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At least 631 records · Page 35Linked to original sources
PubMed1984

Relief of cancer pain in man: alcohol-induced neuroadenolysis vs. electrical stimulation of the pituitary gland.

To explore new methods for the control of intractable pain caused by advanced cancer, the analgesic effect of electrical stimulation of the pituitary gland was investigated in 25 patients. The results were compared with a control study and with the effects of alcohol-induced pituitary neuroadenolysis (NALP) in the same patients. The pain score (0: no pain at all, 4: extreme pain) in the control study was 3.88 +/- 0.33. After electrical stimulation of the pituitary gland it was 1.24 +/- 1.61; and after NALP it was 1.0 +/- 1.60. The pain scores after electrical stimulation and NALP were significantly lower (P less than 0.01) than those in the control study; but there was no significant difference when the two were compared with each other. The duration of pain relief following NALP (59.65 +/- 68.72 days) was significantly longer compared with that recorded following electrical stimulation (2.97 +/- 2.58 days). Autopsy examinations of 3 patients who expired from their malignancies revealed that the pain relief was unrelated to the degree of necrosis induced in the pituitary by alcohol. Naloxone administration did not inhibit the analgesic effect of either NALP or electrical stimulation. The advantages and disadvantages of electrical stimulation, the pain relief mechanism activated by this method, and potential clinical applications are also discussed.

Adult↗
PubMedDate not supplied

Skeletal muscle of a growing organism has a greater transformation after electrical stimulation than adult skeletal muscle.

Six adult sheep and four newborn lambs (5 days old) were implanted with stimulator leads into the latissimus dorsi muscle and connected to a Myostim 7220 pacing system (Telectronics Pacing Systems, Inc., Englewood, CO). Electrical stimulation was started immediately after the operation. After 8 weeks of electrical stimulation, contractile force (CF) in adult sheep decreased to 76-81%, and to 78-82% in lambs. After 2 weeks' delay, CF in adults was 96-98%, and only 89-93% in lambs. After a 30 min intensive stress test, unconditioned control muscle lost 39% in lambs and 43% in adults. Muscle conditioned for 8 weeks lost 7-8% CF. However, after 2 weeks' delay, CF in adult muscle lost 33%, but only 12% in lambs. After cessation of electrical stimulation, the LDH-5 and LDH-1 + 2 fractions reverted to initial levels in adults, whereas in lambs, these levels continued to follow trends established during electrical stimulation. In both adults and lambs, the percent area occupied by the mitochondria increased during electrical stimulation by 6.9% in adults and 6.5% in lambs. After electrical stimulation cessation, the percent area in adults returned to baseline levels, whereas it continued to be elevated in lambs (3.3% vs 5.1%, respectively). The transformed muscle of the lamb did not revert to baseline levels after a delay period.

Adaptation, Physiological↗
PubMed2003

[Effects of electric stimulation on circadian rhythm of plasma cortisone in soldiers].

OBJECTIVE: To observe the effects of electric stimulation on the circadian rhythm of plasma cortisone in soldiers. METHODS: Electric stimulation or phototherapy was respectively performed in the popliteal region (behind the knee) of the soldiers at different time points and radio immunal assay was utilized to examine the plasma cortisone concentration. RESULTS: The plasma cortisone concentration exhibited obvious circadian rhythmicity. At the 3 time points before the lowest core temperature occurred, treatments with electric stimulation or phototherapy resulted in delayed phase of circadian cortisone rhythm, while the same treatments given at the 3 time points after the lowest core temperature caused earlier arrival of the phase. No changes in the rhythm phase in response to treatments at other time points. CONCLUSION: Both of electric stimulation and phototherapy can adjust the phase of the cortisol circadian rhythmicity, and the phase curve displayed photic response to the treatments.

Adolescent↗
PubMed1988

Inhibition and excitation of neck and shoulder muscles during unilateral electrical stimulation of the rat neostriatum.

