Electrodiagnosis of Plexopathies

Brachial Plexus Injury Influences Efferent Transmission on More than Just the Symptomatic Side, as Verified with Clinical Neurophysiology Methods Using Magnetic and Electrical Stimulation

The variety of sources of brachial plexus injuries (BPIs) and the severity and similarity of their clinical symptoms with those of other injuries make their differential diagnosis difficult. Enriching their diagnosis with objective high-sensitivity diagnostics such as clinical neurophysiology may lead to satisfactory treatment results, and magnetic stimulation (MEP) might be an advantageous addition to the diagnostic standard of electrical stimulation used in electroneurography (ENG). The asymptomatic side in BPI cases sometimes shows only subclinical neurological deficits; this study aimed to clarify the validity and utility of using MEP vs. ENG to detect neural conduction abnormalities. Twenty patients with a BPI and twenty healthy volunteers with matching demographic and anthropometric characteristics were stimulated at their Erb's point in order to record the potentials evoked using magnetic and electrical stimuli to evaluate their peripheral motor neural transmission in their axillar, musculocutaneous, radial, and ulnar nerves. MEP was also used to verify the neural transmission in participants' cervical roots following transvertebral stimulations, checking the compatibility and repeatability of the evoked potential recordings. The clinical assessment resulted in an average muscle strength of 3-1 (with a mean of 2.2), analgesia that mainly manifested in the C5-C7 spinal dermatomes, and a pain evaluation of 6-4 (mean of 5.4) on the symptomatic side using the Visual Analog Scale, with no pathological symptoms on the contralateral side. A comparison of the recorded potentials evoked with magnetic versus electrical stimuli revealed that the MEP amplitudes were usually higher, at p = 0.04-0.03, in most of the healthy volunteers' recorded muscles than in those of the group of BPI patients, whose recordings showed that their CMAP and MEP amplitude values were lower on their more symptomatic than asymptomatic sides, at p = 0.04-0.009. In recordings following musculocutaneous and radial nerve electrical stimulation and ulnar nerve magnetic stimulation at Erb's point, the values of the latencies were also longer on the patient's asymptomatic side compared to those in the control group. The above outcomes prove the mixed axonal and demyelination natures of brachial plexus injuries. They indicate that different types of traumatic BPIs also involve the clinically asymptomatic side. Cases with predominantly median nerve lesions were detected in sensory nerve conduction studies (SNCSs). In 16 patients, electromyography revealed neurogenic damage to the deltoid and biceps muscles, with an active denervation process at work. The predominance of C5 and C6 brachial plexus injuries in the cervical root and upper/middle trunk of patients with BPI has been confirmed. A probable explanation for the bilateral symptoms of dysfunction detected via clinical neurophysiology methods in the examined BPI patients, who showed primarily unilateral damage, maybe the reaction of their internal neural spinal center's organization. Even when subclinical, this may explain the poor BPI treatment outcomes that sometimes occur following long-term physical therapy or surgical treatment.

The use of medial support screw was associated with axillary nerve injury after plate fixation of proximal humeral fracture using minimal invasive deltoid-splitting approach

BACKGROUND

The purpose of this study was to evaluate the incidence and risk factors for axillary nerve injury after plate fixation of humeral fractures using minimal invasive deltoid-splitting approach. We hypothesized that the use of medial support screw (MSS) would be associated with the outcome of axillary nerve injury.

METHODS

This study retrospectively evaluated consecutive 32 patients who underwent surgical treatments for proximal or midshaft humeral fractures. Of them, we included 26 patients who were examined by electromyography/nerve conduction (EMG/NCV) study at 3-4 weeks postoperatively. We excluded 6 patients because two of them were not compliant to EMG/NCV and the remaining two died due to unrelated medical illness. Outcome assessments included pain, functional scores, range of motion, and radiographic results.

RESULTS

There were 8 male and 18 female patients with mean age of 67 ± 15 years. Mean duration of follow-up period was 31 ± 11 months. The mean time to EMG/NCS after surgery was 3.5 ± 0.6 weeks. EMG/NCS examinations revealed incomplete axillary nerve injury in 8 patients (31%) without complete nerve injury. Active forward elevation at 3 months postoperatively was significantly lower in patients with axillary nerve injury than in those without it (99° ± 12 and 123° ± 37, respectively, p = 0.047), although final clinical outcomes were not different. At surgery, MSS was used in 17 patients (65%), and 8 of them were associated with nerve injury. The use of MSS was only correlated with the outcome of axillary nerve injury, because the axillary nerve injury developed only in MSS group (p = 0.047). The MMT grade 4 in abduction strength was more common in patients with axillary nerve injury than in those without (p = 0.037).

CONCLUSIONS

Axillary nerve injury was a concern after plate fixation of proximal humeral fracture using minimal invasive deltoid-splitting approach. The use of medial support screw to improve the stability could increase a risk of axillary nerve injury when used with this approach.

Surgical Treatment of Iatrogenic Nerve Injury Following Arthroscopic Capsulolabral Repair

PURPOSE

Case reports of nerve injuries following arthroscopic capsulolabral repair emphasize the proximity of major nerves to the glenoid. This study describes preoperative localization using nerve-sensitive magnetic resonance imaging in a small cohort of patients with iatrogenic nerve injuries following arthroscopic capsulolabral repair and the outcomes of nerve repair in these patients.

METHODS

Cases of iatrogenic nerve injury following arthroscopic capsulolabral repair referred to 2 surgeons from January 2017 to December 2019 were identified. Clinical charts, electrodiagnostic testing, magnetic resonance imaging studies, and operative reports were reviewed.

