PubMed Health⌕ Search

Biomedical subjects

L R Robinson

Publications and source records attributed to L R Robinson.

At least 73 records · Page 4Linked to original sources
PubMed1990

Postpartum femoral neuropathy: relic of an earlier era?

Femoral neuropathy after childbirth is rarely encountered today, although around 1900 an incidence of up to 4.7% was found. A case of postpartum unilateral femoral neuropathy in a 29-year-old primigravida is described. The patient's labor was complicated by poor progression, a prolonged second stage (three hours), and midforceps delivery. The patient received both epidural anesthesia (requiring catheter manipulation) and spinal anesthesia. Total time in the dorsal lithotomy position was four hours; total duration of labor was 27 hours. After delivery, the patient experienced buckling at the right knee and numbness down the leg anteriorly. The electromyogram at one month was consistent with an acute femoral neuropathy. Information about other cases of postpartum lower extremity neuropathy was obtained by a retrospective review of all deliveries at a large maternity hospital between 1971 and 1987. Of 143,019 live births, there were three other cases of postpartum knee extensor weakness (2.8/100,000), five cases of postpartum footdrop (3.5/100,000), and two cases of meralgia paresthetica (1.4/100,000). Although the precise mechanism of injury remains unclear, the declining incidence of femoral neuropathy may reflect decreased duration of labor with modern obstetric practices, particularly more frequent Cesarean delivery.

Adult↗
PubMed1989

Isokinetic testing in young nonathletic able-bodied subjects.

Isokinetic strength testing has been widely used to assess athletic populations. The purpose of this study was to measure isokinetic strength in nonathletic able-bodied subjects to provide a subsequent comparison with nonathletic injured patients. Using a standard isokinetic protocol, with continuous verbal encouragement, a single investigator tested 16 women and nine men aged 20 to 30 years on an isokinetic dynamometer. Subjects had minimal athletic experience, and none were varsity performers. Peak torque as a percentage of body weight was statistically greater for men than for women in most joints tested both at 60 degrees and 180 degrees per second. The ratio of the last five to the first five of 25 repetitions at 180 degrees/second (Endurance Ratio = ER) rarely (ie, 5/154 tests) fell below the commonly accepted value of 50%. Many subjects had an endurance ratio of 100% or greater (range 4% to 171%). Peak torques were well below and endurance ratios well above those published for similarly aged athletes. The results suggest that before isokinetic testing is considered as a possible way to distinguish malingerers among injured patients, normal values in an age-matched, nonathletic, working population should be clearly defined. The endurance ratio may reflect the level of athletic training or the level of vigorous participation in an exercise program.

Adult↗
PubMed1988

Central motor conduction times using transcranial stimulation and F wave latencies.

The purpose of this study was to determine central motor conduction times between the motor cortex and the C8 spinal cord level (MC/C8), the motor cortex and S1 cord level (MC/S1), and C8 and S1 (C8/S1). We stimulated 29 normal subjects with a transcranial high voltage (300-500 V), short duration spike waveform (time constant 50 mu sec) and recorded over the hypothenar or calf muscles. F wave and M response latencies were used to estimate peripheral conduction time. The mean MC/C8 conduction time was 4.4 +/- 0.6 msec. Out of 26 subjects tested, 14 had discernable responses in the calf. The mean MC/S1 conduction time was 13.1 +/- 2.5 msec, and the mean estimated C8/S1 conduction time was 8.5 +/- 2.3 msec. This technique accurately measures conduction time from the motor cortex to the cervical anterior horn cells but is less reliable for monitoring conduction to the sacral cord. These values will facilitate future studies in patients with suspected lesions of the descending motor pathways.

Adult↗
PubMed1975

Basic concepts in family therapy: a differential comparison with individual treatment.

The author presents basic differences between the approaches of family therapy and of the individual therapies on three dimensions: personality development, symptom formation, and the approach to producing therapeutic change. Family therapy bases its view of these factors in psychotherapy on the idea that they are determined by the family's functioning as an interderdependent transactional unit; the individual therapies base their views of these factors on the idea that they are determined by the dynamic intrapsychic functioning of the individual alone.

Family Therapy↗
PubMedDate not supplied

Neurophysiological function in farm workers exposed to organophosphate pesticides.

