Transfer of extensor digiti minimi and extensor carpi ulnaris nerve branches to the intrinsic motor nerve branches: A histological study on cadaver

In cases of high ulnar and median nerve palsy, result of nerve repair in term of intrinsic muscle recovery is unsatisfactory. Distal nerve transfer can alleviate the regeneration time and improve the results. Transfer of the extensor digiti minimi (EDM) and extensor carpi ulnaris (ECU) nerve branches to the deep branch of ulnar nerve (DBUN)/recurrent branch of median nerve (RMN) at wrist had been used to restore intrinsic hand function but, incomplete recovery occurred. The axon count at the donor nerve has a strong influence on the final results.

This cadaveric study aims to analyses the histology of this nerve transfer to evaluate whether these donor nerves are suitable for this transfer or another donor nerve may be considered.

Ten cadaveric upper limbs dissected to identify the location of the EDM, ECU, RMN and DBUN. Surface area, fascicle count, and axon number was determined by histological methods.

The mean of axon number in the EDM, ECU, RMN and DBUN branches was 5931, 7355, 30960 and 35426, respectively. In this study, the number of axons in the EDM and ECU branches was 37% (13281/35426) of that in the DBUN. Also, the number of axons in the EDM and ECU branches was 42% (13281/30960) of that in the RMN.

The axon count data showed an unfavorable match between the EDM, ECU and DBUN/RMN. Therefore, it is suggested that another donor nerve with higher axon number to be considered.

Cadaver study (histological study).