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PubMedDate not supplied

Opposite changes in dopamine metabolites and met-enkephalin levels in the ventricular CSF of patients subjected to thalamic electrical stimulation.

High-frequency electrical stimulations of thalamic nuclei are currently used for the suppression of parkinsonian or essential tremor and for the relief of some types of intractable pain in man. However, the mechanisms by which such stimulations exert their therapeutic effects are essentially unknown. Attempts were made to provide some insight into these mechanisms by measuring the levels of the dopamine metabolites homovanillic acid (HVA) and 3,4-dihydroxyphenylacetic acid (DOPAC), the serotonin metabolite 5-hydroxyindoleacetic acid (5-HIAA) and met-enkephalin-like immunoreactivity in ventricular cerebrospinal fluid (CSF) of patients with Parkinson's disease (PD) or multiple sclerosis (MS) after a 30-minute therapeutic electrical stimulation of the ventralis intermedius nucleus of the thalamus. In nonstimulated control patients, the levels of these compounds did not significantly differ in two CSF samples taken 30 minutes apart. In stimulated patients, a decrease in dopamine metabolite levels associated with a relative increase in met-enkephalin-like immunoreactivity were observed in the CSF sample taken after the 30-minute stimulation as compared to the sample taken immediately before the stimulation. In contrast, the levels of 5-HIAA remained unaffected by the stimulation. These data confirmed the existence of negative interactions between dopaminergic and enkephalinergic systems in man similar to those previously demonstrated in rats. In addition, they suggest that alterations in dopaminergic or enkephalinergic neurotransmission might be involved in the therapeutic action of thalamic electrical stimulation in patients with parkinsonian symptoms and other patients.

Adult↗

PubMed2006

Behavioral effects of high frequency electrical stimulation of the hippocampus on electrical kindling in rats.

Experiments were designed to evaluate the effects of high frequency electrical stimulation (HFS) applied in ventral hippocampus during the hippocampal kindling process, as well as on the expression of fully kindled seizures and the refractoriness for subsequent convulsions during their postictal period. Male Wistar rats, stereotactically implanted in both ventral hippocampus, received daily bilateral HFS (pulses of 60 micros width at 130 Hz at subthreshold current intensity) during 1h immediately after each kindling stimulation (1s train of 60 Hz biphasic square waves, each 1 ms) during 40 days or until the kindled state was achieved. Rats were classified as follows: (a) Responder animals, who required low current intensity for HFS (208+/-38.2 microA), did not show progress of the kindling process and remained in stages II and III seizures. (b) Nonresponders rats, in which the current intensity for HFS was higher (434.5+/-51.7 microA), developed the kindling process as the kindling control group. When HFS was applied before the kindling stimulation in fully kindled rats, animals presented a reduced expression of the fully kindled seizures (nonresponders animals) and an enhanced refractoriness for subsequent seizures during the postictal period (kindling control and nonresponder animals). There was no correlation between the area where the HFS was applied and the effects induced. It was concluded that HFS at 130 Hz in ventral hippocampus is able to modify the epileptogenesis induced by the hippocampal kindling process and the refractoriness to subsequent seizures during the postictal period in rats.

Animals↗

PubMed1987

Treatment of hemifacial spasm with transcutaneous electrical stimulation.

A transcutaneous electrical stimulation method was used to treat hemifacial spasms. This treatment was applied concomitantly with drug therapy to 21 patients, and was found effective in 17 patients (81%). Electrotherapy is considered to be useful in patients with mild spasms and in those with severe spasms for whom surgical treatment is not possible.

Adult↗

PubMed2001

Electrical stimulation alters protein adsorption and nerve cell interactions with electrically conducting biomaterials.

Electrical charges have been shown to enhance nerve regeneration; however, the mechanisms for this effect are unclear. One hypothesis is that an electrical stimulus alters the local electrical fields of extracellular matrix molecules, changing protein adsorption. We have investigated this hypothesis--that electrical stimulation increases the adsorption of serum proteins, specifically fibronectin (FN), to the electrically conducting polymer polypyrrole (PP), thereby, increasing neurite extension. PP was used because electrical stimulation of PP has been shown to significantly enhance neurite outgrowth, and more importantly, PP can be formed into conduits to guide nerve regeneration in vivo. Here, we looked at the effects of electrical stimulation on protein adsorption when an electrical current was applied to PP (1) during protein adsorption (immediate stimulation) and (2) several hours after protein adsorption (delayed stimulation). We found that immediate stimulation of PP increases FN adsorption from purified FN and serum-containing solutions. Correspondingly, PC-12 cells grown on PP films that had been previously adsorbed with FN during immediate stimulation expressed longer neurites. However, for delayed stimulation, no significant differences in adsorption or neurite outgrowth were observed. These studies suggest that increased FN adsorption with immediate electrical stimulation may explain enhanced neurite extension on electrically stimulated PP.

