Assessment of Functional Outcomes of Distal Nerve Transfers in Brachial Plexus and Peripheral Nerve Injuries Using Histomorphometric Parameters As Prognostic Indicators

Introduction In brachial plexus and peripheral nerve injuries, distal nerve transfers provide an early return of function with minimal donor nerve-related morbidity. In the present study, various histomorphometric parameters have been evaluated to prognosticate the surgical outcomes of distal nerve transfers. Materials and Methods Thirty patients with brachial plexus and peripheral nerve injuries were treated by distal nerve transfers. Prior to the nerve transfer approximately 0.5 cm segment from the distal end of donor nerve and proximal end of recipient nerve were sectioned and evaluated for histomorphometry. Relevant histopathological parameters were used to predict the functional outcomes. Results Donor nerve specimens showing good axonal counts had better functional gains. A lack of fibrosis in the suprascapular and spinal accessory nerves resulted in better shoulder functions with majority of patients having upper brachial plexus injury restoring more than 150 degree of active shoulder abduction and abduction strength of at least M4, which was in contrast to patients displaying fibrosis. Inflammation was present in the donor and recipient nerves in majority of cases, though its correlation with functional gains was not as significant as the number of axons and amount of fibrosis. Presence of demyelination and vasculitis had little bearing in the ultimate functional outcomes. Conclusions This study revealed that the histomorphometric factors have an important role in predicting the functional outcomes in nerve transfers. An understanding of the histomorphometric status of the donor and recipient nerves can form a basis for early prediction of functional outcomes.