Continuous wave Doppler ultrasound for evaluation of vasomotor tone of the radial artery.

OBJECTIVE: At present, the sympathetic skin response (SSR) is the only routinely employed technique for evaluating the autonomic function of peripheral nerves. The present study was conducted in order to compare SSR to continuous wave Doppler (CWD) of the radial artery in both healthy control subjects and patients with lower brachial plexus lesions. METHODS: Both methods were performed in 50 healthy volunteers (aged 23 to 70 years; mean age and standard deviation, 39.6+/-14.3 years) and six patients presenting with severe lesions of the lower brachial plexus (aged 22 to 60 years; mean age, 37.6+/-16.0 years). RESULTS: In each control subject, a SSR could be evoked with a mean latency of 1.2+/-0.2 s and a mean amplitude of 2.9+/-1.5 mV. In 45 healthy subjects, CWD revealed both a reduction of systolic, diastolic, and mean peak blood flow velocity after electrical (ES) and acoustic (AS) stimulation as well as after inspiratory cough (IC). The mean latencies to the decrease in flow velocity decrease amounted to 1.8+/-0.7, 2.0+/-0.7, and 1. 4+/-0.4 s, respectively. The resistance (Pourcelot) index increased significantly. CWD failed to show changes of blood flow velocity in five healthy subjects due to high sympathetic tone (no baseline diastolic blood flow) or instability of blood flow caused by respiration. In patients with lower brachial plexus lesions, SSR was diminished and changes in blood flow could not be observed on the affected side. CONCLUSION: CWD sonography allows easy quantitative assessment of arteriolar tone in healthy subjects and patients with autonomic nerve lesions of the limbs.     

Distribution and extent of involvement in brachial plexopathies caused by gunshot wounds, motor vehicle crashes, and other etiologies: a 10-year electromyography study

OBJECTIVE: To examine the differences in the extent and distribution of brachial plexopathy involvement caused by gunshot wounds (GSW), motor vehicle crashes (MVCs), and other etiologies, based on electrophysiologic data. DESIGN: Retrospective review of electrophysiologic data from 1993 to 2002. SETTING: A large urban county hospital. PARTICIPANTS: Sequential patients (N=109) with the diagnosis of brachial plexopathy established by electromyography testing. This included 35 patients with GSW, 25 involved in an MVC, and 49 with other etiologies. INTERVENTIONS: Not applicable.Main Outcome Measures The brachial plexus was divided into 9 regions: upper, middle, and lower root; upper, middle, and lower trunks; and lateral, posterior, and medial cords. Regions involved by needle study on electromyography were denoted as positive or negative. The total number of regions involved was also recorded. RESULTS: Injury was most common in the trunks (52%), cords (36%), and roots (12%) (Pearson chi(2), P<.000). Specifically, the "other" category had the greatest number of injuries to the trunks (54%) (Pearson chi(2), P<.000), whereas the trunks (46%) and cords (45%) were more evenly affected in GSW cases (Pearson chi(2), P=.585). In the MVC group, there was a trend toward more trunks (56%) being affected (Pearson chi(2), P=.076). CONCLUSIONS: Differences were noted in the distribution of injury when examining subtypes of traumatic brachial plexopathies.     

Conduction studies of the medial cutaneous nerve of the forearm

The forearm medial cutaneous nerve is a pure sensory branch from the medial cord of the brachial plexus. Its fibers are derived from the eighth cervical and first thoracic nerves. A simple, easily reproducible antidromic technique for studying conduction of the forearm medial cutaneous nerve is described with the knowledge (obtained from cadaver dissections) of its exact topography. Sixty nerves were studied in 30 able-bodied adults, 15 women and 15 men. Surface stimulation was done over the medial aspect of the middle of the arm at a level where the nerve pierces the deep fascia. Surface recordings were made 18cm distally over the course of its volar branch. Action potentials were obtained in 100% of the subjects without electronic averaging. Mean values obtained were as follows: latency to onset 2.73 +/- 0.17 msec; latency to peak 3.31 +/- 0.19 msec; conduction velocity of the fastest fibers 65.9 +/- 4.3 m/s; amplitude 15.4 +/- 4.1 microvolts, and the mean difference in latency between the right and left nerves in the same subject was 0.1 msec. Conduction studies of this nerve should be useful in electrodiagnostic evaluation of peripheral neuropathy (particularly in below amputees), local neuropathic conditions, and entrapment syndromes involving the medial cord of the brachial plexus.     

