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PubMed1995

Inhibition of withdrawal responses by pelvic nerve electrical stimulation.

In urethane-anesthetized rats, the compound action potential of the pelvic nerve was found to consist of three different waves, two in the A delta fiber and one in the C-fiber range of conduction velocity. Electrical stimulation of the pelvic nerve produced a complete inhibition of the withdrawal response to noxious foot pinch or foot compression. The electromyographic (EMG) activity of the contralateral posterior biceps muscle was used to record the withdrawal response. The withdrawal response inhibition was related to the duration and the frequency of electrical stimulation. Low (5-10 Hz) and high (100-300 Hz) frequencies were ineffective in inhibiting the withdrawal response, whereas intermediate frequencies (20-80 Hz) produced a complete inhibition of the withdrawal response. Short (300 ms) trains of stimulation inhibited the withdrawal response only during the stimulation period. Longer trains of stimulation (500 ms-10 s) produced long-lasting inhibition of the response to noxious stimulation. The inhibition persisted for up to 20 s after the end of electrical stimulation of the pelvic nerve. A delta fiber stimulation was adequate to inhibit the withdrawal response in most (15 out of 17) of the animals. However, A delta plus C-fiber stimulation was needed to inhibit the response to noxious stimulation in two animals. In addition to inhibiting the response to noxious stimulation, pelvic nerve electrical stimulation reflexively activated abdominal muscles. On the basis of present findings using electrical stimulation, it can be suggested that, in the rat, A delta and C-visceral afferents of the pelvic nerve mediate the analgesic effect of vaginocervical probing pelvic and A delta afferents the contraction of abdominal muscles in the fetus-expulsion reflex.

Abdominal Muscles↗

PubMed2002

Force enhancement following muscle stretch of electrically stimulated and voluntarily activated human adductor pollicis.

For electrically stimulated muscles, it has been observed that maximal muscle force during and after stretch is substantially greater than the corresponding isometric force. However, this observation has not been made for human voluntary contractions. We investigated the effects of active muscle stretch on muscle force production for in vivo human adductor pollicis (n = 12) during maximal voluntary contractions and electrically induced contractions. Peak forces during stretch, steady-state isometric forces following stretch, and passive forces following muscle deactivation were compared to the corresponding isometric forces obtained at optimal muscle length. Contractions with different stretch magnitudes (10, 20, and 30 deg at a constant speed of 10 deg s(-1)) and different speeds (10, 20, and 60 deg s(-1) over a range of 30 deg) were performed in triplicate in a random order, balanced design. We found three novel results: (i) there was steady-state force enhancement following stretch in voluntarily contracted muscles; (ii) some force enhancement persisted following relaxation of the muscle and (iii) force enhancement, for some stretch conditions, exceeded the maximum isometric force at optimal muscle length. We conclude from these results that voluntary muscle contraction produces similar force enhancement to that observed in the past with electrically stimulated preparations. Therefore, steady-state force enhancement may play a role in everyday movements. Furthermore, these results suggest that non-uniformities in sarcomere length do not, at least not exclusively, account for the force enhancement following active muscle stretch, and that the stretch magnitude-dependent passive force enhancement observed here may be responsible for the enhancement of force above the isometric reference force at optimal muscle length.

Adult↗

PubMed1989

Osteonecrosis of the femoral head. Results of core decompression and grafting with and without electrical stimulation.

The effectiveness of core decompression and bone grafting with and without electrical stimulation was investigated in patients with avascular necrosis (AVN) of the femoral head. One hundred sixteen hips with AVN had decompression and grafting; 74 were also treated with direct current (DC). The DC stimulation was via a coil inserted directly into the femoral head. These were compared to 55 hips with AVN treated nonoperatively. Hips treated with electrical stimulation showed less roentgenographic progression and achieved a better clinical score than hips treated with decompression and grafting alone. Both groups had a significantly lower incidence of arthroplasty than the nonoperated controls. One patient developed a pulmonary embolus, but there were no fractures or other complications. Decompression and grafting are safe and reasonably effective in retarding the progression of AVN. Supplemental electrical stimulation seems to improve the results even further.

