Peripheral nerve injuries can result in devastating numbness and paralysis. Surgical repair strategies have historically focused on restoring the original anatomy with interposition grafts. Distal nerve transfers are becoming a more common strategy in the repair of nerve deficits as these interventions can restore function in months as opposed to more than a year with nerve grafts. The changes that take place over time in the cell body, distal nerve, and target organ after axotomy can compromise the results of traditional graft placement and may at times be better addressed with the use of distal nerve transfers. A carefully devised nerve transfer offers restoration of function with minimal (if any) detectable deficits at the donor site. A new understanding of cortical plasticity along with patient reeducation allow for good return of strength and function after nerve transfer.
Justin M. Brown, Manish N. Shah and Susan E. Mackinnon
Mark A. Mahan, Jaime Gasco, David B. Mokhtee and Justin M. Brown
Surgical transposition of the ulnar nerve to alleviate entrapment may cause otherwise normal structures to become new sources of nerve compression. Recurrent or persistent neuropathy after anterior transposition is commonly attributable to a new distal compression. The authors sought to clarify the anatomical relationship of the ulnar nerve to the common aponeurosis of the humeral head of the flexor carpi ulnaris (FCU) and flexor digitorum superficialis (FDS) muscles following anterior transposition of the nerve.
The intermuscular septa of the proximal forearm were explored in 26 fresh cadaveric specimens. The fibrous septa and common aponeurotic insertions of the flexor-pronator muscle mass were evaluated in relation to the ulnar nerve, with particular attention to the effect of transposition upon the nerve in this region.
An intermuscular aponeurosis associated with the FCU and FDS muscles was present in all specimens. Transposition consistently resulted in angulation of the nerve during elbow flexion when this fascial septum was not released. The proximal site at which the nerve began to traverse this fascial structure was found to be an average of 3.9 cm (SD 0.7 cm) from the medial epicondyle.
The common aponeurosis encountered between the FDS and FCU muscles represents a potential site of posttransposition entrapment, which may account for a subset of failed anterior transpositions. Exploration of this region with release of this structure is recommended to provide an unconstrained distal course for a transposed ulnar nerve.
Arvin R. Wali, Charlie C. Park, Justin M. Brown and Ross Mandeville
Peripheral nerve transfers to regain elbow flexion via the ulnar nerve (Oberlin nerve transfer) and median nerves are surgical options that benefit patients. Prior studies have assessed the comparative effectiveness of ulnar and median nerve transfers for upper trunk brachial plexus injury, yet no study has examined the cost-effectiveness of this surgery to improve quality-adjusted life years (QALYs). The authors present a cost-effectiveness model of the Oberlin nerve transfer and median nerve transfer to restore elbow flexion in the adult population with upper brachial plexus injury.
Using a Markov model, the authors simulated ulnar and median nerve transfers and conservative measures in terms of neurological recovery and improvements in quality of life (QOL) for patients with upper brachial plexus injury. Transition probabilities were collected from previous studies that assessed the surgical efficacy of ulnar and median nerve transfers, complication rates associated with comparable surgical interventions, and the natural history of conservative measures. Incremental cost-effectiveness ratios (ICERs), defined as cost in dollars per QALY, were calculated. Incremental cost-effectiveness ratios less than $50,000/QALY were considered cost-effective. One-way and 2-way sensitivity analyses were used to assess parameter uncertainty. Probabilistic sampling was used to assess ranges of outcomes across 100,000 trials.
