ELECTRODIAGNOSTIC REFERENCE VALUES FOR ULNAR MOTOR NERVE CONDUCTION RECORDED FROM THE FLEXOR CARPI ULNARIS MUSCLE
DOI:
https://doi.org/10.55374/jseamed.v10.310Keywords:
electrodiagnosis, nerve conduction study, ulnar nerve, reference values, flexor carpi ulnarisAbstract
Background: Ulnar nerve entrapment at the elbow is the second most common compressive neuropathy of the upper extremity. The flexor carpi ulnaris (FCU) muscle may improve diagnostic accuracy in localizing ulnar neuropathy, particularly when distal recording is not feasible because of severe muscle atrophy.
Objective: The present study aimed to establish the electrodiagnostic reference values for the ulnar nerve recorded at the FCU muscle.
Methods: A total of 73 upper extremities from 44 patients with suspected carpal tunnel syndrome underwent nerve conduction study. For the FCU muscle, the active electrode was placed 10 cm below the medial epicondyle, and the reference electrode was placed at the pisiform bone. The ulnar nerve was stimulated at the wrist, the medial epicondyle, and 10 cm proximal to the medial epicondyle. The recorded parameters included onset latency at the elbow and above the elbow, as well as CMAP amplitude, area, and duration.
Results: The mean DML and CMAP amplitude following stimulation at the medial epicondyle were 2.35 ± 0.35 ms and 8.89 ± 2.84 mV, respectively. The mean NCV across the elbow was 65.12 ± 10.28 m/s. Conclusion: The upper limit of normal for DML was 3.05 ms, and the lower limit of normal (LLN) for CMAP amplitude was 3.21 mV, both derived using the mean ± 2 SD. In contrast, the LLN for NCV across the elbow was 50.51 m/s, based on the 2.5th percentile.
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