Papilloedema and optic nerve disorders: Viva

This is a branching oral built to probe the reasoning that holds the neuroimaging before the lumbar puncture at the centre, the Friedman criteria and the Frisén grading, and to expose the candidate who has memorised the headline without the safety-critical corners. The questions escalate from the framing to the neuroimaging, the Friedman criteria, the treatment pathway and the optic neuritis, with the deliberate probes into the antibody-mediated disease and the surgery. [1]

Opening question: framing the problem

The examiner opens with the headache and the bilateral disc swelling and asks: how do you frame this problem in a single sentence, and what is your first step? [1]

A strong answer names the bilateral disc swelling as the papilloedema of the raised intracranial pressure until proven otherwise, and states that the first step is the urgent neuroimaging. [1][2]

Model answer. This child has the papilloedema of the raised intracranial pressure until proven otherwise, and the first step is the urgent magnetic resonance imaging with the venography to exclude the tumour, the hydrocephalus and the venous sinus thrombosis, because the lumbar puncture must not precede the neuroimaging in case of the obstructed flow. [1]

Probe one: the neuroimaging and the lumbar puncture

The examiner presses: why the neuroimaging before the lumbar puncture, and how is the opening pressure measured? [2]

A strong answer explains the safety and the technique. The neuroimaging precedes the lumbar puncture because the blind lumbar puncture in the obstructed cerebrospinal fluid can cause the fatal herniation, and the magnetic resonance imaging with the venography excludes the mass, the hydrocephalus and the venous sinus thrombosis. The lumbar puncture is performed in the lateral decubitus position with the child relaxed and the legs extended, and the opening pressure is measured with the manometer before the fluid is removed, and the value above two hundred and eighty millimetres of cerebrospinal fluid is the threshold for the raised pressure in the child. The cerebrospinal fluid is analysed for the cells, the protein and the glucose to exclude the meningitis and the inflammation. [1][3]

Pitfall probe. What if the magnetic resonance imaging shows the venous sinus thrombosis? The diagnosis becomes the secondary intracranial hypertension, and the treatment is the anticoagulation and the treatment of the precipitant, the dehydration or the otitis, and the idiopathic label is withdrawn. [2]

Probe two: the Friedman criteria

The examiner asks: what are the Friedman criteria, and why the idiopathic label? [1]

A strong answer names the five requirements. The papilloedema or the cranial-nerve palsy is the sign. The pressure is raised, above two hundred and eighty millimetres of cerebrospinal fluid in the child. The neuroimaging is plain, with no tumour, no hydrocephalus and no venous cause. The cerebrospinal fluid is pure, with the normal cells, the protein and the glucose. The neurological examination is clean, with the cranial-nerve palsy the only deficit allowed. The idiopathic label is given only after the secondary cause is excluded, because the venous sinus thrombosis, the drugs and the infection demand the targeted treatment. [1][2]

Pitfall probe. What drugs cause the secondary intracranial hypertension? The tetracyclines, the vitamin A and the retinoids, the growth hormone and the withdrawal of the chronic corticosteroid, and the careful drug history is essential because the cessation of the drug resolves the disc swelling. [2]

Probe three: the treatment and the surgery

The examiner asks: how do you treat the idiopathic intracranial hypertension, and when the surgery? [3]

A strong answer names the weight loss, the acetazolamide and the surgery. The weight loss of the five to ten percent in the obese adolescent may resolve the papilloedema. The acetazolamide, the carbonic anhydrase inhibitor at approximately fifteen to twenty-five milligrams per kilogram per day in the divided doses, reduces the cerebrospinal fluid production, with the monitoring for the paraesthesia and the metabolic acidosis. The topiramate is the alternative. The optic nerve sheath fenestration is the surgery for the dominant vision loss, and the cerebrospinal fluid shunt is the surgery for the refractory headache, and the venous sinus stenting is the option for the demonstrated stenosis. The surgery is reserved for the progressive vision loss despite the medical therapy. [2][3]

Pitfall probe. Why is the vision surveillance non-negotiable? Because the field loss may appear without the symptom, and the chronic untreated papilloedema produces the secondary optic atrophy and the permanent vision loss, so the acuity, the colour vision, the fields and the optical coherence tomography are reviewed at each visit. [6]

Branch one: the optic neuritis

The examiner pivots: imagine instead an eight-year-old boy with the acute painful visual loss in the right eye. What does this change? [8]

A strong answer names the optic neuritis and the swinging-flashlight test. The optic neuritis presents with the acute visual loss, the pain on the eye movement, the dyschromatopsia disproportionate to the acuity and the relative afferent pupillary defect on the swinging-flashlight test, and the disc may swell with the papillitis or stay flat with the retrobulbar neuritis. The antibody testing for the myelin oligodendrocyte glycoprotein and the aquaporin-four and the magnetic resonance imaging of the brain and the orbits define the cause and the prognosis. The intravenous methylprednisolone at twenty to thirty milligrams per kilogram per day to a maximum of one gram for three to five days is the first-line treatment, and the oral steroid is avoided. [8][9]

Pitfall probe. What is the single most reliable bedside sign of the optic nerve lesion? The relative afferent pupillary defect on the swinging-flashlight test, the paradoxical dilation of the affected eye when the light swings to it. [8]

Branch two: the antibody-mediated disease

The examiner pivots again: the boy is positive for the myelin oligodendrocyte glycoprotein antibody. What is this, and what is the prognosis? [9]

A strong answer names the antibody and the trajectory. The myelin oligodendrocyte glycoprotein antibody disease is the commonest antibody-mediated optic neuritis of the child, presenting with the bilateral optic neuritis, the disc swelling and the frequent association with the acute disseminated encephalomyelitis, and it carries the generally favourable recovery of the visual acuity but the high relapse rate. The aquaporin-four antibody neuromyelitis optica spectrum disorder is the severe form, with the poor recovery, the longitudinally extensive transverse myelitis and the area-postrema syndrome, and it demands the early maintenance immunotherapy with the rituximab or the mycophenolate to prevent the relapse and the disability. [9][10]

Pitfall probe. What is the role of the plasma exchange? It is considered for the severe or the steroid-refractory optic neuritis, particularly the antibody-mediated disease, because the rapid removal of the antibody may rescue the vision when the steroid fails. [9]

Closing question: the pseudopapilloedema

The examiner closes: how would your approach change if the disc swelling were the buried drusen rather than the true papilloedema? [6]

A strong answer names the pseudopapilloedema and the reassurance. The buried optic disc drusen raise the disc and blur the margin without the raised pressure, and they are distinguished by the orbital ultrasound, which shows the calcified reflectivity, and the optical coherence tomography, which shows the buried drusen rather than the elevated nerve fibre layer. The absence of the headache, the visual obscurations and the field defect supports the diagnosis, and the management is the reassurance and the documentation, with no treatment required. The fellow who distinguishes the mimic from the true papilloedema spares the child the lumbar puncture and the anxiety. [6][1]