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PubMed1978

The neuronal origin of prostaglandin released from the rabbit portal vein in response to electrical stimulation.

Transmural electrical stimulation of the isolated portal vein of the rabbit was accompanied by the release of a prostaglandin-like substance (PLS). Thin layer chromatography coupled with bioassay indicated that this substance was probably prostaglandin E2 (PGE2). 2 Indomethacin potentiated the response of the portal vein to electrical stimulation at 2 Hz and abolished the release of the PLS. 3 There was no significant change in the amount of PLS released from the portal vein in response to electrical stimulation at 2 Hz when the contractile response of the portal vein was prevented by pretreatment with phentolamine or guanthidine. 4 In vitro denervation of the portal vein with 6-hydroxydopamine or the omission of Ca2+ from the bathing solution caused a significant reduction in the amount of PLS released from the portal vein in response to electrical stimulation at 2 hertz. 5 It is concluded that electrical stimulation of the isolated portal vein of the rabbit is accompanied by the release of a PLS, probably PGE2, from a neuronal source. The synthesis and release of the PLS is Ca2+ -dependent.

Animals↗
PubMed1991

Focal dorsal raphe stimulation and pinnal electrical stimulation modulate spontaneous and noxious evoked responses in thalamic neurons.

This study investigated the nocieceptive responses of single neurons within the nucleus parafascicularis (PF) thalami of the rat following two modes of electrical stimulation known to induce analgesia. It was found that both focal electrical dorsal raphe stimulation (DRS) and bilateral pinnal (ear) electrical stimulation (PES) converge on the same PF neurons, affecting both the spontaneous discharges and the noxious evoked responses toward these neurons. The effects of different stimulus current intensity, frequency and pulse duration were also examined. It was found that for both DRS and PES at pulse frequency of 10 Hz and current amplitude of 10 microA are the optimal parameters to modulate both the spontaneous and the noxious evoked responses. These stimuli produced prolonged effects related to the duration of stimulation. The external (PES) low current stimulation which was delivered below the sensory threshold was as effective in modulating noxious responses as the invasive DRS in intact animals and in animals with bilateral dorsolateral-funiculus ablation. It was observed that dorsal lateral funiculus ablation (DLFx) did not modify the DRS and the PES effects. These observations further support the existence of an ascending pain modulation pathway.

Animals↗
PubMed2002

Clinical elements for the neuromuscular stimulation and functional electrical stimulation protocols in the practice of neurorehabilitation.

The physicians and their multidisciplinary teams involved in the clinical practice of neurological rehabilitation have more and more opportunities to apply neuromuscular stimulation (NMS) and functional electrical stimulation (FES) of peripheral nerves as a part of their daily practice. In this article, we outline clinical protocols of NMS and FES in the following clinical conditions of upper motor neuron dysfunction: to prevent consequences of disuse of the neuromuscular system of the upper motor neuron, to facilitate recovery processes of impaired upper motor neuron functions due to acute and/or subacute neurological conditions, to maintain or enhance the trophic state of the muscle, to modify altered control of muscle tone, to modify altered patterns of automatic and volitional functional movements, to enhance functional movement of the single joint muscle group within intact functional multijoint movement, and to modify altered neurocontrol of posture, locomotion, and skillful movements. We emphasize the importance of understanding the motor control alteration while developing clinical protocols and defining the goals. It is very important to be aware that similar clinical findings and due to the same cause can have different features of residual motor control, and therefore potentials for recovery or modification can be very different.

Electric Stimulation Therapy↗
PubMed2006

Altered responsiveness of the guinea-pig isolated ileum to smooth muscle stimulants and to electrical stimulation after in situ ischemia.

