A quantitative assessment of the functional recovery of flexion of the elbow after nerve transfer in patients with a brachial plexus injury

Single versus double fascicular transfer for brachial plexus injuries: a systematic review and meta-analysis with meta-regression

The primary objective of this review was to assess whether double fascicular transfer has superior outcomes compared with single fascicular transfer for reanimation of elbow flexion. In total, 58 studies including 1388 patients (mean age 29 years [SD 8]) were included. Subgroup analysis comparing the severity of brachial plexus injury (C5-C6, C5-C7, C5-C8) showed no significant difference in the recovery of MRC grade 3 and 4. The aggregated mean Disabilities of Arm, Shoulder and Hand score was 38 for the single fascicular transfer group and 27 for the double fascicular transfer group. Meta-regression controlling for level of injury showed that double fascicular transfer and C5-C6 injury were significant predictors of achieving MRC grade 3, while double fascicular transfer and shorter duration of surgical delay were significant predictors of achieving MRC grade 4. When controlling for the level of injury, double fascicular transfer is associated with a greater likelihood of achieving MRC grade 3 and 4 compared to single fascicular transfer. Overall donor site morbidity was not significantly different between single fascicular transfer and double fascicular transfer.

Self-assessed outcomes following double fascicular nerve transfer for elbow flexion

Background

Double fascicular nerve transfer (DFT) is often performed to re-animate the elbow flexors. Studies of motor recovery following this surgery have exclusively reported on the objective outcome of muscle power. Questionnaire studies allow researchers and clinicians to learn from patients and better direct care towards their needs. To date, no research has focused on self-assessed recovery following DFT for elbow flexion.

Methods

This observational cross-sectional study aimed to give an account of patient-assessed outcomes following DFT. The bespoke questionnaire included: (a) self-reported strength and (b) the Stanmore percentage of normal elbow assessment.

Results

Sixty-two patients participated in the study. Participants were grouped according to time post-surgery. Statistical analysis confirmed that data were comparable between groups (p=0.10).

Self-assessed strength

Median scores were 0.5 kg <2 years post-surgery, 3 kg at 2 to 5 years, 2 kg at 5 to 8 years and 1.3 kg in the >8 years group.

Stanmore Percentage of Normal Elbow Assessment

Mean scores (%) were 35 (SD ± 25) <2 years, 56 (SD ± 31) at 2 to 5 years, 44 (SD ± 25) at 5 to 8 years and 46 (SD ± 29) >8 years groups.

Conclusions

This is the first study of self-assessed recovery following DFT. Scores peaked around 4 years post-operation. Future research should focus on the long-term self-reported outcome of nerve transfer surgery.

Adult traumatic brachial plexus injuries: advances and current updates

Nerve grafting, tendon transfer and joint fusion are routinely used to improve the upper limb function in patients with brachial plexus palsies. Newer techniques have been developed that provide additional options for reconstruction. Nerve transfer is a tool for restoring upper limb function in total root avulsions where nerve grafting is not possible. In partial brachial plexus injuries, nerve transfers can greatly improve shoulder, elbow, wrist and hand function. Intraoperative electrical stimulation can be used to diagnose precisely which nerve is injured and to choose which nerve fascicles should be transferred. Finally, measuring the postoperative outcome can improve the evaluation of our techniques. The aim of this article was to present the current techniques used to treat patients with brachial plexus injury.

An assessment of co-contraction in reinnervated muscle

Aim: To investigate co-contraction in reinnervated elbow flexor muscles following a nerve transfer. Materials & methods: 12 brachial plexus injury patients who received a nerve transfer to reanimate elbow flexion were included in this study. Surface electromyography (EMG) recordings were used to quantify co-contraction during sustained and repeated isometric contractions of reinnervated and contralateral uninjured elbow flexor muscles. Reuslts: For the first time, this study reveals reinnervated muscles demonstrated a trend toward higher co-contraction ratios when compared with uninjured muscle and this is correlated with an earlier onset of muscle fatigability. Conclusion: Measurements of co-contraction should be considered within muscular function assessments to help drive improvements in motor recovery therapies.

