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PubMed1999

Use of functional electrical stimulation in the lower extremities of incomplete spinal cord injured patients.

After a program of therapeutic electrical stimulation, 3 groups of incomplete spinal cord injured (SCI) patients were identified, those in whom an improvement of both voluntary and stimulated muscle force was observed, those with an increase in stimulation response only, and patients in whom no effect of electrical stimulation training could be recorded. As it is difficult to predict the outcome of the electrical stimulation rehabilitation process, a diagnostic procedure was developed to predict soon after accidents which incomplete SCI patients are candidates for permanent use of a functional electrical stimulation (FES) orthotic aid. The candidates for chronic use of FES are patients with weak ankle dorsiflexors and sufficiently strong knee extensors. These patients are equipped with a single channel peroneal stimulator augmenting dorsiflexion and knee and hip flexion in a total lower limb flexion response. By applying FES to the ankle plantar flexors, the swing phase of walking can be significantly shortened and faster walking obtained.

Ankle Joint↗
PubMedDate not supplied

Use of telekinesthetic feedback in walking assisted by functional electrical stimulation.

A telekinesthetic feedback implemented into functional electrical stimulation (FES) orthosis is described. Single channel FES is used to provoke ankle dorsiflexion during walking. FES is controlled manually by a special lever, built into the handle of the crutch. The angular position of the lever defines the intensity of stimulation and thus the magnitude of the ankle dorsiflexion. The measured joint angle provides the feedback information about the ankle joint position, which is presented to the user as a force feedback applied to the control lever. As the first step in the development of a complex micromechatronic device, a simulated testing environment was prepared. A computer model, comprising dynamic foot characteristics, as well as agonistic and antagonistic muscle groups, substitutes the ankle joint. The model also includes fatiguing of the electrically stimulated muscles. For experimental purposes an actuated control lever was built. The efficacy of the telekinesthetic feedback was evaluated in a group of six healthy persons.

Ankle Joint↗
PubMed1989

Cardiovascular responses and changes in neural activity in the rostral ventrolateral medulla elicited by electrical stimulation of the amygdala of the rat.

Electrical stimulation of the central nucleus of the amygdala (ACe) in anesthetized animals produces a decrease in arterial pressure (AP) as a result of an overall decrease in peripheral resistance. As the cardiovascular neurons that presumably mediate these changes are located in the rostral ventrolateral medulla (RVLM), we recorded spontaneous activity from 89 histologically verified units in the RVLM of urethan-anesthetized rats. Twenty-two of these units were classified as cardiovascular neurons because their spontaneous activity was inhibited by baroreceptor stimulation (2-4 micrograms phenylephrine i.v.) and displayed a cardiac cycle-related rhythmicity. Single or twin pulses (0.5 ms, 180 +/- 55 microA) delivered once per second to arterial depressor sites in the ipsilateral ACe inhibited the activity of 18 of these neurons and excited 4. In 27 additional barosensitive neurons that lacked cardiac cycle rythmicity, a similar distribution of effects was obtained by electrical stimulation of the ACe: 13 inhibited, 5 excited, 9 not affected. Finally, 40 non-barosensitive units were found; stimulation of the ACe inhibited the activity of 16, excited 12 and had not effect in 12. These results are interpreted to indicate that the differential effects of ACe stimulation on different vascular beds are mediated probably by differential influences on cardiovascular neurons in the RVLM, and that functions other than respiratory and cardiovascular control are represented in the RVLM.

Action Potentials↗
PubMed2002

Electrical stimulation improves insulin responses in a human skeletal muscle cell model of hyperglycemia.

Myoblasts from human skeletal muscle were isolated from needle biopsy samples of the vastus lateralis of young and healthy volunteers. Contaminating fibroblasts were removed, and myoblasts were fused into differentiated multinucleated myotubes. These myotubes manifested both basal and insulin-stimulated (1-100 nM) glucose transport and glycogen synthesis. Insulin increased 2-deoxyglucose uptake by 1.4-fold and glycogen synthesis by 2.1-fold. Measurements of impedance of cell-covered gold electrodes (ECIS system) showed increased micromotion of caffeine-stimulated cells, showing their ability to contract. Acute electrical stimulation of the myotubes increased 2-deoxyglucose uptake by about 30%. Treatment with high glucose concentrations (10-20 mM) for 2-8 days reduced both basal and insulin-stimulated glucose uptake. Maximal effect was seen after 2 days of treatment with 20 mM glucose. Baseline glucose uptake and glycogen synthesis were reduced by 35%, insulin-stimulated glucose uptake by 25%, and insulin-stimulated glycogen synthesis by 39%. Total cell content of glycogen was not changed by hyperglycemia. The insulin-stimulated glucose uptake in hyperglycemia-treated cells was improved by electrical stimulation of the cells. In conclusion, a model of hyperglycemia has been established, and electrical stimulation improved insulin responses.

