O-2-31. The usefulness of electrophysiological examinations in the diagnosis of tarsal tunnel syndrome

Abstract

TTS is usually diagnosed based on clinical symptoms and signs, and electrodiagnostic (EDx) tests, typically nerve conduction studies. We aimed to present a case series of TTS and investigate the diagnostic role of EDx. We searched our EMG database from 2008 to 2016 with the keyword of TTS, and retrospectively reviewed clinical and EMG records of extracted patients. The entry criteria were: (1) clinical diagnosis of TTS by the referring doctor, (2) numbness of sole and a positve Tinel’s sign at the ankle, and (3) both the tibial motor conduction study (MCS) and plantar sensory conduction study (SCS) were conducted. Enrolled were 12 patients (20–82 years, 9 men and 3 women). Some EDx tests were abnormal in 8 patients. Plantar SCS was abnormal on the affected side in 5 patients. In 2 of them, tibial MCS showed a bilobed compound muscle action potential (CMAP) indicating the isolated delay of the medial plantar nerve. One patient had abnormal F wave, and 2 patients was shown denervation potentials in the FHB muscle. TTS is in general difficult to confirm electrodiagnostically, although this study supported the role of EDx. Bilobed tibial CMAP may be a previously undescribed sign of TTS.