Median nerve motor conduction to the abductor pollicis brevis.

The median motor conduction study to the abductor pollicis brevis is one of the most commonly performed electrodiagnostic studies, yet there is a need for a more comprehensive normative database for this test. Demographic subgroups of age, gender, and height need to be evaluated with a large enough sample size using modern statistical and electrodiagnostic techniques. In this study, 249 subjects were tested and the following were recorded: latency, amplitude, area, duration, and nerve conduction velocity (NCV). A repeated measures analysis of variance was performed with the waveform measures as the dependent variables and age, gender, and height as the independent variables. Factors that were significant at the P < or = 0.01 level were used to create separate normative databases. Gender was found to be associated with different results for latency and NCV. Age was found to be associated with different results for latency, amplitude, area, and NCV. Once these statistically significant factors were determined, Tukey adjusted pair-wise comparisons of least squares means were used to collapse categories (by decade for age) that were not significantly different from each other at the P < or = 0.05 level. Categories for measures that differed by clinically insignificant amounts (defined as 0.2 ms or less for time measures, 2 m/s or less for NCV, or 5% or less for amplitude and area) were combined as well. Side-to-side and proximal-to-distal differences were analyzed. The normal range was derived as mean +/- 2 standard deviations and at the 97th (third) percentiles of observed values. The findings are presented in this article but include a mean latency of 3.7 +/- 0.5 ms, a mean amplitude of 10.2 +/- 3.6 mV, and a mean nerve conduction velocity of 57 +/- 5 m/s. Subgroupings based on demographic characteristics, percentile distributions, side-to-side, and proximal-to-distal variations are presented.

Ulnar nerve motor conduction to the abductor digiti minimi.

Ulnar motor study to the abductor digiti minimi is commonly performed, but a more extensive database of normative values using modern electrodiagnostic and statistical techniques and temperature control is needed for this test. Demographic subgroups of age, gender, and height should be evaluated using a large subject population to determine whether separate normal ranges should be created for subsets of the general population. In this study, 248 volunteers were tested to measure ulnar motor latency, amplitude, area, duration, and nerve conduction velocity. Side-to-side and distal-to-proximal variability was analyzed. A repeated measures analysis of variance was performed with the waveform measures as the dependent variables and age, gender, and height as independent variables. None of the results were found to vary significantly (at the P < or = 0.01 level) with the subjects' physical characteristics, and thus, the data for all subjects were pooled to create a normative database. The normal range was derived as mean +/- 2 standard deviations and at the 97th (third) percentile of observed values. Mean latency was 3.0 +/- 0.3 ms, and amplitude was 11.6 +/- 2.1 mV. Mean nerve conduction velocity was 61 m/s across all segments tested. The upper limit of normal side-to-side variability (mean + 2 standard deviations) for latency was 0.6 ms; for amplitude, it was 3.6 mV. The upper limit of normal drop in conduction velocity across the elbow was 15 m/s (at the 97th percentile). Additional data are presented for all variables measured, as well as for side-to-side variability and distal-to-proximal change.

Tibial nerve conduction to the flexor digiti minimi brevis.

This study was performed to create an improved database of normative data for tibial motor conduction to the flexor digiti minimi brevis. A total of 205 volunteers were tested to measure lateral tibial motor latency, amplitude, area, and duration. Side-to-side variability was analyzed. A repeated measures analysis of variance was performed with the waveform measures as the dependent variables and age, gender, height, and bimalleolar width as independent variables. An association was noted between increasing age and decreasing amplitude and area. The normal range was derived as mean +/- 2 SD and at the 97th (third) percentile of observed values. Mean onset latency was 6.4 ms (SD, 1.0). Mean amplitude varied by age and ranged from 4.7 mV to 7.8 mV (SD, 3.1-3.2). The upper limit of side-to-side latency variation was 1.8 ms (at mean + 2 SD) or 1.5 ms (at the 97th percentile). The upper limit of normal variation in amplitude from one side to the other was 4.6 mV (by mean + 2 SD) or 6.3 mV (at the 97th percentile). This corresponded to a 58% drop in amplitude. The upper limit of normal difference between the medial and lateral branches was an increase of 3.5 ms of the lateral over the medial latency or a medial latency that was within 0.3 ms of the lateral latency (or longer). The other measures are presented in the article.

