Leprosy neuropathy: correlation of clinical and electrophysiological tests

This report describes the neurological and electrophysiological examination of 35 subjects with leprosy (average duration of symptoms 3.4 years, average time since diagnosis 7.5 months). Clinical examination in the distribution of non-dominant median and ulnar nerves was performed with the following clinical methods: touch sensation with 0.05 gm. Monofilament nylon, thermal sensation with a thermal sensitivity testing device, voluntary muscle testing and nerve palpation. At least one abnormality was found in 22 ulnar and 13 median nerves (63% and 37%, respectively). Nerve palpation was the most frequent clinical abnormality, while the other methods had similar frequencies of abnormality. Electrophysiological studies were performed on the ipsilateral side of the leprosy subjects and on 32 age-matched normal subjects. Electrophysiological responses from the leprosy subjects were evaluated by criteria established from normal subject data. Abnormal or absent responses were found in 21/35 ulnar sensory, 12/35 ulnar motor, 9/35 median sensory and 6/35 median motor responses among the leprosy subjects. The most important electrodiagnostic findings were: (i) low sensory amplitudes and (ii) drops in amplitude and NCV over the across-elbow segment of the ulnar nerve. Both clinical and nerve conduction abnormalities were positively associated with duration of leprosy symptoms. The four clinical methods were compared for concordance with nerve conduction data by cross-tabulation. The two sensory measures, monofilaments and the thermal sensitivity device, had the highest concordances. Usefulness of clinical tests for nerve damage in leprosy may vary depending on whether the purpose is for diagnosis, patient education or clinical follow-up.