22 Sept 2026 · Case #017
Guillain-Barré syndrome (GBS)
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Diagnosis
Guillain-Barré syndrome (GBS)
First-line treatment
IVIG (or plasma exchange)
How the diagnosis is reached
An ascending, symmetric, areflexic flaccid weakness developing over days after a diarrheal illness is the classic presentation of Guillain-Barré syndrome, most often triggered by Campylobacter jejuni through molecular mimicry between bacterial lipo-oligosaccharide and peripheral nerve gangliosides. The examination findings do the diagnostic work: global areflexia with flexor plantars and no sensory level argues against a spinal cord lesion such as transverse myelitis or compression, and preserved bladder function points the same way. Normal pupils, full eye movements and no fatigability argue against botulism and myasthenia gravis respectively. CSF showing markedly raised protein with a normal cell count, albuminocytologic dissociation, is characteristic, though it is often normal in the first week, so a normal early result does not exclude the diagnosis. Nerve conduction studies confirm a demyelinating process with conduction block and absent F waves, the latter reflecting proximal root involvement. The single most important management point is respiratory: the falling forced vital capacity is the reason this patient needs a monitored bed, since neuromuscular respiratory failure develops before hypoxia appears on pulse oximetry, and waiting for desaturation means intubating a patient in extremis. Treatment is IVIG or plasma exchange, equally effective, with nothing gained by combining them; IVIG is usually chosen on practical grounds and given over five days. Corticosteroids, notably, do not help in GBS. None of that addresses tonight, though. Elective intubation is indicated once the FVC falls to roughly 20 mL/kg, around 1.4 L in a man of his size, and at 1.9 L losing half a litre every eight hours he will reach it before morning.
Key clinical clues
- Ascending symmetric flaccid weakness with global areflexia following a diarrheal illness
- No sensory level and normal bladder function, argues against a cord lesion
- Normal pupils and no fatigability, argues against botulism and myasthenia gravis
- CSF with high protein and normal cell count (albuminocytologic dissociation)
- Falling forced vital capacity is the warning sign, not oxygen saturation
The case in full
Presenting complaint
Patient history
A 34-year-old man has five days of progressive leg weakness that began on stairs and ascended to his thighs; since this morning he has been dropping objects. He has tingling in both feet but no numbness he can map. Three weeks ago he had bloody diarrhea after a barbecue.
Neurological examination
Physical examination
There is symmetric flaccid weakness, worse proximally in the legs (3/5) than the arms (4/5). Reflexes are absent throughout, plantars flexor. Sensation is preserved with no sensory level, bladder and bowel normal, pupils and eye movements unaffected.
Bedside respiratory monitoring
Laboratory results
Forced vital capacity is measured at the bedside on admission and repeated four-hourly. Predicted normal for his height is 4.8 L.
| Parameter | Value | Reference |
|---|---|---|
| FVC on admission | 3.1 LRef ≈4.8 predicted | ≈4.8 predicted |
| FVC at 8 hours | 2.4 LRef ≈4.8 predicted | ≈4.8 predicted |
| FVC at 16 hours | 1.9 LRef ≈4.8 predicted | ≈4.8 predicted |
| Single breath count | 18Ref >25 | >25 |
| SpO₂ (room air) | 97 %Ref 95–100 | 95–100 |
Cerebrospinal fluid analysis
Laboratory results
A lumbar puncture is performed on day six of symptoms.
| Parameter | Value | Reference |
|---|---|---|
| CSF protein | 1.4 g/LRef 0.15–0.45 | 0.15–0.45 |
| CSF white cells | 2 /µLRef 0–5 | 0–5 |
| CSF glucose | 3.6 mmol/LRef 2.2–3.9 | 2.2–3.9 |
| CSF opening pressure | 16 cmH₂ORef 10–20 | 10–20 |
| Gram stain and culture | NegativeRef Negative | Negative |
Neuroimaging
Imaging
MRI of the whole spine with contrast shows no cord compression, no intramedullary signal change, and no demyelinating plaques. There is subtle enhancement of the cauda equina nerve roots. MRI of the brain is normal.
Nerve conduction studies
Clinical course
Electrophysiology shows prolonged distal motor latencies, partial conduction block, temporal dispersion and absent F waves in both legs. Sensory conduction is relatively preserved, sparing the sural nerve. Serology is positive for recent Campylobacter jejuni.