Adult↗
PubMed1999

The parafascicular nucleus and two-way active avoidance: effects of electrical stimulation and electrode implantation.

To evaluate whether electrical stimulation of the parafascicular nucleus (PF) can improve short-term (24 h) and/or long-term (21 days) retention of two-way active avoidance, rats were implanted with an electrode at this nucleus (experimental groups) or above it (control groups). After a single 30-trial acquisition session, experimental groups were submitted to a 10-min session of electrical stimulation. Results showed that the simple implantation of an electrode at the posterior PF enhanced by itself the acquisition of two-way active avoidance, in such a way that the subsequent stimulation of this region may have been unable to further improve the performance of the rats. On the other hand, parafascicular stimulation improved the 24-h retention of the task in a site-specific way, since this effect was mainly seen after stimulation of the central PF region. The facilitative effect on 24-h retention could also depend on the level of performance achieved during the acquisition session, because this improvement was only evidenced in poorly learning animals. No effects were found on 21-day retention. The present results confirm the involvement of the PF in learning and memory and the functional heterogeneity of this nucleus.

Analysis of Variance↗
PubMedDate not supplied

Low-molecular-mass endothelial cell-stimulating angiogenic factor in relation to capillary growth induced in rat skeletal muscle by low-frequency electrical stimulation.

The involvement of endothelial cell-stimulating angiogenic factor (ESAF) in capillary growth was studied in adult rat skeletal muscles (tibialis anterior, TA, and extensor digitorum longus, EDL) in which capillary growth was induced by chronic unilateral electrical stimulation (10 Hz, 8 h/day for 7 days), and in sham-operated and unoperated control muscles. ESAF was assayed by its ability to activate latent collagenase in units per hour per milligram protein. Anatomical capillary density (CD, number of capillaries per mm2) and capillary per fibre ratio (C/F) were estimated in frozen sections from the same muscles after staining for endothelial alkaline phosphatase. In control muscles, ESAF levels were inversely related to capillary supply, being highest (1.82 +/- 0.25 units) in the glycolytic cortex of TA (CD 273 +/- 18/mm2, C/F 1.26 +/- 0.07), lowest (1.04 +/- 0.02 units) in its oxidative highly capillarized core (CD 862 +/- 60/mm2, C/F 2.05 +/- 0.04), and intermediate in EDL (ESAF 1.59 +/- 0.37 units, CD 527 +/- 26/mm2, C/F 1.44 +/- 0.06). Neither capillary supply nor ESAF levels were affected by sham operation. However, chronic electrical stimulation increased capillary supply significantly in EDL (CD 61% greater than in controls, C/F 45% greater) and ESAF levels were elevated 3-fold to 4.77 +/- 0.74 units. In TA muscles, stimulation increased capillary supply specifically in the glycolytic cortex (C/F 2.51 +/- 0.09, p < 0.0001 vs. control) and ESAF levels were increased significantly in this region to 3.19 +/- 0.55 units (p < 0.05, vs. control). C/F ratio and ESAF in the oxidative core of TA (2.31 +/- 0.05 and 1.48 +/- 0.23 units, respectively) were not significantly different from control values. Thus, chronic electrical stimulation, which is known to increase both shear stress and wall tension in capillaries and induce angiogenesis, also increased ESAF activity.

Animals↗
PubMed2002

Electrical stimulation as an adjunct to spinal fusion: a meta-analysis of controlled clinical trials.

This study was a meta-analysis to examine whether electrical stimulation has a specific effect on spinal fusion. Little evidence exists on the efficacy of electrical stimulation for improving fusion rate of spinal fusion surgery. Using MEDLINE (1966-2000) and EMBASE (1985-1999), a search for articles was carried out using the Medical Subject Headings: (1) electric stimulation or electromagnetic fields, (2) spinal fusion, (3) controlled or clinical trial, and (4) human. Data were extracted from all the hit articles and additionally collected from appropriate journal lists. A total of five randomized controlled trials (RCT) on bones assessing healing of spinal fusion were identified and scored on methodological quality. All the identified studies reported positive findings, but the quality score of each trial showed wide flaws. Because of relatively homogenous subjects who had spine fusion and radiographic assessment from these studies, pooling of the data was able to be performed. Excluding one trial with the lowest score, the combined results of four trials, whose major endpoints were the success rate of the fusion, revealed a statistically significant effect of electrical stimulation with various techniques, but the selected trials still showed wide variation in view of stimulation modalities and treatment protocol. The pooled result of the studies in this review revealed the efficacy of electrical stimulation based on proved methodological quality. As problems on therapeutic modality and protocol remain, there is a further need for improvement in design to constitute acceptable proof and to establish treatment programs that better demonstrate electrical stimulation effects on spinal fusion.