The authors' base-case model demonstrated that ulnar and median nerve transfers, with an estimated cost of $5066.19, improved effectiveness by 0.79 QALY over a lifetime compared with conservative management. Without modeling the indirect cost due to loss of income over lifetime associated with elbow function loss, surgical treatment had an ICER of $6453.41/QALY gained. Factoring in the loss of income as indirect cost, surgical treatment had an ICER of −$96,755.42/QALY gained, demonstrating an overall lifetime cost savings due to increased probability of returning to work. One-way sensitivity analysis demonstrated that the model was most sensitive to assumptions about cost of surgery, probability of good surgical outcome, and spontaneous recovery of neurological function with conservative treatment. Two-way sensitivity analysis demonstrated that surgical intervention was cost-effective with an ICER of $18,828.06/QALY even with the authors' most conservative parameters with surgical costs at $50,000 and probability of success of 50% when considering the potential income recovered through returning to work. Probabilistic sampling demonstrated that surgical intervention was cost-effective in 76% of cases at a willingness-to-pay threshold of $50,000/QALY gained.
The authors' model demonstrates that ulnar and median nerve transfers for upper brachial plexus injury improves QALY in a cost-effective manner.
Anil Bhatia, Piyush Doshi, Ashok Koul, Vitrag Shah, Justin M. Brown and Mahmoud Salama
It is not uncommon for a severe traumatic brachial plexus injury to involve all 5 roots, resulting in a flail upper limb. In such cases, surgical reconstruction is often palliative, providing only rudimentary function. Nerve transfers are the mainstay of reconstructive strategies due to the predominance of root avulsions. Consistent results are obtained only for restoration of shoulder stability and elbow flexion, whereas restoring useful hand function remains a challenge. The transfer of the contralateral C-7 (cC-7) is commonly used in an attempt to restore basic hand function, but results are notoriously unreliable and inconsistent. Shu-feng Wang and colleagues recently proposed a potentially more successful permutation of this procedure. They advocated direct approximation of the cC-7 to the lower trunk on the paralyzed side, thus avoiding the interposition of nerve grafts. This technique involves a lengthy dissection of the cC-7 transfer across the midline via a prespinal route, as well as extensive mobilization of the ipsilateral lower trunk by cutting a subset of its branches, adducting the arm, and (if necessary) shortening the humerus. Each of these steps is indispensable to achieve direct approximation of the nerve ends. Many surgeons have tried to emulate Wang’s strategy. However, the technical difficulties involved have forced recourse to interposition of nerve grafts once again.
The authors report their observations in the first 22 patients in whom they performed this procedure. Direct cC-7 repair via the prespinal route was performed in 12 patients. Shortening of the humerus was necessary in 9 of these 12 patients. In 10 patients, a direct repair was not feasible and nerve grafting was performed. The median follow-up period was 26 months for the direct coaptation group and 28.5 months for the nerve graft group.
In the direct repair group, 10 of the 12 patients regained Medical Research Council Grade 3 flexion of the wrist and of the middle, ring, and little fingers, while the remaining 2 patients had Grade 2 function. Flexion appeared 12–14 months after the operation. At the latest follow-up, these patients could activate the wrist and hand without requiring significant augmentation maneuvers in the donor limb. In contrast, repair requiring interposition grafts resulted in Grade 3 strength in only 2 of 10 patients, while 7 had Grade 2 strength, and 1 experienced failure. In all grafted cases, the patient had to forcibly contract the contralateral pectoralis major and triceps muscles to produce the weak movements on the reconstructed side.
In this small series, the authors demonstrated a distinct advantage associated with the avoidance of grafts when transferring the cC-7 to restore hand function. The authors conclude that efforts to achieve direct approximation of the donor C-7 and the recipient lower trunk are necessary and justified.
Justin M. Brown, Mark A. Mahan, Ross Mandeville and Bob S. Carter
Neurosurgery is experiencing the emergence of a new subspecialty focused on function restoration. New, evolving, and reappraised surgical procedures have provided an opportunity to restore function to many patients with previously undertreated disorders. Candidates for reconstruction were previously limited to those with peripheral nerve and brachial plexus injuries, but this has been expanded to include stroke, spinal cord injury, and a host of other paralyzing disorders affecting both upper and lower motor neurons. Similar to the recent evolution of the well-established subdisciplines of spinal and vascular neurosurgery, reconstructive neurosurgery requires the adaptation of techniques and skills that were not traditionally a part of neurosurgical training. Neurosurgeons—as the specialists who already manage this patient population and possess the requisite surgical skills to master the required techniques—have a unique opportunity to lead the development of this field. The full development of this subspecialty will lay the foundation for the subsequent addition of emerging treatments, such as neuroprosthetics and stem cell–based interventions. As such, reconstructive neurosurgery represents an important aspect of neurosurgical training that can ameliorate many of the deficits encountered in the traditional practice of neurosurgery.