高频超声在臂丛椎间孔内神经根损伤及病变诊断中的应用

目的 探讨高频超声在诊断臂丛椎间孔内神经根损伤及病变中的价值。方法 高频超声检查和诊断27例臂丛椎间孔内神经根撕脱伤和8例臂丛神经根部发出神经鞘瘤,并与手术所见进行比较,随机选择30例无神经外伤的成年人作为正常对照组,观察颈椎椎间孔内神经节及出椎间孔外臂丛神经声像图。结果 正常臂丛椎间孔内神经与脊髓连接部、脊神经节的声像图表现为低回声结构,椎动脉长轴及横突根部是超声检查椎间孔内神经根的定位标志。臂丛神经椎间孔内C5～C8神经根和出椎间孔外神经,均能得到良好的显示,显示率为100％。27例臂丛神经椎间孔内根性撕脱伤,超声显示椎间孔内神经节低回声区扩大,连续性中断或消失,出椎间孔外远端神经增粗或椎管旁伴有脑脊液囊肿形成。8例臂丛神经根部发出神经鞘瘤,超声显示椎间孔外脊神经节呈瘤样改变,向神经干延伸,内为束状实性回声,有血供信号。结论 高频超声检查臂丛神经椎间孔内神经根性撕脱伤或病变,可以提供有价值的形态学诊断信息。     

Muscle sounds from evoked twitches in the hand

Skeletal muscle emits acoustic signals during voluntary contraction and during twitches produced by electric stimulation of peripheral nerves. Supramaximal, percutaneous electric stimulation was applied to the median or ulnar nerve, while electric and sound signals were recorded from the abductor pollicis brevis or abductor digiti minimi muscles, respectively, in 27 volunteers without known disease. Reproducible waveforms were obtained with the following means and standard deviations: (1) latency from stimulus to onset of sound, median = 6.9 +/- 0.8msec, ulnar = 6.6 +/- 1.0msec; (2) latency from stimulus to peak of sound, median = 15.1 +/- 1.5msec, ulnar = 13.1 +/- 1.5msec; (3) latency from onset of surface electric to onset of sound, median = 3.6 +/- 1.0msec, ulnar = 3.9 +/- 1.1msec; (4) baseline-to-peak amplitude of sound, median = 860 +/- 270mV, ulnar = 640 +/- 230mV; and (5) baseline-to-peak amplitude of surface electric, median = 11.4 +/- 3.0mV, ulnar = 10.1 +/- 2.4mV. Stimulated muscle sounds are useful when artifacts, such as tremor, interfere with voluntary muscle sound recordings, or when quantitative information is needed to relate electric to contractile muscle activity.     

A novel technique for recording from the serratus anterior

OBJECTIVE: To design an electrodiagnostic technique by which to accurately record the serratus anterior compound muscle action potential (CMAP). DESIGN: Observational study. SETTING: Academic electromyography laboratory. PARTICIPANTS: Fifteen healthy volunteers. INTERVENTIONS: The long thoracic nerve was stimulated by using a standard bipolar surface electrode in the axilla, just anterior to the midaxillary line. The serratus anterior CMAP was recorded by using a self-adhesive, 8.0 x 0.5 cm, ring electrode as the E1 placed across the serratus anterior interdigitations starting at the nipple level. A self-adhesive, motor (1 x 1 cm) electrode was used as E2 and placed over the seventh rib. A standard self-adhesive ground electrode was placed over the inferior region of the latissimus dorsi. MAIN OUTCOME MEASURES: Distal motor latency (DML), and CMAP amplitude and duration. RESULTS: After removing 2 outliers, the results are reported as the mean +/- 1.96 standard deviations. Right long thoracic DML was 2.2+/-1.0ms and the left was 2.3+/-0.9ms, with a side-to-side mean difference of 0.3+/-0.4ms. The right serratus CMAP amplitude was 3.8+/-3.9mV and the left was 3.9+/-3.7mV, with a side-to-side mean difference of 0.6+/-1.2mV. Statistical analysis did not reveal a significant side-to-side difference for DML or CMAP amplitude. Both sides were combined to form a single set of trials for DML and CMAP amplitude. The mean DML became 2.2+/-0.7ms, and the CMAP amplitude was 3.5+/-1.9mV. The CMAP duration was 14.5+/-4.3ms on the right and 14.5+/-4.1ms on the left. A significant, positive correlation existed between height and DML ( P <.02). The 95% confidence intervals for DML and CMAP amplitudes were 2.1 to 2.5ms and 1.5 to 3.1mV, respectively. CONCLUSIONS: Our latency, side-to-side comparisons and amplitude data were consistent with other motor nerve conduction findings in the literature. Stimulating the long thoracic nerve in the axilla will provide a reliable technique to aid in the diagnosis and treatment of long thoracic neuropathy.     

