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PubMed1990

A comparison of magnetic and electrical stimulation of spinal nerves.

The utility of the magnetic coil for stimulation of the cervical spinal nerves was compared to electrical stimulation by a monopolar needle cathode placed onto the spinal lamina in six volunteers. No statistical difference in average amplitudes or areas of evoked CMAPs was found although the size of the magnetic coil evoked potentials was less at C7-8 in several subjects. Electrical stimulation resulted in depolarization at a more proximal site. Electrical stimulation was associated with more discomfort, especially at C5-6. We conclude that electrical stimulation using a monopolar needle as the cathode is the superior technique for the clinical electrophysiologic study of the proximal brachial plexus and cervical spinal nerves.

Action Potentials↗
PubMed1983

Neuromuscular electrical stimulation for the head-injured patient.

Recent research has shown that electrical stimulation is effective in treatment programs designed to maintain or gain range of motion, to facilitate voluntary motor control, and to strengthen muscles weakened by disuse. All of these treatment goals are relevant to the head-injured patient who frequently demonstrates profound disuse atrophy, joint contractures with excessive muscle tone, and decreased voluntary motor capabilities. As the cognitive status of the head-injured patient improves, electrical stimulation can be incorporated into traditional treatment programs to enhance their effectiveness. This article discusses using neuromuscular electrical stimulation with programs aimed at managing contractures, reducing spasticity, and facilitating voluntary motion. The limitations of electrical stimulation in the head-injured patient population are addressed.

Adult↗
PubMed2000

Effects on peroneal motoneurons of cutaneous afferents activated by mechanical or electrical stimulations.

The postsynaptic potentials elicited in peroneal motoneurons by either mechanical stimulation of cutaneous areas innervated by the superficial peroneal nerve (SP) or repetitive electrical stimulation of SP were compared in anesthetized cats. After denervation of the foot sparing only the territory of SP terminal branches, reproducible mechanical stimulations were applied by pressure on the plantar surface of the toes via a plastic disk attached to a servo-length device, causing a mild compression of toes. This stimulus evoked small but consistent postsynaptic potentials in every peroneal motoneuron. Weak stimuli elicited only excitatory postsynaptic potentials (EPSPs), whereas increase in stimulation strength allowed distinction of three patterns of response. In about one half of the sample, mechanical stimulation or trains of 20/s electric pulses at strengths up to six times the threshold of the most excitable fibers in the nerve evoked only EPSPs. Responses to electrical stimulation appeared with 3-7 ms central latencies, suggesting oligosynaptic pathways. In another, smaller fraction of the sample, inhibitory postsynaptic potentials (IPSPs) appeared with an increase of stimulation strength, and the last fraction showed a mixed pattern of excitation and inhibition. In 24 of 32 motoneurons where electrical and mechanical effects could be compared, the responses were similar, and in 6 others, they changed from pure excitation on mechanical stimulation to mixed on electrical stimulation. With both kinds of stimulation, stronger stimulations were required to evoke inhibitory postsynaptic potentials (IPSPs), which appeared at longer central latencies than EPSPs, indicating longer interneuronal pathways. The similarity of responses to mechanical and electrical stimulation in a majority of peroneal motoneurons suggests that the effects of commonly used electrical stimulation are good predictors of the responses of peroneal motoneurons to natural skin stimulation. The different types of responses to cutaneous afferents from SP territory reflect a complex connectivity allowing modulations of cutaneous reflex responses in various postures and gaits.

Animals↗
PubMed1997

Efficacy of electrical stimulation at frequencies higher than basal rate in canine stomach.