Electrical stimulation of the caudate-putamen (Cd-Pt) in anesthetized adult male rats was used to determine the nature and extent of the control exerted by the Cd-Pt over the following neck and shoulder muscles: the trapezius, biventer cervicis, rectus capitis and scalenus dorsalis. Unilateral Cd-Pt stimulation resulted in a pattern of muscle responses marked by immediate inhibition of ipsilateral spontaneous activity and subsequent excitation of contralateral activity. Lesions of the substantia nigra pars reticulata blocked the excitation in 3 of the 4 muscles, while globus pallidus lesions had equivocal results. However, control ablations of the frontoparietal motor cortex, which blocked excitation in all muscles, and kainic acid lesions of the Cd-Pt, which had no effect on excitation, suggested that the excitation of muscle activity can only be attributed to the stimulation of corticofugal fibers passing through this region (i.e. the Cd-Pt). The inhibition of spontaneous activity does appear to be attributable to stimulation of the Cd-Pt.

Animals↗
PubMed2006

Response of gait deficits to neuromuscular electrical stimulation for stroke survivors.

Persistent gait deficits after stroke can cause falls, elevated energy cost and poor endurance. Coordination impairment is an underlying cause of gait deficits. Few efficacious interventions have been described that have targeted and measured restoration of coordinated gait components. Neuromuscular electrical stimulation can provide the critical gait practice characteristic of close-to-normal movements, by electrically inducing muscle contractions and coordinated movements that are not possible under volitional effort. Two-channel, surface neuromuscular electrical stimulation can be synchronized with phases of gait and can provide faster, more symmetrical neuromuscular electrical stimulation-assisted gait than gait with no neuromuscular electrical stimulation. Difficulties encountered during the use of surface neuromuscular electrical stimulation for gait training led to the development of neuromuscular electrical stimulation with implanted technologies. Implanted electrodes and/or stimulators proved to be feasible for gait training in stroke survivors. Gait training with a multichannel neuromuscular electrical stimulation system with implanted electrodes proved more advantageous than gait training without neuromuscular electrical stimulation, according to measures of volitional coordinated gait components (neuromuscular electrical stimulation deactivated).

Electric Stimulation Therapy↗
PubMedDate not supplied

Relationship of blood pressure to the responsiveness of an isolated human artery to selected agonists and to electrical stimulation.

Intrinsic vascular responsiveness to norepinephrine, transmural electrical stimulation, 5-hydroxy-tryptamine, and vasopressin was studied in isolated helical cut strips of cystic artery (downstream branch of hepatic artery) from 120 subjects and related to blood pressure. Blood pressure, thickness of the tunica media, and passive elastic properties of arterial strips were each significantly correlated with age. With the exception of blood pressure in the female subjects, it is doubtful that these relationships are of major biologic significance. Nevertheless, in subgroup formation, care was taken to control for age. Hypertension was arbitrarily defined in three different ways as: (a) two diastolic pressure measurements greater than or equal to 90 mm Hg (HT90); (b) two diastolic pressure measurements greater than or equal to 95 mm Hg (HT95); or (c) treatment for hypertension instituted by a physician 6 months to 2 years after arteries were studied (HTQ). In arteries of hypertensive female subjects, responsiveness to norepinephrine (and possibly to 5-hydroxytryptamine) was increased significantly over the first half of the dose-response curve, particularly in the arteries of HT95 and HTQ subjects. Responses to transmural electrical stimulation and vasopressin were not consistently different. Such differences were not seen in arteries of male subjects where, if anything, responsiveness to norepinephrine (but not 5-hydroxytryptamine) was decreased. The present observations were made in the absence of any substantive difference in arterial dimensions (e.g., cross-section area) or in the maximal response to norepinephrine. The data support the notion that, at least for female subjects, alteration in intrinsic vascular responsiveness may play a role in the pathogenesis of human essential hypertension.

Adult↗
PubMed1991

Quantitative characterization and spinal substrates of antinociception produced by electrical stimulation of the subdiaphragmatic vagus in rats.

