Sural-sparing pattern: A study against electrodiagnostic subtypes of Guillain–Barre syndrome

OBJECTIVE: To study sural-sparing pattern in Guillain–Barre syndrome (GBS) and compare it among GBS’s electrodiagnostic subtypes, classified by two recent criteria. METHODS: This study retrospectively reviewed clinical data and electrodiagnostic studies (EDXs) of 88 GBS patients diagnosed in a tertiary care hospital (2010–2019). RESULTS: Overall, 79/88 (89.8%) and 36/45 (80%) patients had bilateral sensory nerve conduction studies (NCS) in the first EDX and follow-up EDX, respectively. Sural-sparing occurred in all subtypes (50% overall occurrence rate), most commonly in demyelination. There was no statistically significant difference in sural-sparing occurrence rates between demyelinating and axonal GBS; however, sural-sparing in axonal GBS tended to show a lower number of abnormal upper-limb sensory nerve action potentials (SNAPs) than demyelinating GBS. Shifting between sural-sparing and no sural-sparing occurred in approximately-one-fourth of patients receiving serial studies. Follow-up EDX additionally discovered 20% of all sural-sparing. Unilateral EDX could have omitted up to 30% of sural-sparing. CONCLUSIONS: Sural-sparing is less obviously manifested in axonal than demyelinating GBS, with respect to the number of affected upper-limb SNAPs. Extended sensory NCS is worth in detecting sural-sparing as a supportive electrodiagnostic GBS feature. SIGNIFICANCE: This report showed one different character of sural-sparing (number of affected upper-limb SNAPs) between demyelinating and axonal GBS.