious virus); rarely airborne (disseminated zoster only)
• Risk: Can cause varicella in susceptible individuals (NOT herpes zoster)

Isolation Precautions

Immunocompetent with Localized Zoster

• No isolation required if rash can be covered
• Avoid contact with:
  • Pregnant women (non-immune)
  • Neonates
  • Immunocompromised individuals
  • Anyone without varicella immunity
• Cover rash with clothing or non-adherent dressing

Disseminated Zoster or Immunocompromised Host [10]

• Airborne + contact precautions
• Negative pressure room (if available)
• N95 respirator for healthcare workers
• Isolation until all lesions crusted

Healthcare Workers

• Ensure varicella immunity (history of chickenpox, documentation of 2 varicella vaccinations, or positive VZV IgG)
• Post-exposure prophylaxis considerations for susceptible individuals

Patient Education

During Acute Illness

• Pain expected: Usually improves as rash heals over 2-3 weeks
• Avoid scratching: Reduces bacterial superinfection and scarring risk
• Gentle cleansing: Soap and water; pat dry
• Loose clothing: Reduce irritation
• Analgesics: Take regularly, not just as needed
• Antiviral compliance: Complete full 7-day course even if improving

Preventing Transmission

• Cover rash
• Avoid contact with at-risk individuals (see above) until crusted
• Hand hygiene after touching rash
• Cannot give someone shingles: Can only cause chickenpox in susceptible individuals

Warning Signs (Return Immediately)

• Eye involvement (pain, redness, vision changes)
• Spreading rash beyond original area
• Severe headache, confusion, neck stiffness
• Weakness or difficulty moving limbs
• Inability to urinate (sacral zoster)
• Severe uncontrolled pain

Post-Healing

• PHN possibility: Pain may persist beyond rash healing; report if lasts > 4 weeks
• Skin changes: Pigmentation changes and scars may take months to fade
• Recurrence: Zoster can recur (5-10% lifetime recurrence rate); consider vaccination

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Complications

Postherpetic Neuralgia (PHN)

Definition

Dermatomal pain persisting or appearing ≥90 days after herpes zoster rash onset. [4,17]

Alternative definitions exist:

• ≥30 days (some studies)
• ≥120 days (more conservative)
• 90-day definition most commonly used in clinical practice and research [4]

Epidemiology

Incidence [4,18]

• Overall: 5-10% of herpes zoster patients
• Age-stratified:
  • less than 50 years: less than 5%
  • 50-59 years: 5-8%
  • 60-69 years: 10-15%
  • 70-79 years: 20-25%
  • ≥80 years: 30-40%

Risk Factors [4,18]

1. Advanced age (strongest predictor):
   • 10-year age increase: OR 1.70 (95% CI 1.63-1.78)
   • Age ≥60 years: 27-fold higher risk vs. less than 50 years at 60 days post-onset
2. Severe acute pain during rash phase
3. Severe rash (extensive, confluent lesions)
4. Prodromal pain before rash
5. Greater rash severity
6. Female sex: OR 1.19 (95% CI 1.10-1.27) [4]
7. Ophthalmic involvement
8. Immunosuppression: Leukemia OR 2.07, lymphoma OR 2.45 [4]
9. Comorbidities: Diabetes mellitus, COPD, hypertension, chronic kidney disease, malignancy [4,18]
10. Smoking and alcohol abuse [18]
11. High VZV viral load [18]
12. Delayed antiviral treatment (> 72 hours or none) [18]

Pathophysiology [17]

Mechanisms

1. Peripheral nerve damage: VZV-induced ganglionitis and axonal degeneration → loss of large myelinated Aβ fibers → disinhibition of pain pathways
2. Ectopic discharges: Damaged neurons generate spontaneous activity
3. Central sensitization: Dorsal horn hyperexcitability and aberrant pain processing
4. Neuroinflammation: Persistent low-grade inflammation in affected ganglia
5. Nerve fiber loss: Permanent reduction in epidermal nerve fiber density

Pain Characteristics

• Constant deep aching or burning pain (most common)
• Intermittent lancinating/shooting pain
• Allodynia: Pain from non-painful stimuli (light touch, clothing)
• Hyperalgesia: Exaggerated pain response to painful stimuli
• Pain typically within original zoster dermatome

