F response characteristics in type I diabetes mellitus

Ulnar and tibial F response parameters were characterized in 17 healthy controls and 26 subjects with type I diabetes mellitus meeting or exceeding criteria for mild diabetic peripheral neuropathy. The presence of mild diabetic peripheral neuropathy was determined by utilizing conventional nerve conduction studies, the neuropathy symptoms score and a neurologic examination. Ulnar and tibial nerve F response latency, amplitude, duration, chronodispersion and persistence were then compared between populations. The relationship between tibial F response persistence and minimal F response latency was assessed in both populations. In addition, the relationship between tibial F response persistence and tibial nerve conduction velocity and tibial nerve compound action potential characteristics (e.g., latency, amplitude and duration) was assessed in the diabetic population. The results indicate that ulnar F response latency and chronodispersion failed to differentiate the subject and control populations; however, significantly decreased ulnar F response amplitude and duration were noted in the diabetic population. In the tibial nerve, the F response persistence was significantly decreased in the diabetic population but persistence did not correlate with compound muscle action potential latency, amplitude, duration or nerve conduction velocity. Finally, the tibial F response latency, amplitude, duration and chronodispersion failed to differentiate the control and diabetic populations.     

Sensory nerve evoked responses in spinal cord injury

Previous studies have documented the presence of fibrillations, positive waves, and decreased motor evoked response amplitudes in spinal cord injury (SCI) subjects. The purpose of this study was to further evaluate sensory nerve status in this population. Twenty-eight subjects with SCI for at least five months and evidence of spasticity were included. Sural sensory and tibial motor evoked response amplitudes were measured. The mean sural sensory amplitude was 8.0 +/- 5.9 microV (normal = 15.0 +/- 5.3 microV). The mean tibial motor amplitude was 5.1 +/- 4.3 mV (normal = 11.7 +/- 3.8 mV). In six subjects with significantly reduced sural sensory amplitudes, more extensive electrodiagnostic testing was performed. These studies showed diffusely decreased lower extremity sensory and motor evoked response amplitudes and diffuse positive waves and fibrillations in no particular distribution. Thus, subjects with SCI may have sensory as well as motor nerve abnormalities. An intact connection between the second order and primary sensory neuron may be necessary for maintenance of axonal integrity of the primary neuron.     

重复经颅磁刺激对截瘫后脊髓兴奋性作用的实验研究

目的观察重复经颅磁刺激对脊髓损伤大鼠脊髓兴奋性的影响并探讨其机制。方法利用重物撞击法制备成年SD大鼠T10脊髓损伤模型，造模8周后脊髓损伤磁刺激组给予0．5Hz阈上强度经颅定位磁刺激，每天500个脉冲，共4周。另设脊髓损伤组及正常对照组。各组大鼠不同时点行后肢F波检测，观察F与M波幅比值；免疫组化法观察5-羟色胺（5-HT）在脊髓损伤区头尾端的变化情况。结果脊髓损伤后8周F波幅增高，M波幅恒定，与正常对照组比较，F／M波幅比值明显升高（P〈0．01）；磁刺激后，F／M波幅比值降低，与脊髓损伤组比较有非常显著性差异（P〈0．01）；脊髓损伤8周时，损伤头、尾端5-HT密度明显降低（P〈0．01）；磁刺激后，损伤头、尾端表达均明显升高（P〈0．01）。结论重复经颅磁刺激可以降低慢性下胸段脊髓不全损伤大鼠脊髓兴奋性，其机制可能与通过残存5-HT能下行传导束增加递质分泌，改善脊髓上位中枢对脊髓损伤尾端的控制有关。     

Alterations of F wave parameters after exercise in symptomatic lumbar spinal stenosis

OBJECTIVES: The purpose of the study is to investigate changes in F wave parameters after exercise in subjects with symptomatic lumbar spinal stenosis. DESIGN: A total of 19 older patients with lumbar spinal stenosis and neurogenic claudication participated in this cohort study. No one withdrew for adverse effects. All subjects underwent physical therapy, with half performing additional interval-walking exercises. Groups were treated for eight sessions, returning for follow-up at weeks 4 and 8. Changes in F wave indices--minimal latency, chronodispersion, and persistence--were calculated. The treatment group demonstrated worsening of F wave persistence at 8-wk follow-up (P < 0.01). CONCLUSIONS: F wave indices worsened after an interval-walking exercise program. Subjects in the treatment group demonstrated worsening of F wave persistence at 8-wk follow-up.     

