Leprosy affects the tibial nerves diffusely from the middle of the thigh to the sole of the foot, including skip lesions

This study investigated where leprosy affects the posterior tibial nerve an d whether neurolysis is beneficial. Nine patients with bilateral posterior tibial leprous neuropathy with no sensorimotor recovery were studied. Preop erative sensory-muscle and nerve conduction velocity testing revealed the t arsal tunnel to be the site of a severe lesion in all cases. During surgery , the most proximal site of the nerve lesion was detected by electrically s timulating the spinal roots from the second lumbar nerve to the fourth sacr al nerve, evoking efferent mixed nerve compound action potentials that were recorded from the exposed tibial nerve. In all patients, the nerve compoun d action potentials became normal only proximal to the sciatic nerve bifurc ation. Epineuriotomy within these seemingly unaffected segments revealed fi brosis of the interfascicular epineurium. Interfascicular neurolysis was pe rformed on all affected segments. A 2-year follow-up showed an increase in girth of the proximal calf musculature in six of eight patients (the ninth patient had no recordable nerve conduction velocity). It was concluded that (1) leprosy affects the tibial nerves in a scattered way from the sciatic nerve main trunk distally to the exit of the tarsal tunnel; and (2) interfa scicular, microsurgical neurolysis is beneficial provided that it is perfor med on all affected nerve segments.