Clinical Presentation

Symptoms

• Persistent or intermittent dermatomal pain (character as above)
• Sensory changes: Hypoesthesia, dysesthesia, paresthesias
• Psychological impact: Depression, anxiety, sleep disturbance, reduced quality of life

Physical Examination

• Dermatome: Corresponds to original herpes zoster distribution
• Skin changes: Post-inflammatory hyperpigmentation or hypopigmentation, scarring
• Sensory abnormalities: Reduced light touch, pinprick sensation; allodynia

Management [17]

First-Line Pharmacological Treatments

Second-Line Agents

• SNRIs: Duloxetine 60mg daily, venlafaxine 75-225mg daily
• Tramadol: 50-100mg TDS-QDS (opioid + SNRI effects)
• Stronger opioids: Oxycodone, morphine (reserve for severe refractory cases; risk of dependence, tolerance, adverse effects)

Combination Therapy Often required; combine agents with different mechanisms:

• Gabapentin or pregabalin + TCA
• Gabapentin or pregabalin + topical lidocaine
• TCA + topical capsaicin

Non-Pharmacological Interventions

• Psychological support: Cognitive-behavioral therapy (CBT), mindfulness
• Physical therapy: Transcutaneous electrical nerve stimulation (TENS), desensitization techniques
• Interventional pain management (refractory cases):
  • Nerve blocks (paravertebral, epidural)
  • Spinal cord stimulation
  • Intrathecal drug delivery

Treatment Duration

• PHN may persist for months to years (median duration 6-12 months if untreated)
• Continue effective treatment for at least 6-12 months; attempt slow taper
• Some patients require long-term therapy

Prevention

Antiviral Therapy

• Early antiviral treatment (within 72 hours) modestly reduces PHN risk [6]
• Magnitude of benefit unclear; some studies show reduction, others minimal effect

Vaccination

• Recombinant zoster vaccine (Shingrix): Reduces PHN incidence by > 90% in vaccinated individuals who still develop zoster (rare) [7]

Ophthalmic Complications [9,19]

Occur in approximately 50% of patients with herpes zoster ophthalmicus (V1 involvement).

Anterior Segment Complications

Keratitis (Most Common Ocular Complication) [9,19]

• Incidence: Up to 65% of HZO patients
• Types:
  1. Epithelial keratitis: Dendritic or geographic ulcers (VZV vs. HSV: VZV dendrites typically larger, fewer branches, "tapered ends")
  2. Stromal keratitis: Immune-mediated; may develop weeks after rash; responds to topical corticosteroids
  3. Disciform keratitis: Disc-shaped stromal edema
  4. Neurotrophic keratopathy: Loss of corneal sensation → persistent epithelial defects → scarring, thinning, perforation (most serious)

Anterior Uveitis [9,19]

• Incidence: 30-40% of HZO
• Features: Often granulomatous; cells/flare in anterior chamber, keratic precipitates
• Complications:
  • Secondary glaucoma (IOP elevation in 40-50% of HZO) [19]
  • Posterior synechiae
  • Cataract formation

Episcleritis/Scleritis [9,19]

• Incidence: 10-15%
• Presentation: Sectoral or diffuse injection, pain
• Scleritis: More serious; risk of scleral thinning, perforation

Conjunctivitis [9,19]

• Nearly universal in HZO
• Hyperemia, chemosis, vesicular lesions on conjunctiva

Posterior Segment Complications (Rare but Serious) [9,19]

Acute Retinal Necrosis (ARN)

• Presentation: Decreased vision, floaters, peripheral retinal whitening, vitritis, retinal vasculitis
• Course: Rapidly progressive; high risk of retinal detachment (up to 75%)
• Treatment: IV aciclovir + intravitreal antivirals + oral corticosteroids (after antiviral coverage); often requires vitreoretinal surgery

Progressive Outer Retinal Necrosis (PORN)

• Population: Severely immunocompromised (AIDS with CD4 less than 50)
• Presentation: Rapidly progressive outer retinal necrosis, minimal vitritis
• Prognosis: Poor; high risk bilateral involvement and vision loss despite treatment

Optic Neuritis

• Unilateral vision loss, RAPD, disc swelling or pallor
• May be ischemic or inflammatory
• Variable recovery

Neurotrophic Keratopathy (Major Long-Term Complication) [9,19,21]

