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PubMed1975

Head-turning induced by electrical stimulation of the caudate nucleus and its antagonism by anti-parkinson drugs.

Intermittent high-frequency electrical stimulation of the caudate nucleus induces contralateralhead-turning in rats. The anti-Parkinson drugs, L-dopa, amantadine and apomorphine, raise the threshold for or completely inhibit head-turning. There was a high correlation between the predicted clinical potency and these drugs based on inhibition of head-turning and their respective clinical anti-Parkinson potency. The centrally acting anticholinergic drugs also antagonized head-turning but there was not a good correlation between the predicted and acutal anti-Parkinson doses used in man. In order to determine if these drugs blocked head-turning by acting on the caudate nucleus, a combination cannula and stimulating electrode was used to administer drugs directly into the same area of the caudate nucleus being stimulated electrically. Dopamine, amantadine and apomorphine each antagonized head-turning when infused into the same site, at doses which did not produce concurrent overt sterotyped behavior. Time- and dose-response data with all three drugs suggest a direct inhibitory action on the caudate nucleus consistent with their proposed mechanism for treatment of Parkinson symptomatology. Head-turning appears to be a useful animal model for the development of new, specific anti-Parkinson drugs and for the study of possible mechanism(s) of action of existing drugs.

Amantadine↗
PubMedDate not supplied

Pain-related factors contributing to muscle inhibition in patients with chronic low back pain: an experimental investigation based on superimposed electrical stimulation.

OBJECTIVE: To evaluate muscle strength, as a component of physical deconditioning, and central activation ratio, representing the performance level during testing, in patients with chronic low back pain as compared to healthy controls, and to evaluate the contribution of cognitive-behavioral and pain-related factors to the central activation ration of patients with chronic low back pain. METHODS: Twenty-five patients with chronic low back pain and 25 age and gender-matched controls participated. Muscle strength, that is, peak torque of the quadriceps muscle, was measured on a Cybex dynamometer. During peak torque, the quadriceps muscle was percutaneously stimulated using superimposed electrical stimulation, generating an additional twitch torque in case of submaximal performance. The central activation ratio was calculated as peak torque/(peak torque + additional twitch torque). To evaluate cognitive-behavioral and pain-related factors influencing the central activation ratio, measures of fear of injury, pain catastrophizing, psychologic distress, and pain intensity were used. Differences between groups were tested using either T tests or Mann-Whitney U tests. Associations were tested by partial correlation coefficients controlling for gender. RESULTS: The male:female ratio was 15:10. Mean age and chronic low back pain duration were 42.7 (+/-9.5) and 9.9 (+/-8.3) years, respectively. Mean muscle torque (per kg lean body mass) in patients (1.95 Nm/kg +/-0.8) was less than in controls (3.16 Nm/kg +/-0.7) (P < 0.01). Median central activation ratio was lower in patients (P < 0.05). Patients experiencing increased psychologic distress and patients with a higher current pain level showed a lower central activation ratio (P < 0.05). CONCLUSIONS: When interpreting decreased muscle strength in terms of physical deconditioning in patients with chronic low back pain, submaximal performance has to be taken into account. The results suggest that patients with chronic low back pain who report increased psychologic distress and a higher level of current pain tend to show increased inhibition of muscle activity, leading to submaximal performance.

Adolescent↗
PubMed1981

Microscopical observations on electrically stimulated bovine muscle.

The application of electrical stimulation to beef carcasses is known to limit the adverse effects of rapid chilling during the pre-rigor period. Structural changes have been observed in the fibres of longissimus dorsi following electrical stimulation and storage at 15 degrees for about 24 h post mortem. The changes were not observed in the samples of semitendinosus muscle which were examined, although this may indicate a limitation in the sampling procedure. Iron haematoxylin densely stains bands of protein which can be observed by light microscopy. In the electron microscope these bands were seen to be zones of severe contraction. Fragmentation of the myofibrils also occurs.

Animals↗
PubMed2006

The effect of surface electrical stimulation on hyolaryngeal movement in normal individuals at rest and during swallowing.

