The effect of a distal site of compression on neural regeneration

Assessment, management, and rehabilitation of traumatic peripheral nerve injuries for non-surgeons

Electrodiagnostic evaluation is often requested for persons with peripheral nerve injuries and plays an important role in their diagnosis, prognosis, and management. Peripheral nerve injuries are common and can have devastating effects on patients' physical, psychological, and socioeconomic well-being; alongside surgeons, electrodiagnostic medicine specialists serve a central function in ensuring patients receive optimal treatment for these injuries. Surgical intervention-nerve grafting, nerve transfers, and tendon transfers-often plays a critical role in the management of these injuries and the restoration of patients' function. Increasingly, nerve transfers are becoming the standard of care for some types of peripheral nerve injury due to two significant advantages: first, they shorten the time to reinnervation of denervated muscles; and second, they confer greater specificity in directing motor and sensory axons toward their respective targets. As the indications for, and use of, nerve transfers expand, so too does the role of the electrodiagnostic medicine specialist in establishing or confirming the diagnosis, determining the injury's prognosis, recommending treatment, aiding in surgical planning, and supporting rehabilitation. Having a working knowledge of nerve and/or tendon transfer options allows the electrodiagnostic medicine specialist to not only arrive at the diagnosis and prognosticate, but also to clarify which nerves and/or muscles might be suitable donors, such as confirming whether the branch to supinator could be a nerve transfer donor to restore distal posterior interosseous nerve function. Moreover, post-operative testing can determine if nerve transfer reinnervation is occurring and progress patients' rehabilitation and/or direct surgeons to consider tendon transfers.

Distal Entrapment of Regenerating Peripheral Nerves After a Proximal Injury: A Case Series and Review of the Literature

A complication of peripheral nerve injuries, of which there exists limited discourse, is the entrapment of the nerve as it regenerates from the site of injury to its end target, resulting in the arrest of axon regeneration and a consequent reduction of functional recovery. This proof-of-concept paper reports a review of the relevant literature alongside a case series of patients who presented with this phenomenon and who were treated with targeted peripheral nerve decompression. Three cases were identified prospectively. The baseline function was recorded pre-and post-operatively. Recovery was assessed using various tools, including the Medical Research Council (MRC) motor grading, ten-test sensory testing, Tinel's sign progression, a visual analogue scale (VAS) for pain, and the Impact of Hand Nerve Disorders (I-HaND) patient-reported outcome measure (PROM). The first case sustained a brachial plexus injury and received decompression at the pronator fascia, carpal tunnel, cubital tunnel, and Guyon's canal. The second case sustained a sciatic nerve injury and was managed with peroneal and tarsal tunnel decompressions. The final case sustained a suprascapular nerve injury and underwent decompression at the suprascapular ligament. In all these cases, motor function, sensory function, and pain (depending on the nerve's original components) improved following decompression. A literature review revealed seven relevant studies, including four case reports, two cohort studies, and a pre-clinical animal study. These cases, and those identified in our review of the literature, suggest that targeted decompressive surgery can be an appropriate treatment for patients who display signs of stalled neural regeneration. This study adds to the limited evidence of this phenomenon and highlights the challenges in proving the efficacy of decompressive surgery for this specific complication. This study is limited by the number of cases included, the heterogeneity of nerve injuries presented, and its observational nature. There is a clear need for further research into this phenomenon, and the authors are working towards developing a prospective study that will investigate the indications, value, predictors of success, and practicality of decompression surgery for this complication of peripheral nerve injury.

