Native paraneurial tissue and paraneurial adhesions alter nerve strain distribution in rat sciatic nerves.

Paraneurial adhesions have been implicated in the pathological progression of entrapment neuropathies. Surgical decompression of adhesions is often performed, with the intent of restoring nerve kinematics. The normal counterpart of adhesions, native paraneurium, is also thought to influence nerve deformation and mobility. However, influences of native or abnormal paraneurial structures on nerve kinematics have not been investigated. We measured regional strains in rat sciatic nerves before and immediately after decompression of native paraneurial tissue, and before and after decompression of abnormal paraneurial adhesions, which formed within 6 weeks of the initial decompression. Strain was significantly higher in the distal-femoral than in the mid-femoral region of the nerve before either decompression. Decompression of native and abnormal paraneurial tissue removed this regional strain difference. Paraneurial tissues appear to play a major role in distributing peripheral nerve strain. Normal nerve strain distributions may be reconstituted following decompression, even in the presence of paraneurial adhesions.