The optimum frequency for electrically stimulating motility in the stomach is still in question. Some studies of gastric electrical stimulation (GES) at near physiologic frequencies have reported gastric electrical entrainment but with little efficacy in improving motility. In this study we examined the effectiveness of electrical stimulation at a broad range of frequencies in entraining gastric electrical activity (GEA) and eliciting contractions in a canine model. The stomachs of six dogs, each implanted with four pairs of stainless steel electrodes and two strain gauges were stimulated at frequencies ranging from 3 to 30 cycles/min. GEA and contractions were monitored before and during electrical stimulation. The ability of GES at different frequencies to reverse the effect of glucagon was also investigated. GEA was entrained in most animals at frequencies close to the intrinsic rate as well as at four to five times the intrinsic rate. At other stimulation frequencies, the recorded electrical control activity either remained unchanged, uncoupled, or became dysrhythmic. Contractile response to stimulation at four to five times the intrinsic rate were significantly higher than those at frequencies close to the intrinsic rate (P < 0.05). GES did not alter the effect of glucagon. Stimulation at a frequency of four times the basal rate of 5/min elicited the largest motility index in dogs. Stimulation at frequencies much higher than the physiologic rate warrants further study as a possible optimum range for GES.

Animals↗
PubMed1994

Bipolar surface electrical stimulation of the vertebrate retina.

BACKGROUND: Retinitis pigmentosa with attendant photoreceptor loss can cause a profound visual handicap. We have postulated that an intraocular prosthesis that could electrically stimulate the inner retina might provide vision to some of these patients. For such a prosthesis to be feasible, electrical stimulation of the inner retina must elicit a focal retinal response. The stimulating current densities required to elicit such a response must not result in irreversible toxic reactions at the electrode-tissue interface. METHODS: To test the feasibility of this approach, we used bipolar platinum wire electrodes to electrically stimulate the inner retinal surface in bullfrog eyecup preparations and, using similar methods, we electrically stimulated rabbit eyes after injecting intravenous sodium iodate (40 mg/kg), a retinal pigment epithelial toxin with secondary effects on the photoreceptors. RESULTS: Surface electrical stimulation of the inner retina in normal eyes and in eyes with outer retinal degeneration can elicit a localized retinal response. The threshold stimulating currents resulted in charge densities of 2.98 microcoulombs per square centimeter (bullfrog), 8.92 microC/cm2 (normal rabbit), and 11.9 microC/cm2 (rabbit retinas with outer retinal degenerations). These charge densities are within the previously delineated safe limits for long-term electrical stimulation of neural tissue using platinum microelectrodes (100 microC/cm2). CONCLUSION: Multifocal electrical stimulation of the retina might be a viable approach to provide some vision to patients who have profound visual loss due to outer retinal degenerations.

Animals↗
PubMed2000

Electrical stimulation: a reflection on current clinical practices.

This paper briefly reviews the basic principles of several clinical applications of electrical stimulation for therapeutic purposes. It is intended to facilitate the integration of electrical stimulation into routine clinical practice by clarifying the terminology and standard conventions of the field, explaining the delivery capabilities of common electrical stimulators commercially available for clinical use, summarizing several examples of evidence-based therapeutic applications, and providing guidelines for selection of most commonly used treatment parameters. Rather than an exhaustive survey of the field, the presentation touches broadly on guidelines for use of transcutaneous electrical stimulation employing surface electrodes for the purposes of analgesia (TENS), drug delivery (iontophoresis), or neuromuscular rehabilitation (NMES), as well as other selected clinical applications. The paper is a general review of common clinical practices of electrotherapy and should serve as an introduction to the important factors for clinicians to consider when contemplating electrical stimulation as a treatment option.

Central Nervous System Diseases↗
PubMed1979

Vestibular effects of electrical stimulation of the cochlea. Monitored in the awake primate.

The effect of electrical stimulation of the cochlea on vestibular response was monitored in six rhesus monkeys. Eye movements and single-unit activity from the vestibular portion of the eighth nerve, vestibular nuclei, reticular formation, and abducens nucleus were observed while electrical stimulation was delivered through an implanted cochlear prosthesis. In one animal of this series, neural activity from the inferior colliculus and cochlear nuclear complex was also recorded. Electrical stimulation elicited eye-movement responses in only one animal. In the animals from which single-unit activity was recorded, no positive vestibular effects were noted. In one animal of this study, responses were elicited from auditory structures by relatively low intensities of electrical stimulation.