Surface electrical stimulation is currently used in therapy for swallowing problems, although little is known about its physiological effects on neck muscles or swallowing. Previously, when one surface electrode placement was used in dysphagic patients at rest, it lowered the hyolaryngeal complex. Here we examined the effects of nine other placements in normal volunteers to determine 1) whether movements induced by surface stimulation using other placements differ, and 2) whether lowering the hyolaryngeal complex by surface electrical stimulation interfered with swallowing in healthy adults. Ten bipolar surface electrode placements overlying the submental and laryngeal regions were tested. Maximum tolerated stimulation levels were applied at rest while participants held their mouths closed. Videofluoroscopic recordings were used to measure hyoid bone and subglottic air column (laryngeal) movements from resting position and while swallowing 5 ml of liquid barium, with and without stimulation. Videofluoroscopic recordings of swallows were rated blind to condition using the National Institutes of Health-Swallowing Safety Scale. Significant (P < 0.0001) laryngeal and hyoid descent occurred with stimulation at rest. During swallowing, significant (P <or= 0.01) reductions in both the larynx and hyoid bone peak elevation occurred during stimulated swallows. The stimulated swallows were also judged less safe than nonstimulated swallows using the National Institutes of Health-Swallowing Safety Scale (P = 0.0275). Because surface electrical stimulation reduced hyolaryngeal elevation during swallowing in normal volunteers, our findings suggest that surface electrical stimulation will reduce elevation during swallowing therapy for dysphagia.

Adult↗
PubMed1995

Growth effects of electrically stimulated contraction on adult feline cardiocytes in primary culture.

The purpose of this study was to determine effects of long-term electrical stimulation of cardiocyte contraction on protein synthesis rates and total protein content. Adult feline cardiocytes were plated on laminin-coated culture trays and maintained in a serum-free medium consisting of M199 supplemented with ascorbate, bovine serum albumin, creatine, carnitine, taurine, and 10(-7) M recombinant insulin. Cardiocytes were electrically stimulated to contract with use of continuous electrical pulses of alternating polarity at a frequency of 1 Hz and pulse duration of 5 ms. Nonstimulated cardiocytes are normally quiescent and were used as the control group. In control quiescent cardiocytes, protein synthesis rate decreased by 14% between days 1 and 4 in culture and then remained stable through day 7. In electrically stimulated cardiocytes, protein synthesis rates increased by 19% between days 1 and 7. Protein synthesis rates were 18% higher on day 4 and 43% higher on day 7 in electrically stimulated than in quiescent cardiocytes. Protein content per cell was determined by measuring total fluorescence per cell by use of confocal microscopy of fluorescein isothiocyanate-stained cells. Electrical stimulation significantly increased cellular protein content by 52% after 7 days compared with controls. Quiescent and electrically stimulated cardiocytes remained rod shaped, retained their myofibrillar architecture, and were responsive to electrical stimulation over the 7-day period. These data demonstrated that electrically stimulated contraction of adult cardiocytes resulted in cell growth, as assessed by an increase in protein content per cell over 7 days in culture. This increase was due, at least in part, to an acceleration of steady-state protein synthesis rates.

Animals↗
PubMed2004

Effects of vitamin E and electrical stimulation on the denervated rat gastrocnemius muscle malondialdehyde and glutathione levels.

Effects of vitamin E treatment and local electrical stimulation on progression of atrophy in the denervated rat gastrocnemius muscle were studied. Denervation was performed by right leg sciatic nerve axotomy. Electrical stimulation (3-10 mA ms(-1), 10 min per day for 7 days) was applied to the right gastrocnemius muscle starting from day 1 of denervation. The muscle samples were assayed for malondialdehyde (MDA) and glutathione levels, as well as the histological appearance after 8 days of denervation. MDA levels were markedly increased following denervation. However, electrical stimulation, vitamin E treatment (30 mg kg(-1), i.m., everyday for 7 days), and combination of electrical stimulation and vitamin E treatment markedly reduced MDA levels. Glutathione levels were significantly decreased in the denervation group. Electrical stimulation, vitamin E treatment, and electrical stimulation plus vitamin E treatment prevented these reductions in glutathione levels. In the vitamin E treatment group, glutathione levels were markedly higher than in the control group. These results indicate that electrical stimulation and vitamin E treatment alone, or in combination, were able to prevent the effects of denervation on muscle atrophy.