1. We evaluated changes in contractility of the guinea-pig isolated ileum, using intact segments and myenteric plexus-longitudinal muscle (MPLM) preparations, after several times (5-160 min) of ischemia in situ. 2. Intestinal ischemia was produced by clamping the superior mesenteric artery. Ischemic and nonischemic segments, obtained from the same guinea-pig, were mounted in organ baths containing Krebs-bicarbonate (K-B) solution, maintained at 37 degrees C and gassed with 95% O2/5% CO2. The preparations were allowed to equilibrate for 60 min under continuous superfusion of warm K-B solution and then electrically stimulated at 40 V (0.3 Hz, 3.0 ms). Thereafter, complete noncumulative concentration-response curves were constructed for acetylcholine (ACh), histamine (HIS), potassium chloride (KCl), and barium chloride (BaCl2). Mean Emax (maximal response) values were calculated for each drug. 3. Our study shows that alterations of chemically and electrically evoked contractions are dependent on ischemic periods. It also demonstrates that contractile responses of ischemic tissues to neurogenic stimulation decreases earlier and to a significantly greater extent than the non-nerve mediated responses of the intestinal smooth muscle. Contractile responses to smooth muscle stimulants were all similarly affected by ischemia. Electron microscopy images indicated necrotic neuronal death. The decrease in reactivity of ischemic tissues to electrical stimulation was ameliorated by dexrazoxane, an antioxidant agent. 4. We consider the guinea-pig isolated ileum as a useful model system to study the processes involved in neuronal ischemia, and we propose that the reduction in maximal responses to electrical stimulation is a useful parameter to study neuroprotection.

Acetylcholine↗
PubMed1986

Electrical stimulation in multiple sclerosis. Comparison of transcutaneous electrical stimulation and epidural spinal cord stimulation.

Forty-nine multiple sclerosis patients with bladder symptoms and/or walking disability were subjected to a therapeutic trial with electrical spinal cord stimulation and transcutaneous electrical stimulation, a second aim being to compare these two treatments. A clear subjective improvement in bladder symptoms was achieved in the majority of the cases, and this was substantiated by objective parameters. In a proportion of cases a more moderate improvement seems to have been achieved in a variety of symptoms. Transcutaneous electrical stimulation seems to be a useful selection procedure for later electrical spinal cord stimulation.

Adult↗
PubMed1993

The dorsomedial frontal cortex of the rhesus monkey: topographic representation of saccades evoked by electrical stimulation.

The dorsomedial frontal cortex (DMFC) of monkeys has been implicated in mediating visually guided saccadic eye movements. The purpose of this study was to determine whether the DMFC has a topographic map coding final eye position, and to ascertain whether this region subserves the maintenance of eye position. The DMFC was stimulated electrically while monkeys fixated a target presented somewhere in visual space. A series of parametric tests was conducted to ascertain the best stimulation parameters to evoke saccades. Electrical stimulation typically produced contraversive saccades that converged onto a region of space, the termination zone. For some stimulation sites, however, stimulation produced ipsiversive saccades. This occurred when the termination zone was located straight ahead of the monkey. Convergence onto an orbital position was never observed during stimulation of the frontal eye fields (FEF), stimulation of which evoked fixed-vector saccades. The latency to evoke a saccade from the DMFC varied with fixation position, such that it increased monotonically the closer the fix spot was to the termination zone. Moreover, the probability of evoking a saccade from the DMFC decreased the closer the fix spot was to the termination zone. The latency for evoking a saccade and the probability of evoking a saccade from the FEF did not vary with fixation position. Horizontal head movements were not evoked from the DMFC while a monkey fixated targets presented in different positions of visual space. Moveover, changing the position of the head with respect to the body did not change the location of a termination zone with respect to the head. The DMFC was found to contain a topographic coding of termination zones, with rostral sites representing zones in extreme contralateral visual space, and caudal sites representing zones straight ahead or ipsilaterally. Furthermore, lateral sites represented zones in upper visual space, whereas medial sites represented zones in lower visual space. Once the eyes were positioned within a termination zone, further stimulation fixed the gaze and inhibited visually evoked saccades. Following release from inhibition, which occurred shortly after the end of stimulation, the saccades reached the visual target accurately. This shows that the stimulation delayed the execution of the saccades without actually aborting their execution. We conclude that the DMFC contains a map representing eye position in craniotopic coordinates, and we argue that this map is utilized to maintain eye position.

