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Composited p-type electrodes with high reflectivity have been investigated in AlGaN-based ultraviolet light emitting diodes (UV-LEDs) to improve the light extraction efficiency, which are composed of a patterned ITO layer and an Al reflector. It is verified that the patterned ITO with a thickness of 30 nm can not only well form Ohmic contact with p-GaN capping layer, but also be nearly 90% transparent to ultraviolet light, and thus presenting a reflectivity of 73% at 280 nm when combined with an Al reflector. Further experimental efforts confirm that the performance of the UV-LEDs is dramatically improved with such p-type electrodes. The maximum light output power and wall plug efficiency in the current range of 0–100 mA are severally increased by 49.8% and 54.2% compared to the device with traditional Ni/Au electrodes. [ABSTRACT FROM AUTHOR]

Soccer is regarded as the most popular sport in the world, with millions of people actively involved in the game. Being a contact sport in nature, soccer players are susceptible to various kinds of injuries, such as lower extremities muscle injury. In addition to those familiar injuries that soccer players sustain during the game, traumatic brain injury is also a possibility. Head impacts in soccer could be a result of head-to-head impact with an opponent player, a headto-elbow impact, an impact with the goal post, an impact with the ground, as well as an impact with the soccer ball, which occurs during a heading manoeuvre. Soccer allows the players to use their heads to hit the ball to pass it to a teammate or even perform heading to score a goal. Although soccer heading is perceived as less harmful as compared to head impacts with other hard objects, many studies have shown compelling evidence that this repetitive heading might harm the brain, thereby leading to traumatic brain injury. Protective headgears designed especially for soccer players have been commercially available in the market for some years. However, the effectiveness of these headgears in reducing the impact due to soccer heading has not been well studied. This paper investigates the effectiveness of two commercially available headgears, the Full90 and the ForceField headgear by means of a heading experiment. An anthropometric test device known as Hybrid III head and neck dummy instrumented with an inertial sensor that consists of a triaxial accelerometer and gyroscope installed at the centre of gravity of the head was used in the experiment. A soccer ball launching machine was used to propel the ball at several inbound velocities. Peak linear acceleration (PLA) and peak angular acceleration (PRA) were recorded, and the head injury criterion (HIC) and the rotational injury criterion (RIC) were calculated. It was found that both headgears failed to reduce the linear components of head acceleration but instead increased the HIC (13 - 66% increment) depending on the inbound ball velocity. With respect to the rotational component of head injury, the Full90 headgear was found to reduce the RIC up to 29%, but the ForceField failed to provide a significant reduction of RIC. Overall, both headgears were found to be ineffective in reducing linear and rotational components of head injury, which could be attributed to the headgear design. Improved headgear design and an improved padded foam are needed to protect soccer player's brain while performing soccer heading. [ABSTRACT FROM AUTHOR]

Objective: To characterize the differences between injuries to the lumbosacral (LS) plexus caused by gunshot wounds (GSW) and motor vehicle crashes (MVC) with regard to the location and extent of involvement., Design: A retrospective review of electrophysiologic data from an electromyography laboratory of a county hospital. Nineteen patients with GSW and ten patients with MVC diagnosed by electromyography with an LS plexopathy were included in the study. Injuries were categorized by the number of anatomic quadrants of the LS plexus: upper anterior, upper posterior, lower anterior, and lower posterior. Comparison of upper vs. lower portions and bilaterality of LS plexus involvement was also made. Statistical analyses were performed with two-tailed Fisher's exact and general association tests., Results: Lower portions of the plexus were involved more frequently in patients with MVC compared those observed in patients with GSW. Upper portions of the LS plexus were more involved compared with the lower portions in patients with GSW injuries. More sections of the plexus were involved in patients with MVC compared with those in patients with GSW., Conclusions: Compared with patients with MVC, patients with GSW had a greater chance of involvement of the upper portion of the plexus. The reverse was true for the lower portion. Hopefully this information will aid the electromyographer and rehabilitation team in the diagnosis and treatment of traumatic plexopathies caused by different etiologies.

This paper is the last of three articles that describe the functional anatomy of the upper limb. It extends the series by presenting the axial anatomy of the forearm and hand. In addition, it provides a table that defines the patterns of muscle denervation specific to six representative sites. This set of articles is clinically useful because it can be used to rapidly identify and describe the innervation of the muscles and skin of the upper limb.

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.