Clinical Assessment of Functional Recovery Following Nerve Transfer for Traumatic Brachial Plexus Injuries

Surgical reconstruction and postoperative rehabilitation are both important for restoring function in patients with traumatic brachial plexus injuries (BPIs). The current study aimed to understand variations in recovery progression among patients with different injury levels after receiving the nerve transfer methods. A total of 26 patients with BPIs participated in a rehabilitation training program over 6 months after nerve reconstruction. The differences between the first and second evaluations and between C5-C6 and C5-C7 BPIs were compared. Results showed significant improvements in elbow flexion range (p = 0.001), British Medical Research Council's score of shoulder flexion (p = 0.046), shoulder abduction (p = 0.013), shoulder external rotation (p = 0.020), quantitative muscle strength, and grip strength at the second evaluation for both groups. C5-C6 BPIs patients showed a larger shoulder flexion range (p = 0.022) and greater strength of the shoulder rotator (p = 0.004), elbow flexor (p = 0.028), elbow extensor (p = 0.041), wrist extensor (p = 0.001), and grip force (p = 0.045) than C5-C7 BPIs patients at the second evaluation. Our results indicated different improvements among patients according to injury levels, with quantitative values assisting in establishing goals for interventions.

Evaluation of muscle strength following peripheral nerve surgery: A scoping review

Peripheral nerve injury (PNI) can result in devastating loss of function, often with poor long-term prognosis. Increased use of peripheral nerve surgical techniques (eg, nerve transfer, nerve grafting, and nerve repair) has resulted in improved muscle strength and other functional outcomes in patients with PNI. Muscle strength has largely been evaluated with the British Medical Research Council (MRC) scale. MRC is convenient to use in clinical settings, but more robust measures of muscle function are necessary to fully elucidate patient recovery. This scoping review aims to examine alternative instruments used to assess muscle function in studies of peripheral nerve surgery for PNI of the upper and lower limbs. A scoping review was conducted using Ovid MEDLINE, CINAHL, EMBASE, and PubMed databases in May and December of 2020, yielding a total of 20 studies pertaining to the review question. Studies pertaining to handheld dynamometry, grip and pinch dynamometry, Rotterdam Intrinsic Hand Myometers, isokinetic dynamometry, ultrasonography, and electromyography were reviewed. We provide a synopsis of each method and current clinical applications and discuss potential benefits, disadvantages, and areas of future research.

Reconstruction of C5-C8 (T1 Hand) Brachial Plexus Paralysis in a Series of 52 Patients

PURPOSE

A C5-C8 brachial plexus root injury, also known as a T1 hand, is associated with paralysis of shoulder abduction or external rotation and elbow flexion, accompanied by variable elbow, wrist, thumb, or finger extension deficits. We report the results of reconstruction for C5-C8 brachial plexus paralysis in 52 patients operated upon within 12 months of injury and having at least 24 months of follow-up.

METHODS

We considered surgery to be indicated if, by the fifth month after trauma, shoulder abduction and external rotation and elbow flexion remained paralyzed. Root grafting was possible in 35% of the patients and was performed concomitantly with nerve transfers. Shoulder motion was reconstructed by transferring the spinal accessory to the suprascapular nerve. Elbow flexion was restored by transferring fascicles from either the median or ulnar nerve to the biceps motor branch. When needed, elbow extension was reconstructed by transferring 1 motor branch of the flexor carpi ulnaris to the triceps lower medial head motor branch. Wrist extension was restored by transferring the distal anterior interosseous nerve to the extensor carpi radialis brevis motor branch.

RESULTS

Within 12 months of injury, we observed preserved or spontaneous recovery of elbow, wrist, finger, and thumb extension in 25%, 12%, 50%, and 68% of patients, respectively. After surgical reconstruction, improved range of motion for shoulder, elbow flexion, and wrist extension scoring at least M3 was present in 90% of our patients. All 10 patients in whom a motor branch of the flexor carpi ulnaris was used for triceps reconstruction recovered elbow extension, while flexor carpi ulnaris function was preserved.

