Guillain-Barre Syndrome — Written Clinical Reasoning

SAQ 1 — Severe Guillain-Barre Syndrome at the Respiratory-Failure Threshold (20 marks, 30 minutes)

Prompt: Outline your integrated assessment and management plan for this patient, covering the confirmation of diagnosis, the immediate respiratory and airway decisions, the disease-modifying therapy with its dose and the evidence supporting it, the supportive care bundle, and the prognostic communication with the patient and family. Justify each decision with reference to evidence and guideline recommendations. [1]

Model Answer

Diagnosis and problem list (3 marks): [1]

This is severe Guillain-Barre syndrome, AIDP variant, post-Campylobacter, now at GBS disability grade 4 (bedbound) and at the threshold of ventilatory failure. The diagnosis is secure: progressive symmetric ascending weakness with areflexia reaching a nadir within 4 weeks, a preceding Campylobacter jejuni infection (the most common identifiable antecedent), CSF albuminocytologic dissociation (protein 1.3 g/L with 3 white cells — high protein, normal cells), and NCS showing demyelination (prolonged distal latencies, conduction block, absent F-waves). The bilateral lower motor neuron facial palsy is a recognised GBS sign and a red flag. The problems are: [1]

1. Severe GBS, AIDP variant, post-Campylobacter, grade 4 — disease-modifying therapy indicated immediately.
2. Impending ventilatory failure — FVC 22 mL/kg and falling, MIP -32 cmH2O, MEP 38 cmH2O, weak cough — needs ICU now.
3. Autonomic risk — dysautonomia is a leading cause of death in severe GBS; needs continuous cardiac monitoring.
4. VTE risk (around 30% without prophylaxis), pain, nutrition, pressure care.
5. Prognostic communication and psychological support. [1]

Immediate respiratory and airway management (4 marks): [1]

This is the priority. The patient has crossed the elective intubation thresholds: FVC below 30 mL/kg and falling by more than 30 percent in hours, MIP more negative than -30 cmH2O, MEP below 40 cmH2O, and a weak cough. Desaturation is a late, pre-terminal sign in Guillain-Barre syndrome — I will not wait for it. I would transfer him to the intensive care unit immediately, inform the anaesthetic/ICU team, and intubate electively before respiratory arrest. I would explain to the patient (who is alert) why we are intervening now: his breathing muscles are failing, and a planned intubation in controlled conditions is far safer than an emergency one. I would set up post-intubation ventilatory support, secure the airway, and continue his GBS-specific therapy. I would not use non-invasive ventilation, because his weak cough and bulbar involvement risk aspiration and NIV would only delay definitive airway protection. The Walgaard 2010 model (PMID 20517939) confirms these features (rapidly falling FVC and MIP, weak cough, short onset-to-admission interval) predict respiratory failure and justify early ICU involvement. [1]

Disease-modifying therapy — IVIG, dose and evidence (5 marks): [1]

I would start intravenous immunoglobulin 0.4 g/kg/day for 5 days (total 2 g/kg) immediately. He is at grade 4 (unable to walk) and within 4 weeks of onset, meeting the treatment indication. The evidence: [1]

• The 1985 GBS Study Group RCT established plasma exchange over supportive care.
• The 1992 Dutch trial (van der Meche, PMID 1552913) showed IVIG was at least as effective as plasma exchange.
• The 1997 Plasma Exchange/Sandoglobulin Trial (PMID 9014908) showed PE, IVIG and the combination were equivalent — combination added no benefit, so I will give IVIG alone, not both. [1]

I would choose IVIG over plasma exchange because it is easier, avoids central venous access and haemodynamic instability, and is preferred in most ANZ and UK centres. I would check his IgA level and renal function beforehand (IgA deficiency risks anaphylaxis; renal impairment and sucrose-stabilised products risk acute kidney injury), ensure good hydration, slow the infusion given his autonomic risk, and prescribe concurrent VTE prophylaxis because IVIG increases thrombosis risk. [1]

I would not give corticosteroids — not oral prednisolone, not IV methylprednisolone. The Hughes Cochrane review (2016, PMID 27775812) established that corticosteroids are ineffective in GBS and may slow recovery, and the van Koningsveld 2004 trial showed only a non-significant trend when methylprednisolone was added to IVIG. This is the key contrast with CIDP, where steroids are first-line and effective. [1]

Supportive care bundle (4 marks): [1]

While ventilated, I will institute the full supportive package: [1]

• Continuous ECG monitoring for dysautonomia — treat bradycardia (atropine, pacing if severe) and blood pressure swings with short-acting agents; avoid drugs that destabilise the autonomic system.
• DVT prophylaxis: enoxaparin 40 mg subcutaneously daily (dose-adjusted for renal impairment) plus intermittent pneumatic compression — the VTE risk is around 30% without prophylaxis.
• Early enteral nutrition: a nasogastric or nasojejunal tube within 24-48 hours — early feeding reduces mortality in ventilated GBS patients.
• Pain management: gabapentin or pregabalin first-line for neuropathic pain, with amitriptyline or opioids as adjuncts; avoid pure opioid monotherapy.
• Pressure care: regular turning, pressure-relieving mattress.
• Physiotherapy: passive range of motion to prevent contractures; early mobilisation as strength returns.
• Tracheostomy at 2-3 weeks if prolonged ventilation is anticipated — it aids weaning and pulmonary toilet.
• Psychological support: screen for depression, anxiety and post-intensive-care distress; the awake, paralysed, ventilated patient is at high risk. [1]

