Considerations in evaluating new treatment alternatives following peripheral nerve injuries: A prospective clinical study of methods used to investigate sensory, motor and functional recovery

Evaluating Outcomes Following Nerve Repair: Beyond the Medical Research Council

Peripheral nerve injuries are common and remain a significant health challenge. Outcome measurements are used to evaluate injury, monitor recovery after nerve repair, and compare scientific advances. Clinical judgement is required to determine which available tools are most applicable, which requires a vast understanding of the available outcome measurements. In this article we discuss the highest yield tools available for clinical application.

Does prophylactic decompression of distal nerves following nerve repair improve functional recovery? A systematic review

BACKGROUND

Peripheral nerve injuries are burdensome on healthcare systems, individuals and society as a whole. The current standard of treatment for neurotmesis is primary neurorrhaphy or nerve grafting. However, several patients do not recover their full function. There has been a suggestion that primary distal neurolysis at common entrapment sites maximises surgical outcomes; however, no guidelines exist on this practice. This scoping review aims to ascertain the existing evidence on prophylactic distal decompression of peripheral nerves following repair.

METHODS

A literature search was performed using Ovid Medline, PubMed, Embase and Cochrane Central Register of Controlled Trials and Cochrane Database of Systematic Reviews for studies published in the past 50 years. Studies were screened using a selection criteria and study quality was assessed using standardised tools. Furthermore, thematic content analysis was performed.

RESULTS

Six studies were eligible for inclusion after screening; all studies were retrospective and at most level 3 evidence. No studies were designed specifically to assess the efficacy of distal neurolysis following proximal repair, thus no comparative data with control cohorts are available. All studies that recommended distal decompression of proximally repaired nerves based their conclusions on cases observed by the authors in practice or from theories on nerve regeneration.

CONCLUSIONS

This systematic review suggests that the evidence on the role of immediate distal neurolysis in primary neurorrhaphy is inadequate. Recommendations are limited by the lack of large-scale and generalisable data. Further research is needed with definitive objective outcomes and patient-related outcome measures.

Bioengineered nerve conduits and wraps for peripheral nerve repair of the upper limb

BACKGROUND

Traumatic peripheral nerve injury is common and incurs significant cost to individuals and society. Healing following direct nerve repair or repair with autograft is slow and can be incomplete. Several bioengineered nerve wraps or devices have become available as an alternative to direct repair or autologous nerve graft. Nerve wraps attempt to reduce axonal escape across a direct repair site and nerve devices negate the need for a donor site defect, required by an autologous nerve graft. Comparative evidence to guide clinicians in their potential use is lacking. We collated existing evidence to guide the clinical application of currently available nerve wraps and conduits.

OBJECTIVES

To assess and compare the effects and complication rates of licensed bioengineered nerve conduits or wraps for surgical repair of traumatic peripheral nerve injuries of the upper limb. To compare effects and complications against the current gold surgical standard (direct repair or nerve autograft).

SEARCH METHODS

We used standard, extensive Cochrane search methods. The latest search was 26 January 2022. We searched online and, where not accessible, contacted societies' secretariats to review abstracts from the British Surgical Society of the Hand, International Federation of Surgical Societies of the Hand, Federation of European Surgical Societies of the Hand, and the American Society for Peripheral Nerve from October 2007 to October 2018.

SELECTION CRITERIA

We included parallel group randomised controlled trials (RCTs) and quasi-RCTs of nerve repair in the upper limb using a bioengineered wrap or conduit, with at least 12 months of follow-up.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane procedures. Our primary outcomes were 1. muscle strength and 2. sensory recovery at 24 months or more. Our secondary outcomes were 3. British Medical Research Council (BMRC) grading, 4. integrated functional outcome (Rosén Model Instrument (RMI)), 5. touch threshold, 6. two-point discrimination, 7. cold intolerance, 8. impact on daily living measured using the Disability of Arm Shoulder and Hand Patient-Reported Outcome Measure (DASH-PROM), 9. sensory nerve action potential, 10. cost of the device, and 11. adverse events (any and specific serious adverse events (further surgery)). We used GRADE to assess the certainty of the evidence.

