The term internal neurolysis means removal of fibrotic tissue inside a nerve trunk. Unfortunately the term was used for procedures with complete isolation of fascicles with all consequences like damage of links between the fascicle and impairment of blood supply. The conclusion based on some negative experiences that all surgery within a nerve trunk has to be avoided cannot be accepted. Neurolysis within a nerve trunk, id est within the epineurium, is a step-wise procedure to decompress fascicles from a constricting fibrosis. It stops immediately if this aim is achieved or continues with resection and reconstruction if an irreparable damage is present. It is better to use terms that describe exactly what was done and abandon the ill-defined term "internal neurolysis". Fibrosis of the paraneurium remains outside the epineurium but causes the same consequences as fibrosis of the epineurium.