Animals↗
PubMed1990

Magneto-electrical stimulation of central motor pathways compared with percutaneous electrical stimulation.

The central motor conduction to the relaxed muscles was studied in 30 normal volunteers using magneto-electrical stimulation (MES) of the central motor pathways. The results were compared with those obtained by the percutaneous electrical stimulation technique (PES) described previously. None of the cortical and spinal latencies (Lcor and Lsp, respectively) and the central motor conduction time were different between MES and PES in the upper limb muscles. In some lower limb muscles, however, the Lsps of MES were significantly shorter than those of PES. This was probably because the magnetic stimulation over the lumbar spinal column activated the motor roots at their exit from the spinal canal rather than the level of conus medullaris, at which activation occurs in the electrical stimulation.

Adult↗
PubMed1994

Comparison of magnetic coil stimulation and needle electrical stimulation in the diagnosis of lumbosacral radiculopathy.

Electrical stimulation (ES) of lumbosacral nerve roots using a needle electrode inserted to the laminar level at the midline of Th12-L1 or L1-2 intervertebral interspace, was compared with magnetic stimulation using a 9-cm diameter coil (MCS) at the L3-4 or L4-5 spine levels, Compound muscle action potentials (CMAP) were superficially recorded from homologous muscles in both sides in 15 normal control subjects and in 20 patients with lumbosacral radiculopathy. Soleus muscles were used for S1, tibialis anterior (TA) for L5, and rectus femoris (RF) muscles for L4 roots. According to the clinical or radiological diagnosis (CAT, MRI and/or myelography) conventional needle EMG was capable to localise the root lesion in 16 of 20 patients (80%) and ES localised the root involvement in 18 of 20 patients (90%); the diagnostic value of MCS was lower, about 65% (13 of 20 patients). Although ES is uncomfortable and invasive, it is superior to needle EMG in localising unilateral or multiple lumbosacral root involvement. At present, MCS is not suitable for the diagnosis of lumbar radiculopathy.

Adult↗
PubMed1994

Transcranial electrical stimulation of the motor cortex in man: further evidence for the site of activation.

1. The motor cortex was stimulated electrically (vertex anode; cathode 6 cm lateral) in neurologically normal subjects undergoing surgery for scoliosis, and the evoked corticospinal volleys were recorded from the spinal cord using epidural electrodes. 2. Stimuli > 330 V produced a complex D-wave volley containing three separate peaks, with high-threshold components, 0.8 ms (D2) and 1.6 ms (D3), in advance of the lowest-threshold component (D1). As stimuli increased up to 1500 V, D3 replaced the later components completely, but there was no further latency 'jump'. 3. Brainstem stimulation using electrodes over each mastoid process produced a descending volley that had the same latencies as D3. At threshold, stimulation of the brainstem or spinal cord attenuated the D wave evoked by simultaneous cortical stimulation. 4. It is concluded that transcranial electrical stimulation of the motor cortex at high intensities can access corticospinal neurones at the pyramidal decussation, and that stimulation of the brainstem (and the spinal cord) preferentially accesses corticospinal axons. At threshold, motor cortex stimulation probably activates corticospinal neurones at or near the cerebral cortex.

Adolescent↗
PubMed1996

An electrical knee lock system for functional electrical stimulation.

