DIAGNOSIS

Incidence:

1-2/100,000.[1,2]
5-8% mortality - respiratory failure, cardiac arrythmias and pulmonary embolism.
10% severly disabled at one year

Definition:

Acute autoimmune polyradiculoneuropathy. Classic triad of weakness, areflexia and elevated CSF protein without pleocytosis.[3]

Features Required for Diagnosis:[4]

Progressive motor weakness of more than one limb
Areflexia/ hyporeflexia.

Features Supportive of the Diagnosis:

Clinical

Progression of weakness: 90% nadir by 4 weeks.
Relative symmetry.
Sensory symptoms/signs
Cranial nerve involvement.
Autonomic dysfunction
Absence of fever at onset.
Recovery

Cerebrospinal fluid features

Elevated CSF protein (more likely after the first week of symptoms)
< 10 mononuclear leukocytes/mm3 in CSF.

Electrodiagnostic features supportive of the diagnosis.

Nerve Conduction Studies.

80% slowing or block.
Distal latencies may be increased but may not be abnormal until several weeks into the illness

Features Casting Doubt on the Diagnosis:

Marked, persistent asymmetry of weakness.
Persistent bladder or bowel dysfunction
CSF pleocytosis (> 50 wcc/mm3)
A very distinct/clear sensory level
Complete ophthalmoplegia (no eye movements, pupillary pareisis)

Subtypes:[5,6,16]

Acute inflammatory demyelinating polyradiculoneuropathy (AIDP).
Acute motor axonal neuropathy (AMAN).
Acute motor-sensory axonal neuropathy (AMSAN)
Miller Fisher syndrome: ataxia, ophthalmoplegia, areflexia.[7]

Differential Diagnosis:

Spinal cord disease (tumour, transverse myelitis)
Brainstem disease (infarction, tumour, demyelination)
Neuromuscular block (myasthenia, botulism)
Periodic paralysis (hypo, hyper or normokalaemia)
Miscellaneous: irritable hip, discitis, abnormal illness behaviour, somatising disorders, porphyri, lead poisoning.