Guillain-Barre Syndrome Viva

Long Case Viva Defence

Candidate's opening statement (model answer)

"Mr Davies is a 54-year-old mechanic who presents with four days of progressive, symmetric ascending weakness that began in his feet and has reached his thighs and hands. Two weeks ago he had a week of bloody diarrhoea, confirmed as Campylobacter jejuni enteritis by his general practitioner. [1]

On examination he is alert and oriented, with a respiratory rate of 22 and oxygen saturation of 97 percent on room air, but he pauses to breathe mid-sentence. He has flaccid, symmetric weakness — power 2 out of 5 in the legs and 4 out of 5 in the arms — with absent reflexes in all four limbs and downgoing plantars. He has mild bilateral lower motor neuron facial weakness, and sensation is reduced to pinprick in a glove-and-stocking pattern. His forced vital capacity is 22 mL/kg, having fallen from 30 mL/kg six hours ago; his maximum inspiratory pressure is -32 cmH2O and his maximum expiratory pressure is 38 cmH2O, and his cough is weak. Cerebrospinal fluid shows a protein of 1.3 g/L with 3 white cells. Nerve conduction studies show prolonged distal latencies, conduction block, and absent F-waves, consistent with AIDP. His HIV test is negative. [1]

His main problems are:

1. Severe Guillain-Barre syndrome, AIDP variant, post-Campylobacter, GBS disability grade 4 — immediate disease-modifying therapy indicated
2. Impending ventilatory failure — FVC and inspiratory pressures at the intubation threshold, bulbar and cough weakness — requires ICU transfer and elective intubation now
3. Autonomic risk — a leading cause of death in severe GBS, needs continuous cardiac monitoring
4. VTE prophylaxis, nutrition, analgesia and pressure care
5. Prognostic communication and psychological support for a patient who will be awake and paralysed on a ventilator" [1]

Examiner probing questions and model answers

Q1: "His FVC is 22 mL/kg and his saturations are normal. Surely he is fine for now — why not just watch him on the ward?" [1]

"Because desaturation is a late, pre-terminal sign in Guillain-Barre syndrome. Young, fit patients maintain their oxygen saturation by increasing their respiratory rate and using accessory muscles until their respiratory muscles are almost completely fatigued, at which point they arrest. His FVC has fallen by more than 30 percent in six hours, his maximum inspiratory pressure of -32 cmH2O is more negative than the -30 cmH2O threshold, his maximum expiratory pressure of 38 cmH2O is below 40, and he has a weak cough. These are the elective intubation criteria. Waiting for desaturation would convert a safe, planned intubation in controlled conditions into an emergency arrest. I would transfer him to ICU and intubate now. The Walgaard 2010 model confirms that a rapidly falling FVC and MIP, a weak cough, and a short onset-to-admission interval predict respiratory failure and justify early ICU involvement." [1]

Q2: "What disease-modifying therapy will you give, and what is the evidence?" [1]

"Intravenous immunoglobulin, 0.4 g/kg per day for five days, for a total of 2 g/kg. He is at grade 4, unable to walk, and within four weeks of onset, which meets the treatment indication. The evidence base is robust: the 1985 GBS Study Group trial established plasma exchange over supportive care; the 1992 Dutch trial by van der Meche showed IVIG was at least as effective as plasma exchange; and the 1997 Plasma Exchange/Sandoglobulin Trial in 383 patients showed that PE, IVIG and the combination were equivalent — combining them added no benefit, so I will give IVIG alone. I would choose IVIG over plasma exchange because it is easier, avoids central access and haemodynamic instability, and is preferred in most ANZ and UK centres." [1]

Q3: "Why not add methylprednisolone to the IVIG — would that not help?" [1]

"No. Corticosteroids are ineffective in Guillain-Barre syndrome and may slow recovery. The Hughes Cochrane review in 2016 was definitive on this. The van Koningsveld 2004 trial of methylprednisolone added to IVIG showed only a non-significant trend toward benefit in the primary intention-to-treat analysis, which is not enough to change practice. This is the key contrast with CIDP, the chronic cousin of GBS, where corticosteroids are first-line and effective. If a patient with suspected GBS improves on steroids, the diagnosis was probably CIDP from the start." [1]

Q4: "He is HIV-negative and his CSF has only 3 white cells. Does a CSF pleocytosis ever change your thinking?" [1]

"Yes. A CSF white cell count above 50 cells per microlitre in suspected Guillain-Barre syndrome should prompt me to look for an alternative or a coexisting cause — most importantly HIV-seroconversion GBS, but also leptospirosis, malignant infiltration of the roots, or an infectious polyradiculopathy. A normal or near-normal cell count with a high protein — albuminocytologic dissociation — is the expected pattern and supports the diagnosis. I should also remember that the CSF protein is often normal in the first week and rises over one to two weeks, so a normal early CSF does not exclude GBS." [1]