Arthroplasty↗

PubMed1982

Response of isolated rat iris dilator to adrenergic and cholinergic agents and electrical stimulation.

Responses of isolated rat iris dilator to some agents and to electrical stimulation were examined. Norepinephrine and epinephrine produced contraction, which was antagonized by 0.03 microM phentolamine. Acetylcholine produced relaxation at low concentrations (1 nM - 1 microM) as great as 80% of the resting tone while contraction at high concentrations (greater than or equal to 1 microM). Both responses were suppressed by 0.02 microM atropine and enhanced by 0.03 microM physostigmine. Electrical stimulation at low voltage or low frequency (up to 10 Hz) elicited relaxation while stimulation at high voltage or high frequency (30 Hz) produced contraction. Stimulation with intermediate strength elicited biphasic response. The contraction and relaxation induced by electrical stimulation were abolished by 3 microM phentolamine or by 0.05 microM atropine, respectively. Both phases were abolished by tetrodotoxin (0.3 microM). It is suggested that in the rat the cholinergic relaxation of the dilator may assist the cholinergic contraction of the sphincter (1). The pronounced cholinergic relaxation of nonvascular tissue is to be noted.

Acetylcholine↗

PubMed1994

Tinnitus suppression by electrical stimulation of the cochlear wall and by cochlear implantation.

Some recent studies have reported on tinnitus suppression by electrical stimulation of the cochlear wall and by cochlear implant. In the present study, the degree of tinnitus in cochlear implant candidates was determined and the effects of promontory stimulation and cochlear implantation on tinnitus were investigated. Of the cochlear implant candidates, all of whom were either severely hearing impaired or totally deaf, 87% experienced tinnitus. When electrical stimulation was applied to the cochlear wall (promontory stimulation test), tinnitus was abolished in 23% and improved in 46% of the patients. Thus, electrical stimulation of the cochlear wall effectively suppressed tinnitus in 69% of the patients. Following cochlear implantation, tinnitus was abolished in 35% and decreased in 42%. Thus, intracochlear electrical stimulation was effective for treatment of tinnitus in 77% of the patients. The suppression of tinnitus continued for several hours after the patients switched off the implant device. In 60% of the patients whose tinnitus was suppressed or abolished after the cochlear implant surgery, tinnitus was also suppressed in the contralateral ear.

Cochlea↗

PubMed1969

Incorporation of [32P]orthophosphate into brain-slice phospholipids and their precursors. Effects of electrical stimulation.

1. The incorporation of [(32)P]phosphate into phospholipids was measured in slices cut from the pial surface of guinea-pig cerebral cortex; incorporation into the phosphorus of some water-soluble precursors of phospholipid was measured under similar conditions. 2. Slices subjected to overall electrical stimulation at a frequency of 5pulses/sec. differed from control slices in their pattern of phospholipid labelling. After 1hr. of stimulation, incorporation of [(32)P]phosphate into phosphatidylcholine, ethanolamine phospholipid and cardiolipin was respectively 54, 55 and 58% of the control value, and that into phosphatidylinositol was 186% of control. Phosphatidic acid labelling tended to increase with electrical stimulation, but the statistical significance of this change was marginal. Labelling of phosphatidylglycerol and di- and tri-phosphoinositides was not affected significantly by electrical stimulation. 3. Electrical stimulation of the tissue altered the specific radioactivities of water-soluble precursors of phospholipid. 4. The turnover rates of the phosphate groups of phospholipids were estimated approximately from the specific radioactivities of phospholipids and their precursors. Phosphatidylinositol (and its lipid-soluble precursors) showed the largest change in turnover rate in response to electrical stimulation of the tissue; the turnover rates of other lipids were also affected. Changes in the specific radioactivity of phospholipids did not correspond to changes in turnover in these experiments.