RESULTS

Four cases of iatrogenic nerve injury were identified. The time to presentation to our institution ranged from 2 weeks to 8 years. The axillary nerves in 3 cases were tethered by a suture at the inferior glenoid, whereas 1 case had a suture tied around the radial and median nerves inferior to the glenohumeral joint capsule. One case underwent excision and nerve transfer, 1 underwent excision and nerve repair, and 2 underwent suture removal and neurolysis. Open and arthroscopic approaches, including a recently described approach to the axillary nerve in the "blind zone," were used. Three cases demonstrated good recovery of all affected motor and sensory functions after surgery. At the 10-month follow-up, 1 case had persistent weakness, but there was evidence of axonal regeneration on electrodiagnostic testing.

CONCLUSIONS

Arthroscopic capsulolabral repair places regional nerves, particularly the axillary nerve, at risk owing to their proximity to the joint capsule and inferior glenoid. Patients with neuropathic pain in the distribution of affected nerves with corresponding sensorimotor loss following arthroscopic capsulolabral surgery should undergo focused magnetic resonance imaging with nerve-sensitive sequences and electrodiagnostic testing to localize the injury. The use of multiple surgical windows to the axillary nerve in the "blind zone" enables full visualization for neurolysis, suture removal, and nerve repair or transfer.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic V.

Roles of preoperative and early postoperative electrodiagnosis in brachial plexus injury patients undergoing nerve transfer operations: retrospective feasibility study

Objective

The purpose of this retrospective observational study was to assess the feasibility of electrodiagnostic parameters, perioperatively, and to discover optimal values as prognostic factors for patients with brachial plexus injury undergoing nerve transfer operations.

Methods

We retrospectively reviewed the records of 11 patients who underwent nerve transfer surgery. The patients underwent perioperative electrodiagnosis (EDX) before and approximately 6 months after surgery. We evaluated the compound muscle action potential (CMAP) ratio, motor unit recruitment, and their interval changes. To evaluate motor strength, we used the Medical Research Council (MRC) grade, 6 and 12 months after surgery. We evaluated the relationships between improved CMAP ratio, and motor unit recruitment and MRC grade changes 6 and 12 months postoperatively.

Results

All parameters increased significantly after surgery. The CMAP ratio improvement 6 months after surgery correlated with the MRC grade change from baseline to 12 months, with a correlation coefficient of 0.813.

Conclusion

EDX parameters improved significantly postoperatively, and the CMAP ratio improvement 6 months after surgery correlated with the clinical outcomes at 1 year. The results of perioperative EDX might help establish long-term treatment plans for patients who undergo nerve transfer surgery.

Brachial and lumbosacral plexopathies: A review

Diseases of the brachial and lumbosacral plexus are uncommon and complex. The diagnosis of plexopathies is often challenging for the clinician, both in terms of localizing a patient's symptoms to the plexus as well as determining the etiology. The non-specific clinical features and similar presentations to other root, nerve, and non-neurologic disorders emphasize the importance of a high clinical index of suspicion for a plexopathy and comprehensive clinical evaluation. Various diagnostic tests, including electrodiagnostic (EDX) studies, neuroimaging (including ultrasound, MRI, or PET), serologic studies, and genetic testing, may be used to confirm a plexopathy and assist in identifying the underlying etiology. EDX testing plays an important role in confirming a plexopathy defining the localization, pathophysiology, chronicity, severity, and prognosis. Given the complexity of the plexus anatomy, multiple common and uncommon NCS and an extensive needle examination is often required, and a comprehensive, individualized approach to each patient is necessary. Treatment of plexopathies often focuses on symptomatic management although, depending on the etiology, specific targeted treatments may improve outcome. This article reviews the clinical features, EDX approaches, and evaluation and treatment of brachial and lumbosacral plexopathies.

Characteristics of metastatic brachial plexopathy in patients with breast cancer

PURPOSE

Brachial plexopathy in cancer patients is a rare but significant complication that causes pain and disability of the upper extremities. Clinical features of breast cancer patients with metastatic brachial plexopathy (MBP) have not been studied. We aimed to investigate the characteristics of MBP in breast cancer patients.

METHODS

We retrospectively reviewed medical records of patients with breast cancer with MBP who visited Asan Medical Center from 2000 to 2016; we enrolled 44 patients. We comprehensively reviewed the characteristics, range of metastatic lymph nodes, initial symptoms, location, and severity of brachial plexus injury by electrodiagnostic study, radiologic findings, and associated complications.

RESULTS

The mean age of patients with MBP was 51.9 ± 9.3 years; 25% were diagnosed with stage IV breast cancer at initial diagnosis. Weakness was the most common initial symptom of MBP (52.3%). Most patients showed limitation of shoulder range of motion and pain; 66% of patients exhibited malignant lymphedema. Forty-one patients were evaluated by electromyography; upper nerve trunk involvement (22.0%) was more frequent than lower nerve trunk involvement (9.8%). Nineteen patients underwent brachial plexus MRI, and supraclavicular area (SCA) metastasis was most frequent (57.9%). Sixteen patients were examined by both brachial plexus MRI and electromyography; patients with SCA metastasis exhibited significantly more frequent malignant lymphedema (p = 0.019) and upper nerve trunk involvement (p = 0.035), compared with patients with non-SCA metastasis.

CONCLUSIONS

Our study revealed clinical features of MBP in breast cancer patients. Additional diagnostic evaluation focused on metastasis or aggravated metastatic tumor is needed when breast cancer patients are diagnosed with brachial plexopathy.