Physiological, chemical or electrical activation of vagal afferents produces antinociception in rats. The present study examined the effects of electrical stimulation of the subdiaphragmatic vagus (SDV) on the nociceptive tail-flick reflex, arterial blood pressure, and heart rate in rats lightly anesthetized with pentobarbital sodium. The intensity of SDV stimulation (20 Hz, 2 msec) necessary to inhibit the tail-flick reflex to a 10 sec cut-off latency for 3 consecutive trials was defined as the threshold to produce antinociception. Electrical stimulation of the SDV suppressed the tail-flick reflex in a linear, intensity-dependent manner. In addition, the threshold varied as a function of either the frequency or the pulse width of SDV stimulation, such that decreases in either frequency or pulse width, from 20 Hz and 2 msec, respectively, systematically increased the threshold current necessary to produce antinociception. SDV stimulation also produced modest decreases in heart rate (HR), but arterial blood pressure (ABP) responses were highly variable in both the magnitude and direction of change. Intrathecal administration of 30 micrograms of the serotonergic receptor antagonist methysergide significantly increased the threshold for antinociception produced by SDV stimulation from 80 to 938.8 microA, whereas 15 micrograms of methysergide had no significant effect. Intrathecal administration of saline, 30 micrograms of naloxone, or 30 micrograms of phentolamine had no significant effect on the threshold of SDV stimulation required to produce antinociception. Systemic administration of naloxone (4 mg/kg i.p. or i.v.) also had no effect on the antinociceptive threshold. Intrathecal administration of these receptor antagonists had no significant effect on the ABP and HR responses produced by electrical stimulation of the SDV at the threshold intensity producing antinociception.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMedDate not supplied

[Functional electrical stimulation in the reciprocal locomotion of paraplegic patients].

The functional electrical stimulations is employed for standing-up posture and reciprocal locomotion in paraplegic patients. Five male paraplegic patients, level D5-D12 mean age 32.4 years, were treated with functional electrical stimulation, during two months. The quadriceps and fibular nerves were stimulated for 30 minutes, twice a day. After the training period, two patients were able to remain in the stand-up position and walk in parallel bars; one of them was able to use a walker. In other patients the technique was without effect for standing and walking. This method is not the solution for locomotion of paraplegics and more research is needed for the improvement of the results of functional electrical stimulation.

Adult↗
PubMed1991

Chronic dermal ulcer healing enhanced with monophasic pulsed electrical stimulation.

The purposes of this randomized, double-blind, multicenter study were to compare healing of chronic dermal ulcers treated with pulsed electrical stimulation with healing of similar wounds treated with sham electrical stimulation and to evaluate patient tolerance to the therapeutic protocol. Forty-seven patients, aged 29 to 91 years, with 50 stage II, III, and IV ulcers were randomly assigned to either a treatment group (n = 26) or a control (sham treatment) group (n = 24). Treated wounds received 30 minutes of pulsed cathodal electrical stimulation twice daily at a pulse frequency of 128 pulses per second (pps) and a peak amplitude of 29.2 mA if the wound contained necrotic tissue or any drainage that was not serosanguinous. A saline-moistened nontreatment electrode was applied 30.5 cm (12 in) cephalad from the wound. This protocol was continued for 3 days after the wound was debrided or exhibited serosanguinous drainage. Thereafter, the polarity of the treatment electrode on the wound was changed every 3 days until the wound progressed to a stage II classification. The pulse frequency was then reduced to 64 pps, and the treatment electrode polarity was changed daily until the wound was healed. Patients in the control group were treated with the same protocol, except they received sham electrical stimulation. After 4 weeks, wounds in the treatment and control groups were 44% and 67% of their initial size, respectively. The healing rates per week for the treatment and control groups were 14% and 8.25%, respectively. The results of this study indicate that pulsed electrical stimulation has a beneficial effect on healing stage II, III, and IV chronic dermal ulcers.

Adult↗
PubMed1999

Pattern electrical stimulation of the human retina.