Pathogenesis

• Loss of corneal sensation (trigeminal nerve damage)
• Impaired corneal epithelial healing, reduced blinking, decreased tear production
• Progressive epithelial breakdown → stromal thinning → perforation risk

Management

• Preservative-free lubricants: Intensive (hourly or more)
• Autologous serum tears (20-50%)
• Bandage contact lens
• Tarsorrhaphy (partial or complete)
• Amniotic membrane transplantation
• Corneal neurotization (emerging technique; transfer of nerve supply)

Recent Evidence [21]

• Bilateral corneal nerve plexus changes detected by in vivo confocal microscopy in acute unilateral HZO even without apparent keratitis
• Hutchinson's sign and reduced corneal sensation associated with more extensive nerve damage
• Bilateral preservative-free artificial tears may help reduce neurotrophic keratopathy risk

Predictors of Poor Visual Outcome [9,19]

• Hutchinson's sign positive: OR for visual loss significant
• Anterior uveitis: Best predictor on multivariate analysis
• Absent corneal sensation
• Corneal epithelial lesions
• Advanced age

Ramsay Hunt Syndrome (Herpes Zoster Oticus) [8,20]

Epidemiology

• Incidence: less than 1% of herpes zoster cases
• Facial nerve palsy etiology: ~10-15% of peripheral facial palsies

Clinical Features (see Clinical Presentation section)

• Classic triad: Facial palsy + ear vesicles + otalgia
• Cranial nerve VIII involvement: Hearing loss, tinnitus, vertigo (50-60% of cases)
• Zoster sine herpete variant: Up to 30% lack rash [8]

Prognosis [20]

• Complete facial nerve recovery: ~50-70% (WORSE than Bell's palsy which is ~85%)
• Partial recovery: 20-30%
• Poor recovery: 10-15%
• Hearing recovery: Variable (~50% improve)

Prognostic Factors

• Early antiviral treatment (less than 72 hours): Improves outcomes
• Severity of initial palsy: House-Brackmann grade V-VI worse prognosis
• Age: Older age worse recovery
• Presence of vertigo: May indicate worse prognosis

Management

See Management section (Ramsay Hunt subsection)

Neurological Complications

VZV Vasculopathy [5]

Epidemiology

• Increased stroke risk in weeks to months following herpes zoster
• Can occur without preceding rash (zoster sine herpete)

Pathogenesis

• VZV infection of cerebral arteries (large and small vessels)
• Transmural inflammation → intimal proliferation → stenosis/occlusion → ischemia or hemorrhage

Clinical Presentations

• Ischemic stroke: Large or small vessel; TIA
• Hemorrhagic stroke: Intracerebral or subarachnoid hemorrhage
• Multifocal involvement: Arterial distribution
• Chronic meningoencephalitis: Subacute cognitive decline, headache

Diagnosis

• MRI brain: Infarcts (multiple territories common)
• MR/CT angiography: Arterial narrowing, irregularities
• CSF: VZV PCR positive; anti-VZV IgG antibody production (CSF:serum ratio)
• Brain biopsy (rarely needed): VZV antigen in arterial walls

Treatment

• IV aciclovir 10-15mg/kg TDS for 14 days (or longer)
• Corticosteroids: Often added (evidence limited)
• Supportive stroke care
• Antiplatelet therapy: Standard stroke prevention

Meningoencephalitis [5]

Presentation

• Fever, headache, altered mental status, seizures, focal neurological signs
• May occur with or without concurrent dermatomal rash

Diagnosis

• CSF: Lymphocytic pleocytosis, elevated protein, VZV PCR positive
• MRI brain: Variable (temporal lobe involvement, multifocal lesions, or normal)

Treatment

• IV aciclovir 10-15mg/kg TDS for 14-21 days
• Supportive care: Seizure management, ICP monitoring if indicated

Myelitis

Presentation

• Acute/subacute paraparesis or quadriparesis, sensory level, sphincter dysfunction
• May follow zoster rash by days to weeks; rarely without rash

Diagnosis

• MRI spine: T2 hyperintensity, enhancement of affected cord segments
• CSF: VZV PCR, pleocytosis

Treatment

• IV aciclovir + corticosteroids
• Rehabilitation

Cranial/Peripheral Neuropathies

Motor Zoster (discussed earlier)

• Segmental paresis affecting myotome corresponding to dermatome
• Variable recovery