Objective: To investigate the effect of isometric biceps brachii contraction and neck flexion on the time course of threshold sural amplitude., Design: Twelve healthy subjects, who were asked to lie supine on an examination bench, performed 1 min of muscle contraction. The sural sensory nerve action potential was recorded before, immediately after, and at 2-min intervals after muscle contraction. The preexercise level of stimulus intensity remained unchanged for sural readings throughout the entire course of the experiment., Results: The temporal changes in sensory nerve action potential amplitudes for both maneuvers were similar (P = 0.9734, two-way interaction). The mean sural amplitude after neck flexion increased from 6.0 +/- 2.9 microV (SD) to 10.6 +/- 6.6 microV (SD) 10 min after contraction. Similarly, mean sural amplitude increased from 6.5 +/- 1.8 microV (SD) to 14.5 +/- 9.7 microV (SD) 8 min after biceps brachii contraction. Statistical analysis performed using repeated measures with post hoc least significant difference showed a significant temporal effect in the two groups (P = 0.04)., Conclusion: The temporal responses of threshold sural amplitudes after isometric biceps brachii contraction and central reinforcement neck flexion maneuvers are nearly identical with regard to increase in the amplitude.

The hypothesis for this study was that catecholamine levels increase during urinary catheterization in human patients with spinal cord injury. Catecholamine levels, blood pressure, and pulse were measured prospectively in 40 subjects at baseline and during urinary catheterization. Results showed a significant increase in norepinephrine levels from baseline 245 +/- 240 pg (standard deviation (SD)) to 314 +/- 311 pg (SD) during catheterization (P = 0.018, Wilcoxon's). Results also showed a nonsignificant increase in epinephrine levels from baseline (56 +/- 70 pg, SD) to catheterization (84 +/- 125 pg, SD; P = 0.35, Wilcoxon's). Systolic blood pressure increased from 114 to 124 mm Hg (P = 0.004, paired t test). Diastolic blood pressure increased from 75 to 78 mm Hg (P = 0.11, paired t test). There was no significant change in diastolic blood pressure or pulse (P = 0.11 and P = 0.29, respectively, paired t test). In conclusion, norepinephrine levels increased during catheterization in patients with spinal cord injury. Knowledge of catecholamine levels in this process may assist in determining both pathophysiology and potential pharmacologic treatment options in future studies.

It is hypothesized that the cane and forearm can be aligned to reduce muscular activity needed during ambulation. In this prospective study, 10 nonimpaired control subjects were tested both in stationary and dynamic weight-bearing states while using different cane prototypes and the platform cane (PC) as compared to the standard cane (SC). The outcome measures were: 1) root mean square (RMS) voltage (&micro;V) of electromyographic (EMG) signal as a measure of muscle power and 2) distance of ambulation. Results of stationary cane use showed that Prototype 1 decreased RMS output by 19 percent (p=0.01), Prototype 2 with wrist splint decreased it by 23 percent (p=0.003), and the PC decreased it by 68 percent (p<0.0001) as compared to the SC (ANOVA, posthoc LSM). In conclusion, the two prototypes and the PC significantly decrease RMS voltage muscle output in the upper limb, compared to the SC.

We previously described the augmentation of sensory nerve action potential amplitudes after near and remote isometric muscle contraction. In this study, we wished to determine if the sensory cortex was involved in this process. In this prospective, intrinsically controlled study, we studied threshold somatosensory evoked potentials in 12 normal subjects with stimulation of the median nerve at 5.1 Hz. The subjects were tested during the following conditions: baseline, 25%, and 75% maximum isometric abductor digiti minimi contraction for 4 min. Each of these conditions was recorded before, during, and 4 min and 8 min after contraction. Results showed that at 25% contraction, there was a significant temporal increase in N9 amplitude (2.1-2.6 microV; P = 0.05, analysis of variance, repeated measures) and a decrease in N20 amplitude with 75% contraction (1.9-1.6 microV; P = 0.03, analysis of variance, repeated measure). No significant changes were noted in the spinal cord or brainstem recordings. In conclusion, it appears that augmentation of the brachial plexus peripheral nervous system recording occurs concurrently with central inhibitory gating. The possibility of peripheral nervous system adaptability will be discussed.

We previously reported that the median sensory nerve action potentials (SNAPs) increased in amplitude during both near (3) and remote (4) muscle contraction. The objective of the present project was to begin to study the pathway by which this occurred. The sural amplitude was measured after one min. of isometric biceps contraction and compared pre and post lidocaine nerve block in 10 healthy subjects. The baseline was defined as the least amount of current needed to elicit a minimal sural response pre contraction. This level of stimulus remained constant throughout the experiment. Results showed that the sural amplitude peaked 4 min. after muscle contraction. An 8.1 microV increase in sural amplitude from baseline was noted pre injection as 5 min. post contraction, and an increase of 13.4 microV was noted comparing pre to post injection amplitudes at the same time. Statistical analysis using two-way interaction comparing the time courses pre and post injection showed a 92% chance the responses were dissimilar Post hoc least significant difference (LSD) analyses were significant at 4 min. (p = .005) and 6 min. (p = 0.29) post contraction. In conclusion, the increase in sural amplitude after remote muscle contraction was no longer apparent after proximal sural nerve block. This suggests that the nerve itself is required in the final common pathway for the transmission of this induced signal.