Experiments were conducted to study if electrical stimulation of the retinal surface can elicit visual sensation in individuals blind from end-stage retinitis pigmentosa (RP) or age-related macular degeneration (AMD). Under local anesthesia, different stimulating electrodes were inserted through the eyewall and positioned over the surface of the retina. Subjects' psychophysical responses to electrical stimulation were recorded. Subjects perceived simple forms in response to pattern electrical stimulation of the retina. A non-flickering perception was created with stimulating frequencies between 40 and 50 Hz. The stimulation threshold was dependent on the targeted retinal area (macular versus extramacular).

Blindness↗
PubMed1981

Effect of electrical stimulation on thermal shrinkage temperature of bovine muscle collagen.

The effect of beef carcass electrical stimulation on the thermal stability of intramuscular collagen was determined. Differential scanning calorimetric determinations of thermal shrinkage temperature revealed that electrical stimulation lowered the shrinkage temperature of collagen by an average of .6 C in the population of cattle studied. No difference between Hereford x Angus crossbreds and Charolais crossbreds were found, but the extent of the reduction of collagen shrinkage temperature caused by electrical stimulation was greater in animals that did not receive high grain diets or received grain for only a short period than in those fed grain for up to 210 days. Furthermore, panel tenderness and Warner-Bratzler shear tests showed that stimulation-induced tenderization was also greater in animals fed no grain or fed grain for a short time. No evidence of stimulation effects on myofibrillar proteins was observed from data on sarcomere length or myofibrillar fragmentation index. The reduction of thermal stability of bovine intramuscular collagen by electrical stimulation may result from a decrease in the number or strength of the collagen cross-links.

Animals↗
PubMed1999

The electrical and magnetical cerebral responses evoked by electrical stimulation of the esophagus and the location of their cerebral sources.

OBJECTIVES: After electrical stimulation of the esophagus cerebral responses are recordable, their cortical source is under discussion. Brain mapping using electroencephalography recordings demonstrated partially controversial results. Sources of evoked responses can be localized more easily using magnetoencephalography than electroencephalography. METHODS: We examined 22 volunteers by recording electrical somatosensory potentials after electrical stimulation of the esophagus. In 9 of these 22 subjects additional recording of magnetic fields was performed and the sources of the evoked magnetic fields were computed. RESULTS: The evoked potentials after electrical stimulation of the esophagus had a similar latency as the previously published data. The source localization done by magnetoencephalography suggest that first a region of the postcentral gyrus is activated which is temporo-lateral to the primary somatosensory cortex of the pharynx. This region is suggested to be the primary somatosensory region of the esophagus. This source was followed by a source in the parietal operculum thought being part of the secondary somatosensory cortex. Simultaneously the insular cortex was activated pointing to a parallel neuronal pathway to the central autonomic nervous system. CONCLUSION: After electrical stimulation of the esophagus somatosensory cortical areas of the temporal postcentral gyrus and the operculum are activated. In parallel activation of the insular cortex as part of the central autonomic network was found.

Adult↗
PubMed2002

MRI quantification of muscle activity after volitional exercise and neuromuscular electrical stimulation.

OBJECTIVE: The efficacy, and even the depth, of muscle stimulation during surface electrode neuromuscular electrical stimulation (NMES) is a matter of debate. This study addresses these issues by assessing the utility of a magnetic resonance imaging (MRI) technique in localizing and quantitating changes in the nature of MRI signals in the quadriceps muscle after volitional exercise and NMES. DESIGN: Volitional isometric and NMES-evoked quadriceps muscle activity was evaluated in two controlled trials. In the first, isometric quadriceps strength was determined during NMES and maximal volitional isometric exercise in six healthy men. In the second, changes in the ratio of MRI T2 signal intensities before and after volitional isometric exercise and NMES were used to quantitate MRI signal changes associated with muscle activation in 12 additional healthy men. RESULTS: MRI clearly detected quadriceps muscle tissue activation after both volitional and stimulated contractions, even though the NMES knee extension torque was only 23.5% that of maximal volitional isometric exercise. In particular, the T2 intensity ratios increased 26.5% +/- 17.3% (mean +/- standard deviation) after volitional exercise and 12.9% +/- 12.8% after NMES. This pattern of volitional isometric exercise, producing larger T2 intensity ratio values than NMES, was present in both deep and superficial layers and throughout the quadriceps muscle. CONCLUSIONS: Although volitional muscle contractions were several times stronger than those induced by NMES in this study, our findings support the idea that MRI can provide a noninvasive way to quantitate and localize volitional and electrically stimulated muscle activation.

