Anterior Interosseous Nerve to Ulnar Nerve Transfer: A systematic review

Assessment, patient selection, and rehabilitation of nerve transfers

Peripheral nerve injuries are common and can have a devastating effect on physical, psychological, and socioeconomic wellbeing. Peripheral nerve transfers have become the standard of care for many types of peripheral nerve injury due to their superior outcomes relative to conventional techniques. As the indications for, and use of, nerve transfers expand, the importance of pre-operative assessment and post-operative optimization increases. There are two principal advantages of nerve transfers: (1) their ability to shorten the time to reinnervation of muscles undergoing denervation because of peripheral nerve injury; and (2) their specificity in ensuring proximal motor and sensory axons are directed towards appropriate motor and sensory targets. Compared to conventional nerve grafting, nerve transfers offer opportunities to reinnervate muscles affected by cervical spinal cord injury and to augment natural reinnervation potential for very proximal injuries. This article provides a narrative review of the current scientific knowledge and clinical understanding of nerve transfers including peripheral nerve injury assessment and pre- and post-operative electrodiagnostic testing, adjuvant therapies, and post-operative rehabilitation for optimizing nerve transfer outcomes.

Updates in peripheral nerve surgery of the upper extremity: diagnosis and treatment options

The loss of function resulting from peripheral nerve injuries confers a significant burden to the patient and society. The treatment of peripheral nerve injuries requires an accurate diagnosis and formulation of a functional reconstructive plan. Advances in peripheral nerve imaging complement electrodiagnostic studies, and provide us with detailed information regarding the status of nerve injury, repair, and regeneration in order to prognosticate recovery and determine the need for surgical intervention. When direct nerve repair is not possible, the methods for bridging a nerve gap are the nerve autograft, allograft and conduit. While current research supports the use of conduits and nerve allografts for shorter nerve gaps, the nerve autograft still remains the gold standard for bridging a nerve gap. When direct nerve repair or nerve grafting fails, or is anticipated to be insufficient, nerve transfers are an alternative for reconstruction. Knowledge of axonal counts, upper limb innervation patterns, location and clustering of upper limb peripheral nerves allows for the design of new nerve transfers. The options of nerve transfers for radial, ulnar and median nerve injuries are outlined, as well as their outcomes. Nerve transfers are an attractive option for restoring motor and sensory function while minimizing donor site morbidity. However, one must consider their limitations, and preserve donor sites for secondary tendon transfer options. This article presents the latest information regarding the imaging of peripheral nerves, methods to bridge a nerve gap, and nerve transfers to aid the peripheral nerve surgeon in choosing a reconstructive plan.

Distal Nerve Transfers in Hand and Forearm for Traumatic Brachial Plexus and Peripheral Nerve Injuries: A Narrative Review

Background

Various studies published good outcomes in brachial plexus injuries using nerve transfers for shoulder and elbow functions. However, little is known about the outcome of the distal nerve transfers in the forearm and hand. Targeting the nerve distally produces an early return of function in brachial plexus and peripheral nerve injuries (BPPNI). Therefore, researchers have focused on nerve transfers from the motor branches of the ulnar, median, and radial nerve. Similarly, sensory reinnervation is also obtained by potential donor transfers in the forearm and hand. There have been various attempts by surgeons to target the muscle and promote early reinnervation by different nerve transfers.

Conclusions

The distal nerve transfers in the forearm and hand are promising when performed early. It effectively restores hand and forearm functions and may be considered a better option than tendon transfer, which has a one-tendon-one function. This narrative review article discusses the different distal nerve transfers for various presentations of BPNNI.

Reverse End-to-Side Transfer to Ulnar Motor Nerve: Evidence From Preclinical and Clinical Studies

The disappointing outcomes of conventional nerve repair or grafting procedures for proximal ulnar nerve injuries have led the scientific community to search for better alternatives. The pronator quadratus branch of the anterior interosseous nerve has been transferred to the distal ulnar motor branch in a reverse end-to-side fashion with encouraging results. This transfer is now becoming commonly used as an adjunct to cubital tunnel decompression in patients with compressive ulnar neuropathy, underscoring the need for this knowledge transfer to the neurosurgical community. However, the mechanism of recovery after these transfers is not understood completely. We have reviewed the existing preclinical and clinical literature relevant to this transfer to summarize the current level of understanding of the underlying mechanisms, define the indications for performing this transfer in the clinic, and identify the complications and best practices with respect to the operative technique. We have also attempted to identify the major deficiencies in our current level of understanding of the recovery process to propose directions for future research.

Surgery as an Effective Therapy for Ulnar Nerve Neuropathic Pain Caused by Gunshot Wounds: A Retrospective Case Series

BACKGROUND

Peripheral nerve injuries remain a major medical problem worldwide and are associated with multiple causes, including gunshot wounds (GSWs), which are the second most common cause of brachial plexus injuries in peacetime and the main, or only, cause reported in wartime studies. The ulnar nerve (UN) is one of the most affected nerves. Peripheral nerve trauma may cause intense neuropathic pain, which is very difficult to control. Particularly UN gunshot injuries may impact individual daily life, as injuries to this nerve result in both sensory and motor deficits within the hand. We evaluated the improvement of neuropathic pain after surgical treatment in a consecutive series of 20 patients with UN injury due to GSWs.

METHODS

This single-center, retrospective, consecutive case series included 20 patients with UN injuries due to GSWs, who presented with excruciating neuropathic pain and underwent surgical treatment between 2005 and 2017.

RESULTS

Of injuries, 13 occurred in the right upper limb (65%); 12 patients had a high UN injury (60%). Regarding associated injuries, 8 patients had bone injuries (40%), and 4 patients had arterial injuries (20%). A neuroma in continuity was detected in 8 cases (40%), and 4 patients (20%) had shrapnel lodged within the UN. All patients had severe neuropathic pain and functional deficit, with a mean visual analog scale score of 8.45 ± 1.4 and a mean reduction of 6.95 points 12 months after surgery; 10 patients (50%) had a British Medical Research Council score ≥M3.

CONCLUSIONS

Surgery is an effective treatment for neuropathic pain from GSWs. Early isolated external neurolysis is associated with better pain management and functional outcomes postoperatively.

Distal anterior interosseous nerve to ulnar nerve motor branch reverse end-to-side transfer in a case of severe ulnar neuropathy

Reverse end-to-side (RETS) distal transfer is gaining popularity in cases of proximal nerve damage with the nerve in continuity, allowing the nerve to potentially retain its ability to regenerate and recover. While preserving the original axon pool, RETS could provide an additional pool of motor axons and/or possibly "babysit" the muscle endplates and distal denervated nerve Schwann cells until reinnervation from the original pool occurs. The authors present a video demonstrating anterior subcutaneous transposition of the ulnar nerve at the elbow coupled with a distal anterior interosseous nerve to ulnar nerve RETS in a case of severe posttraumatic ulnar neuropathy at the elbow. The video can be found here: https://stream.cadmore.media/r10.3171/2022.9.FOCVID2282.