Increased threshold sural amplitude after upper limb isometric contraction in complete paraplegics

OBJECTIVE: To determine whether the enhancement of threshold sural sensory nerve action potentials (SNAPs) occurred in patients with spinal cord injury after upper limb isometric contraction. DESIGN: This prospective study, in which ten paraplegic patients with spinal cord injury were recruited from the Harris County community and served as his/her own control, was performed in the electromyography laboratory at Harris County Hospital District Quentin Mease Hospital. The baseline SNAP was established using ten threshold, signal-averaged stimuli to the sural nerve. With the same stimulus strength, the SNAP was recorded while the subjects' arms were pulled apart against a force gauge at 50% and 100% maximum force. Responses were recorded every 4 min until the values returned to baseline. RESULTS: Results showed an increase in the SNAP amplitude after 50% and 100% maximum force. The mean preexercise SNAP amplitude was 4.0 +/- 0.6 (SE) microV. At 50% force, the SNAP amplitude was 7.57 +/- 1.2 microV; at 100% force, it was 7.29 +/- 1.2 microV. The post hoc analysis of the data revealed P = 0.009 and P = 0.01 for 50% and 100% maximum force, respectively. CONCLUSIONS: The threshold SNAP of the sural nerve was enhanced after isometric exercise in paraplegic patients with spinal cord injury.     

Cardiovascular and endocrine responses during the cold pressor test in subjects with cervical spinal cord injuries

OBJECTIVE: To investigate cardiovascular regulation and endocrine responses during the cold pressor test in patients with chronic spinal cord injury (SCI). DESIGN: Experimental and control study. SETTING: University laboratory, department of rehabilitation medicine, in Japan. PARTICIPANTS: Eight quadriplegic subjects with complete spinal cord transection at the C6 to C8 level and 6 age-matched healthy subjects. INTERVENTIONS: Cardiovascular and endocrine responses were examined during 2 minutes of control, 3 minutes of ice-water immersion of the foot, followed by a 3-minute recovery. MAIN OUTCOME MEASURES: Blood pressure, heart rate, the Borg 15-point Rating of Perceived Pain Scale, and blood samples for measurement of plasma norepinephrine, epinephrine, plasma renin activity, plasma aldosterone, and arginine vasopressin. RESULTS: The rise in the mean arterial blood pressure during the cold pressor test in patients with SCI (baseline, 81.6+/-3.7mmHg; increased by 30%+/-6.1%) was significantly (P<.05) higher than that in healthy subjects (baseline, 101.2+/-4.5mmHg; increased by 20%+/-4.5%). The SCI subjects had no change in heart rate throughout the test, in contrast to the tachycardia noted in normal subjects. Baseline plasma norepinephrine in SCI subjects (63.0+/-18.3pg/mL) was significantly lower than in normal subjects (162.3+/-19.6pg/mL) and plasma norepinephrine increased significantly during the cold pressor test in both groups. CONCLUSIONS: In the SCI subjects, a reflex sympathetic discharge through the isolated spinal cord results in a more profound rise in mean blood pressure during ice-water immersion. This response was free of inhibitory impulses from supraspinal center and baroreceptor reflexes, either of which might restrain the increase in blood pressure.     

Aerobic power during maximal exercise in untrained and well-trained persons with quadriplegia and paraplegia