Justin M. Brown, Bob S. Carter, Keith E. Tansey and Ross Zafonte
Arvin R. Wali, David R. Santiago-Dieppa, Justin M. Brown and Ross Mandeville
Pan–brachial plexus injury (PBPI), involving C5–T1, disproportionately affects young males, causing lifelong disability and decreased quality of life. The restoration of elbow flexion remains a surgical priority for these patients. Within the first 6 months of injury, transfer of spinal accessory nerve (SAN) fascicles via a sural nerve graft or intercostal nerve (ICN) fascicles to the musculocutaneous nerve can restore elbow flexion. Beyond 1 year, free-functioning muscle transplantation (FFMT) of the gracilis muscle can be used to restore elbow flexion. The authors present the first cost-effectiveness model to directly compare the different treatment strategies available to a patient with PBPI. This model assesses the quality of life impact, surgical costs, and possible income recovered through restoration of elbow flexion.
A Markov model was constructed to simulate a 25-year-old man with PBPI without signs of recovery 4.5 months after injury. The management options available to the patient were SAN transfer, ICN transfer, delayed FFMT, or no treatment. Probabilities of surgical success rates, quality of life measurements, and disability were derived from the published literature. Cost-effectiveness was defined using incremental cost-effectiveness ratios (ICERs) defined by the ratio between costs of a treatment strategy and quality-adjusted life years (QALYs) gained. A strategy was considered cost-effective if it yielded an ICER less than a willingness-to-pay of $50,000/QALY gained. Probabilistic sensitivity analysis (PSA) was performed to address parameter uncertainty.
The base case model demonstrated a lifetime QALYs of 22.45 in the SAN group, 22.0 in the ICN group, 22.3 in the FFMT group, and 21.3 in the no-treatment group. The lifetime costs of income lost through disability and interventional/rehabilitation costs were $683,400 in the SAN group, $727,400 in the ICN group, $704,900 in the FFMT group, and $783,700 in the no-treatment group. Each of the interventional modalities was able to dramatically improve quality of life and decrease lifelong costs. A Monte Carlo PSA demonstrated that at a willingness-to-pay of $50,000/QALY gained, SAN transfer dominated in 88.5% of iterations, FFMT dominated in 7.5% of iterations, ICN dominated in 3.5% of iterations, and no treatment dominated in 0.5% of iterations.
This model demonstrates that nerve transfer surgery and muscle transplantation are cost-effective strategies in the management of PBPI. These reconstructive neurosurgical modalities can improve quality of life and lifelong earnings through decreasing disability.
Ross M. Mandeville, Justin M. Brown and Geoffrey L. Sheean
A successful nerve transfer surgery can provide a wealth of benefits to a patient with cervical spinal cord injury. The process of surgical decision making ideally uses all pertinent information to produce the best functional outcome. Reliance on clinical examination and imaging studies alone can miss valuable information on the state of spinal cord health. In this regard, neurophysiological evaluation has the potential to effectively gauge the neurological status of even select pools of anterior horn cells and their axons to small nerve branches in question to determine the potential efficacy of their use in a transfer. If available preoperatively, knowledge gained from such an evaluation could significantly alter the reconstructive surgical plan and avoid poor results. The authors describe their institution’s approach to the assessment of patients with cervical spinal cord injury who are being considered for nerve transfer surgery in both the acute and chronic setting and broadly review the neurophysiological techniques used.