Multihit Injury of the Radial Nerve in a 62-year-old Woman: A Case Report

We report the case of a 62-year-old female patient with a triple-crush radial nerve injury, diagnosed in subsequent order following a fracture of the left humerus. The patient developed flaccid paralysis of all muscles innervated by the left radial nerve except the triceps brachii and reported a sensory deficit corresponding to the innervation territories of the posterior nerve of the forearm as well as the superficial branch of the radial nerve. Following neurolysis of the radial nerve at the humerus level, wrist extension as well as sensory perception on the dorsal aspect of the forearm recovered, but finger extension and thumb abduction were still impossible. Following neurological evaluation and nerve ultrasound, supinator syndrome was diagnosed and the patient underwent decompression surgery. Following surgical decompression, motor recovery was observable but a sensory deficit remained in the area innervated by the superficial branch of the radial nerve. In consequence, the third crush injury of the left radial nerve, that is, Wartenberg syndrome or cheiralgia paraesthetica was diagnosed. Decompression surgery of the superficial branch of the radial nerve was performed and the patient reported profound amelioration of her sensory symptoms during a follow-up examination at our outpatient clinic 6 weeks postoperatively.

Pathological findings identified during the posterior approach to the spinal accessory nerve after high-energy trauma

The spinal accessory to suprascapular nerve transfer is a key procedure for restoring shoulder function in upper brachial plexus injuries and is typically undertaken via an anterior approach. The anterior approach may miss injury to the suprascapular nerve about the suprascapular notch, which may explain why functional outcomes are often limited. In 2014 we adopted a posterior approach to enable better visualization of the suprascapular nerve at the notch. Over the next 6 years we have used this approach for 20 explorations after high-energy trauma. In 7/20 we identified abnormalities at the level of the suprascapular ligament, which we would not have identified with an anterior approach: there were two ruptures, two neuromas-in-continuity and three cases of scar encasement, necessitating neurolysis. Nerve transfer could be undertaken distal to the suprascapular notch, bypassing the site of injury. These pathological findings support the wider adoption of the posterior approach in cases of high-energy trauma.Level of evidence: IV.

Pure neuritic leprosy presenting as ulnar nerve neuropathy: a case report of electrodiagnostic, radiographic, and histopathological findings

Hansen’s disease, or leprosy, is a chronic infectious disease with many manifestations. Though still a major health concern and leading cause of peripheral neuropathy in the developing world, it is rare in the United States, with only about 150 cases reported each year. Nevertheless, it is imperative that neurosurgeons consider it in the differential diagnosis of neuropathy.

The causative organism is Mycobacterium leprae, which infects and damages Schwann cells in the peripheral nervous system, leading first to sensory and then to motor deficits. A rare presentation of Hansen’s disease is pure neuritic leprosy. It is characterized by nerve involvement without the characteristic cutaneous stigmata. The authors of this report describe a case of pure neuritic leprosy presenting as ulnar nerve neuropathy with corresponding radiographic, electrodiagnostic, and histopathological data.

This 11-year-old, otherwise healthy male presented with progressive right-hand weakness and numbness with no cutaneous abnormalities. Physical examination and electrodiagnostic testing revealed findings consistent with a severe ulnar neuropathy at the elbow. Magnetic resonance imaging revealed diffuse thickening and enhancement of the ulnar nerve and narrowing at the cubital tunnel. The patient underwent ulnar nerve decompression with biopsy. Pathology revealed acid-fast organisms within the nerve, which was pathognomonic for Hansen’s disease. He was started on antibiotic therapy, and on follow-up he had improved strength and sensation in the ulnar nerve distribution.

Pure neuritic leprosy, though rare in the United States, should be considered in the differential diagnosis of those presenting with peripheral neuropathy and a history of travel to leprosy-endemic areas. The long incubation period of M. leprae, the ability of leprosy to mimic other conditions, and the low sensitivity of serological tests make clinical, electrodiagnostic, and radiographic evaluation necessary for diagnosis. Prompt diagnosis and treatment is imperative to prevent permanent neurological injury.