Combined Modality Therapy↗
PubMed2004

Design and performance of an electrical stimulator for long-term contraction of cultured muscle cells.

Excitability in muscle cells manifests itself as contractility and may be evoked by electrical stimulation. Here we describe an electrical stimulator device applicable to cells seeded on standard multiwell plates and demonstrate how it effectively stimulates synchronous contraction of skeletal muscle C2C12 cells without damaging them. The electrical stimulator of cultured cells (ESCC) consists of two connection cards and a network of platinum electrodes positioned in such way that each well in a row is uniformly stimulated. The ESCC may produce a range of outputs based on the stimulation parameters it receives from a commercial pulse generator and can be placed in a standard cell incubator, allowing for long-term stimulation as required for biochemical and molecular biological assays. We show that a 90-min stimulation of C2C12 myotubes at 50 V, 30 ms of pulse duration, and 3 Hz of frequency enhances glucose metabolism and glycogen mobilization while oppositely modulating the activity ratio of glycogen metabolizing enzymes. Thus, we demonstrate that long-term electrical stimulation of C2C12 myotubes with the ESCC results in contractility and metabolic changes, as seen in exercising muscle.

Animals↗
PubMed1995

[Early diagnosis of Guillain-Barré syndrome by electric stimulations of the nerve roots].

Ulnar nerve electrical stimulations from motor roots to wrist were used in the early Guillain-Barré syndrome (GBS), to improve the electrophysiological diagnosis yield. 22 patients with a GBS were investigated with this technique between 3 to 17 days after the onset. Conventional electrophysiological examination was sufficient to diagnose an Acute Inflammatory Demyelinating Polyneuropathy in 12 cases. In 10 other patients, standard examination remained negative or not conclusive, and vertebral electrical stimulations were decisive for the diagnosis, showing conduction bloks. This method could be routinely performed for an early diagnosis, in association with conventional motor conduction measurements. This study confirms the possibility of a pure proximal demyelinating impairment of the peripheral nervous system in the early GBS.

Adolescent↗
PubMed2006

Electrical stimulation - an evolving concept in the treatment of colonic motor dysfunctions.

Electrical stimulation of digestive organs is a new approach for the treatment of dismotility-based diseases affecting the gastrointestinal (GI) tract. The most significant advancement in this field has been obtained with stomach stimulation. As a result, a fully implantable stimulation system to treat gastroparesis - the 'Enterra' system - is now commercially available. Similarly, electrical stimulation of the colon may become a valuable alternative to drug therapy and surgical procedures in the treatment of colonic motor dysfunctions. Over the past decade, several stimulation patterns to modulate colon motility have been tested in animal and human models. The results of these studies are reviewed here in connection with aspects regarding physiological mechanisms activated by electrical stimulation of the colon.

Animals↗
PubMed1997

Spectral electromyographic changes during a muscular strengthening training based on electrical stimulation.

The aim of this study is to describe the effects of neuromuscular electrical stimulation on electromyographic power spectrum evolution through a program of muscle strengthening. Ten healthy subjects received electrical stimulation of the quadriceps femoris muscle. Surface EMG was obtained from rectus femoris during maximum voluntary isometric contractions of quadriceps. Directly from EMG the Zero Crossing Rate and Root Mean Square (RMS) were calculated. Afterwards, the Mean Power Frequency and Median Frequency from EMG power spectrum were obtained using the Maximum Entropy method to estimate the spectrum. An analysis of variance for repeated measures revealed a statistical significance for RMS through the sessions and for spectral shifts towards higher frequencies between, before and after electrical stimulation. The evolution of power spectrum through sessions showed a curvilinear evolution, first decreasing towards lower frequencies and then increasing. These results suggest that electrical stimulation produces immediate changes on the motor unit: increasing the recruitment number and action potential velocity and a selective recruitment of type II fibres. During the strengthening program sessions two main phases were detected: the appearance and recovery from fatigue.