The thoracic outlet syndromes: Part 2. The arterial, venous, neurovascular, and disputed thoracic outlet syndromes

The thoracic outlet syndromes (TOSs) are a group of etiologically and clinically distinct disorders with 1 feature in common: compression of 1 or more neurovascular elements as they traverse the thoracic outlet. The medical literature reflects 5 TOSs: arterial; venous; traumatic neurovascular; true neurogenic; and disputed. Of these, the first 4 demonstrate all of the features expected of a syndrome, whereas disputed TOS does not, causing many experts to doubt its existence altogether. Thus, some categorize disputed TOSs as cervicoscapular pain syndrome rather than as a type of TOS. To better understand these disorders, their distinctions, and the reasoning underlying the categorical change of disputed TOS from a form of TOS to a cervicoscapular pain syndrome, a thorough understanding of the pertinent anatomy, pathology, pathophysiology, and electrodiagnostic manifestations of these pathophysiologies is required. This review of the TOSs is provided in 2 parts. In part 1 we covered general information pertinent to all 5 TOSs and reviewed true neurogenic TOS in detail. In part 2, we review the arterial, venous, traumatic neurovascular, and disputed forms of TOS. Muscle Nerve 56: 663-673, 2017.

Traumatic brachial plexus injury: electrodiagnostic findings from 111 patients in a tertiary care hospital in India

OBJECTIVE

The study aims to characterise the electrodiagnostic findings of patients with traumatic brachial plexus injuries (BPIs) in India and to analyse the association between aetiologies and levels of injuries.

METHODS

A total of 111 consecutive electrodiagnostic studies done between January 2009 and June 2011 on persons with traumatic BPI were retrospectively analysed.

SETTING

Electrodiagnostic Laboratory, Department of Physical Medicine and Rehabilitation in a tertiary care university teaching hospital in South India.

MAIN OUTCOME MEASURES

Nerve conduction velocities and electromyography (EMG) to locate the level of BPI, Dumitru and Wilbourne scale to assess the severity of BPI.

RESULTS

We studied 106 males and five females, ranging from 11 to 59 years of age. All but one had unilateral BPI. Motorcycle crashes were the most frequent cause (n=64, 58%). Isolated supraclavicular injury was found in 98 arms (88%) and infraclavicular injury in seven arms (6%). Root-level injuries were more common in motorcycle crashes and occupation-related trauma, while trunk-level injuries were more often found in automobile crashes, falls, bicycle-related trauma and penetrating wounds. Pan root (C5-T1) involvement was more common in the motorcycle trauma group (74%). There was no significant association between aetiologies and levels of BPIs. A total of 73 (65%) plexus injuries were of 'severe' category as per Dumitru and Wilbourn scale.

CONCLUSIONS

Motorcycle crash is the most common cause of traumatic BPIs. Supraclavicular injury is the rule in most cases. Proper attention needs to be given to differentiate the mild to moderate injuries from the severe injuries with EMG techniques since most of the cases are severe. There was no significant association found between aetiologies and levels of injury.

The thoracic outlet syndromes

The term thoracic outlet syndrome (TOS) refers to a heterogeneous group of disorders, all of which have in common compression of one or more neurovascular elements at some point within the thoracic outlet. Of the five disorders comprising this group, four have all of the features expected of a syndrome-a recognized constellation of clinical features; an anatomic derangement accounting for these features; and a method of testing that identifies the anatomic derangement. Consequently, their recognition and management are relatively straightforward. Conversely, one of these five disorders (nonspecific TOS) lacks these correlations, which has generated considerable debate in the literature and caused some experts to doubt its existence altogether. The primary focus in this study is on the neurologic forms of TOS. However, for completeness and a better understanding of these neurologic manifestations, the vascular forms are also reviewed.

External neurolysis may result in early return of function in some muscle groups following brachial plexus surgery

A retrospective chart review, of those individuals seen and operated on by the Multidisciplinary Brachial Plexus Clinic team at the University of Kentucky Chandler Medical Center, was undertaken to determine those individuals who had early return-of-function following surgery for BPI. Seven patients met our criteria, with four of them having substantial improvement of two or more points gained on the MRC rating scale, in one or more muscle groups within six to eight weeks after surgery. Those patients with return-of-function earlier than expected for axonal regrowth from nerve transfer or grafting, had evidence for continuity but no significant reinnervation before surgery in the muscle groups that improved. We theorize that this early improvement is related to a compression-induced dysfunction which inhibited reinnervation and was relieved by performing external neurolysis.

Imaging and electrodiagnostic work-up of acute adult brachial plexus injuries

Imaging and electrodiagnostic studies form an essential part of the evaluation of the patient with traumatic brachial plexopathy, enabling clarification of surgical options, prognostication of outcome and formulation of postoperative management. The primary objective of imaging is to identify pre-ganglionic injury indicative of nerve root avulsion. The presence of one or more nerve root avulsion injuries is a critical factor in surgical decision-making and the prognosis of surgical reconstruction. CT myelography is the current imaging modality of choice for this purpose. Initial electrodiagnostic (EDX) testing is ideally performed no sooner than 4 weeks following injury unless otherwise clinically indicated. Follow-up testing can be helpful at approximately 6 week intervals. The sensory nerve amplitudes are the most important component of nerve conduction testing in distinguishing between pre- and post-ganglionic injuries. Electromyographic studies will also assist in the determination of a pre- from post-ganglionic injury, the level of plexus involvement and identify potential donor nerves that may be suitable for use as transfers.

