Ulnar nerve impairment at the wrist does not contribute to extramedian sensory symptoms in carpal tunnel syndrome.
OBJECTIVE
Extramedian spread of sensory symptoms is frequent in carpal tunnel syndrome (CTS) but its mechanisms are unclear. We explored the possible role of subtle ulnar nerve abnormalities in the pathogenesis of extramedian symptoms.


METHODS
We recruited 350 CTS patients. After selection, 143 patients (225 hands) were included. The hand symptoms distribution was graded with a diagram into median (MED) and extramedian (EXTRAMED) pattern. We tested the correlation of ulnar nerve conduction measures with the distribution and the severity of symptoms involving the ulnar territory. The clinical significance of ulnar nerve conduction findings was explored with quantitative sensory testing (QST).


RESULTS
EXTRAMED distribution was found in 38.7% of hands. The ulnar neurographic measures were within normal values. Ulnar nerve sensory measures were significantly better in EXTRAMED vs MED hands and not significantly correlated to ulnar symptoms severity. Ulnar and median nerve sensory measures were significantly correlated. QST showed normal function of ulnar nerve alphabeta-fibers.


CONCLUSIONS
Ulnar nerve sensory abnormalities do not contribute to the spread of sensory symptoms into the ulnar territory.


CONCLUSIONS
Our data favour the hypothesis that spinal and supraspinal neuroplastic changes may underlie extramedian spread of symptoms in CTS.
Tamburin
Stefano
S
Department of Neurological and Visual Sciences, Section of Rehabilitative Neurology, University of Verona, Italy. stefano.tamburin@univr.it
Cacciatori
Carlo
C
Praitano
Maria Luigia
ML
Marani
Silvia
S
Zanette
Giampietro
G
D000328:Adult; D002349:Carpal Tunnel Syndrome / Q000145:classification / Q000503:physiopathology*; D004568:Electrodiagnosis; D004576:Electromyography; D004594:Electrophysiology; D005260:Female; D005385:Fingers / Q000294:innervation / Q000503:physiopathology; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009431:Neural Conduction / Q000502:physiology; D011601:Psychophysics; D012677:Sensation / Q000502:physiology; D020424:Ulnar Neuropathies / Q000503:physiopathology*; D014732:Vibration; D014953:Wrist / Q000294:innervation*