Multiple Cranial Neuropathies

• Ramsay Hunt may involve CN V, VIII, IX, X, XI, XII
• Other combinations described

Other Complications

Cutaneous Superinfection

Bacterial Superinfection

• Organisms: Staphylococcus aureus, Group A Streptococcus
• Presentation: Increased erythema, purulent discharge, spreading cellulitis, fever
• Management: Topical or systemic antibiotics depending on severity

Scarring

• More likely with secondary infection, scratching, immunocompromise
• Post-inflammatory pigmentation changes common (may take months to resolve)

Visceral Dissemination (Immunocompromised) [10]

VZV Pneumonitis

• Dyspnea, hypoxia, diffuse interstitial infiltrates on CXR
• High mortality if untreated
• Treatment: IV aciclovir + supportive care (oxygen, ventilation if needed)

VZV Hepatitis

• Elevated transaminases, hepatomegaly, jaundice (rare)
• Typically in context of disseminated zoster

VZV Meningoencephalitis

• See above

Zoster Recurrence

Epidemiology

• Lifetime recurrence risk: ~5-10%
• Higher in immunocompromised individuals
• Recurrence may affect same or different dermatome

Management

• Same as initial episode
• Consider antiviral prophylaxis if frequent recurrences (immunocompromised)

---

Prognosis & Outcomes

Natural History

Immunocompetent Adults [1,3,16]

Acute Rash

• New vesicle formation: Ceases by day 3-7
• Crusting: Complete by 2-3 weeks in most cases
• Healing: Typically within 3-4 weeks

Pain Resolution

• Acute pain: Peaks during vesicular/pustular stage (days 3-7)
• Pain resolution: Gradual over 2-4 weeks in majority
• Persistent pain > 90 days (PHN): 5-10% overall (age-dependent; see PHN section)

Complete Recovery

• ~70-80% of immunocompetent adults have complete resolution without long-term sequelae
• Residual skin changes (hyperpigmentation/scarring) common but usually fade over months

Immunocompromised Patients [10]

Prolonged Course

• New lesions may continue for > 1 week
• Crusting delayed (> 3 weeks)
• Higher complication rates

Complications

• Dissemination: 10-40% (depending on degree of immunosuppression)
• Visceral involvement: Rare but serious
• Mortality: less than 1% overall but higher in severe immunosuppression with visceral dissemination

Postherpetic Neuralgia Outcomes [4,17]

Duration

• Median duration (if untreated): 6-12 months
• Resolution:
  • 50% resolve within 1 year
  • 25% persist > 1 year
  • 10-15% persist > 2 years
  • Small proportion have pain lasting many years

Impact on Quality of Life

• Significant functional impairment
• Depression and anxiety common
• Sleep disturbance
• Social isolation
• Reduced employment/productivity (in working-age individuals)

Ophthalmic Zoster Outcomes [9,19]

Visual Outcomes (with appropriate treatment)

• Good outcome (6/6-6/12 vision): ~60-70%
• Mild visual loss (6/18-6/36): ~20-25%
• Moderate-severe visual loss (less than 6/36): ~5-10%

Predictors of Visual Loss

• Severe anterior uveitis (strongest predictor)
• Hutchinson's sign
• Absent corneal sensation
• Delayed treatment
• Advanced age

Long-Term Complications

• Chronic dry eye
• Neurotrophic keratopathy (may develop months to years later)
• Glaucoma
• Cataract
• Recurrent inflammation

Ramsay Hunt Syndrome Outcomes [20]

Facial Nerve Recovery (see Complications section)

• Complete: ~50-70%
• Partial: 20-30%
• Poor: 10-15%

Hearing Recovery

• Improvement in ~50%
• Complete recovery less common

Factors Improving Prognosis

• Early antiviral + corticosteroid treatment (less than 72 hours)
• Less severe initial palsy
• Younger age

Mortality

Overall Mortality

• Herpes zoster itself rarely fatal in immunocompetent hosts
• Deaths typically from complications (rare)

Causes of Death (Rare)

• VZV encephalitis/meningoencephalitis
• VZV pneumonitis (disseminated zoster)
• VZV hepatitis (disseminated zoster)
• Secondary bacterial sepsis
• Stroke (VZV vasculopathy)