Animals↗

PubMed2003

Neonatal deafening causes changes in Fos protein induced by cochlear electrical stimulation.

The influence of neonatal deafness on cochlear electrically evoked Fos expression in the auditory brainstem was examined. Newborn rats were deafened by systemic injection of kanamycin, 1 mg/g daily for 12 days. At 4, 5, 6 or 8 weeks of age, these animals received cochlear electrical stimulation with a basal monopolar electrode for 90 minutes. Age-matched untreated control animals received similar stimulation. Experimental and control animals were assessed for spiral ganglion cell densities and Fos immunoreactive staining in the central nucleus of the inferior colliculus. Spiral ganglion cell assessments showed significant decreases in spiral ganglion cell densities in deafened rats compared to age-matched controls, at 5 weeks of age in lower turns and 6 and 8 weeks in all turns. Cochlear electrical stimulation induced Fos immunoreactive staining in the nucleus of auditory brain stem neurons in treatment and control groups. A significantly greater number of Fos immunoreactive neurons was found in the contralateral central nucleus of inferior colliculus in 5, 6 and 8 week old deafened animals compared to age-matched controls. The increases were larger with a longer duration of deafness. These results suggest that there are changes in auditory processing as a consequence of neonatal deafness.

Age Factors↗

PubMed2002

Microprocessor controlled movement of solid colonic content using sequential neural electrical stimulation.

BACKGROUND AND AIMS: Invoked peristaltic contractions and movement of solid content have not been attempted in normal canine colon. The purpose of this study was to determine if movement of solid content through the colon could be produced by microprocessor controlled sequential stimulation. METHODS: The study was performed on six anaesthetised dogs. At laparotomy, a 15 cm segment of descending colon was selected, the proximal end closed with a purse string suture, and the distal end opened into a collecting container. Four sets of subserosal stimulating electrodes were implanted at 3 cm intervals. The segment of bowel was filled with a mixture of dog food and 50 plastic pellets before each of 2-5 random sessions of non-stimulated or stimulated emptying. Propagated contractions were generated using microprocessor controlled bipolar trains of 50 Hz rectangular voltage having 20 V (peak to peak) amplitude, 18 second stimulus duration, and a nine second phase lag between stimulation trains in sequential electrode sets. RESULTS: Electrical stimulation using the above mentioned parameters resulted in powerful phasic contractions that closed the lumen. By phase locking the stimulation voltage between adjacent sets of electrodes, propagated contractions could be produced in an aboral or orad direction. The number of evacuated pellets during the stimulation sessions was significantly higher than during the non-stimulated sessions (p<0.01). CONCLUSIONS: Microprocessor controlled electrical stimulation accelerated movement of colonic content suggesting the possibility of future implantable colonic stimulators.

Animals↗

PubMed2002

Gastric electrical stimulation in intractable symptomatic gastroparesis.

BACKGROUND: The treatment of gastroparesis remains unsatisfactory despite prokinetic and anti-emetic drugs. Gastric electrical stimulation has been proposed as a therapeutic option. We have assessed the effect of gastric electrical stimulation on symptoms, medical treatment, body weight and gastric emptying in patients with intractable symptomatic gastroparesis in a non-placebo-controlled study. METHODS: In this multicenter study, 38 highly symptomatic patients with drug-refractory gastroparesis were enrolled. Patients first received temporary electrical stimulation using percutaneous electrodes. The 33 responders to temporary stimulation then underwent surgical implantation of a permanent stimulator. Severity of vomiting and nausea was assessed before and after stimulation. Patients were reassessed 3, 6, and 12 months after permanent implantation. RESULTS: With stimulation, 35/38 patients (97%) experienced >80% reduction in vomiting and nausea. This effect persisted throughout the observation period (2.9-15.6 months, 341 patient-months). Gastric emptying did not initially change, but improved in most patients at 12 months. At 1 year, the average weight gain was 5.5% and 9/14 patients initially receiving enteral or parenteral nutrition were able to discontinue it. CONCLUSION: Electrical stimulation of the stomach has an immediate and potent anti-emetic effect. It offers a safe and effective alternative for patients with intractable symptomatic gastroparesis.