Mixed nerve conduction studies of the median and ulnar nerves.

The median mixed nerve conduction study, using an 8-cm technique across the wrist, has been described as a particularly sensitive test for carpal tunnel syndrome. This test is usually performed along with a similar ulnar study to detect relative slowing of one nerve v the other. Several authors have investigated the normal range in nerve conductions of this test. Most of these studies were performed using relatively small numbers of subjects, and some did not use standardized distance measurement and temperature control. They also did not measure all the waveform variables that are easily obtained with modern equipment. The purpose of this study was to create a large database of normal values for the median and ulnar studies. Two hundred forty-eight subjects were tested bilaterally. Data were collected for onset latency, peak latency, onset-to-peak amplitude, peak-to-peak amplitude, area, rise time, duration, side-to-side variability, and between-nerve variability. Increasing age, body mass index, and male gender correlated with decreasing amplitude and area values. For both nerves, the mean onset latency was 1.6 +/- 0.2 ms, and the mean peak latency was 2.1 +/- 0.2 ms. For the median nerve, the mean onset-to-peak amplitude was 75 +/- 47 microV, and the mean peak-to-peak amplitude was 80 +/- 48 microV. For the ulnar nerve, the mean onset-to-peak amplitude was 27 +/- 17 microV, and the mean peak-to-peak amplitude was 29 +/- 22 microV. Mean side-to-side difference for the median and ulnar onset and peak latencies was 0.0 +/- 0.2 ms. The mean difference between onset and peak latencies between the nerves was 0.0 +/- 0.2 ms. The other results are presented in the article.

Tibial nerve F-waves recorded from the abductor hallucis.

The purpose of this study was to develop a large database of normal values for the tibial nerve F-wave. A total of 159 asymptomatic subjects without risk factors for neuropathy were recruited and had ten tibial F-waves performed on each leg. Data were collected for the shortest F-wave (Fmin), the mean F-wave (Fmean), and the range of F-waves (Frange). Age, gender, and height were associated with differences in the results. The mean Fmin was 50.8 +/- 5.3 ms. Mean Fmean was 53.0 +/- 5.6 ms and mean Frange was 4.5 +/- 2.4 ms. The mean side-to-side difference for Fmin was 0.6 +/- 2.3 ms and the mean side-to-side difference for Fmean was 0.4 +/- 2.5 ms.

Peroneal nerve F-wave latencies recorded from the extensor digitorum brevis.

This study was performed to create a large database of normal peroneal F-wave latencies. A total of 180 subjects were tested bilaterally and had their shortest (Fmin), mean (Fmean), and latency range (Frange) of F-waves recorded. The number of F-waves present out of ten stimuli (Fpersist) was also recorded. Demographic characteristics were noted and an analysis of variance was performed to determine whether any of these characteristics were associated with different results for the F-wave measures. Age and height, and, to a lesser extent, gender correlated with differences in Fmin, and Fmean, but not Frange. Race and body mass index (weight divided by height squared) were not associated with any differences in results. The mean Fmin was 50.2 +/- 5.5 ms. Mean Fmean was 52.0 +/- 5.6 ms and mean Frange was 4.9 +/- 2.3 ms. Median Fpersist was between 5 and 6. Mean side-to-side difference for Fmin was 0.7 +/- 2.4 ms. All other results are provided in the article. This article presents a database for normal values and the upper limits of normal for Fmin, Fmean, Frange, and side-to-side differences. A low Fpersist does not seem particularly clinically useful for the peroneal nerve, although a high Fpersist seems to be a sign of normality.

Tibial nerve motor conduction to the abductor hallucis.

