Ulnar sensory nerve impairment at the wrist in carpal tunnel syndrome.
In previous studies, changes in impulse transmission of ulnar motor axons have been documented in patients with carpal tunnel syndrome (CTS). We examined ulnar sensory conduction in 144 CTS hands. In particular, conduction parameters of the dorsal ulnar cutaneous branch (DUC) running outside Guyon's canal were compared with those of the superficial sensory branches (U4 and U5) passing through the canal. U4 and U5 response amplitudes and U5 conduction velocity were significantly lower than in controls. Conduction parameters of the DUC were similar in both groups. Patients with more severely impaired median conduction had smaller ulnar sensory action potentials. We propose that the ulnar nerve may be subject to compression in Guyon's canal as a consequence of high pressure in the carpal tunnel of CTS patients. This may provide insights into the mechanisms underlying extra-median spread of sensory symptoms in CTS patients.
Ginanneschi
Federica
F
Department of Neurological and Behavioral Sciences, Clinical Neurophysiology Unit, University of Siena, Policlinico Le Scotte, Viale Bracci 2, 53100 Siena, Italy.
Milani
Paolo
P
Mondelli
Mauro
M
Dominici
Federica
F
Biasella
Alessia
A
Biasella
Alessio
A
Rossi
Alessandro
A
D000200:Action Potentials / Q000502:physiology; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002349:Carpal Tunnel Syndrome / Q000150:complications*; D004558:Electric Stimulation / Q000379:methods; D004576:Electromyography / Q000379:methods; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009431:Neural Conduction / Q000502:physiology*; D009475:Neurons, Afferent / Q000502:physiology; D020424:Ulnar Neuropathies / Q000209:etiology*; D014953:Wrist