Adolescent↗

PubMed2004

Clinical applications of electrical stimulation after spinal cord injury.

During the last one-half century, electrical stimulation has become clinically significant for improving health and restoring useful function after spinal cord injury. Short-term stimulation can be provided by electrodes on the skin or percutaneous fine wires, but implanted systems are preferable for long-term use. Electrical stimulation of intact lower motor neurons can exercise paralyzed muscles and reverse wasting; improve strength, endurance, and cardiovascular fitness; and may reduce the progression of osteoporosis. Other potential therapeutic uses being investigated include reduction of spasticity, prevention of deep vein thrombosis, and improvement of tissue health. Pacing of intact phrenic nerves in high tetraplegia can produce effective respiration without mechanical ventilation, allowing improved speech, increased mobility, and increased sense of well-being. Improvement of cough has also been demonstrated. Stimulation of intact sacral nerves can produce effective micturition and reduce urinary tract infection; it can also improve bowel function and erection. It is usually combined with posterior sacral rhizotomy to improve continence and bladder capacity, and the combination has been shown to reduce costs of care. Electroejaculation can now produce semen in most men with spinal cord injury. Significant achievements have also been made in restoring limb function. Useful hand grasp can be provided in C5 and C6 tetraplegia, reducing dependence on adapted equipment and assistants. Standing, assistance with transfers, and walking for short distances can be provided to selected persons with paraplegia, improving their access to objects, places, and opportunities that are inaccessible from a wheelchair. This review summarizes the current state of therapeutic and neuroprosthetic applications of electrical stimulation after spinal cord injury and identifies some future directions of research and clinical and commercial development.

Electric Stimulation Therapy↗

PubMed1988

Clinical evaluation of computerized functional electrical stimulation after spinal cord injury: a multicenter pilot study.

This study investigated the safety and effects of computerized functional electrical stimulation (FES) on spinal cord injured individuals. Nineteen subjects two to ten years postinjury, with clinically complete motor and sensory lesions between C4 and T10, participated. All subjects met the specific selection criteria. None had received lower extremity electrical stimulation before. In phase I, subjects received surface electrical stimulation to the quadriceps muscle bilaterally for resistive knee extension 3 times a week for four weeks. The resistance and number of completed lifts was recorded daily. In phase II, 36 sessions provided sequential surface electrical stimulation to the quadriceps, hamstrings, and gluteus muscles bilaterally in order for subjects to pedal a lower extremity ergometer with resistance varied depending on completed run time. For each session, heart rate, blood pressure, temperature, and work performance were recorded. Tests done before and after the training program included fasting blood chemistries, 24-hour urinalysis, arm-crank ergometer stress testing, and midthigh girth measurement. Results indicate that this form of FES is safe, that quadriceps strength and endurance is increased, that endurance for ergometer pedaling is increased, and that there may be a training effect as more work is done at a similar heart rate and systolic blood pressure and as muscle bulk is increased. The FES effect on cardiovascular conditioning and general health requires further research to precisely determine its benefits.

Adult↗

PubMed1983

[Characteristics of the response of rabbit visual cortex neurons to intracortical electric stimulation].