The relationship between lumbosacral plexopathy and pelvic fractures

OBJECTIVE

This study aimed to investigate the relationship between lumbosacral (LS) plexopathy and pelvic fracture in patients with pelvic fractures only.

DESIGN

This study is a retrospective review of patients with pelvic trauma from 1997 to 2007. All patients underwent radiologic examination. The patients with suspected neurologic deficits underwent electrodiagnostic tests. The pelvic fractures were classified based on anatomic location (anterior, lateral, or posterior) and stability (stable, partially stable, or unstable). LS plexopathy was classified based on anatomic quadrant location (upper anterior, upper posterior, lower anterior, or lower posterior) and severity (mild, moderate, or severe) according to electrodiagnostic findings.

RESULTS

A total of 104 patients had pelvic fractures only. Thirty-two of those patients (30.8%) had LS plexopathy (26 unilateral and 6 bilateral patients; 38 limbs with LS plexopathy involvement). The incidence and severity of LS plexopathy were found to increase with the increasing number of involved anatomic fracture locations and with fracture instability. Of the 38 limbs affected by LS plexopathy, 34 (89.5%) involved the lower posterior quadrant. Only four cases (10.5%) involved a solitary quadrant, whereas 12 cases (31.6%) involved all quadrants. There was no correlation between fracture location and LS plexopathy quadrant.

CONCLUSIONS

The incidence and severity of LS plexopathy increases with the increasing number of anatomic fracture locations and with increased fracture instability. LS plexopathy does not correlate with fracture location. LS plexopathy may be the result of both simple direct compression by displaced bone and indirect injury.

Outcomes of common peroneal nerve lesions after surgical repair with acidic fibroblast growth factor

BACKGROUND

There have been no clinical trials concerning the effect of acidic fibroblast growth factor (aFGF) on human peripheral nerve lesions. Our interest was focused on the question of whether a repair strategy incorporating growth factors could be applied to repair of common peroneal nerve lesions.

METHODS

This study involved three groups of patients with common peroneal nerve lesions: group 1 (n = 21) received surgical repair with fibrin glue added with aFGF; group 2 (n = 8) received surgical repair only; group 3 (n = 16) did not receive any surgical intervention. All patients received electrophysiologic examinations and physical examination at baseline, 6 months, and 12 months postsurgically.

RESULTS

Group 1 demonstrated significantly increased average muscle strength score by 0.4299 and 0.5045 at 6 and 12 months after the operation (p = 0.0197 and 0.0297, respectively). In groups 2 and 3 patients, however, significant increase of average muscle strength scores was not achieved either at 6 or 12 months postoperatively. During the first follow-up evaluation the average muscle strength score in group 1 (3.06 +/- 1.60) was significantly higher than those in group 2 (1.04 +/- 0.86) and group 3 (1.65 +/- 1.43) (p = 0.005). However, significant difference was not achieved during the second follow-up evaluation.

CONCLUSION

This study demonstrated the potential of this innovative repair strategy with aFGF treatment to facilitate nerve regeneration and motor function recovery following peripheral nerve lesions.

T1 radiculopathy: electrodiagnostic evaluation

Electromyography (EMG) studies are useful in the anatomical localization of nerve injuries and, in most cases, isolating lesions to a single nerve root level. Their utility is important in identifying specific nerve-root-level injuries where surgical or interventional procedures may be warranted. In this case report, an individual presented with right upper extremity radicular symptoms consistent with a clinical diagnosis of cervical radiculopathy. EMG studies revealed that the lesion could be more specifically isolated to the T1 nerve root and, furthermore, provided evidence that the abductor pollicis brevis receives predominantly T1 innervation.

Concordance and Discrepancy between Electrodiagnosis and Magnetic Resonance Imaging in Cervical Root Avulsion Injuries

To clarify the relationships between electromyography (EMG) and magnetic resonance imaging (MRI), we compared findings in 37 selected patients who presented with cervical root avulsion injuries. Nerve root repair with C4-T1 hemilaminectomy was subsequently performed on 19 patients. The agreement between the two evaluative modalities with complete or incomplete lesions of ventral root and pre- or postganglionic lesions of dorsal root was measured for each root level. Both with ventral and dorsal root evaluation, C6, C7, and C8 yielded high agreement values, ranging from 86% to 94%. C5 manifested the lowest agreement values: 54% on ventral root assessment. Additionally, EMG, in comparison with MRI, revealed a higher quantity of implicated injured components. MRI, in turn, detected more lesion components than surgical exploration alone achieved. The capability of EMG to recognize axonotmesis leads to the discrepant findings between the two modalities. The visualization of mild neurotmesis by MRI, which cannot be achieved by surgical inspection, results in divergent findings between the two modalities. Both EMG and the MRI play crucial roles in preoperative assessment, and they may complement each other.

Spinal cord implantation with acidic fibroblast growth factor as a treatment for root avulsion in obstetric brachial plexus palsy

Nerve root avulsion carries the worst prognosis among brachial plexus injuries and remains a great challenge for surgeons to repair. In this case, a boy with complete avulsion of the left-side C6 root presented with flaccid paralysis of the left arm after birth. As there was no significant spontaneous recovery, the patient underwent operation when he was 6 months old. One end of the nerve graft from the sural nerve was anastomosed with the avulsed C6 root, and the other end was implanted into the ventrolateral aspect of the spinal cord with fibrin glue containing acidic fibroblast growth factor. After 2 years of follow-up, there has been significant improvement in motor function and in electrophysiologic studies over the left upper limb.

