Management of Sural Nerve Neuromas with Targeted Muscle Reinnervation

Applications of Cryoneurolysis in Chronic Pain Management: a Review of the Current Literature

PURPOSE OF REVIEW

The purpose of this review is to evaluate and summarize the literature investigating cryoneurolysis in the treatment of various chronic pain pathologies.

RECENT FINDINGS

There is an increasing amount of interest in the use of cryoneurolysis in chronic pain, and various studies have investigated its use in lumbar facet joint pain, SI joint pain, post-thoracotomy syndrome, temporomandibular joint pain, chronic knee pain, phantom limb pain, neuropathic pain, and abdominal pain. Numerous retrospective studies and a more limited number of prospective, sham-controlled prospective studies suggest the efficacy of cryoneurolysis in managing these chronic pain pathologies with a low complication rate. However, more blinded, controlled, prospective studies comparing cryoneurolysis to other techniques are needed to clarify its relative risks and advantages.

Surgery for mononeuropathies

Advancement in microsurgical techniques and innovative approaches including greater use of nerve and tendon transfers have resulted in better peripheral nerve injury (PNI) surgical outcomes. Clinical evaluation of the patient and their injury factors along with a shift toward earlier time frame for intervention remain key. A better understanding of the pathophysiology and biology involved in PNI and specifically mononeuropathies along with advances in ultrasound and magnetic resonance imaging allow us, nowadays, to provide our patients with a logical and sophisticated approach. While functional outcomes are constantly being refined through different surgical techniques, basic scientific concepts are being advanced and translated to clinical practice on a continuous basis. Finally, a combination of nerve transfers and technological advances in nerve/brain and machine interfaces are expanding the scope of nerve surgery to help patients with amputations, spinal cord, and brain lesions.

Outcomes of Surgical Treatment for Sural Neuritis: A Retrospective Case Series

BACKGROUND

Somatic nerve pain is one of the most common complications following surgery of the foot and ankle but may also arise following traumatic injury or chronic nerve compression. The sural nerve is a commonly affected nerve in the foot and ankle; it is at risk given the proximity to frequently used surgical approaches, exposure to crush injuries, and traction from severe ankle inversion injuries. The purpose of this study is to investigate the outcomes of sural nerve neurectomy with proximal implantation for sural neuromas (SN) and chronic sural neuritis (CSN).

METHODS

Patients that underwent neurectomy with proximal implantation (20 muscle, 1 adipose tissue) by 2 foot and ankle specialists for isolated SN- and CSN-related pain at a single tertiary institution were included. Demographic data, baseline outcomes including 36-Item Short Form Health Survey (SF-36), Foot and Ankle Ability Measure (FAAM), and visual analog scale (VAS) were recorded. Final follow-up questionnaires using Patient Reported Outcomes Measurement Information System (PROMIS) lower extremity function, pain interference (PI), and neuropathic pain quality, FAAM, and VAS were administered using REDCap. Perioperative factors including neuropathic medications, diagnostic injections, the use of collagen wraps, and perioperative ketamine were collected from the medical record. Descriptive statistics were performed and potential changes in patient-reported outcome measure scores were evaluated using Wilcoxon signed-rank tests.

RESULTS

The 21 patients meeting inclusion criteria for this study had a median age of 47 years (interquartile range [IQR], 43-49) and had median follow-up duration of 33.7 months (IQR, 4.5-47.6). Median FAAM activities of daily living score improved from 40.6 (38.7-50.7) preoperatively to 66.1 (53.6-83.3) postoperatively, P = .032. FAAM sports scores improved from 14.1 (7.8-21.9) to 41.1 (25.0-60.9) postoperatively, P = .002. VAS scores improved from a median of 9.0 (8.0-9.0) to 3.0 (3.0-6.0), P < .001. At final follow-up, patients reported PROMIS lower extremity function score median of 43.8 (35.6-54.9), PROMIS neuropathic pain quality score of 54.1 (43.6-61.6), and PROMIS PI of 57.7 (41.1-63.8). Patients with both anxiety and depression reported less improvement in pain and physical. Other perioperative factors lacked sufficient numbers for statistical analysis.

