Evaluation of Hand Intrinsic Muscles Functional Recovery After Distal Neurotization of Ulnar Nerve

• ulnar nerve injuries result in loss of both the sensory and motor elements within the hand. these injuries can be classified by the site of injury into low injuries and high injuries. In low ulnar nerve injuries, the nerve is injured distal to the motor branch of the Flexor carpi ulnaris (FCU) and motor branch to the Flexor digitorum profundus (FDP) of the ring and little fingers. In low injuries, sensation is lost in palmar ulnar hand and paralysis occurs usually to all 7 interossei, the ulnar 2 lumbrical, the 3 hypothenar, the adductor pollicis, and the deep head of the flexor pollicis brevis muscles .
• After peripheral nerve lesion axonal regeneration is at a rate of 1-2 mm/day. Because muscle fibers undergo irreversible changes after 12 months of denervation, it is important that treatment be undertaken as early as possible for successful functional recovery .
• "Babysitting" nerve fiber transfers can be defined as giving fibers from a healthy donor trunk to a denervated recipient trunk, in order to allow these fibers reach the distal effectors to avoid atrophy; such a procedure has originally been described together with partial neurotomy and has been found to be efficient both in experimental and clinical studies
• As far as it concerns proximal ulnar nerve injuries, babysitting by end-to-side nerve transfer has proven effective in 1 of the 3 series reported, where Colonna et al. analyzed an alternative Martin Grubertype( type of of operation) connection created by a bridge nerve graft between median (donor) and ulnar (recipient) trunks in the distal forearm, which gave interesting, but not ideal results ; "supercharged" reverse end-to side nerve transfers have been reported in latter studies . another person reported 7 cases of distal anterior interosseous to ulnar nerve end-to-end coaptation together with palmar cutaneous branch of the median nerve to the ulnar nerve above the wrist in a previous paper . it has not yet been well-established whether end-to-end or end-to-side gives better results.

nowadays, surgeons performing this type of surgery complain inconsistent outcomes, maybe as an effect of the discrepancy between the number of fibers in donor nerves and those in the recipient one