Tibial motor studies to the abductor hallucis are commonly performed in electrodiagnosis. Numerous authors have investigated this nerve to derive the normal ranges for latency, amplitude, and nerve conduction velocity (NCV). Many of the studies were performed without regard to temperature control, fixed distance measurement, and demographic characteristics such as age, gender, and height, which are known to affect nerve conduction studies. They often used small sample sizes, and some did not use true normal controls. This study was performed to create an expanded database of normative values for the tibial nerve. In this study, 250 asymptomatic subjects without risk factors for neuropathy were recruited and tested for their tibial motor response. Latency, amplitude, area, duration, and NCV were recorded. A repeated measures analysis of variance was performed with the waveform measures as the dependent variables and age, gender, and height as independent variables. Factors that were significant at the P < or = 0.01 level were used to create separate normative databases. Age was found to be associated with different results for amplitude, area, and NCV. Height was found to be associated with different results for NCV. Once these statistically significant factors were determined, Tukey-adjusted pair-wise comparisons of least squares means were used to collapse categories (by decade for age) that were not significantly different from each other at the P < or = 0.05 level. Side-to-side and proximal-to-distal differences were analyzed. The normal range was derived as mean +/- 2 standard deviations (SD) and at the 97th (third) percentiles of observed values. Mean onset latency was 4.5 ms (SD, 0.8). Mean amplitude was 15.3 mV (SD, 4.5), 12.9 mV (SD, 4.5), and 9.8 mV (SD, 4.2) for the respective age groups of 19-29, 30-59, and 60-79 yr. Nerve conduction velocity ranged from a mean of 44 to 51 m/s depending on the demographic groups of various ages and heights. The upper limit of side-to-side latency variation was 1.4 ms (at the 97th percentile), and the upper limit of normal amplitude difference from side to side was 50% (at the 97th percentile). The other measures are presented in the article.

Normal range for H-reflex recording from the calf muscles.

This study was performed to derive the normal range for H-reflex latency, recording from the calf, on a large and varied subject population. Two hundred fifty-one asymptomatic subjects without risk factors for neuropathy were tested bilaterally. The results were analyzed to determine whether various demographic characteristics were associated with different results. A repeated measures analysis of variance was performed with the latency as the dependent variable and age, race, gender, body mass index (kg/m2), and height as the independent variables. A significance value of P < or = 0.01 level was used. Side-to-side variability was also examined, and, for this measure, a repeated measurements analysis was not necessary because there was only one measurement per subject; a simple analysis of variance was used. Age and height were noted to be associated with different mean latencies; race, gender, and body mass index were not. The mean H-reflex latency was 30.3 +/- 2.4 ms, and the upper limits of normal (mean + 2 SD) for the various categories of age and height ranged from 30.0 to 38.2 ms. In addition, the upper limits of normal were derived as the 97th percentiles of observed latency values. For all subjects taken together, this value was 35.0 ms, and, for the various subgroups, it ranged from 29.7 to 36.4 ms. Mean side-to-side variability was 0.2 +/- 1.0 ms, with an upper limit of normal of 2.2 ms as the mean + 2 SD or 2.0 ms as the 97th percentile.

Median 14-cm and 7-cm antidromic sensory studies to digits two and three.

The purpose of this study was to derive a normative database for the median digital sensory conduction study using a large and varied subject population. Two hundred fifty-eight asymptomatic volunteers were tested with antidromic sensory technique at 14- and 7-cm distances to digits 2 and 3. Onset latency, peak latency, onset-to-peak amplitude, peak-to-peak amplitude, area, rise time, and duration were recorded. A repeated analysis of variance was performed, with the nerve conduction study measures as the dependent variables and age, race, gender, body mass index, and height as the independent variables. Factors that were significant at the P < or = 0.01 level were used to create separate normal ranges. Both increasing age and increasing body mass index correlated with decreasing amplitudes and area. No other correlations were noted between the results and the physical characteristics. For digit 3, the mean 14-cm onset latency was 2.7 +/- 0.3 ms and mean peak latency was 3.4 +/- 0.3 ms. The mean onset-to-peak amplitude was 41 +/- 20 microV for all subjects taken together. Mean rise time was 0.7 +/- 0.1 ms and mean duration was 2.1 +/- 0.4 ms. Mean side-to-side difference in onset and peak latencies was 0.0 +/- 0.2 ms. The upper limits of normal side-to-side differences in amplitudes and area were approximately 50%-60%.

