Internal neurolysis of the upper
brachial plexus. A scarred nerve
(above, asterisk) is opened and
scar tissue is removed (below).

When nerves are stretched, or chronically compressed, internal scarring and swelling may occur. In select patients, the outer sheath of the affected nerve is opened with a microscope. Scar tissue within the nerve may also be removed. This is called an internal neurolysis.

For swollen nerves, opening this outer sheath relieves pressure and promotes blood flow in the nerve. The nerve is left open. Internal neurolysis is also performed after some traumatic injuries, so that select nerve fascicles (not the complete nerve) can be repaired with a graft (i.e., a split nerve repair).

Injured tibial following a split
graft repair where only select
fascicles are replaced with nerve
grafts. Arrowheads represent graft sutures.