MAIN RESULTS

Five studies involving 213 participants and 257 nerve injuries reconstructed with wraps or conduits (129 participants) or standard repair (128 participants) met the inclusion criteria. Of those in the standard repair group, 119 nerve injuries were managed with direct epineurial repair, and nine autologous nerve grafts were performed. One study excluded the outcome data for the repair using an autologous nerve graft from their analysis, as it was the only autologous nerve graft in the study, so data were available for 127 standard repairs. There was variation in the functional outcome measures reported and the time postoperatively at which they were recorded. Mean sensory recovery, assessed with BMRC sensory grading (range S0 to S4, higher score considered better) was 0.03 points higher in the device group (range 0.43 lower to 0.49 higher; 1 RCT, 28 participants; very low-certainty evidence) than in the standard repair group (mean 2.75 points), which suggested little or no difference between the groups, but the evidence is very uncertain. There may be little or no difference at 24 months in mean touch thresholds between standard repair (0.81) and repair using devices, which was 0.01 higher but this evidence is also very uncertain (95% confidence interval (CI) 0.06 lower to 0.08 higher; 1 trial, 32 participants; very low-certainty evidence). Data were not available to assess BMRC motor grading at 24 months or more. Repair using bioengineered devices may not improve integrated functional outcome scores at 24 months more than standard techniques, as assessed by the Rosén Model Instrument (RMI; range 0 to 3, higher scores better); the CIs allow for both no important difference and a better outcome with standard repair (mean RMI 1.875), compared to the device group (0.17 lower, 95% CI 0.38 lower to 0.05 higher; P = 0.13; 2 trials, 60 participants; low-certainty evidence). Data from one study suggested that the five-year postoperative outcome of RMI may be slightly improved after repair using a device (mean difference (MD) 0.23, 95% CI 0.07 to 0.38; 1 trial, 28 participants; low-certainty evidence). No studies measured impact on daily living using DASH-PROM. The proportion of people with adverse events may be greater with nerve wraps or conduits than with standard techniques, but the evidence is very uncertain (risk ratio (RR) 7.15, 95% CI 1.74 to 29.42; 5 RCTs, 213 participants; very low-certainty evidence). This corresponds to 10 adverse events per 1000 people in the standard repair group and 68 per 1000 (95% CI 17 to 280) in the device group. The use of nerve repair devices may be associated with a greater need for revision surgery but this evidence is also very uncertain (12/129 device repairs required revision surgery (removal) versus 0/127 standard repairs; RR 7.61, 95% CI 1.48 to 39.02; 5 RCTs, 256 nerve repairs; very low-certainty evidence).

AUTHORS' CONCLUSIONS

Based on the available evidence, this review does not support use of currently available nerve repair devices over standard repair. There is significant heterogeneity in participants, injury pattern, repair timing, and outcome measures and their timing across studies of nerve repair using bioengineered devices, which make comparisons unreliable. Studies were generally small and at high or unclear risk of bias. These factors render the overall certainty of evidence for any outcome low or very low. The data reviewed here provide some evidence that more people may experience adverse events with use of currently available bioengineered devices than with standard repair techniques, and the need for revision surgery may also be greater. The evidence for sensory recovery is very uncertain and there are no data for muscle strength at 24 months (our primary outcome measures). We need further trials, adhering to a minimum standard of outcome reporting (with at least 12 months' follow-up, including integrated sensorimotor evaluation and patient-reported outcomes) to provide high-certainty evidence and facilitate more detailed analysis of effectiveness of emerging, increasingly sophisticated, bioengineered repair devices.

Evaluation of outcome after primary median and/or ulnar nerve(s) repair at wrist: clinical, functional, electrophysiologic, and ultrasound study

Background

A major problem in surgery of peripheral nerve injuries of the upper extremities is the unpredictable final outcome. More insight and understanding of the proper methods of outcome assessment and the prognostic factors is necessary to improve functional outcome after repair of peripheral nerves. The objective of this study is to assess the outcome and identify possible prognostic factors for functional recovery of median and/or ulnar nerves repairs at wrist. Forty patients with median, ulnar or combined median-ulnar nerve injuries were included. Smoking, age, sex, repaired nerve, associated artery and/ or tendon repairs, joint stiffness and scar tissue were analyzed as prognostic factors for functional outcome after repair. Outcome parameters were medical research counsel (MRC) scoring for sensory and motor recovery, grip and pinch strength, disability of arm, shoulder and hand (DASH) questionnaire, electrophysiology and ultrasonographic evaluation.

