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.


CONCLUSIONS
The sural-sparing pattern reflects a pathological process common to axonal and demyelinating GBS-subtypes alike.
Department of Neurology, National Neuroscience Institute, Singapore. Electronic address: umapathi@nni.com.sg.
Thirugnanam
T
Umapathi
Yong Loo Lin School of Medicine, National University of Singapore, Singapore.
Zongbin
Z
Li
Department of Neurology, National Neuroscience Institute, Singapore.
Kamal
K
Verma
Departments of Medicine and Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.
Nobuhiro
N
Yuki
D000293:Adolescent; D000328:Adult; D000368:Aged; D001369:Axons / Q000502:physiology; D003711:Demyelinating Diseases / Q000175:diagnosis / Q000503:physiopathology; D005260:Female; D020275:Guillain-Barre Syndrome / Q000175:diagnosis* / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D019846:Miller Fisher Syndrome / Q000175:diagnosis / Q000503:physiopathology; D013497:Sural Nerve / Q000503:physiopathology*; D055815:Young Adult
Electrodiagnosis; Guillain–Barré syndrome; Sural-sparing