Analysis of Variance↗
PubMed1981

Inhibitory actions produced by local electrical stimulation in the caudal spinal trigeminal nucleus in rat.

Inhibitory actions induced by local electrical stimulation (LES) on the tooth pulpal afferent activities were investigated in the caudal part of the rat spinal trigeminal nucleus. For the LES, ipsilateral Yin-Hsiang (intrasegmental point) or Ho-Ku (extrasegmental point) was used as a cathodal point which was stimulated electrically by a single pulse of 0.1 msec in duration or by 0.1 msec-pulse train at 45 Hz for 15 min. We found at least three types of inhibitions in the caudal trigeminal nucleus: Type I--this inhibition is the most forceful, caused by naloxone-reversible endogenous opiate system with a slow onset and prolonged aftereffect. This inhibition is presumably postsynaptic action. Type II--this is evoked by postsynaptical acting inhibition and begins within milliseconds after the stimulus is applied. Type III--this inhibition is elicited by presynaptic action and also begins within milliseconds after the onset of the stimulation. Type I and II inhibitions are evoked by stimulating either intra- or extrasegmental LES points, however, Type III is produced by stimulation of intrasegmental and rarely provoked by extrasegmental point stimulation. Naloxone failed to reverse Type II and III inhibitions. During LES, Type I to III inhibitions co-work for producing the suppressive effect and after the cessation of its stimulation, only Type I inhibition produces the so-called aftereffect of the LES.

Afferent Pathways↗
PubMed1998

Electrical stimulation therapy in the treatment of cigarette smoking.

In this study electrical stimulation therapy (EST) is explored as a possible new treatment for smoking cessation within a randomized controlled trial. The investigation follows reports of several authors that electrical stimulation applied to specific acupuncture points is effective in treating a variety of drug dependencies, including cigarette smoking. Three key features of treatment (electrical stimulation, frequency modulation, and electrode placement), were investigated in a 2 x 2 x 2 factorial design, resulting in eight treatment combinations. Out of 265 smokers recruited into the trial 216 completed the one-week treatment. Outcome was assessed in terms of complete abstinence from smoking and symptomatic relief of withdrawal symptoms. Smokers receiving active electrical stimulation obtained higher abstinence rates than those in the inactive groups although the difference did not achieve statistical significance (all active vs. all placebo groups: lambda 1,1(2) = 0.50, p > 0.10, 95% confidence interval = -8.04 to +17.44%; most effective vs. least effective group: lambda 1,1(2) = 3.11, p = 0.08, CI0.95 = -2.2 to +48.8%). The efficacy of electrical stimulation therapy for smoking is not supported.

Acupuncture Points↗
PubMed2005

Electrical stimulation superimposed onto voluntary muscular contraction.

Electrical stimulation (ES) reverses the order of recruitment of motor units (MU) observed with voluntary muscular contraction (VOL) since under ES, large MU are recruited before small MU. The superimposition of ES onto VOL (superimposed technique: application of an electrical stimulus during a voluntary muscle action) can theoretically activate more motor units than VOL performed alone, which can engender an increase of the contraction force. Two superimposed techniques can be used: (i) the twitch interpolation technique (ITT), which consists of interjecting an electrical stimulus onto the muscle nerve; and (ii) the percutaneous superimposed electrical stimulation technique (PST), where the stimulation is applied to the muscle belly. These two superimposed techniques can be used to evaluate the ability to fully activate a muscle. They can thus be employed to distinguish the central or peripheral nature of fatigue after exhausting exercise. In general, whatever the technique employed, the superimposition of ES onto volitional exercise does not recruit more MU than VOL, except with eccentric actions. Nevertheless, the neuromuscular response associated with the use of the superimposed technique (ITT and PST) depends on the parameter of the superimposed current. The sex and the training level of the subjects can also modify the physiological impact of the superimposed technique. Although the motor control differs drastically between training with ES and VOL, the integration of the superimposed technique in training programmes with healthy subjects does not reveal significant benefits compared with programmes performed only with voluntary exercises. Nevertheless, in a therapeutic context, training programmes using ES superimposition compensate volume and muscle strength deficit with more efficiency than programmes using VOL or ES separately.

Adaptation, Physiological↗
PubMed1985

Electrical stimulation of the brain in treatment of chronic pain. Experience over 5 years.