Autonomic risk and complications (2 marks): [1]

I will watch for autonomic instability (arrhythmia, labile blood pressure, ileus, urinary retention, SIADH), critical illness neuropathy/myopathy complicating prolonged ICU stay, and treatment-related fluctuation (a relapse within 2 months that I would re-treat with a second IVIG course). If his weakness were still progressing beyond 8 weeks, I would re-diagnose as acute-onset CIDP and move to corticosteroids — but at this stage the course is consistent with monophasic GBS. [1]

Prognostic communication (2 marks): [1]

I would speak to him and his family in plain language: "You have Guillain-Barre syndrome, a condition in which your immune system — after fighting off the stomach bug you had two weeks ago — has attacked your nerves by mistake. The weakness will probably get a little worse before it stops, and because your breathing muscles are affected we have put you on a breathing machine to keep you safe while the nerves recover. The treatment we are giving, immunoglobulin, speeds recovery, and most people — around 80 percent — recover well, though it can take months. There is a chance of some lasting weakness, and we will focus your rehabilitation on getting you back to walking and back to work. You will be looked after in intensive care, and although you may not be able to move much, you will be awake and able to hear us — please ask the nurses to explain everything that is happening." I would set realistic expectations, acknowledge the uncertainty of the trajectory (nadir, plateau, then recovery), and arrange regular family updates. [1]

SAQ 2 — Miller Fisher Syndrome: Variant Recognition and Management (10 marks, 15 minutes)

Prompt: A 61-year-old man presents with three days of double vision, unsteadiness, and paraesthesia in his hands. He had a sore throat and diarrhoea two weeks earlier. On examination he is alert and oriented. He has bilateral ophthalmoplegia, areflexia, and a wide-based ataxic gait. His finger-to-nose testing is intact with eyes open, but he is markedly unsteady on standing with his eyes closed (a strongly positive Romberg). His forced vital capacity is 50 mL/kg, his bulbar function is intact, and his plantars are downgoing. Outline your diagnostic reasoning, the investigations you would arrange, and your management plan. [1]

Model Answer

Diagnostic reasoning — recognise Miller Fisher syndrome (3 marks): [1]

This is the Miller Fisher triad of ophthalmoplegia, ataxia and areflexia. The ataxia is sensory (proprioceptive), not cerebellar: finger-to-nose testing is intact with the eyes open, but closing the eyes markedly worsens his balance (positive Romberg), indicating loss of proprioceptive input rather than cerebellar dysmetria. The mechanism is antibody-mediated attack on muscle spindle Ia afferents (which carry the stretch reflex) and on the oculomotor nerves, both of which are rich in the GQ1b ganglioside. The preserved level of consciousness and the downgoing plantars distinguish this from Bickerstaff brainstem encephalitis, which adds drowsiness or coma to the same anti-GQ1b spectrum. Miller Fisher syndrome is a regional variant of Guillain-Barre syndrome. [1]

Investigations (3 marks): [1]

• Cerebrospinal fluid: I would expect albuminocytologic dissociation (high protein, normal white cells), though it may be normal in the first week and does not exclude the diagnosis.
• Nerve conduction studies: in Miller Fisher the sensory action potentials are often reduced (the H-reflex is typically absent), reflecting the proprioceptive afferent involvement; motor studies may be relatively preserved early on.
• Anti-GQ1b IgG antibody: present in over 90 percent of Miller Fisher cases and essentially diagnostic (Chiba 1993, PMID 8413947). It is not required to start treatment in a classical case but confirms the diagnosis and is the marker of ophthalmoplegia across the GBS spectrum.
• MRI brain and orbits: mainly to exclude a brainstem stroke, basilar artery occlusion, or a mass producing ophthalmoplegia and ataxia — important because Miller Fisher can mimic a posterior circulation event.
• Respiratory monitoring: even Miller Fisher patients need FVC and inspiratory pressure monitoring, because a minority progress to generalised GBS with respiratory failure, though his FVC of 50 mL/kg is reassuring. [1]

Management plan (4 marks): [1]

Because Miller Fisher syndrome is part of the GBS spectrum and can progress to generalised weakness with respiratory involvement, I would admit him for monitoring. If he remains at Miller Fisher stage with no limb weakness and preserved respiratory function (grade 2 or better, stable), supportive care and observation may suffice — but the threshold to treat is any progression to inability to walk unaided, respiratory decline, or bulbar weakness. If he reaches that threshold, I would give IVIG 0.4 g/kg/day for 5 days, identical to AIDP. I would avoid corticosteroids for the same reasons as in AIDP (no benefit, possible harm). I would arrange continuous cardiac monitoring for dysautonomia, DVT prophylaxis, and ophthalmological and vestibular input for the diplopia and ataxia. I would explain to him that the ophthalmoplegia and ataxia typically recover over weeks to months, that anti-GQ1b confirms the diagnosis, and that the antecedent sore throat and diarrhoea were the immune trigger. I would arrange outpatient follow-up to monitor for complete recovery and any progression to a CIDP-like course, which would prompt a re-diagnosis and steroid-based therapy. [1]