6B. Guillain-Barre syndrome

From greek.doctor

Guillain-Barre syndrome (GBS) is an umbrella term for acute immune-mediated polyneuropathies, but in the Western world AIDP is the most common form, so it’s almost synonymous with GBS. Patients with AIDP have progressive weakness of the limbs over a few days to 28 days, symmetrical deficit, areflexia, absent or mild sensory disturbance, elevated cerebrospinal fluid protein, and slowing of nerve conduction velocities.

Types:

  • Acute inflammatory demyelinating polyradiculoneuropathy (AIDP)
  • Miller Fisher syndrome (MFS)
  • Acute motor axonal neuropathy
  • Acute sensorimotor axonal neuropathy (AMSAN)
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Etiology

The disorder may be preceded by upper respiratory or gastrointestinal infection 1 to 4 weeks before the onset of the symptoms (in 2/3 of cases). The classical preceding pathogen is campylobacter jejuni, but it can occur following infection by virtually any pathogen.

Pathomechanism

Immune reaction against an earlier infection forms antibodies which, due to molecular mimicry, target antigens on Schwann cells, causing demyelination.

Clinical features

The characteristic symptoms are those of a rapidly progressing polyneuropathy. Symptoms include progressive, symmetrical, flaccid, ascending muscle weakness and hyporeflexia. Sensory symptoms are common but are often mild. Autonomic symptoms, including GI symptoms, ileus, tachy/bradycardia, abnormal blood pressure, are also common. Symptoms may also affect cranial nerves, causing symptoms like facial palsy. The symptoms progress over 2 – 4 weeks.

Bilateral facial palsy may be present. 10 – 30% develop severe respiratory muscle weakness which causes respiratory failure.

Diagnosis and evaluation

The diagnosis is based on typical clinical features, CSF studies, and ENG. CSF studies show albuminocytologic dissociation (high protein, normal cells), and ENG shows demyelination (slow conduction).

Treatment

All patients should be admitted for monitoring, as respiratory failure can develop in many and these patients need ventilation. Patients with tachy/bradycardia require continuous cardiac monitoring.

Treatment is with plasma exchange or IVIG. Both have similar efficacy but IVIG are more practical. Steroids are not used as they’re not helpful.

Prognosis

Most patients regain most motor function. 80% can walk without assist devices after 6 months, and after 12 months 60% have reached complete remission. Improvement may take months or years. However, many develop chronic fatigue or pain.