The aerobic power during maximal exercise was studied in 58 males with traumatic spinal cord lesions from C4 to L4 (25 well-trained "world-class athletes" and 33 untrained). For comparison we tested five well arm-trained and five arm-untrained able-bodied subjects. During maximal wheelchair exercise the aerobic power (VO2 peak), pulmonary ventilation and blood lactate concentration was higher in subjects with lower levels of spinal cord injury. At each injury level above C6-C7, nearly all trained subjects reached higher VO2 peaks than untrained subjects with the corresponding level of lesion. The mean values for trained paraplegic persons were 2.16 +/- 0.38 l x min-1, corresponding to 33.6 +/- 6.7 ml x kg-1 x min-1. The peak heart rate was lower in the quadriplegic than in the paraplegic group with no or only small difference between trained and untrained subjects at the same level of spinal cord injury. Spinal cord lesions with pareses reduce the total active skeletal muscle mass. This can cause physical inactivity, medical complications and social isolation. As a consequence, cardiovascular disorders as cause of death is higher in this group compared to the general population. Therefore, one aim of rehabilitation is to increase the individual's performance in daily life activities. It has been shown that the normal daily life activities of quadri- and paraplegic individuals with no additional physical training are not intense enough to maintain a satisfactory level of physical fitness.(ABSTRACT TRUNCATED AT 250 WORDS)     

Comparison of clinical and neurophysiologic responses to intrathecal baclofen bolus administration in moderate-to-severe spasticity after acquired brain injury

OBJECTIVES: To compare clinical and neurophysiologic responses to intrathecal baclofen (ITB) bolus injection in subjects with spasticity after acquired brain injury. DESIGN: Prospective case series. SETTING: Tertiary care rehabilitation center. PARTICIPANTS: Thirty consecutive ITB pump candidates with dysfunctional spasticity caused by traumatic brain injury, hypoxic encephalopathy, or stroke. INTERVENTION: A single 50-microg ITB bolus. MAIN OUTCOME MEASURES: Lower-extremity Ashworth Scale score at 2, 4, and 6 hours after ITB bolus; soleus Hoffmann reflex (H-reflex)/M-wave amplitude (H/M) ratio and abductor hallucis F-wave persistence and F/M ratio at 5 hours. Nonparametric repeated-measures analysis of variance and paired t test were used for statistical analyses. RESULTS: The Ashworth score on the more involved side significantly decreased from 2.4+/-0.7 at baseline to 1.5+/-0.6 and 1.4+/-0.6 at 4- and 6-hour evaluations, respectively (P<.001). H/M ratio significantly decreased bilaterally (more involved side, 62%+/-28% to 14%+/-19%; less involved side, 59%+/-26% to 11%+/-20%; P<.001). F-wave persistence significantly decreased on the more involved side (86%+/-17% to 75%+/-13%, P<.05) with no change in F/M ratio. There was no significant correlation among these outcome measures before or after the ITB bolus injection. CONCLUSIONS: H/M ratio is more sensitive than the Ashworth score or F-wave persistence in detecting a physiologic response to ITB bolus. H-reflex is useful for verification of ITB bolus administration, as an adjunct to clinical evaluation, particularly among patients with moderate spasticity at rest or with small changes in Ashworth score. However, potential application of the marked sensitivity of the H-reflex to other clinically challenging situations, such as early detection of possible ITB system malfunction, awaits further investigation.     

Decrease of hypertonia after continuous passive motion treatment in individuals with spinal cord injury

OBJECTIVE: To examine the effect of ankle continuous passive motion on the reflex excitability and overall hypertonia of calf muscles in individuals with chronic spinal cord injury and without physical disabilities. DESIGN: Two-way repeated measure experimental design. SETTING: Inpatient rehabilitation department in general hospital. SUBJECTS: The spinal cord injury group comprised eight individuals with chronic complete spinal cord injury and the control group comprised eight healthy people without physical disabilities. An additional eight healthy people were recruited as the sham group. INTERVENTIONS: Each subject received 60 min of continuous passive motion on the ankle joint. MAIN MEASURES: The H-reflex of the soleus muscle was elicited by tibia nerve stimulation just before, immediately after, and 10 min after continuous passive motion. The Modified Ashworth Scale (MAS) score at the ankle joint was recorded for the spinal cord injury group just before and 10 min after continuous passive motion therapy. RESULTS. After 60 min of continuous passive motion of the ankle joint, the H-reflex amplitude at the soleus muscle was depressed in individuals with and without spinal cord injury (77.46 +/- 32.64%, P = 0.047 and 51.76 +/- 26.74% of initial, P<0.0001, respectively). This depression persisted up to 10 min after continuous passive motion only in individuals without spinal cord injury. In individuals with spinal cord injury, the median of MAS scores decreased from 2 to 1.25 after continuous passive motion. CONCLUSION: Sixty minutes of continuous passive motion of the ankle joint decreased reflex excitability and overall hypertonia in people with or without spinal cord injury. The depression of overall hypertonia persisted longer than the reflex excitability in people with spinal cord injury.     