Results

The mean age of the studied patients was 29.1 ± 8.3 and it was statistically correlated with grip strength (p = 0.045), DASH score (p = 0.046) and hyperesthesia score (p = 0.040). EMG results showed signs of regeneration in all patients in the form of small nascent MUAPs and polyphasic MUAPs. CMAP amplitudes of median and ulnar nerves positively correlated with the MRC scale for muscle strength (p = 0.001)

There were statistically significant negative correlations between DASH score and MRC score for sensory evaluation (p = 0.016), grip (p = 0.001), and pinch strength (p = 0.001). There were statistically significant positive correlations between patient's opinion of recovery and MRC score for sensory evaluation (p = 0.029), grip (p = 0.001), and pinch strength (p = 0.001). The MRC score for muscle strength has statistical significant positive correlations with the MRC score for sensory evaluation, grip (p = 0.003), and pinch strength (p = 0.040)

Conclusions

It was concluded that; MRC scale for muscle power, MRC scale for sensory evaluation, functional scores, grip and pinch strength are valuable tools for evaluation of functional outcome. Age, smoking, associated tendon repair, damaged nerve, compliance to rehabilitation protocol, return to work, clinically visible wound adhesions, residual hand joint stiffness, and scar tissue detected by ultrasound were found to be prognostic factors for outcome after nerve repair.

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.

Outcome of surgical repair of adult digital nerve injury: a systematic review

OBJECTIVES

A systematic review to assess the evidence supporting surgical repair of digital nerve injury versus no repair in adults in terms of clinical outcomes.

DESIGN

A Preferred Reporting Items for Systematic Reviews and Meta-Analyses-compliant systematic review with methodology based on the Cochrane Handbook of Systematic Reviews of Interventions.

DATA SOURCES

Databases included OvidMEDLINE, EMBASE, AMED, clinicaltrials.gov and the Cochrane Database of Systematic Reviews, searched from inception until 10 November 2018.

ELIGIBILITY CRITERIA

Adult digital nerve injury in which either direct repair or no repair was undertaken and an outcome measure was recorded.

DATA EXTRACTION AND SYNTHESIS

Study data extracted included demographics, injury type and extent, timing, treatment details, outcome data and time points, adverse outcomes, hand therapy and return to work. The National Institute of Health quality assessment tool for case series was used to assess risk of bias.

RESULTS

Thirty studies were included. One compared surgical repair with non-repair. All studies were case series of between 15 and 110 nerve injuries, with heterogeneous patient, injury and treatment characteristics. Two studies detailed nerve repair without magnification. Static 2-point discrimination (s2PD) was the most commonly reported outcome measure. Return of protective sensation was achieved in most cases in the nerve repair and no nerve repair groups. Repair resulted in better s2PD than no repair, but <25% repaired nerves achieved normal levels. Adverse outcomes were similar between repair and no repair groups.

CONCLUSIONS

Only level IV evidence is available to support surgical repair of digital nerves in adults. Return of normal sensibility is uncommon and almost all unrepaired nerves regained protective sensation by 6 months and all patients declined further surgery. There was no difference in adverse outcomes. There is currently a lack of high-quality evidence to support surgical repair of digital nerve injuries in adults and further research is needed.

PROSPERO REGISTRATION NUMBER

CRD42017065092.

Functional, motor, and sensory assessment instruments upon nerve repair in adult hands: systematic review of psychometric properties

BACKGROUND

Outcome after nerve repair of the hand needs standardized psychometrically robust measures. We aimed to systematically review the psychometric properties of available functional, motor, and sensory assessment instruments after nerve repair.

METHODS

This systematic review of health measurement instruments searched databases from 1966 to 2017. Pairs of raters conducted data extraction and quality assessment using a structured tool for clinical measurement studies. Kappa correlation was used to define the agreement prior to consensus for individual items, and intraclass correlation coefficient (ICC) was used to assess reliability between raters. A narrative synthesis described quality and content of the evidence.

