[Isolated severance of the intrinsic motor branch of the ulnar nerve caused by stab injuries to the hand: A report of three cases].

Laceration of the deep intrinsic motor branch of the ulnar nerve below the Guyon canal is rarely seen in penetrating injuries of the hand. We report three patients (1 woman, 2 men) who underwent microsurgical repair for isolated injuries to the motor nerve branch of the ulnar nerve due to penetrating injuries to the hypothenar area of the hand. Two patients had normal sensation. All the patients had intrinsic muscle paralysis and claw deformity of some fingers, with significantly weakened grip and pinch strengths. Exploration showed isolated severance of the deep intrinsic motor branch of the ulnar nerve. One patient underwent end-to-end repair with epiperineural suture technique. Two patients required bridging with a sural nerve graft from the leg for 2-cm and 4-cm gaps, respectively, that occurred following nerve excision. During the follow-up period, grip and pinch strengths of all the patients approximated to the values of the normal side. Intrinsic muscle function and abduction and adduction of fingers recovered in two patients, whereas in one patient finger adduction was not reversible and claw deformity persisted in one finger even after two years.