Median to radial nerve transfers for restoration of wrist, finger, and thumb extension

Radial nerve injury results in loss of wrist, finger, and thumb extension. Traditionally, radial nerve palsies that fail to recover spontaneously have been reconstructed with tendon transfers or nerve grafts. Nerve transfers are a novel approach to the surgical management of Sunderland grade IV and V radial nerve injuries. We describe our technique for median to radial nerve transfers. In this procedure, the flexor digitorum superficialis nerve is transferred to the extensor carpi radialis brevis nerve for wrist extension, and the flexor carpi radialis nerve is transferred to the posterior interosseous nerve for finger and thumb extension. Our experience with these nerve transfers has demonstrated excellent outcomes up to 10 months after injury. Indeed, unlike tendon transfers, median to radial nerve transfers have the potential to restore normal radial nerve function, including independent finger motion. Tension-free nerve coaptation and postoperative motor re-education are critical factors to achieving these successful outcomes.

Reverse end-to-side nerve transfer: from animal model to clinical use

PURPOSE

Functional recovery after peripheral nerve injury is predominantly influenced by time to reinnervation and number of regenerated motor axons. For nerve injuries in which incomplete regeneration is anticipated, a reverse end-to-side (RETS) nerve transfer might be useful to augment the regenerating nerve with additional axons and to more quickly reinnervate target muscle. This study evaluates the ability of peripheral nerve axons to regenerate across an RETS nerve transfer. We present a case report demonstrating its potential clinical applicability.

METHODS

Thirty-six Lewis rats were randomized into 3 groups. In group 1 (negative control), the tibial nerve was transected and prevented from regenerating. In group 2 (positive control), the tibial and peroneal nerves were transected, and an end-to-end (ETE) nerve transfer was performed. In group 3 (experimental model), the tibial nerve and peroneal nerves were transected, and an RETS nerve transfer was performed between the proximal end of the peroneal nerve and the side of the denervated distal tibial stump. Nerve histomorphometry and perfused muscle mass were evaluated. Six Thy1-GFP transgenic Sprague Dawley rats, expressing green fluorescent protein in their neural tissues, also had the RETS procedure for evaluation with confocal microscopy.

RESULTS

Nerve histomorphometry showed little to no regeneration in chronic denervation animals but statistically similar regeneration in ETE and RETS animals at 5 and 10 weeks. Muscle mass preservation was similar between ETE and RETS groups by 10 weeks and significantly better than negative controls at both time points. Nerve regeneration was robust across the RETS coaptation of Thy1-GFP rats by 5 weeks.

CONCLUSIONS

Axonal regeneration occurs across an RETS coaptation. An RETS nerve transfer might augment motor recovery when less-than-optimal recovery is otherwise anticipated.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic I.

Post-Cervical Decompression Parsonage-Turner Syndrome Represents a Subset of C5 Palsy: Six Cases and a Review of the Literature: Case Report

BACKGROUND:

Approximately 5% of cervical decompression cases are complicated by postoperative weakness. Parsonage-Turner syndrome (PTS) or neuralgic amyotrophy is known to be precipitated by surgery and unrelated to technical or structural issues. Our practice has seen a number of cases of PTS after cervical decompression surgery. In this case report, we discuss a series of such patients, highlighting the commonalities with the more frequently diagnosed C5 palsy. We conclude with our management algorithm.

CLINICAL PRESENTATION:

Six patients with post-cervical decompression PTS were referred to our institution during a 32-month period. All patients were examined physically, radiographically, and electromyographically and were followed for up to 2 years or until symptoms resolved. Conservative management was the rule, and surgical intervention, including nerve releases and nerve reconstruction, was undertaken in select circumstances. In the majority of patients (4 of 6 patients), pain management and physical therapy alone were used and achieved eventual resolution of pain and recovery of motor strength. The other 2 patients required adjunctive surgical procedures to maximize their outcomes.

CONCLUSION:

PTS accounts for a subset of patients experiencing postoperative weakness after cervical decompression operations. Although it is at times difficult to arrive at this diagnosis, an understanding of the history of PTS, among other causes of postoperative weakness, allows a structured approach to these patients. An evidence-based approach to management helps provide the best outcome for a given patient.

Median to radial nerve transfer to restore wrist and finger extension: technical nuances

BACKGROUND

Traditional methods for restoring finger and wrist extension following radial nerve palsy include interposition nerve grafting or tendon transfers. We have described the utilization of distal nerve transfers for the restoration of radial nerve function in the forearm.

