برري الكترودياگنوزيس سندرم تونل تارس به روش مقايسه عصب به عصب

ELECTRODIAGNOSTIC STUDY OF TARSAL TUNNEL SYNDROME BY NERVES TO NERVES COMPARISON METHOD

Tarsal tunnel syndrome (TTS) is a defined as entrapment of the tibial nerve and its plantar divisions under neath the flexor retinaculum as the nerve curves behind the medial malleolus. The purpose of this study was to compare the involved nerves with intact nerves in TTS. This technique allows the subject to serve as his or her own control for early diagnosis. The subjects included 50 healthy adults(25 male,25 female) with an age range of 19 to 54 years and average age of 36 years. Each of these volunteers had no symptoms or signs of neuropathy . To determine compound muscle action potential (CMAP) , the nerves were stimulated proximal and distal to the tarsal tunnel .The upper limit of normal for proximal latency, distal latency and across tunnel latency was 8.5 ms, 6 ms and 3.Sms respectively (mean ± 2SD). To determine compound nerve action potential (CNAP) , plantar nerve was stimulated at the sole of the foot. Recording point was located behind the medial malleolus. The upper limit of normal for plantar CNAP latency was 3.7 ms(mean ± 2SD) .The upper limit of normal for side to side diffrence was lms for across tunnel CMAP latency ,0.8 ms for medial plantar CNAP latency and 0.9ms for lateral plantar CNAP latency (mean ± 2SD) . This value for ipsilateral plantar CNAP to sural sensory nerve action potential was 0.8ms (mean ± 2SD). This study offers a new technique in diagnosis of TTS.