A multicentre prospective study of Guillain-Barré syndrome in Japan: a focus on the incidence of subtypes.

Objective: Guillain-Barré Syndrome (GBS) is classified into the two major subtypes; acute inflammatory demyelinating polyneuropathy (AIDP) and acute motor axonal neuropathy (AMAN). Previous studies have suggested that AIDP is predominant and AMAN is rare in Western countries, whereas AMAN is not always uncommon in East Asia. We aimed to clarify the incidence of the subtypes of GBS in Japan.

Methods: We performed a prospective multicentre survey over 3 years (2007-2010). Clinical and electrophysiological findings were collected from 184 patients with GBS in 23 tertiary neurology institutes. Anti-ganglioside antibodies were measured by ELISA. We also surveyed the incidence of Fisher syndrome (FS).

Results: By electrodiagnostic criteria of Ho et al, patients were classified as having AIDP (40%), or AMAN (22%), or unclassified (38%). Anti-GM1 IgG antibodies were found for 47% of AMAN patients, and 18% of AIDP patients (p<0.001). There were no specific regional trends of the electrodiagnosis and anti-GM1 positivity. During the same study period, 79 patients with FS were identified; the percentage of FS cases out of all cases (FS/(GBS+FS)) was 26%.

Conclusions: The frequency of GBS patients with the electrodiagnosis of AMAN by single nerve conduction studies is approximately 20% in Japan, and the AMAN pattern is closely associated with anti-GM1 antibodies. The incidence of FS appears to be much higher in Japan than in Western countries.