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Nerve compression, membrane excitability, and symptoms of carpal tunnel syndrome
Author(s) -
Han S. Eric,
Lin Cindy S.Y.,
Boland Robert A.,
Kiernan Matthew C.
Publication year - 2011
Publication title -
muscle and nerve
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.025
H-Index - 145
eISSN - 1097-4598
pISSN - 0148-639X
DOI - 10.1002/mus.22078
Subject(s) - carpal tunnel syndrome , electrodiagnosis , medicine , compression (physics) , nerve compression syndrome , median nerve , carpal tunnel , physical medicine and rehabilitation , anatomy , surgery , materials science , composite material
In this study we investigated the changes in axonal excitability and the generation of neurological symptoms in response to focal nerve compression (FNC) of the median nerve in carpal tunnel syndrome (CTS). Methods: Sensory excitability recordings were undertaken in 11 CTS patients with FNC being applied at the wrist using a custom‐designed electrode. Results: During FNC, refractoriness increased significantly (62.4 ± 3.4%; P < 0.001), associated with a rapid reduction in superexcitability (16.9 ± 2.8%; P < 0.001) and sensory nerve action potential amplitude (SNAP) (32.4 ± 3.9%; P < 0.001), consistent with axonal depolarization. Associated with these changes, paresthesiae steadily increased throughout FNC, as did numbness. Reductions in SNAP amplitude and superexcitability developed more rapidly for CTS patients during FNC compared with controls, and these changes were associated with more marked symptoms. Conclusions: Axonal responses to compression are impaired in CTS. This may suggest a greater reliance on axonal membrane Na + /K + ‐ATPase function. Muscle Nerve 44: 402–409, 2011