Brachial plexopathies: classification, causes, and consequences

The brachial plexus, which is the most complex structure of the peripheral nervous system, supplies most of the upper extremity and shoulder. The high incidence of brachial plexopathies reflects its vulnerability to trauma and the tendency of disorders involving adjacent structures to affect it secondarily. The combination of anatomic, pathophysiologic, and neuromuscular knowledge with detailed clinical and ancillary study evaluations provides diagnostic and prognostic information that is important to clinical management. Since most brachial plexus disorders do not involve the entire brachial plexus but, rather, show a regional predilection, a regional approach to assessment of plexopathies is necessary.

Repair of multiple cervical root avulsion with sural nerve graft

To obtain easier access to avulsed roots in the intradural space for patients suffering cervical root avulsion, the authors of this study developed a novel repair method. This involves using nerve grafts to bridge corresponding segments of the spinal cord and the trunk or cord level of the plexus, respectively, in two surgical stages. All eight patients admitted to this study received pre- and post-operative workups of electrophysiological evaluations and muscle power grading through Medical Research Council (MRC) scores. The degrees of impairment were also graded according to a modified version of Dumitru's and Wilbourn's scale (mild = 1; moderate = 2; severe = 3). The preoperative versus post-operative differences in the severity of the injuries and in the grading of the target muscle power were calculated according to the Wilcoxon signed-rank test. The preoperative degree of the severity of the injuries, as measured by electromyography (EMG), was 3.00 +/- 0.00 (mean +/- S.D.). The post-operative result was 2.125 +/- 0.641. Significant change took place after repair (P = 0.0313). Moreover, although little improvement was observed in the triceps, brachioradialis (BR), extensor carpi radialis (ECR), flexor digitorum profundus (FDP) and intrinsic hand muscles, the MRC grading showed significant yet not prominent motor recovery in the deltoid and biceps brachii (both P = 0.0313). We were impressed that the initial significant statistical results of differences in pre- and post-operative severity of the injuries and muscle power grading, demonstrated that regeneration does occur with this repair strategy.

Unilateral brachial plexus injury as a complication of thoracoscopic sympathectomy for hyperhidrosis: a case report

Unilateral brachial plexus injury is a rare complication of thoracoscopic sympathectomy, which is generally considered to be a simple and safe procedure. We report on a 26-year-old man who developed weakness and numbness of the right arm after thoracoscopic sympathectomy for hyperhidrosis. Electromyographic study revealed evidence of denervation in the upper trunk of the right brachial plexus. A nerve conduction study on the right axillary nerve revealed a reduced compound muscle action potential amplitude at the right deltoid muscle. We suggest that this complication was caused by stretch and/or compression when the arm was hyperabducted during the operation. The outcome was excellent, with almost complete recovery 3 months later. The complication can be prevented by minimizing operation time and avoiding hyperabduction of the arm. The prognosis for postoperative brachial plexopathy is usually good with conservative management.

Provocative F waves may help in the diagnosis of thoracic outlet syndrome: a report of three cases

To determine the value of F waves in provocative positions for the diagnosis of thoracic outlet syndrome, we performed provocative maneuvers on three patients with a clinical diagnosis of thoracic outlet syndrome. The patients had complained of intermittent upper limb pain with associated weakness and paresthesias for several years, and previous evaluations included essentially normal cervical and shoulder imaging studies and electrodiagnostic studies. Although upper limb nerve conduction studies, including ulnar and median F waves, were within normal limits, provocative F waves were obtained in the symptomatic and asymptomatic arm. When routine nerve conduction studies are normal, despite a strong clinical suspicion, provocative maneuvers may help to show subtle electrodiagnostic abnormalities to support the diagnosis of thoracic outlet syndrome.

The comparison of electrophysiologic findings of traumatic brachial plexopathies in a tertiary care center

This study was undertaken to demonstrate the distribution of causative factors of brachial plexopathy (BP), to assess the association between the mechanism of injuries and the predominant level of the brachial plexus involved in the injuries, and to characterize the extent and degree of severity of injury in patients with BPI. It consisted of a cross-sectional, retrospective review of electrophysiological data of 5547 patients with 117 patients being identified as having BPI, of whom 86 patients were recruited into the study. The patients were divided into six subgroups according to the mechanism of the damage. The injury was subdivided according to the brachial plexus levels predominantly affected, and each component of the four major anatomical plexus levels-root, trunk, cord and nerve levels was analyzed. The affiliation between the type of injuries and the specified brachial plexus levels was calculated via a two-tailed Fisher's exact test. These findings demonstrated that the type of brachial plexus injury (BPI) is significantly related to the brachial plexus level involved. The motorcycle and birth injury groups were affected at the trunk level, the fall group at the nerve level, the automobile group at the cord level, and the blunt injury group at the cord or nerve level. Moreover, the majority of patients in the motorcycle, fall, and pedestrian groups suffered from severe, incomplete lesions, while the neurophysiological results of the other groups varied.