Acoustic Stimulation↗
PubMed1987

Epidural spinal electrical stimulation in peripheral vascular disease.

Epidural spinal electrical stimulation (ESES) has been valuable in the control of pain arising from peripheral vascular disease. Thirty-two of 34 patients experience some relief of pain and 12 of 24 patients showed healing of ischemic ulcers. This technique may prove to be useful in preventing or delaying amputation of ischemic limbs. A prospective randomized study has been undertaken to assess whether this form of electrical stimulation can save limbs.

Electric Stimulation Therapy↗
PubMed1983

Postoperative pain control: contribution of psychological factors and transcutaneous electrical stimulation.

The influence of transcutaneous electrical stimulation (TES) and psychological factors in determining the intensity of acute postoperative pain was examined in a prospective, double-blind controlled trial completed by 30 patients having elective surgery. Psychometric tests were administered prior to surgery. Postoperative pain was assessed by cumulative morphine requirement (M48) administered intramuscularly, and the mean score of a visual analogue scale of pain (VAS), in the first 48 h following surgery. M48 was significantly correlated with the VAS score (r = 0.62, P less than 0.001), and with the psychometric test scores for trait-anxiety (r = 0.70, P less than 0.001) and neuroticism (r = 0.67, P less than 0.001). Though patients treated with TES required 25% less morphine than those treated with placebo, the difference was not significant using monovariate analysis and applying unpaired two-tailed Student's t-test (P less than 0.2). When the contribution of neuroticism to the variance of M48 was adjusted using multiple regression analysis, the effect of TES became significant at the 0.05 level. Covariance analysis showed that TES contributed some 19% to the explained variance of M48 while neuroticism contributed about 80%, and there was no interaction between these two factors. These findings allow a degree of prediction of the individual patient's postoperative pain and narcotic requirement, and point to a strong correlation between postoperative pain perception and personality.

Acute Disease↗
PubMed1979

Observations on fast axoplasmic transport in peripheral nerve following repetitive electrical stimulation.

In a series of 13 cats the effect of electrical stimulation of peripheral nerve on the mechanism of fast axoplasmic transport was studied. Electrical stimulation was used for varying time periods at parameters reported in the range of those used to produce electroanalgesia in man. Our results indicate that at these parameters, electrical stimulation produced no effect on this important aspect of nerve function, and, therefore, our work lends support to the safety of these devices in pain states.

Animals↗
PubMedDate not supplied

[Physiologic reactions to electric stimulation of the labyrinth].

Physiological responses to electric stimulation of the skin projections of labyrinths on the outer ear were investigated. The experiments were carried out on 56 test subjects using electric current in the range of 20 microA to 1.5 mA with the frequency 0.2-0.5 Hz. Thresholds for the emergence of autonomic, somatomotor and sensory manifestations were detected. It was found that autonomic reactions may develop independently of somatomotor responses. It is postulated that autonomic, motor and sensory reactions to electric stimulation of labyrinths constitute a combined response which is of afferent vestibular and skin origin.

Adolescent↗
PubMed1981

Repetitive electrical stimulation of peripheral nerve and spinal cord activity.

Spinal cord neuron and dorsal column fiber responses to electrical stimulation of the sciatic nerve in anesthetized cats were recorded before, during, and after periods of repetitive electrical stimulation of the sciatic nerve through an implantable nerve cuff stimulator device of the type and method used in human patients for pain relief. In previous publications from this laboratory using similar experimental conditions, we reported that repetitive electrical stimulation of the peripheral nerve suppressed all components of the compound action potential of nerves. The present study confirms that 5 percent of the spinal cord units studied showed facilitated discharge, 46 percent showed inhibited or depressed discharge, 36 percent underwent no change, and 13 percent showed equivocal responses to repetitive electrical stimulation. Inhibition of dorsal column fiber activity following repetitive electrical stimulation of peripheral nerve is not consistent with the Melzack-Wall gate hypothesis in which suppression of small fiber nociceptive input is mediated by large fiber activity. Our work suggests that the most commonly observed effect of electroanalgesia is to cause a more diffuse depression of nociceptive as well as nonnociceptive spinal cord activity.