Treatment based on H-reflexes testing improves disability status in patients with cervical radiculopathy

BACKGROUND: Postural modification in patients with lumbosacral radiculopathy either causes further H-reflex suppression, indicating increased root compression, or it effects recovery, indicating decompression of the spinal root. The posture that effects maximum recovery of the H-reflex amplitude is called optimum spinal posture (OSP) and is suggested as a therapeutic exercise to decompress the compromised nerve root. The focus of this study was to identify the OSP that effects the maximum recovery of the flexor carpi radialis (FCR) H-reflex and to study its effect on the disability status in patients with cervical radiculopathy. SUBJECTS AND METHODS: Fourteen patients (46 +/- 12 y) with confirmed symptoms of C7 radiculopathy for the previous 6 months volunteered for the study. The FCR H-reflex was elicited by electrical stimulation of the median nerve at the cubital fossa (0.5 ms, 0.2 pps at H-max). Signals from the FCR muscle were recorded using a Cadwell 5200A EMG unit. The FCR H-reflex was recorded in natural sitting position with the head in natural position and in the OSP. Four traces of the H-reflex were recorded and averaged. The disability status was evaluated, using the Neck Disability Index (NDI), before exercising in the OSP and after 2 days of exercise in the OSP. DATA ANALYSIS: Paired t-test and Spearman's correlation coefficients were used. RESULTS: The H-reflex amplitude and latency were significantly different in the OSP and with the head in a natural position (P < 0.004; P < 0.011). Larger reflex amplitude and shorter latency were recorded in the OSP. The NDI scores were considerably improved after exercising in the OSP (P < 0.001). Spearman's correlation coefficient showed negative association between the H-reflex amplitude and the NDI scores (r = -0.64 to -0.54; P < 0.05). CONCLUSION: Exercising in the OSP increased the H-reflex amplitude and decreased latency of the compromised cervical root. It resulted in decreasing the disability status in this group of patients.     

3.0T核磁skyra 3D-CISS序列与3D-SPACE序列对臂丛神经成像的对比研究

目的:比较3.0T、MRI两种扫描序列对臂丛神经成像的应用价值。材料与方法:收集临床需要扫描颈椎病MRI患者40例,都通过可变反转角三维快速自旋回波(3D-SPACE)序列、三维双回波稳态构成干扰序列(3D-CISS)序列、常规序列等方式进行检查,所有图像均进行后处理重建。结果:3D-CISS序列神经根-椎体CNR高于3D-SPACE序列,而3D-CISS序列神经根-脑脊液CNR低于3D-SPACE序列(P<0.05),3D-CISS序列较优,3D-SPACE序列图像质量较差。对受压神经根清晰度的显示,3D-CISS序列与3D-SPACE序列对比,优于3D-SPACE序列(P<0.05)。结论:对于展示臂丛神经神经根结构和对神经根病变做诊断等方面,3D-CISS序列明显优于3D-SPACE序列,对颈神经根成像及颈神经根受压等情况的临床诊断更具优势。     

Monoparesis with complex regional pain syndrome-like symptoms due to brachial plexopathy caused by the varicella zoster virus: a case report

Viral invasion of the motoneurons and the subsequent inflammation in the anterior horn cells by the varicella zoster virus results in a weakness in the area of the cutaneous eruption. The exact mechanism of zoster paresis is uncertain. The occurrence of symptoms resembling complex regional pain syndrome (CRPS) is common in subjects where the herpes zoster (HZ) outbreak affects an extremity, particularly if it is the distal extremity that is involved. We report the case of a 54-year-old man with monoparesis, hyperalgesia, allodynia, edema, and both color and skin-temperature changes in his left arm after a skin eruption. Electrophysiologic examination revealed the partial degeneration of the superior, middle, and inferior truncus in the brachial plexus, with evidence of HZ infection. Magnetic resonance imaging of the cervical spine and brachial plexus showed degenerative changes without any evidence of nerve root compression. Brachial plexopathy may be the direct cause of the reversible upper-limb paresis resulting from HZ with CRPS-like symptoms.     

