Study of carpal tunnel syndrome in peripheral neuropathy with comparison of two methods: Inching method and second lumbrical-interossei test

Abstract

Diabetes mellitus is the most common metabolic disease. The carpal tunnel syndrome (CTS) occurs frequently in this disease. In diabetes mellitus due to effects of generalized neuropathy on peripheral nerves, the diagnosis of CTS with conventional EDX criteria (onset latency of median SNAP or distal latency of median CMAP) is challenged, so another methods such as 2nd lumbrical-interossei test is used. On the other hand Inching method is a technique in which used for diagnosis and determining the site of compression in carpal tunnel. The purpose of the present study is to evaluate diagnostic value of the inching method and 2nd lumbrical-interossei test in patients with diabetic peripheral neuropathy and signs or symptoms of carpal tunnel syndrome. Thirty hands with history of diabetes mellitus and signs and symptoms of CTS that confirmed diagnosis of peripheral neuropathy with conventional electro-diagnosis were evaluated. Then for diagnosis of CTS, sensory and motor median distal latencies were measured by nerve conduction study. In the next step, inching method and second lumbrical-interossei test was performed for all hands and sensitivity and specificity of two tests was calculated. Mean age of participants was 53.87 ± 11.53 years (range 26 to 70 years). Ten participants were female and 6 participants were male. The sensitivity and specificity of inching method in this study were 95.65 and 85.71, respectively and the results for second lumbrica-interossei test 73.91 and 71.42 were calculated. In this study, we showed the inching method is more sensitive and specific than second lumbrical-interossei test in diagnosis of CTS in diabetic peripheral neuropathy with sensitivity and specificity 95.65 and 85.71, respectively and also the sensitivity of inching method was greater than specificity.