Action Potentials↗
PubMedDate not supplied

Electrical stimulation of spinal fusion: a scientific and clinical update.

BACKGROUND CONTEXT: For over two decades, a number of electrical stimulation devices have achieved increasing acceptance as adjuncts to lumbar spinal fusion. Direct current electrical stimulation, pulsed electromagnetic fields and more recently capacitive coupling have been shown to have varying effectiveness when used to increase the success of lumbar spinal fusion. PURPOSE: The various electrical stimulation devices will be reviewed with respect to the available basic science evidence validating their use as spinal fusion adjuncts, as well as a review of the current clinical data available to allow not only a discussion of their overall clinical applicability, but more specifically their use in specific spinal disorders and spinal fusion techniques. METHODS: The existing peer-reviewed scientific literature will be used to ascertain the scientific and clinical efficacy of electrical stimulation to enhance lumbar spinal fusion. CONCLUSION: Electrical stimulation devices have emerged as valid adjuncts to attaining a solid lumbar spinal fusion. However, not all stimulators are equally scientifically effective nor are they equally effective clinically in achieving increased fusion success.

Electric Stimulation Therapy↗
PubMed1988

Prevention of disuse muscle atrophy by means of electrical stimulation: maintenance of protein synthesis.

The effect of percutaneous electrical stimulation in preventing immobilisation-induced muscle atrophy was determined from measurements of quadriceps mass, composition, and rate of protein synthesis in seven men who had a fracture of one tibia immobilised in a long-leg cast for 6 weeks. These features were compared with those of fourteen men with similar injuries who did not use an electrical stimulator. In men who did not use the stimulator, quadriceps cross-sectional area (CSA) at midthigh, measured by ultrasonography, fell by a mean (SD) 17 (10)% and the rate of muscle protein synthesis was 23 (10)% lower on the immobilised than on the control side (0.037 [0.016] vs 0.048 [0.02]%/h). In contrast, in those who used the stimulator, quadriceps CSA (55.5 [7.3]) cm2 control leg, 50.9 [9.0] cm2 immobilised leg) and the rate of muscle protein synthesis (0.053 [0.009] %/h control leg, 0.059 [0.012] %/h immobilised leg) were similar on the two sides. The results suggest that brief periods of low-voltage percutaneous electrical stimulation will reduce quadriceps atrophy secondary to knee immobilisation, and that the mechanism includes prevention of the fall in muscle protein synthesis that usually occurs on immobilisation.

Adolescent↗
PubMed1995

Effects of amphetamine on carrier-mediated and electrically stimulated dopamine release in slices of rat caudate putamen and nucleus accumbens.

The effects of (+)-amphetamine on carrier-mediated and electrically stimulated dopamine release were investigated using fast cyclic voltammetry in rat brain slices incorporating the nucleus accumbens, and in the caudate putamen. In the caudate putamen, dopamine release either increased with increasing frequency of local electrical stimulation (hot spots) or did not increase significantly (cold spots); dopamine release increased with increasing frequency of electrical stimulation in the nucleus accumbens. Local pressure application of (+)-amphetamine from a micropipette caused dopamine efflux at all sites examined, and this was not affected by sulpiride, indicating that efflux of dopamine caused by (+)-amphetamine is not regulated by dopamine D2 autoreceptors. (+)-Amphetamine reduced single-pulse electrically stimulated dopamine release at all sites; sulpiride reversed this decrease, indicating that endogenous dopamine released by (+)-amphetamine activates dopamine D2 autoreceptors. In nucleus accumbens and hot spots, (+)-amphetamine did not affect 20-pulse 50-Hz-stimulated dopamine release, whereas in cold spots it potentiated 20-pulse 50-Hz-stimulated dopamine release. We conclude that (+)-amphetamine modifies electrically stimulated dopamine release by uptake inhibition or by indirect activation of D2 autoreceptors; the precise mechanism is determined by site and duration of electrical stimulation.