CONCLUSIONS

In approximatively 90% of our patients, distal nerve transfers resulted in functional recovery of shoulder abduction, elbow flexion or extension, and wrist extension.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

Volumetric MRI is a promising outcome measure of muscle reinnervation

The development of outcome measures that can track the recovery of reinnervated muscle would benefit the clinical investigation of new therapies which hope to enhance peripheral nerve repair. The primary objective of this study was to assess the validity of volumetric Magnetic Resonance Imaging (MRI) as an outcome measure of muscle reinnervation by testing its reproducibility, responsiveness and relationship with clinical indices of muscular function. Over a 3-year period 25 patients who underwent nerve transfer to reinnervate elbow flexor muscles were assessed using intramuscular electromyography (EMG) and MRI (median post-operative assessment time of 258 days, ranging from 86 days pre-operatively to 1698 days post- operatively). Muscle power (Medical Research Council (MRC) grade) and Stanmore Percentage of Normal Elbow Assessment (SPONEA) assessment was also recorded for all patients. Sub-analysis of peak volitional force (PVF), muscular fatigue and co-contraction was performed in those patients with MRC > 3. The responsiveness of each parameter was compared using Pearson or Spearman correlation. A Hierarchical Gaussian Process (HGP) was implemented to determine the ability of volumetric MRI measurements to predict the recovery of muscular function. Reinnervated muscle volume per unit Body Mass Index (BMI) demonstrated good responsiveness (R² = 0.73, p < 0.001). Using the temporal and muscle volume per unit BMI data, a HGP model was able to predict MRC grade and SPONEA with a mean absolute error (MAE) of 0.73 and 1.7 respectively. Muscle volume per unit BMI demonstrated moderate to good positive correlations with patient reported impairments of reinnervated muscle; co- contraction (R² = 0.63, p = 0.02) and muscle fatigue (R² = 0.64, p = 0.04). In summary, volumetric MRI analysis of reinnervated muscle is highly reproducible, responsive to post-operative time and demonstrates correlation with clinical indices of muscle function. This encourages the view that volumetric MRI is a promising outcome measure for muscle reinnervation which will drive advancements in motor recovery therapy.

Optimizing nerve transfer surgery in tetraplegia: clinical decision making based on innervation patterns in spinal cord injury

OBJECTIVE

Nerve transfers are increasingly being utilized in the treatment of chronic tetraplegia, with increasing literature describing significant improvements in sensorimotor function up to years after injury. However, despite technical advances, clinical outcomes remain heterogenous. Preoperative electrodiagnostic testing is the most direct measure of nerve health and may provide prognostic information that can optimize preoperative patient selection. The objective of this study in patients with spinal cord injury (SCI) was to determine various zones of injury (ZOIs) via electrodiagnostic assessment (EDX) to predict motor outcomes after nerve transfers in tetraplegia.

METHODS

This retrospective review of prospectively collected data included all patients with tetraplegia from cervical SCI who underwent nerve transfer at the authors' institution between 2013 and 2020. Preoperative demographic data, results of EDX, operative details, and postoperative motor outcomes were extracted. EDX was standardized into grades that describe donor and recipient nerves. Five zones of SCI were defined. Motor outcomes were then compared based on various zones of innervation.

RESULTS

Nineteen tetraplegic patients were identified who underwent 52 nerve transfers targeting hand function, and 75% of these nerve transfers were performed more than 1 year postinjury, with a median interval to surgery following SCI of 24 (range 8-142) months. Normal recipient compound muscle action potential and isolated upper motor neuron injury on electromyography (EMG) were associated with greater motor recovery. When nerve transfers were stratified based on donor EMG, greater motor gains were associated with normal than with abnormal donor EMG motor unit recruitment patterns. When nerve transfers were separated based on donor and recipient nerves, normal flexor donors were more crucial than normal extensor donors in powering their respective flexor recipients.

CONCLUSIONS

This study elucidates the relationship of the preoperative innervation zones in SCI patients to final motor outcomes. EDX studies can be used to tailor surgical therapies for nerve transfers in patients with tetraplegia. The authors propose an algorithm for optimizing nerve transfer strategies in tetraplegia, whereby understanding the ZOI and grade of the donor/recipient nerve is critical to predicting motor outcomes.