Median nerve F-wave latencies recorded from the abductor pollicis brevis.

This study was performed to create a normative database for median nerve F-wave responses for a large subject population so normal ranges could be created for subsets of the general population and the effect of various physical characteristics on F-wave results could be determined. One hundred ninety-five asymptomatic subjects without risk factors for neuropathy were recruited. Ten consecutive supramaximal stimuli were applied to the wrists of each arm to obtain median nerve F-wave results. The shortest F-wave latency (Fmin), mean latency (Fmean), range of latencies (Frange), and number of stimuli that resulted in F-wave recordings (Fpersist) were recorded. An analysis of variance revealed that age, gender, and height were associated with different results for Fmin and Fmean. For all subjects taken together, the mean Fmin was 26.8 +/- 2.4 ms. The mean Fmean was 28.3 +/- 2.6 ms, and the mean Frange was 3.4 +/- 1.9 ms. Five or more F-waves were elicited in 94% of the subjects. The mean side-to-side difference in Fmin was 0.2 +/- 1.2 ms. Additional findings are presented in the article.

Ulnar 14-cm and 7-cm antidromic sensory studies to the fifth digit: reference values derived from a large population of normal subjects.

The ulnar antidromic sensory conduction study to the fifth digit is commonly performed in clinical electrodiagnosis. Several authors have published normal ranges for this study, but these published reports have been limited by generally small sample sizes. The purpose of this article is to present a large database of normal ranges for this nerve study. After obtaining Institutional Review Board approval, 258 asymptomatic subjects were tested bilaterally with an ulnar antidromic sensory technique recording from the fifth digit. Stimulation was performed 7 cm and 14 cm proximal to the recording electrode. Onset latency, peak latency, onset-to-peak amplitude, peak-to-peak amplitude, area, duration, and rise time were recorded. Side-to-side and 14- to 7-cm comparisons were made. A repeated measures analysis of variance was performed to determine whether any of the subjects' demographic characteristics of age, race, gender, height, or body mass index (kg/m2) were associated with different results for the nerve conduction measures. Increasing age and body mass index were found to correlate with decreasing amplitude and area. No other correlations were noted between the results and the physical characteristics. Mean onset latency was 1.4 +/- 0.2 ms at 7-cm and 2.6 +/- 0.2 ms at 14-cm stimulation. Mean peak latency was 2.0 +/- 0.2 ms at 7-cm and 3.4 +/- 0.3 ms at 14-cm stimulation. Mean onset-to-peak amplitude was 32 +/- 20 microV at 7-cm and 33 +/- 17 microV at 14-cm stimulation. Mean negative-to-positive-peak amplitude was 55 +/- 36 microV at 7-cm and 50 +/- 32 microV at 14-cm stimulation. Mean side-to-side difference for onset latency was 0 +/- 0.2 ms. Additional data is presented in the study.

Peroneal nerve motor conduction to the extensor digitorum brevis.

