Brachialis to Anterior Interosseous Nerve Transfer: Comprehensive Anatomic Rationale.

BACKGROUND AND

OBJECTIVES

Distal nerve transfers for muscle reinnervation and restoration of function after upper and lower motor neuron lesions are a well-established surgical approach. The brachialis to anterior interosseous nerve (BrAIN) transfer is performed for prehension reanimation in lower brachial plexus and traumatic cervical spinal cord injuries. The aim of the study is to shed light on the inconsistent results observed in patients who undergo the BrAIN transfer.

METHODS

An anatomic dissection was conducted on 30 fresh upper limb specimens to examine the intraneural topography of the median nerve (MN) in the upper arm at the level of the BrAIN transfer and the presence of intraneural fascicular interconnections distally.

RESULTS

Fascicular interconnections between the AIN and other MN branches were consistently found in the distal third of the upper arm. The first interconnection was at 3.85 ± 1.82 cm proximal to the interepicondylar line, and the second one, after further proximal neurolysis, was at 9.45 ± 1.16 cm from the interepicondylar line. Intraneural topography of the AIN at the transfer level varied, with dorsomedial, dorsolateral, and purely dorsal locations observed.

CONCLUSION

Consistent fascicular interconnections between the AIN and MN branches and intraneural topography variability of the MN may lead to aberrant reinnervation.