Electrodiagnostic approach to the patient with suspected brachial plexopathy

Of the four major PNS plexuses, disorders of the brachial plexus are encountered far more frequently than those of the others. The EDX examination is probably the best procedure available by which to evaluate brachial plexus lesions. It provides localizing, pathologic, pathophysiologic, severity, and prognostic information. By localizing the lesion and identifying the underlying pathophysiology, it often predicts the underlying etiologic process; for example, (1) major T1 APR involvement with true neurogenic thoracic outlet syndrome; (2) C8 APR involvement with postmedian sternotomy brachial plexopathies; (3) supraclavicular demyelinating conduction block with classic postoperative paralysis (often confined to the upper plexus); (4) widespread infraclavicular demyelinating conduction blocks with radiation plexopathy; (5) severe progressive axon loss with neoplastic processes; (6) motor NCS abnormalities exceeding sensory NCS abnormalities for the same peripheral nervous system segment with intraspinal canal lesions (e.g., avulsions); (7) demyelinating conduction block with sparing of the pertinent sensory NCS study with multifocal motor neuropathy; and (8) lack of EDX abnormalities with hysteria, conversion reactions, and malingering, as well as with disputed neurogenic thoracic outlet syndrome. In addition, incorrect clinical considerations may be excluded (e.g., when abnormal SNAPs are identified, an isolated radiculopathy is excluded). Among the various EDX study components, the sensory NCS are the most useful for brachial plexus element localization. One drawback of the sensory NCS for localization occurs in the setting of concomitant carpal tunnel syndrome; the latter negates the utility of the median sensory NCS for brachial plexus localization. The motor NCS and NEE often overcome this drawback and, regardless of sensory NCS findings, are always performed.

Electrophysiologic findings and muscle strength grading in brachioplexopathies

The electrophysiological evaluations and the British Medical Research Council (MRC) scale (0-5) findings of target muscles in brachioplexopathies before surgery and 1 year postsurgery were conducted. Each component of the brachial plexus was analyzed in 15 patients with injuries, among them, to 5 roots, 19 trunks, 7 cords, and 13 terminal nerves. In each of these cases, neurolysis and/or nerve transfer and/or neurotization were performed, within 3 weeks to 6 months after the injury was incurred, to ameliorate the resulting severe disabilities. The degrees of impairment were graded using a modified version of Dumitru's and Wilbourn's scale (mild: normal to slight decrease of SNAP amplitude and CMAP amplitude, and occasional denervation; moderate: profound decrease of SNAP amplitude and CMAP amplitude, constant denervation, and normal to slight decrease in motor unit recruitment; severe: absent SNAP amplitude, absent CMAP amplitude, marked denervation, and profound decrease or no volitional motor unit recruitment. mild = 1; moderate = 2; severe = 3). The motor power of the target muscles was graded through MRC scores. The presurgical versus postsurgical differences in the severity of the injury to each brachial plexus component, and differences in the grading of target muscle power, were calculated through the Wilcoxon signed-rank test. The presurgical degrees of the severity of injury, as measured by the electromyography (EMG) were 3.00 +/- 0.00 (mean +/- SD) in root, 2.84 +/- 0.50 in trunk, 3.00 +/- 0.00 in cord, and 2.85 +/- 0.38 in terminal nerves. The postsurgical results were 2.60 +/- 0.55 in root, 2.53 +/- 0.70 in trunk, 2.43 +/- 0.53 in cord, and 1.77 +/- 0.73 in terminal nerves. There was significant improvement at the trunk, cord, and terminal nerve levels after repair, but not at the root levels. Moreover, although the MRC grading showed significant motor recovery in the infraspinatus, deltoid, biceps, and triceps muscles, there was little apparent improvement in the pectoralis major, EDC, APB, and ADM muscles. Nerve repair was notably successful in all plexuses except at the root level. However, our cases demonstrated only poor motor power gains in the forearm and the hand muscles. Consequently, future surgical techniques for brachioplexopathy repairs need further improvement.

Nerve lesions in proximal humeral fractures

In the literature nerve injury is not frequently considered a problem in proximal humeral fractures. Only a few studies exist concerning traction injury of nerves in fractures of the proximal humerus after low-velocity trauma. Almost all of them are retrospective and did not use electromyography. Patients with identical fractures can show quite different outcomes, which vary between complete recovery and severely limited shoulder function. On the assumption that nerve lesions can play a role in the recovery of conservatively and operatively treated proximal humeral fractures, we started a prospective follow-up study with electromyographic investigation. For this study, 143 consecutive proximal humeral fractures due to low-velocity trauma were included. According to the Neer classification, 93 were nondisplaced and 50 were displaced fractures. Denervation on the electromyogram was found in 96 patients (67%). The nerves most frequently involved were the axillary nerve (83 [58%]) and the suprascapular nerve (69 [48%]). Frequently a combination of nerve lesions was seen. Nerve lesions were much more frequent in displaced fractures (82% [41/50]) than in nondisplaced fractures (59% [55/93]). Complicating nerve lesions in patients older than 20 years of age were seen in about the same percentage of patients per decade. Nerve injury and the corresponding loss of muscle strength recovered well in all patients; however, the duration of the recovery was prolonged in cases with nerve lesions. Restoration of the function of the shoulder was less favorable. It is important to realize that, in both conservative and operative treatment of proximal humeral fractures, a paresis due to nerve injury can affect the restoration of shoulder motions. An electromyogram can be useful in the investigation of nerve lesions, because detection only by clinical examination proved to be very difficult. Because of the favorable electrophysiological recovery, no indication for exploration of nerve lesions was present in this series of fractures due to low-velocity trauma.

