Acute idiopathic axonal neuropathy (AIAN): a clinical and electrophysiological observation.

Twenty patients (M:F 15:5) with electrophysiological evidence of predominant axonal lesion and fulfilling clinical criteria for Guillain Barré Syndrome were observed during a period of 6 years (1985-1990). Their mean age was 27.5 years (range 5-55). Seven patients had antecedent febrile illness. Peak motor deficit was reached at a mean period of 6.5 days (range 2-21 days). All the patients had distal muscle weakness out of proportion to proximal muscle weakness. Facial paresis (13 patients), bulbar palsy (2), respiratory failure (1), sensory deficits (7) and dysautonomia (1) were other salient features. CSF analysis revealed albumino-cytological dissociation in 12 patients. One patient died and in the remaining patients the recovery was delayed and incomplete. Presence of predominant distal muscle wasting and weakness, low amplitude CMAP or inexcitable nerves, absence of conduction block or significant temporal dispersion, normal or only slightly reduced conduction velocity and evidence of poor recovery suggest that the primary pathology in these patients may be axonal degeneration. These cases may represent a distinct entity and need to be differentiated from the more commonly observed acute idiopathic demyelinating neuropathy.