CONCLUSION

Sural nerve neurectomy and proximal implantation (20 muscle, 1 adipose) provided significant improvement in pain and function for patients with sural neuromas and chronic sural neuritis at median follow-up of 33.7 months. Anxiety and depression were associated with significantly poorer outcomes following surgery. Patients with CRPS as well as recent nicotine use tended to report less improvement in pain and worse function after surgery, although this sample size was too limited for statistical analysis of these variables. Further research is needed to identify the ideal surgical candidates and perioperative factors to optimize patient outcomes.

LEVEL OF EVIDENCE

Level IV, retrospective case series.

Demystifying Targeted Muscle Reinnervation: A Systematic Review of Nerve Transfers for the Lower Extremity

Targeted muscle reinnervation (TMR) outcome studies reveal the benefit amputees experience and the potential functional improvement by optimizing neurocutaneous signaling for myoelectric prosthesis control. However, there are still many settings where these techniques are not offered to patients requiring lower extremity amputations or neuroma reconstruction. With growing consistency in the literature, it is helpful to systematize the nerve transfers described for lower extremity TMR and to simplify its integration into reconstructive care.

Methods

A systematic literature review was performed and contained the following inclusion criteria: original cases of primary or secondary lower extremity amputation defects or nerve-related pain that underwent TMR with clearly described target muscles for each nerve transfer. Studies were excluded if the cases had been previously described or contained incomplete data. The primary outcomes were nerves transferred and muscles targeted. Target muscle options were presented in tables specific to anatomic region, and cross-sectional schematics were created for intraoperative assistance.

Results

Seventeen studies presenting original cases with clearly described nerve transfers and target muscles in the lower extremity were included in the review. Target muscle selection for all nerve transfers at the transfemoral and transtibial levels were presented in separate tables.

Conclusions

Reports of early experience at multiple institutions identify trends in the selection of certain target muscles for nerve transfers in transfemoral and transtibial TMR. Familiarity with these common target muscles and nerve transfers can simplify intraoperative decision-making and enhance integration of lower extremity TMR in amputation care and in the treatment of nerve-related pain.

Target Receptors of Regenerating Nerves: Neuroma Formation and Current Treatment Options

Neuromas form as a result of disorganized sensory axonal regeneration following nerve injury. Painful neuromas lead to poor quality of life for patients and place a burden on healthcare systems. Modern surgical interventions for neuromas entail guided regeneration of sensory nerve fibers into muscle tissue leading to muscle innervation and neuroma treatment or prevention. However, it is unclear how innervating denervated muscle targets prevents painful neuroma formation, as little is known about the fate of sensory fibers, and more specifically pain fiber, as they regenerate into muscle. Golgi tendon organs and muscle spindles have been proposed as possible receptor targets for the regenerating sensory fibers; however, these receptors are not typically innervated by pain fibers, as these free nerve endings do not synapse on receptors. The mechanisms by which pain fibers are signaled to cease regeneration therefore remain unknown. In this article, we review the physiology underlying nerve regeneration, the guiding molecular signals, and the target receptor specificity of regenerating sensory axons as it pertains to the development and prevention of painful neuroma formation while highlighting gaps in literature. We discuss management options for painful neuromas and the current supporting evidence for the various interventions.

Sensory nerve regeneration and reinnervation in muscle following peripheral nerve injury