A Sledgehammer on the Brachial Plexus: Thoracic Outlet Syndrome, Subclavius Posticus Muscle, and Traction in Aggregate

Özçakar L, Güney M?, Özda? F, Alay S, K?ralp MZ, Görür R, Saraço?lu M. A sledgehammer on the brachial plexus: thoracic outlet syndrome, subclavius posticus muscle, and traction in aggregate.Reported here is a 30-year-old man who was seen because of pain and weakness in the upper extremities after a tractional injury. Physical examination revealed significant atrophy in the left deltoid and right intrinsic hand muscles, generalized hypoesthesia, decreased deep tendon reflexes bilaterally, and decreased strength in various muscle groups. Roos (right) and hyperabduction (bilateral) tests were positive. Electrodiagnostic studies were consistent with bilateral brachial plexopathy. Cervical radiographs showed long transverse process of C7 on the right side and a small rudimentary rib articulating with C7 on the left side. Brachial plexus magnetic resonance imaging demonstrated an aberrant muscle and compressive brachial plexus injury on the left side. Surgery via transaxillary approach was performed on the left side. The occurrence of traumatic brachial plexopathy in the presence of underlying thoracic outlet syndrome and subclavius posticus muscle is discussed for the first time in the literature.     

Median nerve determinations: analysis of two techniques

The objective of this study was to compare two techniques of obtaining median motor and sensory nerve determinants. One method utilized premeasured electrode placement, while the other used anatomic landmarks. It was postulated that increased accuracy could be achieved by more precise measuring techniques. The right median nerve in 50 able-bodied subjects was investigated. Each subject was tested by both anatomic and premeasured methods. Skin temperatures were maintained between 31C and 33C. Latencies were measured to onset and peak, and amplitudes were gauged from baseline to peak. Latency studies were evaluated. Results concluded that mean distal motor latencies, stimulating 8cm from active recording electrode, was 3.1msec +/- 0.4 and amplitude was 11.1mV +/- 3.0. Stimulating at distal wrist crease, mean latency was 2.6msec +/- 0.38 and amplitude was 11.3mV +/- 3.6. Sensory latencies to onset of response when stimulating 14cm from active ring electrode with reference 4cm distally were 2.1msec +/- 0.25. Sensory latency when stimulating at wrist crease and ring electrodes over proximal interphalangeal and distal interphalangeal joints was 2.1msec +/- 0.25 to onset and 2.8msec +/- 0.32 to peak and amplitude was 36.1 +/- 14.6. The authors concluded that there was no statistically significant difference in accuracy between the premeasured and anatomic methods.     

Pancoast tumor presenting as cervical radiculopathy

A case of Pancoast tumor presenting as cervical radiculopathy is reported, including the clinical, EMG, and radiologic findings. A 64-year-old man with a two-month history of left shoulder pain and left arm numbness at the medial aspect of the hand and forearm presented for electrodiagnostic examination, and a severe C8 radiculopathy was documented. Subsequent radiologic evaluation (myelogram and routine chest x-ray) yielded the diagnosis of left apical lung tumor (Pancoast tumor), eroding through the C7 and T1 pedicles and T1 vertebral body, with cut-off of the left C8 nerve root. Pancoast tumor has long been implicated as a cause of brachial plexopathy. The EMG presentation of isolated cervical radiculopathy, however, has not been previously reported, despite the tumor's known tendency for local invasion which may include the nerve roots and even the spinal canal in its advanced stages. This patient's normal sensory studies argue against any significant coexisting lower brachial plexopathy. The possibility of Pancoast lesion should be considered not only in the presence of brachial plexopathy, but also when C8 or T1 radiculopathy is found.     