To investigate neurophysiological effects of low-level exposure to foliar organophosphate residues during one season among agricultural workers, the authors performed a cross-sectional study of 67 Hispanic farm workers and 68 age-, gender-, ethnicity-, and education-matched reference subjects. The neurophysiological examination included sensory and motor nerve conduction and neuromuscular junction testing. Erythrocyte cholinesterase activity was measured at the time of examination. No statistically significant neurophysiological differences between the exposed and reference groups were observed. Farm workers and reference subjects had similar sensory nerve latency and amplitude (sural), motor nerve conduction velocity (ulnar), and neuromuscular junction function (ulnar). No relationship between duration of exposure during the season and electrophysiological measures of nerve function was found. Exposure of farm workers to the low levels of organophosphate pesticides during one season experienced by farm workers in this study was not associated with impaired peripheral neurophysiological function.

Adolescent↗
PubMedDate not supplied

Burn-associated peripheral polyneuropathy. A search for causative factors.

This study sought to evaluate the timing of burn-associated polyneuropathy (BAPN) and its relationship to burn severity or size. Seventeen burned subjects were studied 1 wk after thermal burns. Eleven subjects remained in the study to complete 6-wk follow-up studies. Nerve conduction studies were done on at least three nerves in two unburned limbs; results were numerically summarized by calculating Z scores for each parameter. A composite Z score, termed Ztotal, measured global nerve function. One week postburn, motor and sensory distal latencies were prolonged (mean Z, -0.72 and -0.85, respectively), motor conduction velocities slowed (mean Z, -1.31) and sensory nerve action potentials reduced in amplitude (mean Z, -0.66). Associations of Ztotal scores with total burn surface area and depth were not statistically significant. Those with severe neuropathy had higher levels of c-reactive protein (Spearman correlation, -0.624; P = 0.0129). There were no significant changes in Z scores at 6 wk. We conclude that BAPN is common after thermal injury, and the electrophysiologic manifestations of BAPN are present within the first week. Thermal injuries may induce an inflammatory cascade that results in alterations of nerve function.

Adolescent↗
PubMedDate not supplied

Comparison of techniques for detecting digital neuropathy.

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.

Adult↗
PubMedDate not supplied

Augmented sensory nerve action potentials during distant muscle contraction.

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.

Adult↗
PubMedDate not supplied

Body cooling may not improve somatosensory pathway function in multiple sclerosis.

We tested the hypothesis that reducing core body temperature in subjects with multiple sclerosis (MS) improves the cortical somatosensory evoked potential (SEP) response. Twenty subjects with definite MS were compared with 20 subjects without neurologic symptoms or disease. SEPs were recorded with stimulation of the tibial and median nerves unilaterally at 3.1 and 6.1 Hz. The procedure was repeated after a cooking vest and hat reduced core body temperature by an average of 0.46 +/- 0.28 degrees C. No appreciable change in latency or amplitude of the SEP responses occurred in either the control or MS group with cooling. Although the amplitude of the cortical SEP response was less at the 6.1 Hz rate than at 3.1 Hz, there were no statistically significant differences between the MS and control groups or between stimulation rates with cooling. We conclude that, although some reports suggest symptomatic improvements during cooling in subjects with MS, this improvement may not be associated with changes in the SEP.

Adult↗
PubMedDate not supplied

Effect of isometric contraction on threshold somatosensory evoked potentials.

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.

Adult↗
PubMedDate not supplied

Comparison of speech-evoked v tone-evoked P300 response: implications for predicting outcomes in patients with traumatic brain injury.

The P300 response is a cognitive event-related potential recorded over the scalp. The tone-evoked P300 response has been used to predict outcomes of patients with brain injury. However, it may lead to false predictions because some normal people have a very small tone-evoked P300 response. It is hypothesized that speech may generate a more robust P300 response than tones. A voice-generator prototype was designed for this study. The rare speech signal was the word "mommy" in a female voice. The common signal was a 1000-Hz tone. Twenty-two normal adults (11 males, 11 females; age range, 18-60 yr) were tested for both speech-evoked and tone-evoked P300 responses. Speech-evoked P300 responses had significantly larger amplitudes (mean, 12.1 microV) than the tone-evoked responses (mean, 5.9 microV; P < 0.0001). Six subjects with brain injury were also tested using the same protocol: two subjects with severe brain injury showed no response to either stimulus. Both died within 1 wk after the testing. Although two subjects with moderate brain injury could not complete the testing because of agitated behavior, two other subjects with mild traumatic brain injury showed a larger speech-evoked than tone-evoked P300 response. The speech-evoked P300 response may be promising in predicting outcomes of patients with brain injury.

Adolescent↗