Distal nerve transfer for thenar palsy: A cadaveric study

Abstract

Introduction Severe proximal median nerve palsies often result in irreversible thenar atrophy and thumb abduction function loss. Tendon transfer involves substantial limitations and challenges; but, distal nerve transfer may provide an alternative treatment. Our goal was to validate the anatomical suitability of two distal ulnar nerve branches for thenar muscle reanimation. Materials and Methods We assessed nerve transfer to the recurrent branch of median nerve (RMN) in 16 embalmed cadaveric hands. The ulnar motor branch to the flexor digiti minimi brevis (FDMBn) and the ulnar motor branch to the third lumbrical (3rdLn) were assessed for transfer. Coaptation success was measured by the overlap of the nerve donor with the RMN and correspondence of nerve diameters. Results The mean transferable length and width of the RMN were 20.7 ± 4.5 and 1.0 ± 0.3 mm, respectively. We identified an average of three branches in the branching anatomy from the ulnar nerve to the hypothenar muscles. The maximal transferable lengths and widths of the FDMBn and the 3rdLn were 13.8 ± 4.4 and 0.5 ± 0.1 mm and 24.1 ± 6.4 and 0.4 ± 0.1 mm, respectively. The overlap with the RMN of the FDMBn and 3rdLn was 9.0 ± 3.6 (2.0–15.3) and 17.8 ± 6.0 (4.7–27.5) mm, respectively. Conclusions This anatomical study demonstrates the feasibility of distal nerve transfers between the ulnar and median nerves in the hand for reanimation of thenar muscles. Ulnar motor donors of the BrFDMBn and 3rdLn likely represent the least morbid donors with short distances for regeneration and a single coaptation repair.

WITHDRAWN: Opponensplasty Using Distal Nerve Transfer in High Median Nerve Injuries: a Case Series

“…Moreover, the synergistic activation of fth nger palmar exion could facilitate relearning of thumb opposition and palmar abduction. [15] Nevertheless, the diameters of these two branches are substantially smaller than the RMN.…”

“…Distal nerve transfer for opponensplasty yields more rapid recovery of thumb function and motor strength, limited antagonistic co-contraction, reinnervation of all thenar muscles, and reversal of atrophy. Notably, in cases in which nerve transfer fails, tendon transfer is still available [15,17]. Nerve transfer to the thenar muscles should be done before motor endplate degeneration.…”

“…Tendon or muscle transfer may be the last option for opponensplasty. The main unfavorable concerns about tendon transfers are prolonged immobilization of small joints which leads to contracture, requirement of extensive hand therapy, abnormal biomechanics, poor cosmesis, and failure [15]. Abductor digiti minimi muscle transfer can well restore abduction, but rotation and exion are somewhat less well achieved [16].…”

“…Cadaveric studies have been shown that the extensor indicis proprius branch of the posterior interosseous nerve, the ulnar motor branch to the exor digiti minimi brevis, and the ulnar motor branch to the third lumbrical may be used as a donor for reanimation of thenar muscles but the clinical e cacy of these donor has not been shown yet.) [15].…”