Sensory afferent fibers are an important component of motor nerves and compose the majority of axons in many nerves traditionally thought of as "pure" motor nerves. These sensory afferent fibers innervate special sensory end organs in muscle, including muscle spindles that respond to changes in muscle length and Golgi tendons that detect muscle tension. Both play a major role in proprioception, sensorimotor extremity control feedback, and force regulation. After peripheral nerve injury, there is histological and electrophysiological evidence that sensory afferents can reinnervate muscle, including muscle that was not the nerve's original target. Reinnervation can occur after different nerve injury and muscle models, including muscle graft, crush, and transection injuries, and occurs in a nonspecific manner, allowing for cross-innervation to occur. Evidence of cross-innervation includes the following: muscle spindle and Golgi tendon afferent-receptor mismatch, vagal sensory fiber reinnervation of muscle, and cutaneous afferent reinnervation of muscle spindle or Golgi tendons. There are several notable clinical applications of sensory reinnervation and cross-reinnervation of muscle, including restoration of optimal motor control after peripheral nerve repair, flap sensation, sensory protection of denervated muscle, neuroma treatment and prevention, and facilitation of prosthetic sensorimotor control. This review focuses on sensory nerve regeneration and reinnervation in muscle, and the clinical applications of this phenomena. Understanding the physiology and limitations of sensory nerve regeneration and reinnervation in muscle may ultimately facilitate improvement of its clinical applications.

Failed Targeted Muscle Reinnervation: Findings at Revision Surgery and Concepts for Success

Although it was initially described for improved myoelectric control, targeted muscle reinnervation (TMR) has quickly gained popularity as a technique for neuroma control. With this rapid increase in utilization has come broadening indications and variability in the described technique. As a result, it becomes difficult to interpret published outcomes. Furthermore, there is no literature discussing the management of failed cases which are undoubtedly occurring.

Targeted muscle reinnervation for a recurrent traumatic neuroma of the sural nerve: illustrative case

BACKGROUND

Traumatic neuromata often recur after resection. Recently, targeted muscle reinnervation (TMR) has been shown to be a promising alternative for the treatment of traumatic neuroma, also in nonamputees. This case shows that TMR can also be applied for this indication in recurrent traumatic neuroma.

OBSERVATIONS

A 55-year-old patient with a history of cerebral palsy presented with a painful swelling in his right knee, 40 years after multiple Achilles tendon surgeries for contractures. On imaging, the lesion was suspect for a traumatic neuroma of the posterior sural nerve. After two failed resections, TMR was performed by connecting the proximal end of the sural nerve to the motor branch of the lateral gastrocnemius muscle. During outpatient visits at 3, 6, and 12 months, the patient reported significantly less pain compared to before the TMR. He had no weakness of plantar flexion. Postoperative imaging, however, showed atrophy of the lateral gastrocnemius muscle.

LESSONS

This case shows that TMR can be a successful strategy to treat recurrent traumatic neuroma after previous failed transection of single neuromata in nonamputee cases. In the authors’ patient, TMR did not result in motor deficit, but more research is needed to investigate this consequence of TMR for this indication.

RPNI, TMR, and Reset Neurectomy/Relocation Nerve Grafting after Nerve Transection in Headache Surgery

In the context of headache surgery, greater occipital nerve (GON) transection is performed when the nerve appears severely damaged, if symptoms are recurrent or persistent, and when neuromas are excised. Lesser occipital nerve (LON) excision is commonly performed during the primary decompression surgery. Advanced techniques to address the proximal nerve stump after nerve transection such as regenerative peripheral nerve interface (RPNI), targeted muscle reinnervation (TMR), relocation nerve grafting, and reset neurectomy have been shown to improve chronic pain and neuroma formation. These techniques have not been described in the head and neck region.

"The Feasibility of Targeted Muscle Reinnervation for the Management of Morton's Neuroma"

BACKGROUND

Despite multiple surgical modalities available for the management of Morton's neuroma, complications remain common. Targeted muscle reinnervation (TMR) has yet to be explored as an option for the prevention of recurrence of Morton's neuroma. The purpose of the present investigation was to determine the consistency of the relevant foot neurovascular and muscle anatomy and to demonstrate the feasibility of TMR as an option for Morton's neuroma.

METHODS

The anatomy of 5 fresh-tissue donor cadaver feet was studied, including the course and location of the medial and lateral plantar nerves (MPNs and LPNs), motor branches to abductor hallucis (AH) and flexor digitorum brevis (FDB), as well as the course of sensory plantar digital nerves. Measurements for the locations of the muscular and sensory branches were taken relative to landmarks including the navicular tuberosity (NT), AH, FDB, and the third metatarsophalangeal joint (third MTPJ).