RESULTS

Sixteen studies were included for final critical appraisal scores. Kappa ranged from 0.31 to 0.82 and ICC was 0.81. Motor domain had manual muscle testing with Kappa from 0.72 to 0.93 and a dynamometer ICC reliability between 0.92 and 0.98. Sensory domain had touch threshold Semmes-Weinstein monofilaments (SWM) as the most responsive measure while two-point discrimination (2PD) was the least responsive (effect size 1.2 and 0.1). A stereognosis test, Shape and Texture Identification (STI), had Kappa test-retest reliability of 0.79 and inter-rater reliability of 0.61, with excellent sensibility and specificity. Manual tactile test had moderate to mild correlation with 2PD and SWM. Function domain presented Rosén-Lundborg score with Spearman correlations of 0.83 for total score. Patient-reported outcomes measurements had ICC of 0.85 and internal consistency from 0.88 to 0.96 with Patient-Rated Wrist and Hand Evaluation with higher score for reliability and Spearman correlation between 0.38 and 0.89 for validity.

CONCLUSIONS

Few studies included nerve repair in their sample for the psychometric analysis of outcome measures, so moderate evidence could be confirmed. Manual muscle test and Rotterdam Intrinsic Hand Myometer dynamometer had excellent reliability but insufficient data on validity or responsiveness. Touch threshold testing was more responsive than 2PD test. The locognosia test and STI had limited but positive supporting data related to validity. Rosén-Lundborg score had emerging evidence of reliability and validity as a comprehensive outcome following nerve repair. Few questionnaires were considered reliable and valid to assess cold intolerance. There is no patient-reported outcome measurement following nerve repair that provides comprehensive assessment of symptoms and function by patient perspective.

The Thermal Sensitivity Test in Evaluating Outcome after Peripheral Nerve Injury

The purpose of this study was to evaluate the ability to discriminate temperatures in patients following peripheral nerve injury. Knowing that temperature sensibility is mediated by different receptors, the scores were compared to other functional hand scores in order to determine whether the ability to discriminate temperatures is restored to a different extent compared with other commonly evaluated hand function modalities. The test was performed using the NTE-2 device (Physitemp Instruments Inc., 154 Huron Avenue, Clifton, New Jersey, USA). Out of 57 patients, 27 had normal thermal discrimination scores, and 9 could not tell the temperatures apart in the differences set on the measuring device. Overall, patients with better thermal discrimination had also better hand function as evaluated with different methods. However, some patients who did regain the ability to differentiate temperatures correctly did not have any measurable return of hand function in other tests. Thermal discrimination scores correlated similarly with different functional scores, except for vibration sensibility, which did not show any significant correlation. The development and severity of cold intolerance seem to be unrelated to temperature sense.

Functional restoration of diaphragmatic paralysis: an evaluation of phrenic nerve reconstruction

BACKGROUND

Unilateral diaphragmatic paralysis causes respiratory deficits and can occur after iatrogenic or traumatic phrenic nerve injury in the neck or chest. Patients are evaluated using spirometry and imaging studies; however, phrenic nerve conduction studies and electromyography are not widely available or considered; thus, the degree of dysfunction is often unknown. Treatment has been limited to diaphragmatic plication. Phrenic nerve operations to restore diaphragmatic function may broaden therapeutic options.

METHODS

An interventional study of 92 patients with symptomatic diaphragmatic paralysis assigned 68 (based on their clinical condition) to phrenic nerve surgical intervention (PS), 24 to nonsurgical (NS) care, and evaluated a third group of 68 patients (derived from literature review) treated with diaphragmatic plication (DP). Variables for assessment included spirometry, the Short-Form 36-Item survey, electrodiagnostics, and complications.

RESULTS

In the PS group, there was an average 13% improvement in forced expiratory volume in 1 second (p < 0.0001) and 14% improvement in forced vital capacity (p < 0.0001), and there was corresponding 17% (p < 0.0001) and 16% (p < 0.0001) improvement in the DP cohort. In the PS and DP groups, the average postoperative values were 71% for forced expiratory volume in 1 second and 73% for forced vital capacity. The PS group demonstrated an average 28% (p < 0.01) improvement in Short-Form 36-Item survey reporting. Electrodiagnostic testing in the PS group revealed a mean 69% (p < 0.05) improvement in conduction latency and a 37% (p < 0.0001) increase in motor amplitude. In the NS group, there was no significant change in Short-Form 36-Item survey or spirometry values.