Adolescent↗
PubMed1976

Acupuncture and transcutaneous electric stimulation in the treatment of chronic sacrolumbalgia and ischialgia.

A comparison was made between 50 patients treated with acupuncture and 50 patients treated with transcutaneous electric stimulation. All patients suffered from chronic sacrolumbalgia or ischialgia of more than six months' duration. Two to 10 treatments were given at weekly sessions, the mean being 5 in both groups. Stimulation points were selected by the same principle in both groups: one point along the course of the nerve trunk affected, and one point at a dermatome proximal to the affected segment. The stimulation was given bilaterally. Needles were inserted as deep as the muscular layer and twirled at 5 min intervals. In the electric stimulation square-wave impulses of 1.0 msec duration and 50 Hz frequency were used. The electrodes were 0.9 cm in diameter. Each acupuncture and electric stimulation was of 20 min duration. Pain relief was complete or moderate in the acupuncture group in 58% of the cases, and in 46% in the electric stimulation group. After 2 months 30 patients in the acupuncture group and 23 patients in the electric stimulation group still reported satisfactory relief of pain. After 6 months 15 patients in the acupuncture group and 10 patients in the electric stimulation group still reported satisfactory relief of pain.

Acupuncture Therapy↗
PubMed1976

Electrical stimulation of the arcuate nucleus in ovariectomized rats inhibits episodic luteinizing hormone (LH) release but excites LH release after estrogen priming.

The effect of electrical stimulation of the arcuate nucleus of the hypothalamus (ARH) on the blood levels of luteinizing hormone (LH) was studied in ovariectomized (ovx) rats. Unanesthetized, unrestrained rats were bled continuously (30 or 50 mul whole blood/4-6 min) through indwelling right atrial cannulae for 1 1/2-2h prior to the onset of stimulation. The bleeding was continued for the following three hours, during which electrical stimulation was applied for two 60 min periods separated by a 60 min non-stimulation period. Whole blood was analyzed for LH by radioimmunoassay. Electrical stimulation of the ARH in ovx rats inhibited the episodic LH release characteristic of these animals. The inhibition was rapid in onset, beginning within minutes, and lasted for most if not all of the stimulation period or longer. The blood LH levels returned to control values prior to the second stimulation period during which the inhibitory response was again seen. Stimulation in other hypothalamic areas outside the ARH was generally ineffective, although repeatable inhibition of episodic LH release did occur in 2 of 3 rats stimulated in the periventricular nucleus. In a second study, ovx rats were primed with 5 mug estradiol benzoate/100 g body weight/day for 2 days prior to stimulation. In these rats, stimulation of the ARH or median eminence produced increases in LH release, whereas stimulation in other hypothalamic areas outside the ARH was ineffective. The parameters of electrical stimulation that produced increases in LH release were the same as those that caused the inhibition of episodic LH release. The results demonstrate that electrical stimulation of the ARH inhibits LH release in ovx rats, but increases LH release if the animals have been primed with estrogen.

Animals↗
PubMed2000

[Clinical study of effects of submaxillary transcutaneous electrical stimulation of genioglossus on obstructive sleep apnea syndrome].

OBJECTIVE: To investigate the effect of submaxillary transcutaneous electric stimulation of genioglossus on obstructive sleep apnea syndrome (OSAS). METHOD: Nineteen patients (male) with OSAS were diagnosed by polysomnography previously. Fixed the provocative locus of genioglossus and its controlling nerve with local anatomy. Estimated obstructive level of pharyngeal cavity by observing muller's maneuver under fiberolaryngoscope. Determined the effects of electric stimulation on different levels of narrow pharyngeal cavity with control study method. RESULT: The effect of electrical stimulation was different in different narrow level. The best effect was found on the obstruction of retrotongue-base-pharynx level, data of breath disorder (P < 0.05), oxygen saturation (P < 0.05) and clinical symptoms were significantly improved. The data were partly improved on multilevel obstructions of retrotongue-base-pharynx or above, no improvement was found on the obstruction of retrotongue-base-pharynx level. Dormant index was not worse. CONCLUSION: Submaxillary electrical stimulation is effective to the treatment of OSAS and its curative effect perhaps has a close relationship with obstructive level of with upper-airway. Further research on the mechanism showed that stimulating upper-airway dilating muscle which formed mainly by genioglossus could push the tongue ahead and effectively open pharyngeal cavity. Maybe it is a reason that the best effect took place on the retrotongue-base-pharynx level. Sleep was not affected by electrical stimulation.

Adult↗
PubMed1978

[Physiopathological study of coupled electric stimulation].