Shoulder dystocia

Shoulder dystocia is an infrequent and unexpected emergency requiring rapid and deft solution. Identifiable risk factors include maternal diabetes, fetal macrosomia (especially in the presence of diabetes), and maternal history of previous delivery of a large infant. Other reported risk factors include arrest and protraction disorders of labor and midpelvic operative delivery; however, more than 50% of shoulder dystocia occurs in instances without identifiable risk factors, and permanent neonatal injury is thus unpredictable. Therefore, all personnel in the delivery suite must be well versed in the timely and appropriate application of corrective measures. Although most instances of shoulder dystocia cannot be predicted, the judicious use of CS delivery in diabetic patients with expected birth weights of more than 4250 g should reduce the risk of shoulder dystocia in this subgroup of patients. A trial of labor for nondiabetic patients with suspected fetal macrosomia is recommended because predicting actual birth weights in this population remains difficult.

Electromyographic findings in shoulder dislocations and fractures of the proximal humerus: comparison with clinical neurological examination

There is no consensus of opinion about the frequency of associated nerve lesions in anterior shoulder dislocations and fractures of the proximal humerus. We undertook a prospective study to assess the incidence, the severity of the nerve injury and the diagnostic value of electromyographic examination; 215 patients were included. We performed neurological examination and needle electromyography (EMG). Nerve injury was graded according to a denervation score at the EMG. EMG disorders were seen in 133 patients (62%). Testing of sensibility and clinical reflexes proved not to be a reliable indicator for EMG abnormalities. Detection of axonal lesions by grading muscle strength based on the MRC score after these shoulder traumas is difficult. The findings of this study imply that by clinical examination alone a large number of axonal lesions remain undetected.

Iliac artery pseudoaneurysm following renal transplantation presenting as lumbosacral plexopathy

A renal transplant patient developed chronic and progressive back and lower extremity pain followed by foot weakness. The correct diagnosis of lumbosacral plexopathy was made after electromyography and nerve conduction studies and the etiology of radiculopathy due to nerve root compression was excluded. This prompted further investigations that led to the discovery of a large internal iliac artery pseudoaneurysm. We emphasize the use of electrodiagnostic studies to investigate patients with back and limb pain for correctly localizing responsible pathology. In this case a potentially lethal situation was correctly identified in a transplant patient.

AAEM minimonograph 32: the electrodiagnostic examination in patients with radiculopathies. American Association of Electrodiagnostic Medicine

The anatomy and pathophysiology of radiculopathies are reviewed, and the electrodiagnostic approaches used in evaluating patients with suspected root lesions are discussed. Such electrophysiologic procedures include motor and sensory nerve conduction studies, late-response studies, somatosensory and motor evoked potentials, nerve root stimulation, and needle electromyography. The value and limitations of these different procedures are considered. At the present time, needle electromyography is the single most useful approach. The findings in patients with radiculopathies at different levels are summarized.

The timing of congenital brachial plexus injury: a study of electromyography findings in the newborn piglet

OBJECTIVE

Permanent congenital brachial plexus palsy is a recognized serious complication associated with shoulder dystocia. The timing and etiology of this injury remains controversial. Previous authorities have used adult-derived, non-brachial plexus data to extrapolate the anticipated timing for electromyographic denervation changes to date such injuries in the newborn. With use of a domestic swine model, this investigation tests the hypothesis that electromyographic evidence of brachial plexus denervation in the newborn is temporally different than that in the adult.

STUDY DESIGN

Five healthy 2-day-old and two adult pigs underwent unilateral sharp transection of the brachial plexus. Daily electromyographic studies were performed in brachial plexus innervated muscle groups on the involved and contralateral (control) front limbs. Postmortem measurements of the transected nerve segments were obtained in one piglet and one adult animal. Representative hard copy recordings of individual electromyographic studies were collected.

RESULTS

Immediately after surgical transection of the brachial plexus, no electromyographic evidence of denervation was observed. Uniformly in the newborn piglets, at 24 hours after transection, denervation in the form of fibrillation potentials, positive sharp waves, and complex repetitive discharges was seen. Serial testing demonstrated proximal to distal gradients of denervation over the next 24 to 48 hours. A delay in electromyographic evidence of denervation was observed in the two adult pigs until days 5 and 8, respectively. Control limb studies remained normal throughout the study period. Nerve length measurements for individual muscle groups were as follows for the adult and newborn pigs, respectively: deltoid 11.4 cm, 2.5 cm; cleidobrachialis 16.0 cm, 4.0 cm; triceps 15.5 cm, 4.5 cm; forelimb flexors 26.0 cm, 6.5 cm; and extensor carpi radialis 31.0 cm, 9.0 cm.

CONCLUSION

Electromyographic evidence of brachial plexus denervation after surgical transection differs between the newborn and the adult pig. Consistent with wallerian degeneration, a correlation exists between length of the distal nerve segment and timing for electromyographic signs of denervation. These findings suggest it would be inappropriate to extrapolate the anticipated timing for electromyographic changes in the newborn on the basis of previously established adult non-brachial plexus data.

Brachial plexopathy in gunshot wounds and motor vehicle accidents: comparison of electrophysiologic findings

OBJECTIVE

To characterize the extent and degree of severity in subjects with gunshot wounds (GSWs) to the brachial plexus and to investigate the association between type of injuries and the predominant level involved.

DESIGN

A cross-sectional, retrospective review of electrophysiologic data.

SETTING

Electromyography laboratory of a county hospital.

PATIENTS

Thirty consecutive patients with GSWs and 14 patients with traction brachial plexopathies during a 5-year period (1992 through 1996).

MAIN OUTCOME MEASURES

The injury was categorized according to the level predominantly involved, and each component of the four major levels of the plexus was analyzed. The association between type of injury and predominant level involved was assessed via two-tailed chi 2 test. The mean number of elements per subject to each level involved was compared between GSW and motor vehicle accident (MVA) patients using unpaired t test.