Forty-eight patients underwent electrical stimulation of the brain for treatment of chronic pain between 1978 and 1983. Average pain duration prior to treatment was 4.5 years. Before selection for this procedure patients underwent pain treatment in a multidisciplinary pain center, intensive psychological and psychiatric evaluation, and assessment of pain responsiveness to intravenous administration of placebo, morphine, and naloxone. A total of 71 electrodes were placed in the 48 patients at a variety of stimulating targets, including the periaqueductal gray matter, periventricular gray matter, thalamus, and internal capsule. Seventy-two percent of patients experienced complete or partial pain relief. In addition, 59% of patients were able to discontinue narcotic usage. Twenty-five percent of patients returned to normal physical activities and another 33% showed marked improvement in functional capacity. Follow-up periods ranged from 2 to 60 months; with a mean follow-up period of 20 months. A variety of relatively minor complications occurred, but no mortality or permanent sequelae were experienced. No patient's pain was made worse as a result of electrical stimulation. Electrical stimulation of the brain offers a safe and relatively effective method for the treatment of chronic pain in appropriately selected patients, who are unresponsive to other forms of therapy.

Adult↗
PubMed1992

Stapedius reflexes to electrical stimulation in the rabbit for the assessment of hearing.

The possibility of using electrically induced stapedius reflexes as a means of objective hearing evaluation was investigated in the rabbit as an animal model. The contralateral stapedius reflex to acoustic and electrical stimulation was measured in anesthetized rabbits. For electrical stimulation, the middle ear was opened surgically and stimulation was applied by a monopolar electrode placed at or into the round window. Contraction of the middle ear muscle was monitored by digital sampling and averaging of the impedance changes in the contralateral ear. Acoustically evoked reflexes were recorded within expected limits despite anesthesia. The level of the electrical stimulus was raised until mass reflexes of the neck muscles were observed. A contralateral stapedius reflex to electrical stimulation could not be demonstrated. In our experiment, monopolar electrical stimulation at the round window could not elicit contralateral stapedius reflexes.

Acoustic Stimulation↗
PubMed2000

Functional electrical stimulation equipment: a review of marketplace availability and reimbursement.

Functional electrical stimulation (FES) is a rehabilitation tool that has broad application in disability management for improving consumer health and independence. This review examines the availability and delivery of electrical stimulation equipment in a managed care environment, focusing particularly on recent advances and marketplace influences. New electrical stimulation products that are unique in their ability to improve function after disease or injury over conventional drug therapy, surgical intervention, or other rehabilitation techniques are described. Research directions, including new uses for existing products to expand patient indications, are discussed. Guidelines to assist providers and developers of FES technology with managing the reimbursement process are provided. The successful introduction of recent FES products should pave the way for even more exciting developments. However, reimbursement requires careful and early planning to ensure that FES technologies are available to people who may benefit from them.

Electric Stimulation↗
PubMed1989

Modified impulse diminishes discomfort of transcranial electrical stimulation of the motor cortex.

Transcranial electrical stimulation of the motor cortex has been developed in 1980 for electrophysiological assessment of the descending pathways. However, the widespread use of this procedure is limited by its painfulness due to simultaneous excitation of the sensory receptors and muscles of the scalp, especially if higher stimulus strengths are necessary in patients with motor deficits to evoke electromyographic responses. The present invention concerns a device which allows modification of the impulse delivered by a commercially available motor stimulator. By interruption on the exponentially decreasing impulse, "cutting" it after a freely selectable time by a low resistant short circuit on the patient's side, discomfort due to excitation of the sensory receptors and muscles of the scalp can be diminished with identical electromyographic responses regarded amplitudes and latencies of the potentials, thus making electrical stimulation less painful. Considering the applied charges we found a marked reduction of charge per phase using the modified impulse as compared to the original one with the difference increasing linearily depended on the preselected voltage.

Electric Stimulation↗
PubMed1997

Maximal functional electrical stimulation in routine practice.

