Involvement of sensory fibres in axonal subtypes of Guillain-Barré syndrome

Margherita Capasso (1) , Francesca Notturno (1) , Claudia Manzoli (1) , Antonino Uncini (1)

1 University G. d'Annunzio Chieti

Background: Acute motor axonal neuropathy (AMAN) and acute motor and sensory axonal neuropathy (AMSAN) are due to an anti-ganglioside antibodies-mediated attack thought to be restricted to motor fibres in AMAN. Sensory symptoms and minor sensory conduction abnormalities, however, have been reported in some AMAN patients. Objective: To verify whether sensory fibres are truly spared in AMAN and whether AMAN and AMSAN represent a continuum. Methods: We reviewed serial conduction studies in 13 AMAN and three AMSAN patients. To evaluate the variation of sensory nerve action potential (SNAP) amplitude in serial recordings, we calculated the least significant change (LSC) in a test-retest study of 20 controls. LSCs for median, ulnar and sural nerves were 44%, 47% and 58%. Results: In 34% of initially normal sensory nerves of six AMAN patients, SNAP amplitude significantly increased by 57-518%. In three nerves of three AMAN patients, SNAP significantly decreased by 50-69%. Overall, serial recordings allowed to detect sensory fibres involvement in 49% of nerves and in 69% of AMAN patients. In one AMSAN patient, SNAP increased in two nerves by 150-300%; in another patient, SNAPs, unrecordable at baseline in six nerves, reappeared during follow-up and normalize in three nerves. In five nerves of three AMAN and in eight nerves of two AMSAN patients, SNAP amplitudes increased rapidly suggesting reversible conduction failure of sensory fibres. In other nerves SNAP increased over months as for axonal regeneration. Conclusions: Sensory fibres are often involved subclinically in AMAN. Reversible conduction failure may develop in sensory as well as in motor fibres in both AMAN and AMSAN. AMAN and AMSAN represent a continuum in axonal GBS.

Mots clés: GUILLAIN-BARRE SYNDROME; NEUROPHYSIOLOGY

Margherita Capasso, Francesca Notturno, Claudia Manzoli, Antonino Uncini. Involvement of sensory fibres in axonal subtypes of Guillain-Barré syndrome. Journal of Neurology, Neurosurgery and Psychiatry, 2011, 82 (6), pp.664. ⟨10.1136/jnnp.2010.238311⟩. ⟨hal-00627137⟩