Usefulness of segmental and comparative tests in the electrodiagnosis of carnal tunnel syndrome: the Italian multicenter study

The Italian CTS Study Group performed a wide multicentric and multiparametr ic study to quantify the increase of electrodiagnostic sensitivity using an extended neurophysiological protocol and particularly segmental and compar ative tests. The study also evaluated the clinical features of carpal tunne l syndrome (CTS) diagnosed by these tests, using validated physician- and p atient-oriented measurements. The study group was composed of 740 patients for a total of 1123 idiopathic CTS hands. Overall, the sensitivity of stand ard tests (median digit-wrist sensory conduction velocity and wrist-thenar distal motor latency) was 83.5%. Comparative/segmental tests disclosed abno rmal findings in a further 11.4% of cases, providing CTS electrodiagnosis i n about 7 of 10 "standard negative" cases. The overall sensitivity of the e lectrodiagnostic protocol was 94.9%. The CTS population diagnosed by segmen tal/comparative tests had a clinical picture characterized by a high percen tage of pain, and severe discomfort but no limitation in functional daily a ctivity. Our data confirm the usefulness of a complete neurophysiological a ssessment by using segmental/comparative tests when standard tests yield no rmal results.