Immunocompromised Patients

• Mortality higher if disseminated with visceral involvement
• Overall mortality in severely immunocompromised with disseminated zoster: 5-15% (historical data; lower with modern antiviral therapy)

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Prevention

Recombinant Zoster Vaccine (RZV, Shingrix) [7]

Composition

• Antigen: Recombinant VZV glycoprotein E (gE)
• Adjuvant: AS01B (enhances immune response)
• Type: Non-live recombinant subunit vaccine

Indications [7]

Recommended Populations

1. Adults ≥50 years (immunocompetent)
2. Adults ≥18 years who are or will be immunocompromised due to:
   • Disease (HIV, malignancy)
   • Therapy (immunosuppressive medications, chemotherapy, transplant)

Advantages Over Live Zoster Vaccine (Zostavax)

• Higher efficacy (> 90% vs. ~50-70%)
• Sustained efficacy in older adults (remains > 90% even in ≥70 years)
• Safe in immunocompromised (non-live vaccine)
• Longer duration of protection (at least 7+ years; ongoing studies)

Dosing Schedule [7]

• Two-dose series: 0 and 2-6 months
• Route: Intramuscular (deltoid)
• Interchangeability: RZV can be given regardless of prior live zoster vaccine (Zostavax); wait at least 12 months after Zostavax before RZV

Efficacy [7]

Prevention of Herpes Zoster

• Overall efficacy (≥50 years): 97.2% (95% CI 93.7-99.0)
• Age 50-59 years: 96.6%
• Age 60-69 years: 97.4%
• Age ≥70 years: 91.3%

Prevention of PHN

• Overall reduction in PHN: > 90%
• Among the small number who develop zoster despite vaccination, PHN risk also reduced

Immunocompromised Populations [7]

• Efficacy: 68-91% depending on underlying condition
• Safety: Acceptable safety profile in immunocompromised adults
• Studied in: HIV, hematological malignancy, solid tumors (chemotherapy), solid organ transplant, renal disease, autoimmune diseases

Adverse Effects [7]

Local Reactions (Very Common)

• Pain at injection site (> 75%)
• Redness, swelling
• Usually mild-moderate, resolve within 2-3 days

Systemic Reactions (Common)

• Myalgia (40-50%)
• Fatigue (40-45%)
• Headache (30-40%)
• Fever (15-20%)
• Gastrointestinal symptoms (10-15%)

Management

• Paracetamol or NSAIDs for symptom relief
• Symptoms typically resolve within 2-3 days
• Second dose may have similar or slightly less reactogenicity

Contraindications

• Severe allergic reaction to previous RZV dose or any component
• Moderate-severe acute illness (defer vaccination)
• Pregnancy (theoretical risk; defer until after pregnancy)

Timing Considerations

Immunocompromised Patients

• Ideally vaccinate BEFORE immunosuppression begins (if possible)
• If already immunosuppressed, vaccinate when immunosuppression lowest or stable
• Hematopoietic stem cell transplant: Vaccinate ≥12 months post-transplant
• Chemotherapy: Between cycles or after completion

Recent Herpes Zoster

• Can vaccinate after herpes zoster episode
• No specific waiting period required; some recommend waiting until acute episode resolved
• Reduces risk of recurrence

Cost-Effectiveness

• Highly cost-effective in adults ≥50 years
• Prevents substantial morbidity (PHN, ophthalmic complications)

Live Zoster Vaccine (Zostavax) - Historical

Status: Largely replaced by RZV in most countries; still used in some settings

Efficacy: 51% reduction in herpes zoster (≥60 years); 67% reduction in PHN Contraindications: Immunocompromise (live vaccine) Single-dose regimen

Public Health Measures

Varicella Vaccination (Childhood)

• Universal childhood varicella vaccination reduces varicella burden
• Long-term effect on herpes zoster incidence unclear (ongoing surveillance)
• Theoretical concern: Reduced exogenous boosting may increase zoster; not consistently demonstrated

Healthcare Worker Vaccination

• Ensure immunity to varicella (history, serology, or documentation of 2 varicella vaccine doses)
• Consider RZV for healthcare workers ≥50 years

Post-Exposure Prophylaxis (Preventing Varicella, Not Zoster)

Varicella-Zoster Immune Globulin (VZIG)