Amphetamine↗
PubMed1998

Axons, but not cell bodies, are activated by electrical stimulation in cortical gray matter. II. Evidence from selective inactivation of cell bodies and axon initial segments.

The results presented in the companion paper showed that extracellular electrical stimulation of the gray matter directly activates axons, but not cell bodies. The second set of experiments presented here was designed to separate the contribution of the axon initial segments and cell bodies from that of the axonal branches to the pool of presynaptic neuronal elements activated by electrical stimulation. For that purpose, N-methyl-D-aspartate (NMDA) iontophoresis was used to induce a selective inactivation of the cell body and of the adjoining portion of the axon by depolarization block, without affecting axonal branches that lack NMDA receptors. After NMDA iontophoresis, the neurons located near the iontophoresis electrode became unable to generate action potentials in an irreversible manner. When the NMDA-induced depolarization block was performed at the site of electrical stimulation, an unexpected increase in the amplitude of the orthodromic responses was observed. Several control experiments suggested that the field potential increase was due to changes of the local environment in the vicinity of the iontophoresis pipette, which led to an increased excitability of the axons. After the period of superexcitability, the orthodromic responses displayed an amplitude that was 15-20% lower than that observed before the NMDA-induced depolarization block, even though cell bodies and axon initial segment at the site of stimulation could not be activated by electrical stimulation. This result shows a low contribution for axon initial segments to the pool of neuronal elements activated by the electrical stimulation. Altogether, these experiments demonstrate that the postsynaptic responses obtained after electrical stimulation of the cortical gray matter result almost exclusively from the activation of axonal branches. Since the neocortex is organised as a network of local and long-range reciprocal connections, great attention must be paid to the interpretation of data obtained with electrical stimulation.

Animals↗
PubMed1995

Functional anatomy of the thalamic centrolateral nucleus as revealed with the [14C]deoxyglucose method following electrical stimulation and electrolytic lesion.

The effects of electrical stimulation and electrolytic lesion of the thalamic intralaminar centrolateral nucleus were studied in the rat brain by means of the quantitative autoradiographic [14C]deoxyglucose method. Unilateral electrical stimulation of the centrolateral nucleus induced: (i) local increase in metabolic activity within the stimulated centrolateral nucleus and the ipsilateral thalamic mediodorsal nucleus, (ii) metabolic depression in all layers of the ipsilateral frontal cortex, (iii) bilateral increase in glucose consumption within the periaqueductal gray, pedunculopontine nucleus, and pontine reticular formation, and (iv) contralateral metabolic activation in the deep cerebellar nuclei. The unilateral electrolytic lesion of the thalamic centrolateral nucleus elicited metabolic depressions in several distal brain areas. The metabolic depression elicited in the mediodorsal, ventrolateral, and lateral thalamic nuclei, as well as in the caudate nucleus, the cingulate, and the superficial layers of forelimb cortex were ipsilateral to the lesioned side. The metabolic depression measured in the medulla and pons (medullary and pontine reticular formation, periaqueductal gray, locus coeruleus, dorsal tegmental, cuneiformis, raphe and pedunculopontine tegmental nuclei), the cerebellum (molecular and granular layers of the cerebellar cortex, interpositus and dentate nuclei), the mesencephalon (substantia nigra reticulata, ventral tegmental area and deep layers of the superior colliculus), the diencephalon (medial habenula, parafascicular, ventrobasal complex, centromedial and reticular thalamic nuclei), the rhinencephalon (dentate gyrus and septum), the basal ganglia (ventral pallidum, globus pallidus, entopeduncular and accumbens nuclei) and the cerebral cortex (superficial and deep layers of the frontal and parietal cortex, deep layers of the forelimb cortex) were bilateral. These functional effects are discussed in relation to known anatomical pathways. The bilateral effects induced by the centrolateral nucleus lesion reflect an important role of the centrolateral nucleus in the processing of reticular activating input and in the interhemispheric transfer of information. The cortical metabolic depression induced by centrolateral nucleus stimulation indicates the participation of this nucleus in attentional functions.

Animals↗