Q5: "He is ventilated and stable on day 5. He now has a heart rate of 28 with a brief asystolic pause and blood pressure swinging between 70/40 and 200/110. What is happening and what do you do?" [1]

"This is autonomic dysfunction — a leading cause of death in ventilated Guillain-Barre patients, driven by involvement of the autonomic nerve fibres. I would ensure continuous cardiac monitoring, treat symptomatic bradycardia with atropine and escalate to temporary pacing if it is recurrent or severe, and manage the labile blood pressure with short-acting vasoactive agents, avoiding drugs with prolonged effects that destabilise the system further. I would not attribute it to a primary cardiac event in the first instance, because the combination of bradycardia with labile hypertension and hypotension is the signature of dysautonomia, not of ischaemia or sepsis — though I would of course exclude those with an ECG, troponin, and cultures." [1]

Q6: "What is his prognosis?" [1]

"He has adverse prognostic features: a Campylobacter (diarrhoeal) antecedent, a severe nadir requiring ventilation at grade 4 to 5, and older age. The Erasmus GBS Outcome Score at two weeks — using age, antecedent diarrhoea and the GBS disability score — would place him in a higher-risk group for poor outcome at six months. Overall, around 80 percent of GBS patients recover to independent walking, around 20 percent cannot walk unaided at six months, and mortality is around 5 percent. I would give him and his family an honest but hopeful assessment: the disease will plateau and then recover over months, intensive rehabilitation will maximise his function, and there is a realistic chance of independent walking, though some residual weakness and fatigue are possible. Persistent pain affects up to half of patients and needs active management." [1]

Short Case Discussion

Scenario: "Examine this patient's neurological system. They were admitted three days ago with progressive leg weakness."

Candidate presentation (model): [1]

"I examined Mr Davies's neurological system. He is alert and cooperative but is using his accessory muscles to breathe and speaks in short phrases. [1]

On general inspection there is no facial asymmetry at rest, but on cranial nerve testing there is mild bilateral lower motor neuron facial weakness, with reduced eye closure and a symmetrical smile. Eye movements are full. The cough is weak. [1]

In the upper limbs, tone is reduced. Power is 4 out of 5 in the arms proximally and distally, symmetric. In the lower limbs, tone is reduced. Power is 2 out of 5 in the legs, symmetric, worst at the feet and toes. Reflexes are absent in all four limbs. The plantar responses are downgoing. [1]

Sensation is reduced to pinprick and light touch in a glove-and-stocking distribution. Joint position sense is impaired at the toes. Coordination cannot be tested in the legs because of weakness but is intact in the arms. [1]

In summary, these findings — symmetric flaccid weakness with areflexia, a downgoing plantar, bilateral lower motor neuron facial weakness, and declining respiratory function — are consistent with acute Guillain-Barre syndrome. My immediate priorities are to assess his ventilatory capacity with forced vital capacity and inspiratory pressures and to arrange cerebrospinal fluid examination and nerve conduction studies." [1]

Examiner: "Why are the plantars downgoing in a patient this weak?" [1]

"Because Guillain-Barre syndrome is a lower motor neuron lesion. The pathology is in the peripheral nerve and the nerve root, below the anterior horn cell, so the corticospinal (upper motor neuron) pathway is intact and the plantar response remains flexor. Upper motor neuron signs — spasticity, hyperreflexia and extensor plantars — require a lesion of the corticospinal tract itself. The combination of profound weakness with areflexia and downgoing plantars is therefore a clue that the lesion is in the peripheral nerve rather than the spinal cord." [1]

Examiner: "How would you distinguish this from a spinal cord lesion?" [1]

"I would look for the features that indicate a cord lesion: a clear sensory level, bowel and bladder (sphincter) involvement at the level, and upper motor neuron signs below the lesion — hyperreflexia, spasticity and extensor plantars. Mr Davies has none of these. His weakness is symmetric and ascending without a sensory level, his reflexes are absent rather than brisk, and his plantars are downgoing. If any of those cord features were present, or if the weakness were asymmetric or predominantly proximal with facial sparing, I would arrange urgent MRI of the spine to exclude cord compression or transverse myelitis. In a classical ascending areflexic presentation, MRI is mainly to exclude mimics." [1]

Examiner: "He has bilateral lower motor neuron facial weakness. What is the significance?" [1]

"Bilateral lower motor neuron facial palsy is a recognised feature of Guillain-Barre syndrome — it occurs in around half of severe cases — and it is a red flag that should never be dismissed as two separate Bell palsies. The other important causes of bilateral facial palsy include Lyme disease, sarcoidosis, basilar meningitis (including tuberculous and carcinomatous), and HIV seroconversion. In the context of ascending areflexic weakness and a preceding Campylobacter illness, the facial palsy is part of the GBS, but I would still consider and test for those alternatives if the picture were atypical." [1]