Functional neuromuscular stimulation for standing after spinal cord injury

A study was undertaken to determine if functional neuromuscular stimulation could be used to obtain standing in patients with traumatic spinal cord injury. Twenty-five subjects were selected during the study, and standing was accomplished in 21 using bilateral quadriceps stimulation with the hips in hyperextension. Four subjects elected not to continue participation to the point of standing. Stimulation parameters were 0 to 120V pulse amplitude, frequency 13Hz or 20Hz, and pulse width of 0.4msec. Confirmation of standing with support of 95% of the body weight by the legs was verified by quantitative measurements with a dual-scale force platform or a biomechanics force platform. Subjects initially selected had injury levels between C7 and T11 and ranged in age from 22 to 47 years, with duration of injury from one to 13 years. The subjects had complete lesions, with no active motor function below the last normal level, and absent sensation or partial sparing of sensation with vague perception of pinprick, but no position sense. Six subjects stood at home and 15 stood only in the laboratory. This five-year experience indicates that paraplegic individuals may obtain standing with functional neuromuscular stimulation.     

F波对糖尿病周围神经病诊断的意义

目的：研究糖尿病患者及健康人F波，探讨其对诊断糖尿病周围神经病(DPN)的意义。方法：检测68例糖尿病患者和41例健康人上肢正中神经和下肢胫神经F波，检测参数包括F波最短潜伏期(Flmi)，潜伏期离散度(Fchd)、F波传导速度(Fwcv)、F比值(Fratio)。结果：病例组中糖尿病周围神经病变53例，其Flmi、Fchd、Fwcv及Fratio与健康组比较均差异有显著性。F波各参数异常率普遍较高(32．1％～66．0％)，总阳性率为79．2％；糖尿病无周围神经病变15例，其中Fchd增加4例、Flmi延长2例、FWCV减慢2例。结论：F波是诊断糖尿病周围神经病的敏感指标，并可发现亚临床病变，多个参数相结合有助于提高阳性检出率。     

Adrenal gland volume after spinal cord injury

OBJECTIVE: Spinal cord injury in adult men may result in hypothalamic-pituitary-adrenal axis dysfunction. Atrophy of adrenal glands was speculated in these patients. This study was undertaken to clarify the functional-anatomic correlation between adrenal volume and body surface area in subjects with spinal cord injury with impaired adrenal reserve. DESIGN: Twenty male subjects with chronic spinal cord injury with impaired adrenal reserve were identified by adrenocorticotropic hormone stimulation test from a group of 42 subjects. All subjects with spinal cord injury and healthy volunteers underwent computed tomographic imaging with contiguous 3-mm section over adrenal glands for volumetric measurements. Ten pairs of subjects with spinal cord injury and controls with matched height and weight were included in the statistical analysis. RESULTS: Significantly increased relative adrenal volumes were noted among subjects with chronic spinal cord injury and impaired adrenal reserve as compared with the body weight-matched and height-matched control group. CONCLUSIONS: Increased relative adrenal volumes were found after chronic spinal cord injury. Hyperplasia of the zona glomerulosa may be the cause of increased relative adrenal volume after chronic spinal cord injury.     

完全性脊髓损伤患者肛门直肠动力学研究

目的 探索颈、胸段完全性脊髓损伤后肛门直肠功能降碍对排便的影响。方法 利用肛门直肠动力检测仪，对照比较30例颈、胸段完全性脊髓损伤患者和30例正常人排便时肛门直肠动力学参数的变化。结果 颈、胸段完全性脊髓损伤患者排便时肛管压力下降幅度、直肠—肛管压力梯度和排便指数小于正常人(P＜0．01)。结论 脊髓损伤破坏了用力排便时肛门直肠活动的协调性，使自主排便机制受损，非自主排便成为主要排便机制。     