The palmaris brevis (PB) is the only muscle frequently innervated by the superficial branch of the ulnar nerve. It is clinically involved in patients with sensory impairment of the ulnar nerve sparing the deep branch as seen in mild cases of cyclist or crutch palsy. It is also involved in palmaris brevis spasm syndrome. A technique is described that makes it possible to localize the PB distinctly from its neighbors by electromyographic (EMG) pin examination. Methods include prospective (1) anatomic measurement in 10 cadavers and (2) EMG pin examination in 12 normal subjects measuring rise time (ms) and RMS voltage output (microV). Results showed (1) the area of the PB in elderly cadavers was 2.1+/-0.7 x 2.1+/-0.3 cm with a thickness of 0.2+/-.01 cm and (2) in the live subjects, the muscle could be located with identification of motor unit potentials having a rise time <1 ms 100% of the time. In conclusion, the PB can be localized for EMG analysis by using an approach parallel to surface of the palm. Clinically, it could be a useful complement to diagnose neuropathy involving the superficial fibers of the ulnar nerve.

Objective: To determine if norepinephrine (NE) levels increased during autonomic dysreflexia (AD) hypertension in spinal cord injured rats., Design: Prospective, randomized study of three groups of eight rats that underwent C8 spinal cord transection. Two days postoperatively, catecholamine samples were collected from the animals as follows: group 1 without preoperative chemical sympathectomy using 6-hydroxydopamine (6-OH DA) or induced AD; group 2 with induced AD; and group 3, preoperative chemical sympathectomy with 6-OH DA and induced AD., Setting: Basic science research laboratory in an academic institution., Participants: Sprague-Dawley male rats weighing 300g., Intervention: Three episodes of induced AD hypertension with bowel distension for 1 minute., Results: Results showed a significant difference between groups 1 and 2, 2 and 3, and 1 and 3 (p=.0002, ANOVA, Y1/2, post hoc Tukey). The mean NE levels in groups 1, 2, and 3 were 465+/-400 ng/mL, 1,328+/-1,116 ng/mL, and 31+/-61 ng/mL, respectively., Conclusion: NE increased during AD in the spinal cord injured rat. NE levels were effectively blocked by 6-OH DA when AD was induced. Knowledge of catecholamine levels in this process may assist in determining both pathophysiology and potential pharmacologic treatment options in future human studies.

Objective: To determine which nerve conduction parameters can predict the presence of acute denervation in carpal tunnel syndrome., Setting: The electrodiagnostic laboratories of a hospital and a county hospital district., Design: A retrospective review., Patients: A total of 1,590 consecutive cases from January 1992 to June 1996, diagnosed as having median neuropathy at the wrist., Main Outcome Measures: Evidence of acute denervation on needle electromyography of the abductor pollicis brevis and its relationship to patient age, gender, and parameters obtained from nerve conduction studies, including median sensory latency and amplitude, and median motor latency and amplitude., Results: Logistic regression analysis identified gender, median motor latency, and median motor amplitude (all p < or = .008) as contributing to the prediction of denervation. Needle examination of the cases with a median motor amplitude <7 mV detected 95.3% (141/148) of all cases with denervation and could have spared 52% (708/1,362) of the population from a needle examination of the abductor pollicis brevis., Conclusion: The median motor amplitude can predict the presence of acute denervation in the thenar muscles in median neuropathy at the wrist and possibly eliminate a painful needle examination of the median-innervated thenar muscles in over 50% of the cases.

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.

Studying the effect of spinal cord reinforcement maneuvers (SCRMs) on H reflex assists in understanding aspects of motor control. Our objective was as follows: (1) to elucidate the effects of four neck positions (neck resting at neutral position (control); passive hyperflexion of the neck; hyperextension of the neck with simultaneous abdominal contraction; and sustained active neck hyperflexion); (2) to evaluate the temporal changes of soleus H reflexes repeatedly evoked after a period of sustained neck flexion. We used a prospective, intrinsically controlled trial of the effects of these SCRMs on the H reflexes and M-responses in ten healthy volunteers. Pre- and postmaneuver measures included H reflex and M-response latencies and amplitudes, H/M maximum amplitude ratio, and H threshold. The four maneuvers showed no significant effect on the H reflex or M-response measures. To investigate temporal changes in the H reflex amplitude, H reflexes were repeatedly evoked at two-minute intervals after a one-minute period of active neck flexion. The amplitude of the H reflex was enhanced (P = 0.0356; analysis of variance), and the post hoc least significant difference test was significant at four minutes postmaneuver. Peak magnitude of the H reflex occurred at four minutes after relaxation, and the response returned to pretest baseline at eight minutes. The results of this study document the time course of repeated H reflexes after SCRM, and the timing of the H reflex was found to be a contributing variable that should be considered in future study designs.