RESULTS

The mean number of nerve branches to FDB identified was 2. These branch points occurred at an average of 8.6 cm down the MPN or LPN, 9.0 cm from the third MTPJ, 3.0 cm distal to AH distal edge, and 4.8 cm from the NT. The mean number of nerves to AH was 2.2. These branch points occurred at an average of 6.3 cm down the MPN, 11.9 cm from the third MTPJ, 0.8 cm from the AH distal edge, and 3.8 cm from the NT.

CONCLUSIONS

Recurrent interdigital neuroma, painful scar, and neuropathic pain are common complications of operative management for Morton's neuroma. Targeted muscle reinnervation is a technique that has demonstrated efficacy for the prevention and treatment of neuroma, neuropathic pain, and phantom limb pain in amputees. Herein, we have described the neuromuscular anatomy for the application of TMR for the management of Morton's neuroma. Target muscles, including the AH and FDB, have consistent innervation patterns in the foot, and consequently, TMR represents a viable option to consider for the management of recalcitrant Morton's neuroma.

LEVELS OF EVIDENCE

V.

Stump-plasty: An Operation Born of Necessity in Gaza

Aim and objective

The most recent wave of lower limb amputees in Gaza arises from ballistic injuries sustained during protests. This study evaluates the requirement for surgical revision of these mature stumps to allow prosthetic fit and mobility.

Materials and methods

A multidisciplinary team (MDT) comprising a prosthetist, orthopaedic and plastic surgeons and a physiotherapist screened 104 amputee stumps (103 cases). The 27 cases selected for surgical revision (stump-plasty) are the subject of this study.

The MDT prescriptions of care issued at screening were compared to surgical procedures performed at stump-plasty and the findings. Compliance with the MDT prescription was recorded. Stump issues are identified to propose modifications of primary amputation technique to mitigate future revisions.

Patients’ healthcare status was assessed by questionnaire (EQ-5D-L5) at screening, then subsequently post-stump-plasty.

Results

More below-knee amputees (BKAs) than above-knee amputees (AKAs) required stump-plasty. Revisions varied according to the quality of tissue present at the amputation level. AKA revisions addressed bulk and contour issues whereas BKA revisions related to bone prominence, neuroma formation and lack of soft tissue cover. Despite many variations in tissue-targeted procedures being possible, the MDT prescription was followed accurately at surgery.

Suggested modifications at primary amputation to decrease revisions include improved bone tip bevelling at BKA and greater soft tissue reduction at AKA. Severed nerve management needs to be rationalised to reduce primary neuroma formation and neuroma revision at stump-plasty requires consideration to attempt to reduce the recurrent risk. Removal of the fibular remnant in short BKA stumps at primary amputation could mitigate common peroneal nerve hypersensitivity later.

Following stump-plasty, amputees recorded a significantly improved score in three of five dimensions of the EQ-5D-L5 questionnaire: activities, anxiety levels and pain.

Conclusion and clinical significance

Primary ballistic injury dictates the level of amputation and the resultant stump quality. Issues arising in these complex amputee stumps benefited from measured decisions and specialist care delivered by the MDT. Stump-plasty aims to improve the amputees’ prosthetic fit, mobility and health.

How to cite this article

Godwin Y, Almaqadma A, Abukhoussa H, et al. Stump-plasty: An Operation Born of Necessity in Gaza. Strategies Trauma Limb Reconstr 2021;16(2):102–109.

Targeted Muscle Reinnervation for the Treatment of Neuroma

Targeted muscle reinnervation (TMR) is the surgical rerouting of severed nerve endings to nearby expendable motor nerve branches. These nerve transfers provide a pathway for axonal growth, limiting the amputated nerve ends' disorganized attempt at regeneration that leads to neuroma formation. In the amputee population, TMR is successful in the treatment and prevention of chronic phantom limb pain and residual limb pain. In the nonamputee population, applications of TMR are ever expanding in the treatment of chronic neuroma pain owing to trauma, compression, or surgery. This article reviews the indications for TMR, preoperative evaluation, and various surgical techniques.