The charges of left ventricular function provoked by coupled electrical stimulation were studied in 17 patients with severe chronic aortic incompetence and 9 controls. These results were compared with those obtained after isolated extrasystole in 24 cases of aortic incompetence and 10 controls, and during paired electrical stimulation in 12 cases of aortic incompetence. Left ventricular function increased uniformly after post-extrasystolic potentiation whatever the mode of stimulation. The preload did not change significantly, the increased ventricular function being mainly due to increased contractility. Coupled electrical stimulation mobilised the greatest contractility reserve (ejection fraction : +32 % in controls and +37 % in aortic incompetence and averaged circumferentiel fibre shortening +55 % in controls and +47 % in aortic incompetence). The contractility reserve is inversely proportional to the initial ejection fraction except when its value is less than 35 %. The myocardial response then becomes variable so that left ventricles with probable irreversible hypocontractility may be distinguished from those whose ventricular funciton would improve after surgical correction.

Adult↗
PubMed1983

Activation of lipolysis by epinephrine and electrical stimulation in the perfused hindquarters of lean and obese-diabetic (db/db) mice.

The effects of epinephrine and electrical stimulation on lipolysis in the skeletal muscles of lean, and obese-diabetic (db/db) mice were studied using the perfused mouse hindquarter preparation. The rate of glycerol release from the obese mouse preparation was two times that of their lean littermates. Epinephrine sensitivity in the db/db mice was reduced only with respect to lipolytic activation, but was unaltered with respect to tissue cyclic AMP elevation and glycogen phosphorylase activation. Electrical stimulation caused a prompt increase in lactate production in both lean and obese mice and elevated glycerol release only in the obese mice. Glycerol release was also increased in the lean mice by stimulating at voltages exceeding 10 volts. Cyclic AMP levels were unaffected by electrical stimulation. Omission of calcium from the perfusion medium severely blunted lipolytic activation by electrical stimulation, which could be restored by calcium readdition. These results suggest that an impairment in lipolytic activation by epinephrine distal to activation of adenylate cyclase exists in the skeletal muscle of young db/db mice. Despite of this impairment, however, lipolysis in the obese mouse muscle was more sensitive to activation by electrical stimulation through a mechanism unrelated to changes in cyclic AMP, but is dependent on extracellular calcium.

Animals↗
PubMed1990

Chronic intracochlear electrical stimulation in the neonatally deafened cat. I: Expansion of central representation.

Intracochlear electrical stimulation via cochlear prostheses has been employed as a means of providing some hearing to deaf children. Since chronically restricted stimuli are known to have profound effects on central nervous system development, it is important to examine the effects of chronic intracochlear electrical stimulation in a neonatally deafened animal model. In this study neonatally deafened cats were implanted with a scala tympani electrode consisting of two pairs of electrodes. Chronic electrical stimulation was delivered using one electrode pair and consisted of charge-balanced biphasic pulses (200 microseconds/phase, 30 pps) at 2 dB above the electrically evoked auditory brain stem response (EABR) threshold for 4 h/day or at 6 dB 1 h/day, 5 days/week, for up to 3 months. The second electrode pair was unstimulated and served as an internal control. Following chronic stimulation, acute mapping experiments were performed in the central nucleus of the inferior colliculus (ICC) using single unit and multi-unit recording techniques and activating each electrode pair separately. In addition to these chronically stimulated animals, 2 other groups of experimental animals were studied: A normal group consisting of prior normal adult cats that were acutely implanted; and an unstimulated control group consisting of neonatally deafened adult cats that were either acutely implanted or implanted at 8-10 weeks of age but not chronically stimulated. Among the major findings of this study are: Electrical stimulation of the intracochlear bipolar electrode consistently produces activation of a reproducibly limited sector of the ICC. The location of this activated sector was found to be consistent with the known cochleotopic organization of the ICC and the intracochlear location of the stimulating electrodes. No major differences in the spatial representation of activated electrodes were found between prior normal cats and neonatally deafened unstimulated cats. The locations, shapes and widths of these spatial representations were virtually indistinguishable indicating that ICC cochleotopic organizations were equivalent in these two experimental groups. In contrast, the ICC representation of chronically stimulated electrode pairs were found to be significantly different. The average area activated by chronically stimulated electrode pairs at 6 dB above minimum threshold was approximately twice that of unstimulated deafened animals and prior normal animals; and it was larger, but not significantly so, than the average of the unstimulated electrode pair in the same experimental group.(ABSTRACT TRUNCATED AT 400 WORDS)

Acoustic Stimulation↗