How to assess the recovery of muscular function following nerve injury: A view from surgeons and patients

Patient experience of motor recovery from denervation paralysis is complex and textured. The Medical Research Council (MRC) system of grading muscle peak volitional force is widely used as a single measure of assessment. However, it is becoming clear that current motor function assessments are not reflecting the patient lived experience of muscle reinnervation. Therefore, this study aimed to engage international expert nerve surgeons in a classical Delphi process to achieve a consensus of opinion on the ideal clinical assessment of motor function. This was compared with patient-reported impairments of reinnervated muscle. Invitations to engage in the Delphi process were extended to expert peripheral nerve surgeons across two international specialist meetings. For comparison, patients who attended a "Nerve Injury Community Day" were invited to complete a questionnaire on patient-reported impairments of reinnervated muscle. Questions were designed on the basis of a literature review and the clinical experiences of a specialist nerve injury unit. A combination of direct yes/no, multiple choice, open-ended and Likert questions were employed throughout the questionnaires. Eighteen surgeons engaged with the Delphi process; 18 and 11 responded to the first and second rounds respectively. Thirty-one patients responded to the questionnaire. It was found that clinicians were strongly biased towards efferent assessments of muscular function, while patients strongly favoured muscular fatigue, co-contraction and pain when monitoring their own recovery. The findings suggest that current clinical assessments of muscular function are inadequate and should embody measurements of afferent muscular function to better reflect the lived experience of muscle reinnervation.

Elbow flexion strength and contractile activity after partial ulnar nerve or intercostal nerve transfers for brachial plexus injuries

We compared the outcomes of 23 partial ulnar nerve and 15 intercostal nerve transfers for elbow flexion reconstruction in patients with C56 or C567 brachial plexus injuries using manual muscle power, dynamometric measurements of elbow flexion strength and electromyography. The range of elbow flexion and muscle strength recovery to Grade 3 or 4 were comparable between the two groups. The patients with C567 injuries had significantly stronger eccentric contraction after the partial ulnar nerve transfer than after the intercostal nerve transfer (p < 0.05). Electromyography of individual muscles demonstrated that the patients with partial ulnar nerve transfers were unable to voluntarily isolate biceps contraction and recruited forearm flexors and extensors. The patients after partial ulnar nerve transfer had significantly more activity of the forearm muscles during concentric elbow flexion than after intercostal nerve transfers (p < 0.05). We conclude that partial ulnar nerve transfers were superior to intercostal nerve transfers when assessed quantitatively with the dynamometer to evaluate elbow flexion, although simultaneous recruitment of forearm muscles may have contributed to the increased elbow flexion strength in the patients with the partial ulnar nerve transfer.Level of evidence: III.

Finger sensory impairment after elbow flexion reconstruction using concomitant nerve transfer from the median and ulnar nerves

PURPOSE

Single and double fascicular nerve transfer using the ulnar or median nerve is performed to restore elbow flexion following injuries to the brachial plexus or nerve root. However, little is known regarding the postoperative changes involved in the sensory alteration of the hand after a single and double fascicular nerve transfer. We evaluated the sensory alteration of the hand in patients who underwent single and double fascicular nerve transfer for two years.

METHODS

A total of five patients that underwent single or double fascicular nerve transfer participated in this study. The injury mechanism was avulsion (n = 2), stretching (n = 1), open injury (n = 1), and compression (n = 1). The touch sensation of the index and the little fingers before surgery at 6 months, 1 year, and 2 years after nerve transfer was evaluated using the Semmes-Weinstein monofilaments test (SWM-t). Muscle strength of the elbow flexion and the wrist flexion was evaluated.

RESULTS

The touch sensation of the index finger at 24 months was equal to the preoperative evaluation. On the other hand, the touch sensation of the little finger at 24 months slightly improved compared to what it had been at the preoperative evaluation. Moreover, the median of the SWM-t score in the index and little finger at 24 months after surgery was beyond 3.61 that mean diminished light touch level.

CONCLUSIONS

The results of this study indicate that the touch sensory deficit of the index and little fingers persist for up to 2 years after nerve transfer.

