Microsurgical neurolysis: its anatomical and physiological basis and its classification.

Neurolysis is a procedure which has to be performed if the gliding apparatus of a peripheral nerve does not function, and consequently, adhesions and fibrosis develop. The gliding tissue has to provide the ability for the nerve to adapt to the different position of the extremity by longitudinal passive movement. The paraneurium provides movements between the nerve and the surrounding tissue; the interfascicular epineurium provides the possibility of the movement within the nerve. Internal neurolysis is defined as surgery within the nerve if the epifascicular epineurium is completely transected. A classification of different degrees of fibrosis is given with special reference to the procedure which has to be done in each case. Neurolysis is a step-wise procedure with the aim to decompress the fascicles and which is immediately stopped if this aim is achieved. In very severe cases, if the gliding tissue does not regenerate, a gliding tissue flap to envelope the nerve may solve the problem.