Responses of visual cortex neurons to single and rhythmical intracortical electrical stimulation were investigated in rabbits. Stimulating and recording electrodes were separated by 0.7-1.2 mm. Thresholds of responses to single stimuli were in general about 150-180 microA, to serial stimuli -- 30-60 microA. Latency of the first spike was 5-15 ms, but probability of discharge was very low (3-6%). The length of the inhibitory phrase in the response increased in a half of the investigated neurons with the increase in the stimulus strength. Spontaneous activity after a series of stimuli increased during 4-6 s. Repeated single stimuli induced in about a half of the investigated neurons the same types of dynamic modifications in activity, as those produced by light stimulation. However, in response to electrical stimulation more neurons developed discharge sensitization and less habituation. It is supposed that intracortical stimulation induces in the visual cortex excitation of local hypercolumns and inhibition of the neighbouring ones.

Animals↗

PubMed1985

Transcutaneous electrical stimulation for postoperative pain.

A prospective randomised trial was conducted to assess transcutaneous electrical stimulation in the management of postoperative pain and its effect on postoperative pulmonary function and respiratory complications. Consecutive patients undergoing abdominal surgery were allocated to receive transcutaneous electrical stimulation or 'sham' therapy. There was no significant difference in the amount of postoperative pain as measured by linear analogue pain scales or morphine requirements. Arterial oxygen and carbon dioxide tensions were similar in both groups. There was no difference in the incidence of postoperative chest infection. These results do not support the use of transcutaneous electrical stimulation following abdominal surgery.

Adult↗

PubMed1997

Inhibitory effect of mitragynine, an alkaloid with analgesic effect from Thai medicinal plant Mitragyna speciosa, on electrically stimulated contraction of isolated guinea-pig ileum through the opioid receptor.

Effect of mitragynine, an indole alkaloid isolated from Thai medicinal plant kratom (Mitragyna speciosa), on electrically stimulated contraction was studied in the guinea-pig ileum. Mitragynine (1 nM-3 microM) inhibited the ileum contraction elicited by electrical stimulation, and its pD2 value was 6.91 +/- 0.04 (n = 5). Morphine (1 nM-1 microM) also inhibited the electrically stimulated contraction in a concentration-dependent manner (pD2 7.68 +/- 0.11; n = 5). Mitragynine was 10 fold less potent than morphine. Mitragynine (3-10 microM) did not show any effect on the smooth muscle contraction induced by acetylcholine or histamine. Naloxone (10-300 nM) reversed the inhibitory effect of mitragynine on electrically stimulated contraction. Furthermore, naloxone showed a shift of concentration-response curve of mitragynine to the right. There was no significant difference in the affinity of naloxone (i.e. pA2) in the presence of mitragynine or morphine. Mitragynine (3-10 microM) inhibited the naloxone-precipitated withdrawal contraction following a brief (5 min) exposure of the ileum to morphine. Tetrodotoxin (1 microM) and atropine (1 microM) inhibited the withdrawal contraction. The present results suggest that mitragynine inhibits the electrically stimulated contraction of guinea-pig ileum through the opioid receptor.

Acetylcholine↗

PubMed1989

[Electromagnetic stimulation of the nervous system. II. Normal values in the peripheral nervous system and comparison with electrical stimulation methods].

In 15 healthy subjects we stimulated the peripheral nervous system by a brief intense magnetic field and recorded evoked muscle potentials from peripheral muscles. Latencies were compared with those obtained by conventional electrical stimulation techniques. Amplitudes of muscle responses after magnetic stimulation were often smaller than those obtained after electrical stimulation; however, latencies were comparable at all stimulation sites.

Adult↗

PubMed1988

Effects of electrical stimulation of brain reward sites on release of dopamine in rat: an in vivo electrochemical study.