An electrical knee lock system that can be combined with functional electrical stimulation was designed for paraplegic patients. This knee system unlocks the knee electrically and allows knee flexion during the swing phase of the gait. When the knee is extended by electrical stimulation of the knee extensors, the knee is automatically locked by the weight of the locking bar, and the stimulation of the knee extensors is stopped. Since the knee extensors are stimulated for only a short period, muscle fatigue of the knee extensors seldom occurs. We applied this system to a T8 completely paraplegic patient. Standing-up, standing, walking, and sitting-down motions were all restored by our hybrid system. No electrical stimulation was necessary during standing, and the knee extensors were stimulated during only a small percentage of the 1-gait cycle.

Adult↗
PubMed2000

[Treatment of tachycardic atrial fibrillation by catheter-assisted electrical stimulation of the cardiac parasympathetic nervous system].

UNLABELLED: Treatment of tachycardic atrial fibrillation (AF) is difficult in patients with congestive heart failure because many drugs which exert negative dromotropic effects (beta-blockers, calcium channel antagonists) may depress ventricular contractility and/or decrease arterial blood pressure. We have identified 2 intravascular sites in the superior (SVC) and inferior vena cava (IVC) where parasympathetic nerves, which innervate the atrioventricular node, can be stimulated electrically. In 8 dogs, a 7-F catheter with an expandable electrode basket at its tip was non-fluoroscopically positioned in the SVC and in the proximal IVC (time for positioning: 3-5 minutes). High-frequency electrical parasympathetic stimulation (PS) with 20 Hz at an impulse duration of 0.1 ms was performed during pacing induced AF. RESULTS: With increasing stimulus strength, a graded ventricular rate slowing was observed during PS in the SVC and IVC (P < 0.01, ANOVA). The negative dromotropic effect started instantaneously after onset of PS and ceased immediately after termination of PS. During ventricular pacing at a constant rate, no decrease of the arterial blood pressure was observed during PS. PS in the IVC yielded significantly lower stimulation thresholds than in the SVC. CONCLUSIONS: Transvenous parasympathetic stimulation for ventricular rate control during AF can easily be achieved in the SVC and IVC in dogs. This procedure may provide a foundation for investigating the usefulness of PS in humans. If the results translate to patients, PS may be very beneficial in the treatment of AF in patients with congestive heart failure.

Animals↗
PubMed1997

Combined neuromuscular electrical stimulation and transcutaneous electrical nerve stimulation for treatment of chronic back pain: a double-blind, repeated measures comparison.

OBJECTIVES: A preliminary examination of NMES and combined NMES/TENS for the management of chronic back pain. DESIGN: Double-blind, placebo-controlled, randomized repeated measures. SUBJECTS AND SETTING: Consecutive sample of 24 chronic back pain patients (16 women and 8 men) attending an outpatient pain clinic (mean age 51.67 years, mean pain duration 3.83 years). All treatments were administered at home. INTERVENTIONS: Subjects self-administered NMES, combined NMES/TENS, TENS, and placebo treatments. Each treatment had a duration of 5 consecutive hours per day over 2 consecutive days, with a 2-day hiatus between treatments to minimize carryover effects. MAIN OUTCOME MEASURES: Pain reduction was assessed through pretreatment to posttreatment differences on the Present Pain Intensity (PPI) scale, and a visual analogue scale of Pain Intensity (VAS-I). Posttreatment pain relief was assessed using a visual analogue scale of Pain Relief (VAS-R). RESULTS: Combined treatment, NMES, and TENS each produced significant pretreatment to posttreatment reductions in pain intensity as measured by both the PPI and VAS-I (p < .05). Combined treatment was superior to placebo on pain reduction (p = .001, p = .016) as well as pain relief (p < .001). Combined treatment was also superior to both TENS and NMES for pain reduction and pain relief (p < .01). NMES and TENS were superior only to placebo for pain relief (p < .001). CONCLUSIONS: Combined NMES/TENS treatment consistently produced greater pain reduction and pain relief than placebo, TENS, or NMES. NMES alone, although less effective, did produce as much pain relief as TENS. Although preliminary, this pattern of results suggests that combined NMES/TENS may be a valuable adjunct in the management of chronic back pain. Further research investigating the effectiveness of both NMES and combined NMES/TENS seems warranted.