Adsorption↗

PubMed1998

[Spatial tuning curve recording in inferior colliculus during electrical stimulation of the cochlea].

OBJECTIVE: To explore the electrical activity mechanism of auditory center to intracochlear electrical stimulation and provide physiological foundation for spatial encoding of electrical stimulation in multiple channel cochlear implant. METHODS: The spatial tuning curves(STC) in the inferior colliculus(IC) to monopolar electrical stimulation, bipolar electrical stimulation and tone stimulation in cats were composed by using the single unit and the multi-units cluster recording method. RESULTS: The bipolar electrical stimulation excited the response in the specific region in IC, which was similar to the response induced by tone stimulation. The monopolar electrical stimulation excited an extensive response and could not provide the spatial encoding. CONCLUSION: Using the bipolar electrical stimulation, the stimulation region is the key point for improving the spatial encoding. The physiological results of spatial encoding of monopolar electrical stimulation contradicted the psychophysical conclusion and the clinical effect of CI patients. The explanation to this needs further studies.

Animals↗

PubMed1996

Early effects of electrical stimulation on osteogenesis.

The mechanism by which electrical stimulation causes osteogenesis is unknown. Bone marrow of the rabbit was stimulated by direct electrical current or electromagnetic fields to clarify the mechanism of osteogenesis by electrical stimulation. A total of 105 rabbits were separated into five groups: a direct current stimulation by Kirshner wire insertion group; a pulsed electromagnetic fields stimulation (PEMF) group; a PEMF with Kirshner wire insertion group; a Kirshner wire insertion group; and an intramedullary drilling control group. Measurement of intramedullary new bone formation and determination of alkaline phosphatase activity within the bone marrow were performed. Argylophilic nuclear organizer region (AgNOR) staining was done to evaluate the change in proliferative activity of the osteoblasts during electrical stimulation. In the direct current stimulation group and the PEMF accompanied by the insertion of the Kirshner wire group, alkaline phosphatase activity in the bone marrow and AgNOR staining increased at 7 days after surgery. At 14 days after surgery, alkaline phosphatase activity and proliferative activity of osteoblast were significantly higher in these two groups than in the other groups (PEMF group, Kirshner wire insertion alone group, intramedullary drilling group). Intramedullary new bone formation was most active in the direct current stimulation group. Electromagnetic stimulation of the inserted Kirshner wire also promoted bone formation significantly. The Kirshner wire insertion alone group and the intramedullary drilling group showed bone formation, but it was significantly less. Electromagnetic stimulation without the insertion of the Kirshner wire showed little bone formation. These findings revealed that the degree of osteogenesis induced by electrical stimulation is influenced by the tissue environment, and that osteogenesis is promoted markedly when electrical stimulation is provided in the environment of inflammation and reactive cells.

Alkaline Phosphatase↗

PubMed1983

Strengthening of human quadriceps muscles by cutaneous electrical stimulation.

The effectiveness of cutaneous electrical stimulation as a muscle-strengthening technique was evaluated by comparison with an isometric regime. Sixteen normal healthy subjects were randomly assigned to either an electrical group or an isometric group. A pretest was given of maximum voluntary force in the quadriceps (extensor) muscles, measured with a cable tensiometer. Subjects then trained (isometrically or by electrical stimulation) four days per week for three weeks. Training by electrical stimulation was via a square-wave pulse (75 Hz and 0.1 ms) with the voltage determined by subject tolerance for ten, 10-sec induced contractions (with 50-sec rest intervals). Isometric training consisted of ten, 10-sec maximal contractions (with 50-sec rest intervals) at each session. Feedback of the generated force was standardised for both groups. Post-training measures were then administered using the same protocol as the pretest. Both groups demonstrated a marked improvement in quadriceps strength of 22 +/- 5.3% for the electrical group and 25 +/- 6.9% increase for the isometric group (p less than 0.02). The change in strength was apparently not dependent on the magnitude of the stimulating voltage (5-10 V) nor on the tension induced. There was no significant difference in the strength gains achieved by the two regimes (p greater than 0.05). No pain, muscle lesions or other ill effects were observed with electrical stimulation. We conclude that cutaneous electrical stimulation is a viable strengthening technique. There are obvious practical applications of this technique to the rehabilitation of patients who are not able to maintain an effective voluntary contraction.