诱发电位在组织移植修复脊髓损伤中的变化及意义

目的:通过测定诱发电位变化探讨不同神经组织移植对成鼠损伤脊髓功能恢复的影响。方法:成鼠胸髓损伤后,分别移植带血管蒂正中神经(VPN组)、孕14d胚胎脊髓(FSC组)、带血管蒂正中神经加胚胎脊髓(V+F组)。术后1,2,4,8,12周行体感诱发电位(SEP)和运动诱发电位(MEP)检查。结果:各组SEP和MEP的峰潜伏期在2-8周内均有恢复,V+F组显著优于对照组(P<0.05)。结论:带蒂神经与胚胎脊髓联合移植对脊髓传导功能的恢复有较好作用。     

Electrodiagnostic values through the thoracic outlet using C8 root needle studies, F-waves, and cervical somatosensory evoked potentials

Mid-humerus cadaver determinations of ulnar F-wave, C7 spinal somatosensory evoked potential (SEP), and modified C8 root stimulation (RS) were performed bilaterally on 20 normal subjects to standardize technique and obtain normal values for the segment from mid-humerus to cervical spine. Our cadaver study shows that the best position for upper extremity measurement of mid-humerus-cervical spine distance is at 60 degrees of shoulder abduction, 45 degrees of internal rotation, and at the distance of 35cm, measured by caliper. Using this position and distance the following normal values were obtained: 1) Mid-humerus F-wave minimal, maximal, and mean latencies, and minimal nerve conduction velocity (NCV) were 21.8 +/- 1.2msec, 22.3 +/- 1.2msec, 22.3 +/- 1.1msec, and 59.7 +/- 2.4m/sec, respectively. Latency difference between minimal and maximal F-wave was 1.4 +/- 0.4msec. 2) Cervical spine SEP was 5.1 +/- 0.4msec, with left to right difference of less than 0.9msec. 3) C8 RS and mid-humerus ulnar nerve (UN) pick-up latency and NCV were 4.9 +/- 0.2msec and 71.4 +/- 2.2m/sec, whereas C8 root pick-up and mid-humerus UN stimulation latency and NCV were 5.2 +/- 0.4msec and 66.9 +/- 5.2m/sec, respectively. To evaluate proximal nerve conductivity through the thoracic outlet, the sequential use of the three modified techniques for 35cm mid-humerus-cervical spine distance is recommended.     

A型肉毒毒素局部注射对远隔部位F波影响的临床研究

目的观察A型肉毒毒素局部注射后远隔部位F波改变，揭示对脊髓运动神经元兴奋性的影响，探讨其机制。方法选取29例原发性痉挛性斜颈患者，应用A型肉毒毒素进行颈部肌肉注射治疗，检测和比较注射前、注射后1周和12-16周尺神经及胫神经F波的潜伏期及出现率。结果痉挛性斜颈患者A型肉毒毒素局部注射后1周及12～16周，尺神经及胫神经M波波幅、潜伏期和神经传导速度与注射前差异无统计学意义；局部注射后1周，尺神经及胫神经F波潜伏期较注射前显著延长（P〈0．05），出现率差异无统计学意义；注射后12～16周，尺神经及胫神经F波潜伏期及出现率与注射前差异无统计学意义；胫神经和尺神经F波潜伏期变化值（注射前后差值）差异元统计学意义，与A型肉毒毒素注射剂量元明显相关性。结论A型肉毒毒素局部注射存在“远隔效应”，远隔部位F波潜伏期显著延长，脊髓运动神经元兴奋性显著降低。注射部位距离及剂量不起决定作用，其发生机制复杂，可能有多因素参与。     

