Sural-sparing is seen in axonal as well as demyelinating forms of Guillain-Barré syndrome.

Objective: The "sural-sparing pattern" of Guillain-Barré syndrome (GBS) is believed to reflect demyelinating pathology. We asked if it is present in non-demyelinating GBS-subtypes, namely acute motor axonal neuropathy (AMAN), acute motor-sensory axonal neuropathy (AMSAN) and Miller Fisher syndrome (MFS), in addition to acute inflammatory demyelinating polyneuropathy (AIDP).

Methods: We studied the occurrence of sural-sparing pattern in clinically defined GBS and MFS patients. Using serial electrodiagnostic studies, GBS patients were divided into AIDP, according to appearance of demyelination-remyelination and AMAN/AMSAN, if there were signs of reversible conduction failure or Wallerian-like degeneration. Equivocal cases were left unclassified. We defined sural-sparing as a greater decrease in median and or ulnar sensory nerve action potential than that of the sural, compared to age and height-matched normal controls.

Results: Twelve of 30 GBS and 7 of 20 MFS patients had sural-sparing. This pattern was seen in 4 of 8 AIDP, 5 of 13 AMAN/AMSAN and 3 of 9 unclassified cases. Sequential studies uncovered sural-sparing, initially covert, in additional 1 MFS, 1 unclassified, 1 AIDP and 1 AMAN/AMSAN patient.

Conclusions: Sural-sparing occurs in axonal and demyelinating GBS subtypes.

Significance: The sural-sparing pattern reflects a pathological process common to axonal and demyelinating GBS-subtypes alike.