Adult↗

PubMed1980

Release of autonomic neuromediators by local ventricular electrical stimulation.

Trains of electrical stimuli were applied to the ventricular epicardium in pentobarbital-anesthetized dogs. The trains, delivered during the absolute refractory period via Walton-Brodie strain gauge arches, resulted in a highly localized potentiation of ventricular contractile force. The magnitude of the potentiation was directly related to the intensity of the trains. The positive inotropic response of either ventricle to trains of stimuli was abolished following chronic cardiac denervation or beta-adrenergic blockade with tolamolol, indicating that the response was probably mediated by the excitation of local sympathetic nerve fibers. Following the elimination of adrenergic influences, a slight negative inotropic response to trains of stimuli was observed in some animals. Administration of atropine blocked the negative inotropic response. When the adrenergic system was intact the administration of atropine resulted in a significant augmentation of the positive inotropic response of both ventricles to trains of stimuli. Thus in addition to norepinephrine release, it also appeared that electrical stimulation of the ventricles resulted in activation of local parasympathetic fibers with subsequent release of acetylcholine.

Animals↗

PubMed1984

Effects of electrical stimulation of the nucleus tractus solitarius on self-stimulation behavior.

The electrical stimulation of the nucleus tractus solitarius (NTS) produced profound suppression of self-stimulation (ICSS) in cats. This effect depended on the sequence and side of NTS stimulation, as well as on the stimulus parameters and locus of self-stimulation. The suppressive effect of NTS stimulation on ICSS was not abolished by ipsilateral vagotomy, thus the vagal bradycardia probably is not involved in the suppression of ICSS.

Animals↗

PubMed1994

Study on the elbow movement produced by functional electrical stimulation (FES).

Functional electrical stimulation (FES)-induced movements of the upper extremity using the electromyography (EMG)-based stimulation data, which were created on the basis of EMG analysis of elbow flexion and extension in a normal human subject, were examined. As a result of the FES to the elbow flexors and extensors in another normal subject, smooth and reproducible elbow flexion and extension were controlled. This result seems to indicate not only an advantage of EMG-based stimulation data in the FES but also a great potential of FES as a new technique for the functional anatomy of the human extremities.

Elbow Joint↗

PubMed2006

Systematic review: applications and future of gastric electrical stimulation.

BACKGROUND: Over the past 20 years, gastric electrical stimulation has received increasing attention among researchers and clinicians. AIM: To give a systematic review on the effects, mechanisms and applications of gastric electrical stimulation. METHODS: Medline was used to identify the articles to be included in this review. Key words used for the search included gastric electrical stimulation, gastric pacing, electrical stimulation, stomach, gastrointestinal motility, central nervous system, gastroparesis, nausea and vomiting; obesity and weight loss. Combinational uses of these keywords were made to identify relevant articles. Most of the articles included in this review ranged from 1985 to 2006. RESULTS: Based on the general search, the review was structured as follows: (i) peripheral and central effects and mechanisms of gastric electrical stimulation; (ii) clinical applications of gastric electrical stimulation for gastroparesis and obesity and (iii) future development of gastric electrical stimulation. CONCLUSIONS: Great progress has been made during the past decades. Gastric electrical stimulation has been shown to be effective in normalizing gastric dysrhythmia, accelerating gastric emptying and improving nausea and vomiting. Implantable device has been made available for treating gastroparesis as well as obesity. However, development of a new device and controlled clinical studies are required to further prove clinical efficacy of gastric electrical stimulation.

Animals↗

PubMed1982

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↗

PubMed1994

Electrical stimulation and language.

Electrical stimulation has been used for over half a century in clinical settings to facilitate the surgical treatment of patients with intractable seizures and cortical structural lesions. It should be employed as the final result of a stepwise process in patient management but, when called for, can be very accurate in localizing critical functional areas. We discuss the use of this technique in patient evaluation, with an emphasis on the evaluation of patients with seizure disorders.