Strategies for Peripheral Nerve Repair

PURPOSE OF REVIEW

This review focuses on biomechanical and cellular considerations required for development of biomaterials and engineered tissues suitable for implantation following PNI, as well as translational requirements relating to outcome measurements for testing success in patients.

RECENT FINDINGS

Therapies that incorporate multiple aspects of the regenerative environment are likely to be key to improving therapies for nerve regeneration. This represents a complex challenge when considering the diversity of biological, chemical and mechanical factors involved. In addition, clinical outcome measures following peripheral nerve repair which are sensitive and responsive to changes in the tissue microenvironment following neural injury and regeneration are required.

SUMMARY

Effective new therapies for the treatment of PNI are likely to include engineered tissues and biomaterials able to evoke a tissue microenvironment that incorporates both biochemical and mechanical features supportive to regeneration. Translational development of these technologies towards clinical use in humans drives a concomitant need for improved clinical measures to quantify nerve regeneration.

Evaluation of functional outcomes after brachial plexus injury

Major nerve injuries such as those of the brachial plexus present a significant challenge for both rehabilitation and evaluation of outcome. With these often complex and multi-faceted injuries, correct selection of outcome measures is important. Healthy nerve function in humans heightens our interactions with the world, creating quality and enjoyment through our experiences of movement and touch. Therefore, assessments should be holistic and representative of all of these features. This article considers the assessment and evaluation of all of the features of nerve injury: sensorimotor, sensation (including that of pain), function and the psychosocial aspects. Current practice is described and combined with clinical experience and research findings to provide suggestions and recommendations for the selection of the most appropriate tools for use with this patient group.

Quantifying regeneration in patients following peripheral nerve injury

Healthy nerve function provides humans with the control of movement; sensation (such as pain, touch and temperature) and the quality of skin, hair and nails. Injury to this complex system creates a deficit in function, which is slow to recover, and rarely, if ever, returns to what patients consider to be normal. Despite promising results in pre-clinical animal experimentation effective translation is challenged by a current inability to quantify nerve regeneration in human subjects and relate this to measurable and responsible clinical outcomes. In animal models, muscle and nerve tissue samples can be harvested following experimental intervention. This allows direct quantification of muscle mass and quality and quantity of regeneration of axons; such an approach is not applicable in human medicine as it would ensure a significant functional deficit. Nevertheless a greater understanding of this process would allow the relationship that exists between neural and neuromuscular regeneration and functional outcome to be more clearly understood. This article presents a combined commentary of current practice from a specialist clinical unit and research team with regard to laboratory and clinical quantification of nerve regeneration. We highlight how electrophysiological diagnostic methods (which are used with significant recognised limitations in the assessment of clinical medicine) can potentially be used with more validity to interpret and assess the processes of neural regeneration in the clinical context, thus throwing light on the factors at play in translating lab advances into the clinic.

Minimum Ten-Year Outcomes of Partial Ulnar Nerve Transfer for Restoration of Elbow Flexion in Patients with Upper Brachial Plexus Injury

Background: Partial ulnar nerve transfer to the biceps motor branch of the musculocutaneous nerve (Oberlin's transfer) is a successful approach to restore elbow flexion in patients with upper brachial plexus injury (BPI). However, there is no report on more than 10 years subjective and objective outcomes. The purpose of this study was to clarify the long-term outcomes of Oberlin's transfer based on the objective evaluation of elbow flexion strength and subjective functional evaluation of patients. Methods: Six patients with BPI who underwent Oberlin's transfer were reviewed retrospectively by their medical records. The mean age at surgery was 29.5 years, and the mean follow-up duration was 13 years. The objective functional outcomes were evaluated by biceps muscle strength using the Medical Research Council (MRC) grade at preoperative, postoperative, and final follow-up. The patient-derived subjective functional outcomes were evaluated using the Quick Disability of the Arm, Shoulder, and Hand (QuickDASH) questionnaire at final follow-up. Results: All patients had MRC grade 0 (M0) or 1 (M1) elbow flexion strength before operation. Four patients gained M4 postoperatively and maintained or increased muscle strength at the final follow-up. One patient gained M3 postoperatively and at the final follow-up. Although one patient achieved M4 postoperatively, the strength was reduced to M2 due to additional disorder. The mean score of QuickDASH was 36.5 (range, 7-71). Patients were divided into two groups; three patients had lower scores and the other three patients had higher scores of QuickDASH. Conclusions: Oberlin's transfer is effective in the restoration of elbow flexion and can maintain the strength for more than 10 years. Patients with upper BPI with restored elbow flexion strength and no complicated nerve disorders have over ten-year subjective satisfaction.

