Acute Motor And Sensory Axonal Neuropathy

A rare motor-sensory, axonal form of Guillain-Barré syndrome (GBS).

Epidemiology

The overall annual incidence of GBS is estimated at between 1/91,000 and 1/55,000. The axonal (AMSAN and acute motor axonal neuropathy, AMAN; see this term), forms account for only 3-5% of cases of GBS in Western countries but are much more frequent (30%-50% of GBS cases) in Asia and Latin America.

Clinical description

Patients present with a clinical picture (muscle weakness and sensory deficits) similar to that of the more frequent demyelinating form of GBS, acute inflammatory demyelinating polyradiculoneuropathy (AIDP; see this term) but the disease course in AMSAN tends to be more severe. As in other types of GBS, an infectious disease precedes the onset of limb weakness in the majority of cases.

Etiology

Although the exact pathological mechanism is poorly understood, both AMAN and AMSAN are associated with the presence of antiganglioside antibodies (anti-GM1/GD1a/GM1b/GalNAc-GD1a) and may be caused by antibody-mediated primary axonal degeneration or antibody-mediated inhibition of voltage-gated sodium channels.

Prognosis

AMSAN is generally a severe form of GBS and recovery is often poor.