Cerebral Cortex↗

PubMed1977

Heroin detoxification with acupuncture and electrical stimulation.

Acupuncture with electrical stimulation is a feasible nonchemical method for detoxification of heroin addicts, with particular limitations as regards to heavy users. Short-term follow-up seems to indicate reversion to heroin is comparable to other detoxification methods. It could be of great interest to study the effect of easily available postdetoxification maintenance acupuncture as an alternative to heroin. Withdrawal symptoms are relieved in a hierarchial manner with apparent parasympathetically mediated symptoms subsiding first, and frequently with incomplete resolution of bone and joint pain.

Acupuncture Therapy↗

PubMed1982

Anal sphincter responses after perianal electrical stimulation.

By perianal electrical stimulation and EMG recording from the external anal sphincter three responses were found with latencies of 2-8, 13-18 and 30-60 ms, respectively. The two first responses were recorded in most cases. They were characterised by constant latency and uniform pattern, were not fatigued by repeated stimulation, were most dependent on placement of stimulating and recording electrodes, and always had a higher threshold than the third response. The third response was constantly present in normal subjects. It had the longest EMG response and the latency decreased with increasing stimulation to a minimum of 30-60 ms. This response represented the clinical observable spinal reflex, "the classical anal reflex". The latencies of the two first responses were so short that they probably do not represent spinal reflexes. This was further supported by the effect of epidural anaesthesia which left the first responses unaffected but abolished the classical anal reflex. The origin of the two first responses is discussed and models involving antidromal impulse propagation in the efferent fibre as the afferent limbs of the responses are proposed.

Anal Canal↗

PubMed1977

Management of acute traumatic pain by peripheral transcutaneous electrical stimulation.

Peripheral transcutaneous electrical stimulation has been used in an attempt to relieve the pain associated with fractured ribs. Sixty-two per cent of the patients considered their pain to be greatly relieved by this electro-analgesic technique and a further 28% gained some relief. Pain was assessed by means of a visual analogue scale. In most of the patients there was a clinical improvement in their condition, the degree of which correlated well with the pain relief. This trial indicated that transcutaneous electro-analgesia is a useful technique for producing analgesia in patients suffering from acute trauma, without some of the side-effects inherent in more conventional forms of therapy.

Acute Disease↗

PubMed1976

[Structural-functional changes in the synaptic membranes of the cerebral cortex of rats during electric stimulation in vitro].

Electric stimulation (EC) of a suspension of native synaptic membranes of rat brain cortex in the Krebs-Ringer-glucose medium revealed Ca-dependent inhibition of Na+, K+-ATPase and inhibition of transport Ca-activated, Mg-dependent ATPase. The effects observed are not induced by a change in the SH-groups of the membrane proteins and are removed by an addition of total lipids of the brain (membrane protein: lipid = 5:1) or 0.35 mM novocaine. Cyclic 3',5'-AMP in concentrations of 0.1--1.0 mM causes an inhibition (up to 50%) of Na+, K+-ATPase of native synaptic membranes. The Na+, K+-ATPase activity of purified membrane preparations is not changed either by the cyclic nucleotide, or by EC. It is assumed that depolarization of excitable membranes results in structural changes, mediated by the activation of protein kinase, and manifesting themselves as labilization of protein-lipid ratios.

Adenosine Triphosphatases↗

PubMed1998

Evaluation of patterned stimulation for use in surface functional electrical stimulation systems.

The rapid onset of muscle fatigue is one of the major limiting factors when using electrical stimulation to restore functional movement in individuals with a neurological deficit. It has been proposed that muscle efficiency can be improved by using variable frequency pulse trains (VFT), consisting of repeated doublets, rather than a constant frequency train (CFT) of stimulating impulses. The aim of this study was to test this hypothesis. Experiments were conducted on fifteen non-impaired and one spinal cord injured subjects. It was shown that a VFT delivering the same electrical energy with a CFT produces a relative increase in muscle output, attaining a maximum for VFTs composed of doublets with an inter-pulse interval of 5 ms. It was also shown that this effect is highly dependent on the experimental conditions and especially the intensity of applied stimulation and this effect diminishes at high intensity levels. We suggest that any improvement in muscle output observed when using a VFT can be attributed to changes in motor unit recruitment and is not an intrinsic property of the muscle. Our results show that there is practically no benefit in using VFTs for alleviating the problem of fatigue in functional electrical stimulation systems.

Adult↗