Peroneal motor studies to the extensor digitorum brevis are commonly performed in electrodiagnosis. They have been investigated by many authors to derive the normal ranges for latency, amplitude, and nerve conduction velocity. Many of these studies, particularly the older ones, have methodological limitations, especially in light of modern technique and statistical applications. They often used small sample sizes. The objective of this study was to generate an expanded database of normative values for the peroneal nerve. In this study, 242 asymptomatic subjects without risk factors for neuropathy were tested, and their peroneal motor response was analyzed for latency, amplitude, area, duration, and nerve conduction velocity. Side-to-side and proximal-to-distal variation was recorded. Mean +/- 2 standard deviations (SD) and percentiles of normality are presented. Mean onset latency was 4.8 ms (SD, 0.8). Mean amplitude was 6.8 mV (SD, 2.5) and 5.1 mV (SD, 2.5) for the younger and older than 40-yr age groups, respectively. Mean nerve conduction velocity ranged from 44 to 49 m/s, depending on the demographic group (SD, 4-5). The upper limit of normal side-to-side latency variation was 1.4 ms (mean + 2 SD). The upper limit of normal drop in nerve conduction velocity from the low leg to the across knee segment was 10 m/s (mean - 2 SD) or 12% (97th percentile). The upper limit of normal amplitude difference from side to side was 61 % (at the 97th percentile), and the upper limit of normal drop in amplitude from below to above the fibular head stimulation was 25% (at the 97th percentile). The other measures are presented in the article.

Ulnar nerve F-wave latencies recorded from the abductor digiti minimi.

This study was performed to create a large database of normal values for the ulnar F-wave study and to investigate the effect of various demographic factors on F-wave results. The study was designed to incorporate a standard distance measure and temperature control, which are lacking in some previous studies. One hundred ninety-three asymptomatic volunteers without risk factors for neuropathy were recruited and had ten F-waves performed on each arm. Data were collected for the shortest F-wave (Fmin), mean F-wave (Fmean), the number of F-waves present out of ten stimuli (Fpersist), and the range of latencies (Frange). An analysis of variance statistical procedure was applied, and the Fmin and Fmean were found to correlate with age, gender, and height, although the gender effect was relatively weak. For all subjects taken together, the mean Fmin was 26.5 +/- 2.5 ms. The Fmean was 27.7 +/- 2.5 ms, and the mean Frange was 2.6 +/- 1.2 ms. Ninety-seven percent of subjects had an Fpersist of five or more. Mean side-to-side difference for Fmin was 0.2 +/- 1.1 ms.

Race effect on nerve conduction studies: a comparison between 50 blacks and 50 whites.

OBJECTIVE: To determine whether there are any differences in nerve conduction study results between blacks and whites. DESIGN: The following studies were performed: median, ulnar, peroneal, and tibial motor studies; median and ulnar mixed motor/sensory studies; sural and radial sensory studies; and H-reflex studies. SETTING: Private office or university-based clinic. PARTICIPANTS: Fifty adult blacks and 50 adult whites who met inclusion criteria, recruited through advertisements. MAIN OUTCOME MEASURES: Differences between blacks and whites were compared to determine whether they exceeded a cutoff of 0.2 msec for latencies, 20% difference for amplitudes, 5 m/sec for conduction velocity, and 1.2 msec for H-reflex times. A repeated analysis of variance was performed to detect statistically significant differences (defined as p< or =.01). RESULTS: Only values for the mean peroneal and tibial motor latencies exceeded the cutoff times. The mean peroneal response was faster by 0.3 msec and the mean tibial response was slower by 0.3 msec in blacks than whites. These differences were not statistically significant at a level of p< or =.01. CONCLUSION: There is no significant difference between blacks and whites in normal nerve conduction study findings in healthy adults.

Martial arts.

The martial arts have a reputation for being a high-risk activity, but are generally practiced in a safe environment. This article presents the results of a survey which is used to calculate risk of injury per 1000 hours of practice. The injury rate compares favorably with other mainstream activities; in fact, the martial arts are generally considered safer than most. The most common injuries occur to the wrist, hand, finger, foot, knee, head, and thigh. Special issues of importance for prevention and treatment of these injuries are discussed.

Preliminary electrophysiological characterization of functionally vestigial muscles of the head: potential for command signaling.