OBJECTIVE

We review the neuroanatomy of the forearm and outline the steps required for the implementation of this transfer.

METHODS AND RESULTS

We use a step-by-step procedural outline and detailed photographs, line drawings, and video to describe the procedure.

CONCLUSION

This approach is technically feasible and is a reconstructive option for patients with this nerve deficit.

DISTAL MEDIAN TO ULNAR NERVE TRANSFERS TO RESTORE ULNAR MOTOR AND SENSORY FUNCTION WITHIN THE HAND

ULNAR NERVE INJURIES can be severely debilitating and result in weakness of wrist flexion, loss of hand intrinsic function, and ulnar-sided hand anesthesia. When these injuries produce a Sunderland fourth- or fifth-degree injury, surgical intervention is necessary for functional recovery. Traditional methods for restoring hand intrinsic function after ulnar nerve palsy include interposition nerve grafting for timely presentations or tendon transfers for either complex injuries or late presentations. Distal median to ulnar nerve transfer to restore ulnar intrinsic nerve muscle function was first performed in 1991. We continue to find it advantageous for recovery of ulnar intrinsic function in patients with proximal ulnar nerve injuries by significantly reducing denervation time and directing motor fibers into this critical motor distribution. Several case reports have been published discussing the concept behind this approach, but none have outlined the specific steps involved in this operation. As such, this article discusses our operative methodology behind the distal median to ulnar neurotization, which includes a Guyon canal release, identification of donor median and recipient ulnar nerve fascicular anatomy within the forearm, and an operative tutorial on proper technique for neurotization to restore both ulnar motor and sensory function. We present the technical nuances of the following nerve transfers to restore ulnar nerve function within the hand: anterior interosseous nerve to deep motor branch of ulnar nerve, third webspace sensory contribution of median nerve to volar sensory component of ulnar nerve, and end-to-side reinnervation of ulnar dorsal cutaneous to the remaining median sensory trunk.

Nerve transfers in the forearm and hand

In the forearm, vital and expendable functions have been identified, and tendon transfers use these conventions to maximize function and minimize disability. Using similar concepts, distal nerve transfers offer a reconstruction that often is superior to reconstruction accomplished by traditional grafting. The authors present nerve transfer options for restoring motor and sensory deficits within each nerve distribution on the forearm and hand.

Patient outcome after common peroneal nerve decompression

Object

This study examines common peroneal nerve decompression and its effect on nerve function.

Methods

Fifty-one peroneal nerve decompressions were retrospectively reviewed. All patients were evaluated preoperatively and postoperatively for motor and sensory function of the peroneal nerve as well as for pain.

Results

Postoperatively, 40 (83%) of 48 patients who had preoperative motor weakness had improvement in motor function. Likewise, 23 (49%) of 47 patients who had sensory disturbances and 26 (84%) of 31 patients who had preoperative pain improved after surgical decompression of the peroneal nerve.

Conclusions

Common peroneal nerve decompression is a useful procedure to improve sensation and strength as well as to decrease pain.

Distal nerve entrapment following nerve repair

Failure of nerve repair or poor functional outcome after reconstruction can be influenced by various causes. Besides improper microsurgical technique, fascicular malalignment and unphysiologic tension, we found in our clinical series that a subclinical nerve compression distal to the repair site can seriously impair regeneration. We concluded that the injured nerve, whether from trauma or microsurgical intervention, could be more susceptible to distal entrapment in the regenerative stage because of its disturbed microcirculation, swelling and the increase of regenerating axons followed by increased nerve volume. In two cases we found the regenerating nerve entrapped at pre-existing anatomical sites of narrowing resulting in impaired functional recovery. In both cases the surgical therapy was decompression of the distal entrapped nerve and this was followed by continued regeneration. Thorough clinical and electrophysiologic follow-up is necessary to detect such adverse compression effects and to distinguish between the various causes of failed regeneration. Under certain circumstances primary preventive decompression may be beneficial if performed at the time of nerve coaptation.