• Indication: Non-immune individuals exposed to varicella or herpes zoster who are at high risk for severe disease
  • Pregnant women (non-immune)
  • Neonates (maternal varicella peripartum)
  • Immunocompromised individuals
• Timing: Within 10 days of exposure (ideally within 96 hours)
• Effect: May prevent or attenuate varicella; does NOT prevent herpes zoster

Varicella Vaccination Post-Exposure

• Non-immune immunocompetent individuals: Varicella vaccine within 3-5 days of exposure may prevent or modify varicella

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Evidence & Guidelines

Key Guidelines

1. Werner RN, et al. European consensus-based (S2k) Guideline on the Management of Herpes Zoster. J Eur Acad Dermatol Venereol. 2017;31(1):20-29. PMID: 27709655 [1]

   • European multidisciplinary consensus on herpes zoster management including antivirals, pain management, and special populations

2. Dworkin RH, et al. Recommendations for the management of herpes zoster. Clin Infect Dis. 2007;44(Suppl 1):S1-26. PMID: 17143845 [6]

   • Comprehensive US guidelines on herpes zoster and PHN management; antiviral therapy recommendations

3. Public Health England. Shingles (herpes zoster): the green book, chapter 28a. Updated 2021.

   • UK vaccination policy and recommendations

Key Primary Evidence

4. Forbes HJ, et al. Quantification of risk factors for postherpetic neuralgia in herpes zoster patients: A cohort study. Neurology. 2016;87(1):94-102. PMID: 27287218 [4]

   • Large UK cohort (119,413 zoster patients); quantified PHN risk factors including age, sex, immunosuppression, comorbidities

5. Nagel MA, Gilden D. Neurological complications of varicella zoster virus reactivation. Curr Opin Neurol. 2014;27(3):356-60. [5]

   • VZV vasculopathy and neurological complications pathophysiology and management

6. Cohen JI. Herpes zoster. N Engl J Med. 2013;369(3):255-263. PMID: 23863052 [3]

   • Comprehensive clinical review of herpes zoster epidemiology, pathogenesis, and management

7. Lal H, et al. Efficacy of an adjuvanted herpes zoster subunit vaccine in older adults. N Engl J Med. 2015;372(22):2087-96. [7]

   • Pivotal ZOE-50 trial demonstrating 97.2% efficacy of recombinant zoster vaccine (Shingrix) in adults ≥50 years

8. Crouch AE, et al. Ramsay Hunt Syndrome. StatPearls. 2025 Jan. PMID: 32491341 [8]

   • Comprehensive review of Ramsay Hunt syndrome epidemiology, presentation, management, and outcomes

9. Minor M, et al. Herpes Zoster Ophthalmicus. StatPearls. 2025 Jan. PMID: 32491711 [9]

   • Detailed overview of ophthalmic zoster complications, management, and outcomes

10. Kawai K, et al. Systematic review of incidence and complications of herpes zoster: towards a global perspective. BMJ Open. 2014;4(6):e004833. [10]

    • Global systematic review of herpes zoster epidemiology including immunocompromised populations

Supporting Evidence

11. Arvin AM. Varicella-zoster virus. Clin Microbiol Rev. 1996;9(3):361-81. PMID: 8809466 [1]

    • Classic comprehensive review of VZV virology, pathogenesis, and clinical manifestations

12. Eshleman E, et al. Varicella zoster virus latency. Future Virol. 2011;6(3):341-355. PMID: 21695042 [2]

    • Detailed discussion of VZV latency mechanisms, cellular localization, and gene expression

13. Lee CN, et al. Risk of herpes zoster and postherpetic neuralgia in patients with psoriasis treated with biologics. Br J Dermatol. 2025;193(1):105-114. PMID: 40112174 [13]

    • Large Taiwan cohort demonstrating varying herpes zoster risk across biologic agents

14. Kennedy PGE, Cohrs RJ. Varicella-zoster virus human ganglionic latency: a current summary. J Neurovirol. 2010;16(6):411-8. PMID: 20874010 [14]

    • Summary of VZV latency in human ganglia: cellular localization, viral gene expression, epigenetic regulation

15. Abendroth A, Arvin A. Varicella-zoster virus immune evasion. Immunol Rev. 1999;168:143-56. PMID: 10399071 [15]

    • VZV immune evasion strategies including MHC downregulation

16. Patil A, et al. Herpes zoster: A Review of Clinical Manifestations and Management. Viruses. 2022;14(2):192. PMID: 35215786 [16]