RESULTS

The type of injury (GSW vs MVA) is significantly associated with the level involved. GSWs were implicated in infraclavicular rather than supraclavicular injury. Compared with MVA, the GSW plexopathies had significant lower mean number of components involved at the root and cord levels, but higher at the terminal nerve branches of plexus. In GSWs, nearly two thirds of all components were severely injured and 60% were completely damaged.

CONCLUSION

These findings demonstrate that gunshot plexopathies are characterized with multielement distribution and a mixture of lesions with or without continuity.

Magnetic nerve root stimulation in two types of brachial plexus injury: segmental demyelination and axonal degeneration

Magnetic cervical nerve root stimulation was performed in 9 patients with plexopathies secondary to suspension (SP) and in 12 cases with neurogenic thoracic outlet syndrome (NTOS). The findings were compared with those of the previously reported case groups: n-hexane polyneuropathy (HPNP), inflammatory demyelinating polyneuropathy (IDP), and motor neuron disease (MND). Muscle responses elicited by magnetic stimulation had very high rates of amplitude and area loss in the neck-axilla segments of the 6 SP patients. This, along with the other electrophysiological findings, suggested the presence of segmentally demyelinating plexus lesions. In NTOS patients, magnetic stimulation findings were not significantly different from those of the controls. Neck-axilla segment amplitude and are reduction rates in SP and IDP patients were significantly higher than those found in NTOS, HPNP, and MND groups, implying that magnetic nerve root stimulation may have a role in the demonstration of segmentally demyelinating lesions involving proximal nerve segments.

Fecal incontinence after pelvic radiotherapy: evidences for a lumbosacral plexopathy. Report of a case

PURPOSE

Clinical manifestations of radiation-induced lumbosacral plexopathy remain a rare event. We report the case of a 62-year-old woman with neurogenic fecal incontinence that occurred after radiotherapy of cervical carcinoma.

METHODS

Anorectal, bladder, and lower limb sensory-motor functions, as biologic and morphologic explorations, were performed on repeated occasions.

RESULTS

Anorectal manometry, conduction times of pudendal nerves, sacral latencies, and pudendal nerve-evoked corticals disclosed lesions of the lumbosacral plexus that was confirmed by bladder manometry and electromyography of lower limbs. Biologic and morphologic explorations were within normal ranges.

CONCLUSION

Because no other cause except radiation was demonstrated in this case, we suggest that plexopathy may be a late-occurring complication of radiotherapy.

Relation between needle electromyography and nerve conduction studies in patients with carpal tunnel syndrome

Four hundred eighty cases of electrodiagnostically confirmed carpal tunnel syndrome were reviewed to determine if the findings on nerve conduction studies could predict the presence or absence of fibrillation potentials or motor unit changes on the needle examination of the abductor pollicis brevis (APB). The needle examination is more uncomfortable and the ability to predict the findings in this setting from standard nerve conduction studies (NCS) would make the test more acceptable to patients. All patients had median and ulnar nerves (both sensory and motor) tested, as well as the needle evaluation of the APB. Two hundred thirty-one patients had an abnormal needle evaluation as defined by presence of one of the following conditions: abnormal spontaneous activity, increased motor unit action potential (MUAP) amplitude, or increased MUAP polyphasia. One hundred five patients had fibrillation potentials. The mean median motor and sensory amplitudes and latencies, as well as age, did differ in the normal and abnormal needle examination groups, but the sensitivity for predicting an abnormality ranged from 57% to 68%. The ratio of the median to the ulnar amplitudes did not improve the sensitivity of predicting the abnormal needle findings. Motor and sensory evoked potential latencies were the most important predictors of an abnormal needle examination.

Coaptation of the anterior rami of C-3 and C-4 to the upper trunk of the brachial plexus for cervical nerve root avulsion

No surgical procedure has been available to repair cervical nerve root avulsion inside the spinal canal. Results with peripheral neurotization of denervated muscles have been discouraging. The authors have performed bridge-graft coaptation in three patients with C-5 and C-6 nerve root avulsion. The components of the coaptation included the anterior primary rami of C-3 and C-4 as the donor material, the entire upper trunk as the recipient, and the sural nerve graft as the bridge. This procedure resulted in restoration of motor function in the biceps and shoulder-girdle muscles and produced improved sensation. Stimulation of the C-3 and C-4 nerve roots elicited electrical responses in the biceps and deltoid muscles that indicated nerve growth through the graft and the brachial plexus into these muscles. This reconstructive procedure is effective and should stimulate development of new approaches to treatment of cervical nerve root avulsion and proximal brachial plexopathy.

Acute brachial neuropathy in athletes

Acute brachial neuropathy is an uncommon etiology of shoulder pain and disability. It can, however, present in association with athletic activity and therefore must be included in the differential diagnosis of athletes with such symptomatology. Findings that should alert the examiner to the possible presence of acute brachial neuropathy include 1) onset with noncontact as well as contact sports, 2) rather acute onset of pain without specific inciting trauma, 3) persistent, often severe pain that continues despite rest, 4) patchy brachial plexus and/or peripheral nerve involvement, and, 5) dominant arm predominance of symptoms and signs. Electromyography and nerve conduction studies often can confirm the diagnosis. Treatment begins with rest and continues through a rehabilitation phase. Followup of athletes with acute brachial neuropathy discloses that weakness may persist in the affected muscles. Absolute strength parity may be difficult to achieve, so permission to participate in athletics must be given on a case by case basis.