Ulnar nerve conduction abnormalities in carpal tunnel syndrome

Area of Science:

• Neuroscience
• Neurology
• Clinical Electrophysiology

Background:

• Carpal tunnel syndrome (CTS) is a common condition characterized by median nerve compression.
• The spread of symptoms beyond the typical median nerve distribution in CTS is not fully understood.
• Ulnar nerve involvement in CTS has been suggested but requires further investigation.

Purpose of the Study:

• To determine if ulnar nerve fibers are involved in carpal tunnel syndrome.
• To explore the relationship between ulnar nerve conduction parameters and symptom spread in CTS.
• To investigate the impact of median neuropathy on the ulnar nerve.

Main Methods:

• Electrophysiological studies were performed on 93 hands with CTS and 76 control hands.
• Ulnar nerve conduction parameters, including distal motor latency (DML), distal sensory latency (DSL), and sensory conduction velocities (SCVs), were measured.
• Patients were assessed for the presence of symptoms in the fifth finger, indicative of potential ulnar nerve involvement.

Main Results:

• Patients with CTS showed significantly longer ulnar nerve DML and DSL, and lower amplitudes compared to controls.
• Increased median nerve DML was correlated with increased ulnar nerve DSL and reduced sensory amplitudes and SCVs.
• CTS patients with symptoms in the fifth finger exhibited lower ulnar nerve SCVs and amplitudes than those without.

Conclusions:

• Pathological processes in CTS can impact both motor and sensory fibers of the ulnar nerve within the Guyon canal.
• Ulnar nerve involvement provides a potential explanation for the observed extra-median spread of sensory symptoms in carpal tunnel syndrome.
• These findings highlight the importance of considering ulnar nerve function in the comprehensive evaluation of CTS.