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Biomedical subjects

J Goodgold

Publications and source records attributed to J Goodgold.

At least 19 recordsLinked to original sources

A noninvasive technique to assess completeness of spinal cord lesions in humans.

The effect of scalp stimulation delivered through electrodes overlying the motor cortex was evaluated in five healthy subjects and six patients with traumatic spinal cord injury. The latency to the onset of the electromyographic response was measured in the biceps brachii and abductor pollicis brevis muscles. In all the patients, latencies to the muscle (biceps brachii) whose innervation originated above the lesion were in the normal range; whereas, latencies to the muscle (abductor pollicis brevis) whose innervation originated below the lesion were prolonged. Electromyographic signals were recorded in muscles which showed no voluntary motor activity. No lateral differences in latencies were found in healthy subjects; however, in the patients, significant differences were obtained between the right and left abductor pollicis brevis muscles. The results of this study demonstrate that the spinal cord of patients with a lesion deemed to be clinically complete, contains nerve fibers which descend through the lesion and are capable of conveying impulses leading to muscle contraction.

Adolescent

Visually displayed EMG feedback: single case studies of hemiplegic upper extremity rehabilitation.

The efficacy of visually displayed EMG feedback in treating hemiplegic upper limb motor disorders was investigated in 5 patients (0.5-4 years poststroke). A single case experimental method "multiple-baseline across target behaviors" was used to compare performance during the feedback phase to that occurring in the monitored baseline phase. The nonfeedback baseline phase was followed by the staggered introduction of audiovisual feedback for each of the targeted pairs of muscles. EMG feedback obtained from muscle pairs (shoulder: anterior deltoid and upper trapezius; elbow: brachial triceps and biceps; digits: extensor digitorum communis and digit flexors) was displayed as two distinct waveforms on a videomonitor during therapy. Nonfeedback assessment of each of the three pairs was performed during each session. The effects of feedback were not uniformly distributed. Elbow control responded best, and statistical tests confirmed the effects of intervention observed clinically in all 5 patients. Clinical improvements in shoulder flexion were observed in 4 patients but could be statistically attributed to EMG gains in just 1. Improvement in finger extension observed clinically in 3 patients was statistically attributable to EMG gains in 2. All patients regained control of at least one target activity. EMG gains were accompanied by increases in active range of motion and by varying functional improvement. Marked functional gains in 3 patients were obtained with recovery of finger control.

Adult

Sensory nerve action potentials of the medial and lateral plantar nerve.

A simple, reliable method of recording sensory nerve action potentials (SNAP) from the medial and lateral plantar nerves was established using 30 healthy adults as subjects. Potentials were recorded with surface electrodes both antidromically and orthodromically. The mean latency and amplitude of the SNAP of the medial plantar nerve using antidromic stimulation were 2.5msec (+/- 0.32) and 16.3microV (+/- 6.5), respectively. Orthodromically, the latency was 2.5msec (+/- 0.35) and the amplitude 16.5microV (+/- 7.14). For the lateral plantar, antidromically the nerve latency was 2.5msec (+/- 0.35) and the amplitude 14.8microV (+/- 4.41). With the orthodromic procedure, the latency remained unchanged but the amplitude was 11.0microV (+/- 5.59). In the case of the lateral plantar nerve, the antidromic technique consistently resulted in higher amplitude responses.

Adolescent

Electrical stimulation effect on denervated skeletal myofibers in rats: a light and electron microscopic study.

The purpose of the present study was to determine morphologically the effect of electrical stimulation on denervated rat extensor digitorum longus (EDL) muscle. Fifteen adult male rats were divided in to 3 groups: control, denervated-nonstimulated, and denervated-stimulated. Electrical stimulation treatment (1 hr/day for 24 days) began 4 days postsurgery. All animals were sacrificed 28 days after surgery; the EDL muscle was fixed in situ, removed, and processed for light and electron microscopic examination. Fibers from sections taken from the middle third of the muscle were differentiated into types I and II; fiber diameters were obtained and compared for each experimental group. Although both types atrophied following denervation, type I atrophied to a lesser extent than type II. Electrical stimulation was beneficial in retarding denervation atrophy for both types. Membrane-glycogen complexes were found on electron microscopy to be in high proportion in type II stimulated fibers but were observed infrequently in denervated nonstimulated muscles and were not apparent in control muscles. These glycogen arrays may be expressions of sarcoplasmic reticulum anabolic functions, indicating a high degree of regenerative metabolic activity in treated fibers. This study indicates that electrical stimulation as a method to induce muscle activity, can retard denervation atrophy.

Animals

Sensory conduction study of distal radial nerve.

The technique of recording superficial radial sensory nerve action potential (SNAP) from the thumb was compared with that of recording from the 1st web space. The spread of stimulus to the median nerve in the forearm when stimulating the radial sensory nerve with relatively high intensity was also investigated. Recording the radial SNAP from the 1st web space produces a larger amplitude response with a sharper takeoff point compared with that of recording from the thumb. Furthermore, with the former technique, the radial SNAP is uncontaminated by a component arising in the median distribution which makes interpretation of its configuration more reliable.

Action Potentials

Computer analysis in clinical electromyography.

Electromyographic findings are traditionally evaluated in terms of the duration, amplitude and shape of the myoelectric potentials as well as the pattern of discharge. Unfortunately, the evaluation is frequently dependent on the examiner's subjective observations with the result that mild, early cases or variations in the typical symptoms of the disease may be missed. To overcome these deficiencies, various approaches employing either analog or digital computer techniques have been explored. Programs have ranged from recognition and measurement of motor unit potentials to quantification of the interference pattern. Studies have also compared completely automatic analysis with operator-computer interaction and measurements performed manually. It is evident that the general format is still in the developmental stage. The prime need at the present time, however, is not only for quantification of the electromyogram but for innovative approaches which will expand our knowledge and increase diagnostic accuracy.

Action Potentials

Mercury poisoning in a dentist.

We examined a dentist with chronic elemental mercury poisoning electrophysiologically. Motor conduction in the upper and lower limbs was normal. Sensory nerve action potentials in the ulnar and median nerves were normal, but could not be elicited in the superfical peroneal nerves. Conduction velocity of the sural nerves was normal, but the action potential amplitude was abnormal. Following treatment with penicillamine, sensory conductions in the lower limbs returned to normal.

Dentistry

The effect of angiography on the electrophysiological state of the spinal cord. A study in control and traumatized cats.

The tonic vibration reflex (TVR) and evoked cerebral potential (ECP) were used to evaluate the effects of aortic injections of Renografin- 76, saline, and a mixture of sodium and sucrose on the spinal cord in 7 control cats and 12 which were recovering from trauma. Results showed that Renografin-76 produced different toxic effects in control and traumatized spinal cords as measured by the TVR. The disappearance of either ECP or TVR following the Renografin injection in 4 cases exemplifies the enhanced risk of injecting angiographic materials into traumatized spinal cords during recovery. The TVR shows promise as an electrophsiological criterion of minimal toxic effects of angiographic contrast agents on the spinal cord.

Angiography

Letter: H reflex.

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H-Reflex