Adult↗
PubMed1984

Extracochlear electrical stimulation.

Extracochlear electrical stimulation was carried out in 7 patients. We used square-wave signals. Electrode positions at the oval and round window showed the lowest current thresholds. The threshold of sound sensations elicited by electrical stimulation was higher in the high frequency than in the low frequency range. All 7 patients had hearing sensations for electrical stimulation with frequencies from 75 Hz to 1 000 Hz, 4 of them to 3 000 Hz. Varying the frequency of the electric signals gave variations of pitch sensation. A higher input amplitude gave variation in pitch sensation in some patients even if the electric frequency remained constant, at least for frequencies below 500 Hz. It seems possible to give prosodic information by transforming the speech from a microphone into electric pulses. This may be especially valuable information of the intelligibility of speech when combined with lip reading.

Auditory Threshold↗
PubMed1982

Ocular accommodation in the cat after electrical stimulation of mesencephalic reticular formation.

We measured ocular accommodation in the cat with a continuously recording infrared optometer. The brain stem reticular formation in an anesthetized cat was stimulated electrically with microelectrodes to evoke accommodation. Sites in the mesencephalic reticular formation caudal and ventral to the III nerve nucleus near the midline gave large positive accommodation responses. The velocity and amplitude of postive accommodation was graded, depending on the applied current and frequency of stimulation. Relaxation of accommodation proceeded at a fairly constant rate upon cessation of electrical stimulation. These findings provide new information on the amplitude and dynamic aspects of ocular accommodation in the cat. Also, the location of the stimulating electrodes suggest that in addition to the Edinger-Westphal nucleus, areas in the mesencephalic reticular formation between the cerebellum and the oculomotor nucleus are involved in ocular accommodation in the cat.

Accommodation, Ocular↗
PubMedDate not supplied

The effect of electric stimulation of caudate nucleus and nucleus accumbens septi on serotonergic neurons in the rat brain.

Nucleus caudatus--putamen (CP) or nucleus accumbens septi (A) were stimulated electrically for 30 min in free moving rats. Immediately or 30 min after the stimulation we studied the level of 5-HTP and DOPA accumulated in the mesencephalon+pons+medulla oblongata, after inhibition of activity of aromatic amino acids decarboxylase by NSD 1015, and intensity of histofluorescence of serotonin in the midbrain raphe nuclei. The electrical stimulation of either structure did not significantly change the content of 5-HTP and DOPA, but stimulation of nucleus accumbens depressed the level of serotonin in the neurocytes of dorsal and ventral raphe nuclei.

5-Hydroxytryptophan↗
PubMed1995

Clinical applications of functional electrical stimulation.

Functional Electrical Stimulation (FES) allows the restoration of controlled muscle contractions, and hence limb function via computer control, in patients with irrecoverable upper motor neuron lesions. Wide experience has been recorded in spinal cord injured paraplegics and tetraplegics and to a lesser extent in cerebrovascular accident victims. The electrodes, either surface or implanted, stimulate muscles electrically through a stimulator activated by a control source which is in turn activated by the remaining functions of the user. Future advances in electrode technology and control and command sources activation systems as well as development of "close-loop" systems need to be made if wide patient acceptance of this modality is to be ensured.

Cerebrovascular Disorders↗
PubMedDate not supplied

[Apparatus "Stimul-1" foe electric stimulation of muscles].

The apparatus "Stimul-1" has been designed and recommended for batch production, its purpose being broad application in the medical practice of electrical stimulation of the muscles. For stimulation is used sinusoidal a.c. current with frequency of 2 kHz, which produces and effective contraction of the muscles without causing any sensation of pain. The unit is constructed by using up-to-date components, including microminiature logic circuits, operational amplifiers and field-effect transistors.

Electric Stimulation Therapy↗