CONCLUSIONS

Phrenic nerve operations for functional restoration of the paralyzed diaphragm should be part of the standard treatment algorithm in the management of symptomatic patients with this condition. Assessment of neuromuscular dysfunction can aid in determining the most effective therapy.

Sensory Neuron Death After Upper Limb Nerve Injury and Protective Effect of Repair

BACKGROUND:

Extensive death of sensory neurons after nerve trauma depletes the number of regenerating neurons, contributing to inadequate cutaneous innervation density and poor sensory recovery. Experimentally proven neuroprotective neoadjuvant drugs require noninvasive in vivo measures of neuron death to permit clinical trials. In animal models of nerve transection, magnetic resonance imaging (MRI) proved a valid tool for quantifying sensory neuron loss within dorsal root ganglia (DRG) by measuring consequent proportional shrinkage of respective ganglia.

OBJECTIVE:

This system is investigated for clinical application after upper limb nerve injury and microsurgical nerve repair.

METHODS:

A 3-T clinical magnet was used to image and measure volume (Cavalieri principle) of C7-T1 DRG in uninjured volunteers (controls, n = 14), hand amputees (unrepaired nerve injury, n = 5), and early nerve repair patients (median and ulnar nerves transected, microsurgical nerve repair within 24 hours, n = 4).

RESULTS:

MRI was well tolerated. Volumetric analysis was feasible in 74% of patients. A mean 14% volume reduction was found in amputees' C7 and C8 DRG (P &lt; .001 vs controls). Volume loss was lower in median and ulnar nerve repair patients (mean 3% volume loss, P &lt; .01 vs amputees), and varied among patients. T1 DRG volume remained unaffected.

CONCLUSION:

MRI provides noninvasive in vivo assessment of DRG volume as a proxy clinical measure of sensory neuron death. The significant decrease found after unrepaired nerve injury provides indirect clinical evidence of axotomy-induced neuronal death. This loss was less after nerve repair, indicating a neuroprotective benefit of early repair. Volumetric MRI has potential diagnostic applications and is a quantitative tool for clinical trials of neuroprotective therapies.

Identification of three movement phases of the hand during lateral and pulp pinches using video motion capture

BACKGROUND

Hand injuries affect a person's ability to engage successfully in activities of daily living (ADLs). Video motion capture (VMC) facilitates measurement of dynamic movement. No study to date has used VMC as a means of quantifying the simultaneous movement patterns of all joints of all digits of the hand during active purposeful movement.

METHOD

The purpose of this study was to analyze all joints of all five digits during active completion of the lateral and pulp pinches. VMC data were collected from four participants during completion of two pinches. Joint angles were plotted to facilitate identification of movement patterns.

RESULTS

Range of motion recorded in all joints with VMC, excluding flexion of the thumb carpometacarpal of both pinches, coincided with the normative goniometric data. Three phases were observed: initiation, preshaping, and pinch phases. Patterns of movement in all digits were identified for the two pinches.

CONCLUSION

VMC is a feasible and valid method for objectively quantifying dynamic movement of multiple joints simultaneously. The results provide new insight to the dynamics of hand movement as well as a basis for subsequent evaluations of movement patterns performed in ADLs and instrumental ADLs.

Comparison of quantitative sensory testing and heart rate variability in Swedish Val30Met ATTR

Patients with transthyretin amyloidosis (ATTR) polyneuropathy, a hereditary fatal disease, often report defects in both thermal perception and autonomic nervous system function as their first clinical symptoms. While elevated thermal perception thresholds (TPT) for cold and warmth only recently have been shown as an early marker of small nerve fiber dysfunction in these patients, heart rate variability (HRV) has frequently been used to quantify autonomic neuropathy. The main purpose with this report was to elucidate a possible relationship between estimates of HRV and TPT in a selected group of early and late-onset Swedish Val30Met ATTR patients. The results show significantly more pronounced elevation of TPT in early compared to late-onset patients. Significant correlations between HRV and TPT were found among late-onset cases, indicating a possible relationship between loss of thin nerve fibers in somatic and autonomic nerves, while generally no such relationships were found among early-onset cases. This observation emphasizes the importance of testing both HRV and TPT to ensure optimal early detection of neuropathic changes in an as wide as possible range of small nerve fibers in suspected ATTR patients. This is of particular importance as the phenotype of the ATTR disease varies between groups with different age of onset.