不同平面脊髓损伤患者膈肌运动和肺功能的相关分析

目的:探讨不同平面脊髓损伤患者的肺功能和膈肌运动的特点及其影响因素。方法:选取我院105例脊髓损伤患者进行研究,分析颈、胸、腰段各平面脊髓损伤患者的肺功能指标,包括第1秒用力呼气容积(FEV1)、用力呼气肺活量(FVC)、最大通气量(MVV)、肺活量(VC)和膈肌运动功能(右侧隔肌平静呼吸和用力呼吸时的运动幅度),并对肺功能与性别、年龄、吸烟史、损伤平面、残损分级、ASIA感觉/运动评分、膈肌运动幅度的相关性进行分析。结果:不同平面脊髓损伤肺功能指标差异具有统计学意义(P0.05);不同平面脊髓损伤平静呼吸和深呼吸时右侧膈肌运动幅度、ASIA感觉/运动评分差异具有统计学意义(P0.05);回归分析显示肺功能下降与损伤平面、残损分级、膈肌运动、ASIA感觉/运动评分和性别、吸烟史具有相关性(P0.05)。结论:脊髓损伤患者(特别是颈髓损伤患者)均存在不同程度肺功能障碍,而损伤平面、残损分级、ASIA感觉/运动评分和膈肌运动是影响脊髓损伤患者肺功能的重要指标。     

Wavelet analysis of skin blood oscillations in persons with spinal cord injury and able-bodied subjects

OBJECTIVE: To assess the blood oscillations in the skin over the ischial tuberosity (high-risk area for pressure ulcer) using spectral analysis of laser Doppler flowmetry signals based on wavelet transform. DESIGN: Wavelet analysis of skin blood oscillations in persons with spinal cord injury (SCI) and able-bodied subjects. SETTING: Seating and body support interface laboratory. PARTICIPANTS: Ten men were recruited for this study, of whom 5 were able-bodied subjects (age, 31.2+/-3.3 y) and 5 were persons with SCI (age, 37.2+/-7.3 y). INTERVENTIONS: External pressure of 16.0 kPa (120 mmHg) was applied to the ischial tuberosity via 1 specifically designed pneumatic indentor. The loading duration was 30 minutes. MAIN OUTCOME MEASURES: Skin blood flow was monitored for 10 minutes prior to loading and 20 minutes after the prescribed loading period. With spectral analysis based on wavelet transform, 5 frequency intervals were identified (.01-.02, .02-.06, .06-.15, .15-.40, .40-2.0 Hz) corresponding to endothelial related metabolic, neurogenic, myogenic, respiratory, and cardiac activities, respectively. RESULTS: The relative amplitude of the metabolic component for persons with SCI was significantly lower (F=5.26, P=.032) during the resting conditions as compared with able-bodied subjects. During the postloading period, the response of oscillatory activities was evidently lower in the skin over the ischial tuberosity for persons with SCI when compared with able-bodied subjects. In addition, the relative amplitude of the neurogenic component (.02-.06 Hz) during postloading was significantly lower for persons with SCI (F=5.44, P=.029). CONCLUSIONS: These findings suggest that the contributions of endothelial related metabolic and neurogenic activities to the blood perfusion regulation become relatively less for persons with SCI during the resting and postloading periods, respectively.     

急性脊髓损伤患者血清中单核趋化蛋白-1表达的意义

背景近年来国内外学者发现趋化性细胞因子可能参与了外周血细胞向损伤脊髓组织的募集.单核细胞趋化蛋白-1(MCP-1)属CC型趋化因子亚家族,对单核/巨噬细胞有较特异性的趋化作用.目的观察急性不完全脊髓损伤患者血清中MCP-1的表达,探讨继发性脊髓损伤的可能机制.设计以患者和健康者为研究对象,非随机化同期对照,探索性研究.单位一所大学医院的骨科.对象来源于武汉大学人民医院骨科2001-01/2002-12收治的急性不完全脊髓损伤患者8例和单纯椎体压缩骨折患者8例,另选健康者8例做对照.方法患者入院次日清晨空腹抽取外周静脉血8～10 mL,静置,离心取血清.ELISA方法检测其中MCP-1的水平.健康者于检查日晨空腹抽血,程序同患者组.主要观察指标各组血清中MCP-1的浓度.结果健康对照、单纯椎体压缩骨折及急性不完全脊髓损伤组患者血清中MCP-1的浓度分别为(124±15),(184±21),(428±11)ng/L,组间比较差异有非常显著性意义(P＜0.01).结论MCP-1可能通过向脊髓损伤部位募集炎症细胞而参与脊髓损伤部位的继发性炎症反应.     

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.