We previously reported that the median sensory nerve action potentials (SNAP) increased in amplitude during ipsilateral abductor pollicis brevis contraction. The objectives of the present project were to study the timing and origin of this phenomenon and to eliminate the possibility of local artifact. Ten normal subjects were recruited. The baseline was established using ten threshold stimuli, which were delivered to the median nerve at the wrist at 0.2 Hz. Using the same stimulus strength, the SNAP was recorded while the tibialis anterior was contracted at 25, 50, 75, and 100% of maximum force. Responses were signal-averaged. Results showed an increase in ipsilateral SNAP amplitude between baseline and maximum contraction of 6 +/- 2 microV (standard error, P = 0.004) and contralateral amplitude of 8 +/- 2 microV (standard error, P = 0.01). Statistical analysis was performed with analysis of variance for repeated measures and paired t test. The effect peaked between 0 and 10 min after contraction and lasted from 1.5 to more than 20 min after muscle relaxation. In conclusion, SNAP appear to be enhanced during and after muscle contraction. Theories concerning underlying causes for this event are discussed.

A complication of endoscopic carpal tunnel release (6/53 consecutive cases) is rupture of a digital branch. The objective of this study was to find a method for detecting neuropathy of the digital branch innervating the radial side of the fourth digit and the ulnar side of the third digit. This study examined whether the following sensory nerve conduction techniques would enhance diagnosis of this neuropathy: (1) recording with standard digital ring electrodes; (2) recording with ring electrodes from two adjacent fingers; and (3) disc electrodes placed between two fingers. Ten healthy individuals were studied before and after lidocaine anesthesia of the digital branch between the ring and middle finger. Statistical analysis was performed with a two-tailed, paired t test. Results show that after lidocaine injection there was a decrease in antidromic amplitude of 94% for ring electrodes on the fourth digit, 62% for rings on the third digit, 77% for disc electrodes between the fourth and third digits, and 74% for rings on digits 4 and 3 (P < 0.005), with no significant change in peak latency (P > 0.3). In conclusion, although all techniques used in this model yielded a significant change in amplitude, rings on the third digit compared with the second and discs between digits 4/3 compared with 3/2 were most specific without false-positives from normal data. It is hoped this study will aid the electromyographer in postoperative diagnosis.

Severe pain occurs in 5-30% of the spinal cord-injured (SCI) population and is difficult to treat. Subarachnoid lidocaine has been used in selected patients with some success. Mexiletine, an analog of lidocaine that acts at Na+/K+ channels in the peripheral nerve, has been found effective in persons with diabetic dysesthetic neuropathy. The effect of mexiletine in the treatment of spinal cord dysesthetic pain was examined in this study. Fifteen patients were enrolled, and 11 patients completed the prospective, randomized, placebo-controlled, double-blind, crossover design trial. Inclusion/exclusion criteria were carefully defined. A 1-wk washout period was followed by a 4-wk drug trial of either mexiletine (450 mg/day) or placebo. This was repeated for the second medication in the second arm of the study. Patients were followed weekly with McGill and visual analog pain scales. Baseline, midpoint, and endpoint Barthel function scores were recorded. The Wilcoxon's signed-rank test and paired t test were used for statistical analysis. Results showed no significant effect of mexiletine on SCI dysesthetic pain scales or Barthel index. In conclusion, in this trial, mexiletine did not appear to decrease spinal cord injury-related dysesthetic pain.

Autonomic dysreflexic hypertension occurs in up to 80% of spinal cord injury patients with lesions thoracic level 6 or higher. Pharmacologic agents directed at each part of the autonomic dysreflexic circuit were tested for efficacy in a rat model. Guanethidine (15 mg/kg intraperitoneally), alpha-methyl-paratyrosine (20 mg/kg intraperitonally), propranolol (3 mg/kg intraperitonally) and control were each tested on groups of three rats with intrinsic control blood pressure measurements. Results show an increase of 15 +/- 5 mm Hg diastolic pressure in control animals compared with no detectable increase with guanethidine or alpha-methyl-paratyrosine. There was an 11 +/- 2 mm Hg increase in diastolic pressure with propranolol. In conclusion, screening drug trials show that the ganglionic blocking agent, guanethidine, and competitive tyrosine uptake precursor, alpha-methyl-paratyrosine, effectively blocked dysreflexic hypertension, whereas the beta-blocker, propranolol, did not.