Clinimetric evaluation of questionnaires used to assess activity after traumatic brachial plexus injury in adults: a systematic review

OBJECTIVES

To identify upper limb questionnaires used in the brachial plexus injury (BPI) literature to assess activities and to evaluate their clinimetric properties. DATA SOURCES; STUDY SELECTION;

DATA EXTRACTION

This systematic review was undertaken in 2 stages. In stage 1, 10 electronic databases and 1 Internet journal were searched for quantitative studies (ie, randomized controlled trials, comparative studies, case series, and case studies) that evaluated outcome after BPI, irrespective of language or date of publication, from date of database inception to September 2010. All outcome instruments used were extracted and classified using the International Classification of Functioning, Disability and Health framework. Questionnaires were identified that apportioned >50% of the total score to the assessment of upper limb activity. In stage 2, 4 electronic databases were searched for papers that evaluated the clinimetric properties of all identified activity questionnaires with respect to peripheral nerve injuries of the upper limb. Two independent reviewers assessed the clinimetric properties of identified questionnaires according to standardized criteria.

DATA SYNTHESIS

Stage 1 identified 4324 papers, of which 265 met the inclusion criteria. One hundred and three outcome measures were identified, the majority of which assess body function or body structure. Twenty-nine questionnaires assessed upper limb activity. Two questionnaires, the ABILHAND and Disability of the Arm, Shoulder and Hand (DASH), attributed >50% of the overall score to activity of the upper limb. The DASH had some published evidence of clinimetric properties in individuals with peripheral nerve injuries. Neither had been clinimetrically evaluated for BPI, nor met all quality criteria.

CONCLUSIONS

Day-to-day activities of the upper limb are infrequently evaluated after BPI. While attempts have been made to measure activity, there is a paucity of clinimetric evidence on activity questionnaires for individuals with BPI. We recommend that a core set of items be developed which evaluate activity, as well a body structure, body function, and participation.

Sensory Neurons of the Human Brachial Plexus

BACKGROUND:

Extensive neuron death following peripheral nerve trauma is implicated in poor sensory recovery. Translational research for experimentally proven neuroprotective drugs requires knowledge of the numbers and distribution of sensory neurons in the human upper limb and a novel noninvasive clinical measure of neuron loss.

OBJECTIVE:

To compare optical fractionation and volumetric magnetic resonance imaging (MRI) of dorsal root ganglia (DRG) in histological quantification and objective clinical assessment of human brachial plexus sensory neurons.

METHODS:

Bilateral C5-T1 DRG were harvested from 5 human cadavers for stereological volume measurement and sensory neuron counts (optical fractionator). MRI scans were obtained from 14 healthy volunteers for volumetric analysis of C5-T1 DRG.

RESULTS:

The brachial plexus is innervated by 425 409 (standard deviation 15 596) sensory neurons with a significant difference in neuron counts and DRG volume between segmental levels (P &lt; .001), with C7 ganglion containing the most. DRG volume correlated with neuron counts (r = 0.75, P &lt; .001). Vertebral artery pulsation hindered C5 and 6 imaging, yet high-resolution MRI of C7, C8, and T1 DRG permitted unbiased volume measurement. In accord with histological analysis, MRI confirmed a significant difference between C7, C8, and T1 DRG volume (P &lt; .001), interindividual variability (CV = 15.3%), and sex differences (P = .04). Slight right-left sided disparity in neuron counts (2.5%, P = .04) was possibly related to hand dominance, but no significant volume disparity existed.

CONCLUSION:

Neuron counts for the human brachial plexus are presented. These correlate with histological DRG volumes and concur with volumetric MRI results in human volunteers. Volumetric MRI of C7-T1 DRG is a legitimate noninvasive proxy measure of sensory neurons for clinical study.