Behavioral studies suggest that mesencephalic dopamine neurons mediate the rewarding effects of electrical stimulation of the medial forebrain bundle. Yet there is little direct evidence that rewarding electrical stimulation actually activates dopamine-containing neurons. The purpose of the present study was to determine, using in vivo electrochemistry, if electrical stimulation applied to lateral hypothalamic or ventral tegmental reward sites would elicit changes in extracellular levels of dopamine. In vivo high speed chronoamperometric recordings were performed in anesthetized rats that had been previously trained to respond for rewarding electrical stimulation of the medial forebrain bundle or ventral tegmental area. We found that a single 500 msec train of pulses elicited a small transient electrochemical signal, the magnitude of which was dependent on the pulse duration and frequency. This signal was potentiated by inhibition of dopamine reuptake. Prolonged electrical activation with a self-stimulation-like regimen resulted in the gradual accumulation of an electroactive compound, tentatively identified as dihydroxyphenylacetic acid (DOPAC). Taken together, the data reported here support the idea that rewarding electrical stimulation causes the release of dopamine.

Animals↗

PubMed1992

GABAB receptor-mediated inhibitory postsynaptic potentials evoked by electrical stimulation and by glutamate stimulation of interneurons in stratum lacunosum-moleculare in hippocampal CA1 pyramidal cells in vitro.

Following micropressure application of glutamate (500 microM) in stratum lacunosum-moleculare (L-M), inhibitory postsynaptic potentials (glut-IPSPs) were recorded in CA1 pyramidal cells. These glut-IPSPs were blocked by tetrodotoxin (1 microM) and, thus, were probably generated by the activation of local interneurons. The effects of pharmacological antagonists on glut-IPSPs and on electrically-evoked early and late IPSPs were assessed in the same cells during the same application of the antagonist. Local application of the GABAB antagonist 2-OH saclofen (1-4 mM) reduced both glut-IPSPs and late IPSPs but not early IPSPs. In contrast, the GABAB antagonist phaclofen (20 mM) reduced late IPSPs but not early IPSPs but not early IPSPs or glut-IPSPs. Early IPSPs were blocked by the GABAA antagonists bicuculline and picrotoxin but late IPSPs and glut-IPSPs were not. Repetitive electrical stimulation depressed early and late IPSPs as well as glut-IPSPs, suggesting that interneurons activated with glutamate were also stimulated electrically. Thus, interneurons in str. lacunosum-moleculare appear to inhibit pyramidal cells via a GABAB receptor-mediated IPSP. The discrepancy in the pharmacological profile of the GABAB glut-IPSPs and of the GABAB late IPSPs may suggest the presence of two GABAB mechanisms in CA1 pyramidal cells.

Animals↗

PubMed2002

Origins of surface potentials evoked by electrical stimulation of oculomotor nerves: are they related to electrooculographic or electromyographic events?

OBJECT: Evoked potentials elicited by electrical stimulation of the oculomotor nerve and recorded from surface electrodes placed on the skin around the eyeball reportedly originate in the eye and are represented on electrooculograms. Because evoked potentials recorded from surface electrodes are extremely similar to those of extraocular muscles, which are represented on electromyograms, the authors investigated the true origin of these potentials. METHODS: Evoked potentials elicited by electrical stimulation of the canine oculomotor nerve were recorded from surface electrodes placed on the skin around the eyeball. A thread sutured to the center of the cornea was pulled and the potentials that were evoked during the resultant eye movement were recorded. These potentials were confirmed to originate in the eye and to be represented on electrooculograms because their waveforms were unaffected by the administration of muscle relaxant. To eliminate the influence of this source, the retina, a main origin of standing potentials of the eyeball, was removed. This resulted in the disappearance of electrooculography (EOG) waves elicited by eye movement. Surface potentials elicited by oculomotor nerve stimulation were the same before and after removal of the retina. Again the oculomotor nerve was electrically stimulated and electromyography (EMG) response of the extraocular muscles was recorded at the same time that potentials were recorded from the surface electrodes. In their peak latencies, amplitudes, and waveforms, the evoked potentials obtained from surface electrodes were almost identical to EMG responses of extraocular muscles. CONCLUSIONS: Evoked potentials elicited by electrical stimulation of the oculomotor nerves and obtained from surface electrodes originated from EMG responses of extraocular muscles. These evoked potentials do not derive from the eye.

Abducens Nerve↗