    • Recent comprehensive review of clinical presentations, management, and complications

17. Koshy E, et al. Epidemiology, treatment and prevention of herpes zoster: A comprehensive review. Indian J Dermatol Venereol Leprol. 2018;84(3):251-262. PMID: 29516900 [17]

    • Comprehensive review including PHN pathophysiology and treatment

18. Wang J, et al. Risk factors for postherpetic neuralgia: a meta-analysis. Front Immunol. 2025;16:1667364. PMID: 41103428 [18]

    • Recent meta-analysis confirming age, severe rash, prodromal pain, smoking, diabetes, COPD, and other factors as PHN risk factors

19. Liesegang TJ. Herpes zoster ophthalmicus natural history, risk factors, clinical presentation, and morbidity. Ophthalmology. 2008;115(2 Suppl):S3-12. PMID: 18243930 [19]

    • Detailed review of ophthalmic zoster epidemiology, risk factors, and ocular complications

20. Jeon Y, Lee H. Ramsay Hunt syndrome. J Dent Anesth Pain Med. 2018;18(6):333-337. PMID: 30637343 [20]

    • Clinical review of Ramsay Hunt syndrome pathophysiology, presentation, and treatment

21. Della Franca B, et al. Bilateral In Vivo Confocal Microscopic Changes of the Corneal Subbasal Nerve Plexus in Patients with Acute Herpes Zoster Ophthalmicus. Ophthalmol Ther. 2025;14(5):941-957. PMID: 40085366 [21]

    • Novel evidence of bilateral corneal nerve changes in acute unilateral HZO; implications for neurotrophic keratopathy prevention

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Patient & Family Information

What is Shingles?

Shingles (herpes zoster) is a painful rash caused by the same virus that causes chickenpox. After you recover from chickenpox (usually in childhood), the virus stays dormant ("sleeping") in nerve cells in your body. Years later, the virus can reactivate and travel along a nerve to your skin, causing shingles.

Who Gets Shingles?

• 1 in 3 people will get shingles during their lifetime
• Risk increases with age, especially after age 50
• Anyone who has had chickenpox can get shingles
• People with weakened immune systems are at higher risk

Symptoms

Before the Rash (1-5 days)

• Pain, burning, tingling, or numbness in a specific area on one side of your body
• Feeling unwell, tired, or having a headache

The Rash

• Appears as a band or strip of blisters on one side of your body
• Most common on the chest, back, or around one side of the waist
• Painful, itchy, or sensitive to touch
• Blisters fill with fluid, then crust over and heal (typically 2-4 weeks)

Pain

• Can range from mild to very severe
• Usually improves as the rash heals
• In some people (especially older adults), pain can persist for months or years after the rash has healed (postherpetic neuralgia)

When to Seek Immediate Medical Care

See a doctor within 72 hours of rash appearing for best treatment results.

Seek urgent care if you have:

• Rash or blisters near your eye or on your nose
• Severe pain that is not controlled with over-the-counter painkillers
• Rash spreading beyond the original area
• Weakened immune system (due to illness or medications)
• Severe headache, confusion, or neck stiffness
• Weakness in arms or legs
• Difficulty urinating

Treatment

Antiviral Medications

• Work best if started within 72 hours of rash appearing
• Help the rash heal faster, reduce pain, and may prevent long-term complications
• Take the full course (usually 7 days) even if you feel better

Pain Relief

• Over-the-counter pain relievers (paracetamol, ibuprofen)
• Prescription pain medications if needed
• Creams or patches for skin pain

Rash Care

• Keep the rash clean and dry
• Wear loose-fitting clothing
• Avoid scratching (can lead to infection and scarring)
• Cool compresses may provide relief

Is Shingles Contagious?

• You cannot catch shingles from someone with shingles
• You can catch chickenpox from someone with shingles if you have never had chickenpox or the chickenpox vaccine
• The virus spreads through direct contact with fluid from the blisters
• Avoid contact with pregnant women who haven't had chickenpox, newborns, and people with weakened immune systems until all blisters have crusted over

Prevention: Shingles Vaccine (Shingrix)

Who Should Get Vaccinated?

