Involvement of Distal Ulnar Nerve in Carpal Tunnel Syndrome

J Korean Assoc EMG Electrodiagn Med 2010;12(1):32-38.
Published online June 1, 2010.

Abstract

Objectives: To investigate involvement of ulnar sensory nerve that can be cause of the extra-median spread of sensory symptoms in carpal tunnel syndrome (CTS) patients. Methods: Forty two hands (mean age 60.5 years) with established diagnosis of CTS patients and twenty one hands with healthy controls were included in this study. Patients were categorized into 3 subgroups by distribution of paresthesias: median, glove and all-fingers. We categorized the severity of symptom into 2 subgroups according to Simovic clinical scale and divided the electrodiagnostic severity into 3 classes by Stevens classification. We examined ulnar sensory nerve conduction with 4th and 5th finger recordings (U4, U5) and conduction parameters of the dorsal ulnar cutaneous nerve. Results: There were no significant differences in ulnar nerve conduction parameters between CTS and control group. But, in patients who had extra-median (glove or all-fingers) symptoms, U4 and U5 amplitudes were significantly lower than those of patients with median symptoms. And the U4 and U5 amplitudes decreased with increasing the CTS severity. Conclusion: The results provided possible evidence of sensory fiber involvement to the ulnar nerve at the wrist in patients with severe CTS or extra-median sensory symptoms.

Key Words: Carpal tunnel syndrome, Nerve conduction studies, Ulnar nerve