The Value of Electrophysiological Examination of the Flexor Carpi Ulnaris Muscle in the Diagnosis of Ulnar Nerve Lesions at the Elbow

The aim of the present study was to answer the question whether electrophysiological examination of the m.flexor carpi ulnaris, especially of the distal latency (stimulation point 2 cm above the sulcus ulnaris) to this muscle, represents a valid procedure for the localisation of an ulnar nerve lesion at the elbow. In 64 patients, a total of 68 ulnar nerve lesions at the elbow were subjected to conventional clinical and electrophysiological examinations. A pathologically prolonged distal latency to m.flexor carpi ulnaris (> 4.0 ms) was found in 82.4% of the patients. In terms of their value in the topo-diagnosis of an ulnar lesion, measurement of the distal latency to m.flexor carpi ulnaris and conventional analysis of trans-sulcal motor conduction velocity of the fibres to the hypothenar muscles yield equivalent information. However, evaluation of the distal latency to m.flexor carpi ulnaris is not only subject to fewer sources of error but is also technically much easier to perform. In the localisation of a clinically suspected ulnar nerve lesion at the elbow, we therefore suggest that the electrophysiological investigation should commence with an examination of the distal latency to m.flexor carpi ulnaris.