• Adults aged 50 and older
• Adults aged 18+ with weakened immune systems

Benefits

• Reduces your risk of getting shingles by more than 90%
• If you do get shingles despite vaccination, it is likely to be milder
• Reduces risk of long-term pain after shingles

Dosing

• Two doses, 2-6 months apart
• Given as an injection in the upper arm

Side Effects

• Sore arm, tiredness, muscle aches, headache, fever (usually mild and go away in 2-3 days)

Can You Get the Vaccine if You've Already Had Shingles?

• Yes, you can get vaccinated even if you've had shingles before
• The vaccine reduces the risk of getting shingles again

Long-Term Outlook

• Most people with shingles recover fully within 3-5 weeks
• Postherpetic neuralgia (PHN): Long-term nerve pain affects 10-18% overall, more common in older adults (up to 30% of those over 80)
• Shingles can recur but this is uncommon (5-10% lifetime risk)

Living with Shingles

During the Illness

• Rest as needed
• Manage pain with medications
• Keep the rash covered
• Maintain good hygiene

Emotional Support

• Pain and discomfort can affect mood and sleep
• Talk to your doctor if you feel low or anxious
• Join support groups if needed

Questions to Ask Your Doctor

• Should I start antiviral medication?
• What pain relief options are right for me?
• When should I come back for follow-up?
• Am I at risk for complications?
• Should I get the shingles vaccine after I recover?
• Who should I avoid contact with while I have shingles?

Resources

• NHS Shingles Information: https://www.nhs.uk/conditions/shingles
• CDC Shingles (Herpes Zoster): https://www.cdc.gov/shingles
• Patient.info Shingles: https://patient.info/infections/shingles-herpes-zoster

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Summary for Clinicians

Key Takeaway Points

1. Herpes zoster results from VZV reactivation from latently infected sensory ganglia, producing a painful unilateral dermatomal vesicular rash. Lifetime risk ~30%, increasing with age and immunosuppression. [1,3]

2. Early antiviral therapy (within 72 hours) with valaciclovir, aciclovir, or famciclovir reduces acute pain, accelerates healing, and may reduce PHN risk. [6]

3. Postherpetic neuralgia (PHN) is the most common complication, affecting 10-18% overall but up to 30-40% of those ≥80 years. Age is the strongest predictor. [4,18]

4. Ophthalmic zoster (V1) = ophthalmology emergency. Hutchinson's sign (nasal tip vesicles) indicates ~76% risk of ocular involvement. Urgent same-day referral mandatory. [9,19]

5. Ramsay Hunt syndrome (geniculate ganglion zoster) presents with facial palsy + ear vesicles + otalgia; recovery worse than Bell's palsy (~50-70% complete recovery). Early IV or high-dose oral antivirals + corticosteroids. [8,20]

6. Recombinant zoster vaccine (Shingrix) demonstrates > 90% efficacy in preventing herpes zoster and PHN in adults ≥50 years and is safe in immunocompromised individuals. Recommend universally. [7]

7. Disseminated zoster (> 20 lesions outside dermatome) indicates significant immunocompromise. Requires IV antivirals, isolation, and investigation for underlying immunodeficiency. [10]

8. Red flags: Ophthalmic involvement, immunocompromise, dissemination, motor weakness, sacral involvement with urinary retention, and CNS signs mandate urgent specialist referral. [9,10]

Clinical Algorithms

Acute Herpes Zoster Management Pathway

1. Clinical diagnosis (dermatomal vesicular rash)
2. Assess for red flags (see above)
3. Within 72 hours of rash?
   • Yes → Start oral antivirals (valaciclovir 1g TDS × 7 days preferred)
   • Beyond 72h → Consider antivirals if: new lesions forming, immunocompromised, > 50 years, moderate-severe pain, ophthalmic/facial/genital involvement
4. V1 involvement? → URGENT ophthalmology referral (same day)
5. Immunocompromised or disseminated? → IV aciclovir; isolate; investigate
6. Analgesia: Paracetamol/NSAIDs; neuropathic agents (gabapentin, pregabalin, amitriptyline) if needed
7. Patient education: Cover rash, avoid at-risk contacts, warning signs for return
8. Follow-up: Review for complications; assess for PHN at 4-8 weeks; recommend vaccination after recovery

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Last Updated: 2026-01-11
Evidence Level: High
Total Citations: 21
Target Examinations: MRCP, MRCS, FRACP, FRACS, PLAB, USMLE