Maximal functional electrical stimulation is now an established treatment for urgency and urge incontinence. Many studies have been presented with good and consistent results. In a number of prospective studies we have previously recorded very favourable effects in stress incontinence and urge incontinence. In the present study, we have compared our previous experience with a retrospective analysis of a series of maximal functional electrical stimulation given according to a simple routine protocol and including 84 patients. The overall subjective improvement rate was 54% but the cure rate was only 5%, which is far below our experience in previous studies, as well as in others. The subjective outcome was in agreement with changes in mictrurition variables as recorded in voiding diaries. The discrepancy probably depends on a number of factors. It is suggested that the most crucial ones are patient selection, the intensity of stimulation, and the number of sessions given. It is important to realize the limitations and pitfalls of the technique when it is applied in routine practice.

Adult↗
PubMed2003

Functional electrical stimulation and rehabilitation--an hypothesis.

Functional Electrical Stimulation (FES), used to mimic a weak or paralysed movement, sometimes is followed by a specific recovery of voluntary power in that movement. The mechanism by which this occurs is unclear, and the presumption has often been that FES may somehow promote adaptive changes in cortical connectivity. However, the unique feature of electrical stimulation is that it activates nerve fibres both orthodromically and antidromically. The antidromic impulse in motor nerve fibres will reach the anterior horn cell, but it can go no further up the neuraxis. If the corticospinal-anterior horn cell synapse is a Hebb-type modifiable synapse (i.e. one that is strengthened by the coincidence of presynaptic and postsynaptic activity), then FES, combined with coincident voluntary effort through a damaged pyramidal motor system, could help to promote restorative synaptic modifications at anterior horn cell level, by this unique adaptive mechanism.

Adaptation, Biological↗
PubMed1994

Changes in the cat cochlear nucleus following neonatal deafening and chronic intracochlear electrical stimulation.

The effects of chronic intracochlear electrical stimulation on the cochlear nucleus (CN) were studied in eight cats that were neonatally deafened by daily intramuscular injections of neomycin. Profound hearing loss was confirmed in each animal by auditory brainstem response (ABR) and frequency following response (500 Hz) testing. Five of the kittens were implanted unilaterally with a scala tympani electrode array at ages 8-16 weeks. These kittens were stimulated daily for four hours at 2 dB above the evoked ABR threshold, over a period of three months, and subsequently euthanized for histological analysis at 26-32 weeks of age. The three remaining deaf kittens were maintained without stimulation over prolonged periods in order to study the long-term consequences of neonatal deafening, and were euthanized at 66-133 weeks of age. This study compares the CN of these deafened experimental animals and the CN of normal adult cats. Three experimental parameters were examined: CN volume, cross-sectional area of spherical cells in the rostral anteroventral cochlear nucleus (AVCN), and spherical cell density in this same region. The CN in animals that received electrical stimulation showed significant bilateral degenerative changes in all three measured parameters. Total nuclear volume was reduced by 35-36%, spherical cell size was reduced by 20-26%, and spherical cell density decreased by 36-42%, as compared to the normal cat CN. Comparisons were also made in the stimulated animals between CN ipsilateral to the stimulated cochlea and the contralateral, unstimulated CN.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1998

Effects of an abdominal binder and electrical stimulation on cough in patients with spinal cord injury.

We explored the effect of an abdominal binder, with or without electrical stimulation, on peak expiratory flow rate (PEFR) in 12 paraplegics with complete thoracic cord (T2-T12) injury (mean age 36.0 +/- 1.5 yr) and 12 quadriplegics with complete cervical cord (C4-C8) injury (mean age 36.2 +/- 1.9 yr). The cough was assessed by measuring the PEFR during forceful expiration in a sitting position. The subjects underwent the following experimental maneuvers in a random order with a 10-minute interval between any two maneuvers: 1) voluntary coughing, 2) voluntary coughing with an abdominal binder, and 3) voluntary coughing with an abdominal binder and electrical stimulation. The electrical stimulator (50 Hz with 300 microseconds pulse width) was applied to the abdominal wall. Data were analyzed using multivariate analysis of variance for repeated measures. The abdominal binder did not significantly increase PEFR in either paraplegics or quadriplegics; the abdominal binder combined with electrical stimulation significantly increased PEFR by 15% in the paraplegics and 18% in the quadriplegics. These results indicate that electrical stimulation combined with an abdominal binder improves the cough ability in patients with cervical or thoracic spinal cord injury.

Abdominal Muscles↗