Effect of interelectrode distance on sural nerve action potential parameters

OBJECTIVE: To assess differences in amplitude, latency, and duration, using a 3-cm vs. 4-cm distance between the active and reference electrodes when performing sural nerve conduction studies (NCS). Current normative data in lower-limb studies are generally based on 3-cm interelectrode differences, although 4-cm differences have been reported to be optimal in the upper limb. DESIGN: Prospective study comparing the onset latency, peak latency, duration, and amplitude for the sural sensory nerve action potential (SNAP) recording at two interelectrode distances in adult volunteers. RESULTS: Forty-three sural nerves were studied in 22 normal subjects. Peak latencies recorded with a 4-cm interelectrode distance were significantly longer than those recorded with a 3-cm distance (mean difference = 0.06 msecs [SD = 0.09, P = 0.0073]). Duration was significantly longer (mean difference = 0.03 msecs [SD = 0.07, P = 0.0270]), conduction velocities were significantly slower (mean difference = -0.7 msecs [SD 1.0, P = 0.0012]), and onset latency and amplitude were not found to differ significantly. Average differences in peak latencies, duration, velocity, onset latency, and amplitude were not correlated with gender, age, or BMI. CONCLUSIONS: In contrast to studies of upper-limb sensory NCS, sural SNAP parameters obtained with 3- and 4-cm interelectrode distances did not differ for onset latencies and amplitude. Peak latencies, duration, and conduction velocity differences, though statistically significant, were of insufficient magnitude to be clinically meaningful. By using a 4-cm instead of a 3-cm interelectrode difference for sural nerve studies, the small prolongation of 0.06 msecs in peak latency and tiny increment of 0.27 muV observed in our investigation is unlikely to influence the electrodiagnostician's interpretation of the study.     

Saphenous nerve conduction in healthy subjects

Saphenous nerve conduction was studied in 40 healthy subjects utilizing a slight modification of the method described by Wainapel et al. The mean values obtained were as follows: distal sensory latency, 2.9 +/- 0.3 msec for 10 cm distance; conduction velocity, 46.6 +/- 3.5 m/sec; and amplitude of sensory nerve action potential, 10.7 +/- 4.3 microV. The technique should be useful in the electrodiagnostic differentiation between lumbar root (L3, L4) lesions and postganglionic lesions such as lumbar plexus and femoral nerve lesions and entrapment neuropathy of the saphenous nerve.     

经颅电刺激咀嚼肌诱发电位:非创伤性评估皮质脑干束功能

目的对健康个体进行经颅电刺激咀嚼肌诱发电位的研究,建立评估皮质脑干束的检查方法.方法对56名健康志愿者进行经颅电刺激,在双侧咀嚼肌同时接受,分别记录同侧的根运动诱发电位(root motor evoked potentia1,R-MEP)和对侧的皮层运动诱发电位(cortical motor evoked potential,C-MEP)的潜伏期、波幅.结果R-MEP的潜伏期为(3.55±0.44)ms,波幅为(3.49±2.73)mV;C-MEP的潜期为(5.83±1.40)ms,波幅为(563.84±525.07)μV.C-MEP的潜伏期与年龄无明显相关性(P＞0.1).结论C-MEP是一种非创伤性评估皮质脑干束的检测方法.     

高频超声在正常臂丛神经检查中的应用

目的 探讨高频超声显示臂丛神经的可行性及方法学。方法 用高频超声检查12例正常人臂丛神经，确认其与周围组织解剖定位关系。结果 正常臂丛神经长轴显示多条线性平行回声，短轴呈圆形中等回声，内有点状弱回声，斜角肌间隙、锁骨下动脉和颈深动脉是检查中的重要标志，C5-7显示率100％（12／12例），C8、T1显示率83．3％（10／12例）。结论 高频超声可为臂丛神经的形态学观察提供新的影像检查方法。     

Electrodiagnostic localization of traumatic upper trunk brachial plexopathy

Eighteen patients having traumatic upper trunk brachial plexopathy ("the stinger"), a common football injury, were investigated electrodiagnostically. Proximal nerve conduction was determined by stimulating the supraclavicular fossa and at the C5 root and recording from muscles supplied by the long thoracic, suprascapular, musculocutaneous, axillary, lateral pectoral and thoracodorsal nerves. The accessory nerve was stimulated in the lateral posterior triangle and the evoked potential recorded from the upper trapezius muscle. Median and ulnar nerves were also tested, sensory and motor fibers being stimulated peripherally and proximally. Conduction slowing was observed in 16 patients mainly in the proximal segments of the axillary, musculocutaneous, suprascapular and accessory nerves. The most commonly observed electromyographic abnormalities were an increase in polyphasic waves and decreased recruitment. Spontaneous activity was sparse. These abnormalities appear to result most likely from compression of the most superficially located fibers of the brachial plexus at Erb's point. As a significant etiologic factor, the impact of ill-fitting shoulder pads against the neck during a football tackle is suggested. This empirical observation was supported by the decrease of "stingers" after the improvement of the shoulder gear.     

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.