In devastating neurological disorders, such as quadriplegia resulting from high-level spinal cord injury, it is essential to focus on functions that have been spared and optimally exploit them to enhance the individual's quality of life. It follows that certain muscles, which prior to the paralysis of much of the rest of the body seemed to have no useful function, might be used to provide unique signals to control assistive devices. This report presents preliminary electrophysiological data demonstrating potentially useful myoelectrical signals from 3 functionally vestigial muscles in humans; the posterior, anterior, and superior auricular muscles. In phylogenetically lower species, these muscles serve to position the ear to enhance hearing. The auricular muscles receive their major innervation from cranial nerve VII and should not be compromised by even high-level spinal cord lesions. In this study, it was found that the muscles could be voluntarily activated and, by standard surface-electrode recording, had potentials ranging to 680 microV in amplitude. Posterior auricular muscle potentials were used to command a paddle in a computer ping-pong task that employed a CyberLink interface. The t values for accuracy scores and ball hits were both significant at the p = .0001 level. These facts indicate that the auricular muscles may be useful for controlling assistive devices.

Body mass index effect on common nerve conduction study measurements.

This study was performed to determine whether there is a difference in nerve conduction study (NCS) measures based on body fat (body mass index; BMI). Two hundred fifty-three subjects had the following NCS tests performed on them: median, ulnar, peroneal, and tibial motor studies; median, ulnar, radial, and sural sensory studies; median and ulnar mixed nerve studies; and H-reflex studies. BMI was calculated as weight (kg) divided by height (m) squared. A repeated measures analysis of variance was run adjusting for age, sex, and height and using BMI as both a continuous variable and by dividing BMI into upper, middle, and lower thirds. The sensory and mixed nerve amplitudes correlated significantly (P < or = 0.01) with BMI for all nerves tested, with means being approximately 20-40% lower in the obese than in the thin subjects. No correlation was noted between BMI and nerve conduction velocity, H-reflex latency, or most of the other motor/sensory/mixed measures. The correlation between increased BMI and lower sensory/mixed nerve amplitudes should be taken into account in clinical practice.

The evolution of glutathione metabolism in phototrophic microorganisms.

Of the many roles ascribed to glutathione (GSH) the one most clearly established is its role in the protection of higher eucaryotes against oxygen toxicity through destruction of thiol-reactive oxygen byproducts. If this is the primary function of GSH then GSH metabolism should have evolved during or after the evolution of oxygenic photosynthesis. That many bacteria do not produce GSH is consistent with this view. In the present study we have examined the low-molecular-weight thiol composition of a variety of phototrophic microorganisms to ascertain how evolution of GSH production is related to evolution of oxygenic photosynthesis. Cells were extracted in the presence of monobromobimane (mBBr) to convert thiols to fluorescent derivatives, which were analyzed by high-pressure liquid chromatography. Significant levels of GSH were not found in the green bacteria (Chlorobium thiosulfatophilum and Chloroflexus aurantiacus). Substantial levels of GSH were present in the purple bacteria (Chromatium vinosum, Rhodospirillum rubrum, Rhodobacter sphaeroides, and Rhodocyclus gelatinosa), the cyanobacteria [Anacystis nidulans, Microcoleus chthonoplastes S.G., Nostoc muscorum, Oscillatoria amphigranulata, Oscillatoria limnetica, Oscillatoria sp. (Stinky Spring, Utah), Oscillatoria terebriformis, Plectonema boryanum, and Synechococcus lividus], and eucaryotic algae (Chlorella pyrenoidsa, Chlorella vulgaris, Euglena gracilis, Scenedesmus obliquus, and Chlamydomonas reinhardtii). Other thiols measured included cysteine, gamma-glutamylcysteine, thiosulfate, coenzyme A, and sulfide; several unidentified thiols were also detected. Many of the organisms examined also exhibited a marked ability to reduce mBBr to syn-(methyl,methyl)bimane, an ability that was quenched by treatment with 2-pyridyl disulfide or 5,5'-bisdithio-(2-nitrobenzoic acid) prior to reaction with mBBr. These observations indicate the presence of a reducing system capable of electron transfer to mBBr and reduction of reactive disulfides. The distribution of GSH in phototrophic eubacteria indicates that GSH synthesis evolved at or around the time that oxygenic photosynthesis evolved.