Ulnar nerve involvement in carpal tunnel syndrome

Area of Science:

• Neurology
• Clinical Electrophysiology

Background:

• Carpal tunnel syndrome (CTS) is a common condition affecting the median nerve.
• The potential co-occurrence of other nerve entrapments, like ulnar neuropathy, is often overlooked.

Purpose of the Study:

• To investigate the prevalence of ulnar nerve involvement in patients diagnosed with carpal tunnel syndrome.
• To determine the electrophysiological characteristics of associated ulnar nerve abnormalities.

Main Methods:

• Retrospective analysis of 248 patients with electrodiagnostically confirmed carpal tunnel syndrome.
• Electrodiagnostic criteria for CTS: median sensory nerve action potential (SNAP) > 3.6 ms or motor distal latency > 4.3 ms.
• Electrodiagnostic criteria for ulnar nerve involvement: SNAP peak latency > 3.7 ms or motor distal latency > 4.2 ms at the wrist.

Main Results:

• 46% of patients (114/248) exhibited delayed ulnar SNAP peak latency at the wrist.
• Bilateral ulnar nerve involvement was present in 100 of these cases.
• Reduced motor nerve conduction velocity was observed in 24% for the median nerve and 15% for the ulnar nerve.
• Double crush syndrome was incidentally found in 14% of patients.

Conclusions:

• Ulnar nerve involvement, particularly affecting sensory fibers at the wrist, is frequently associated with carpal tunnel syndrome.
• These findings highlight the importance of considering concurrent ulnar neuropathy in CTS evaluations.
• The high incidence suggests a potential shared pathophysiology or common contributing factors.