An assessment of fatigability following nerve transfer to reinnervate elbow flexor muscles

AIMS

Improvements in the evaluation of outcomes following peripheral nerve injury are needed. Recent studies have identified muscle fatigue as an inevitable consequence of muscle reinnervation. This study aimed to quantify and characterize muscle fatigue within a standardized surgical model of muscle reinnervation.

PATIENTS AND METHODS

This retrospective cohort study included 12 patients who underwent Oberlin nerve transfer in an attempt to restore flexion of the elbow following brachial plexus injury. There were ten men and two women with a mean age of 45.5 years (27 to 69). The mean follow-up was 58 months (28 to 100). Repeated and sustained isometric contractions of the elbow flexors were used to assess fatigability of reinnervated muscle. The strength of elbow flexion was measured using a static dynamometer (KgF) and surface electromyography (sEMG). Recordings were used to quantify and characterize fatigability of the reinnervated elbow flexor muscles compared with the uninjured contralateral side.

RESULTS

The mean peak force of elbow flexion was 7.88 KgF (sd 3.80) compared with 20.65 KgF (sd 6.88) on the contralateral side (p < 0.001). Reinnervated elbow flexor muscles (biceps brachialis) showed sEMG evidence of fatigue earlier than normal controls with sustained (60-second) isometric contraction. Reinnervated elbow flexor muscles also showed a trend towards a faster twitch muscle fibre type.

CONCLUSION

The assessment of motor outcomes must involve more than peak force alone. Reinnervated muscle shows a shift towards fast twitch fibres following reinnervation with an earlier onset of fatigue. Our findings suggest that fatigue is a clinically relevant characteristic of reinnervated muscle. Adoption of these metrics into clinical practice and the assessment of outcome could allow a more meaningful comparison to be made between differing forms of treatment and encourage advances in the management of motor recovery following nerve transfer. Cite this article: Bone Joint J 2019;101-B:867-871.

Quantitative assessment of elbow flexion by handheld dynamometry in brachial plexus palsy

The purpose of this study was to assess the relative and absolute reliability of a handheld dynamometer when used for examining elbow flexion power in patients with brachial plexus palsy. The assessment of the intra-rater and inter-rater reliability coefficients for the handheld dynamometer was done using the stationary Kin-Com® dynamometer as the reference standard. We determined the measurement errors and checked the systematic biases of the handheld dynamometer. The inter-rater and intra-rater reliabilities of the handheld dynamometer had a very high intraclass correlation coefficient. The values of handheld dynamometer readings had a high correlation to Kin-Com® readings. The Medical Research Council grading was a comparatively inaccurate method for quantitative assessment of motor power. We conclude that a handheld dynamometer measurement is more precise and reliable than the Medical Research Council grading for measuring recovery of elbow flexion in patients with brachial plexus palsy. Level of evidence: III.

The Use of Dynamic Assist Orthosis for Muscle Reeducation following Brachial Plexus Injury and Reconstruction

Therapeutic management of brachial plexus injuries remains complex. The impact of brachial plexus injuries on everyday human functioning should not be underestimated. Early active-assisted range of motion following such injuries may prevent myostatic contractures, minimize muscle atrophy, facilitate muscle fiber recruitment, and enable a faster return to baseline strength levels. The dynamic assist elbow flexion orthosis proposed is designed to provide patients with a graded system for muscle reeducation and function. No clinical data are currently available on the use of this orthosis design; however, this article presents a treatment option based on sound clinical reasoning to facilitate rehabilitation following this devastating injury.