Neuropathic pain in patients with upper-extremity nerve injury

PURPOSE

The purpose of this review was to present an analysis of the literature of the outcome studies reported in patients following traumatic upper-extremity (UE) nerve injuries (excluding amputation), to assess the presence of an association between neuropathic pain and outcome in patients following traumatic UE nerve injuries, and to provide recommendations for inclusion of more comprehensive outcome measures by clinicians who treat these patients.

SUMMARY OF KEY POINTS

A Medline and CINAHL literature search retrieved 48 articles. This review identified very few studies of patients with peripheral nerve injury that reported neuropathic pain. When pain was reported, visual analogue or numeric rating scales were most frequently used; standardized questionnaires measuring pain or psychosocial function were rarely administered. Recent evidence shows substantial long-term disability and pain in patients following peripheral nerve injury.

RECOMMENDATION

To better understand neuropathic pain in patients following peripheral nerve injury, future outcome studies should include valid, reliable measures of physical impairment, pain, disability, health-related quality of life, and psychosocial functioning.

Evaluation of pain measurement practices and opinions of peripheral nerve surgeons

The purpose of this study was to evaluate the opinions and practices of peripheral nerve surgeons regarding assessment and treatment of pain in patients following nerve injury. Surgeons with expertise in upper extremity peripheral nerve injuries and members of an international peripheral nerve society were sent an introductory letter and electronic survey by email (n = 133). Seventy members responded to the survey (49%) and 59 surgeons completed the survey (44%). For patients referred for motor or sensory dysfunction, 31 surgeons (52%) indicated that they always formally assess pain. In patients referred for pain, 44 surgeons (75%) quantitatively assess pain using a verbal scale (n = 24) or verbal numeric scale (n = 36). The most frequent factors considered very important in the development of chronic neuropathic pain were psychosocial factors (64%), mechanism of injury (59%), workers' compensation or litigation (54%), and iatrogenic injury (48%). In patients more than 6 months following injury, surgeons frequently see: cold sensitivity (54%), decreased motor function (42%), paraesthesia or numbness (41%), fear of returning to work (22%), neuropathic pain (20%), and emotional or psychological distress (17%). Only 52% of surgeons who responded to the survey always evaluate pain in patients referred for motor or sensory dysfunction. Pain assessment most frequently includes verbal patient response, and assessment of psychosocial factors is rarely included. Predominately, patient-related factors were considered important in the development of chronic neuropathic pain.

Clinical evaluation of a resorbable wrap-around implant as an alternative to nerve repair: a prospective, assessor-blinded, randomised clinical study of sensory, motor and functional recovery after peripheral nerve repair

Peripheral nerve injures are common and often result in impaired functional recovery. The majority of injuries involve the arm and/or the hand. The traditional treatment for peripheral nerve injuries is repair by using microsurgical techniques, either by primary nerve suture or nerve graft, but research to find more successful methods that could improve recovery is ongoing. Tubulisation has been investigated by several authors and is suggested as an alternative to microsurgical techniques. The resorbable poly[(R)-3-hydroxybutyrate] (PHB) is one of the materials that has been previously tested experimentally. In this prospective, randomised, assessor-blinded clinical study, PHB was investigated as an alternative to epineural suturing in the treatment of peripheral nerve injuries at the wrist/forearm level of the arm. Twelve patients, with a complete, common, sharp injury of the median and/or ulnar nerve at the wrist/forearm level, were treated by either using PHB or microsurgical epineural end-to-end suturing. All patients were assessed using a battery of tests, including evaluation of functional, sensory and motor recovery by means of clinical, neurophysiological, morphological and physiological evaluations at 2 weeks and 3, 6, 9, 12 and 18 months after surgery. No adverse events or complications considered as product related were reported, and thus PHB can be regarded as a safe alternative for microsurgical epineural suturing. The majority of the methods in the test battery showed no significant differences between the treatment groups, but one should consider that the study involved a limited number of patients and a high variability was reported for the evaluating techniques. However, sensory recovery, according to the British Medical Research Council score and parts of the manual muscle test, suggested that treating with PHB may be advantageous as compared to epineural suturing. This, however, should be confirmed by large-scale efficacy studies.