TARSAL TUNNEL SYNDROME Tarsal tunnel syndrome: A type of compression neuropathy (nerve disease due to compression of the nerve) in the ankle and foot. Tarsal tunnel syndrome (TTS) is similar to the better-known carpal tunnel syndrome (CTS) caused by compression and irritation of the median nerve within the carpal tunnel, a bony canal in the palm side of the wrist that provides passage for the median nerve to the hand. The irritation of the median nerve is specifically due to