Adult↗
PubMed1993

Nerve function in experimental diabetes in rats: effects of electrical stimulation.

The effects of unilateral electrical stimulation of the peroneal sciatic nerve branch were studied in streptozocin-diabetic rats of 12-wk duration. Stimulation was carried out over 7 days (10 Hz, 8 h/day) with chronically implanted electrodes. Compared with controls, there was a 25% conduction velocity (CV) deficit for the peroneal nerve supplying tibialis anterior muscle in the unstimulated leg, which was corrected by stimulation. For tibial fibers supplying soleus muscle, a similar diabetic CV deficit (20%) was normalized by stimulation, although soleus axons were not directly activated. In saphenous nerve, which has a functionally separate vascular supply, peroneal stimulation was ineffective. In anesthetized diabetic rats, stimulation caused an 18% reduction in tibialis anterior CV after 4 h. However, serial measurements showed progressive normalization of CV over 4 days of stimulation. On termination, CV returned to diabetic levels over 36-60 h. Sciatic nerve showed a 70% increase in resistance to hypoxic conduction failure with diabetes, which was halved by chronic stimulation. Acute experiments demonstrated that peroneal stimulation increased sciatic vascular conductance by 60%. We conclude that stimulation causes activity-related improvements in diabetic nerve blood flow and metabolism.

Animals↗
PubMed2003

Local suppression of epileptiform activity by electrical stimulation in rat hippocampus in vitro.

High frequency electrical stimulation of deep brain structures (DBS) has been effective at controlling abnormal neuronal activity in Parkinson's patients and is now being applied for the treatment of pharmacologically intractable epilepsy. The mechanisms underlying the therapeutic effects of DBS are unknown. In particular, the effect of the electrical stimulation on neuronal firing remains poorly understood. Previous reports have showed that uniform electric fields with both AC (continuous sinusoidal) or DC waveforms could suppress epileptiform activity in vitro. In the present study, we tested the effects of monopolar electrode stimulation and low-duty cycle AC stimulation protocols, which more closely approximate those used clinically, on three in vitro epilepsy models. Continuous sinusoidal stimulation, 50 % duty-cycle sinusoidal stimulation, and low (1.68 %) duty-cycle pulsed stimulation (120 micros, 140 Hz) could completely suppress spontaneous low-Ca2+ epileptiform activity with average thresholds of 71.11 +/- 26.16 microA, 93.33 +/- 12.58 microA and 300 +/- 100 microA, respectively. Continuous sinusoidal stimulation could also completely suppress picrotoxin- and high-K+-induced epileptiform activity with either uniform or localized fields. The suppression generated by the monopolar electrode was localized to a region surrounding the stimulation electrode. Potassium concentration and transmembrane potential recordings showed that AC stimulation was associated with an increase in extracellular potassium concentration and neuronal depolarization block; AC stimulation efficacy was not orientation-selective. In contrast, DC stimulation blocked activity by membrane hyperpolarization and was orientation-selective, but had a lower threshold for suppression.

Animals↗
PubMed1984

Discharge patterns of cat primary auditory fibers with electrical stimulation of the cochlea.

Intact and destroyed cat cochleae were electrically stimulated through round window electrodes. Intact cochleae provided information about fiber properties with acoustic stimuli. With sinusoidal currents thresholds for synchronization were 4-68 microA rms. Thresholds were independent of the fiber's characteristic frequencies and thus of their places of origin in the intact cochleae. This shows large current spread. Phase-locking of the responses to electric stimulation was much stronger than it was to acoustic stimulation. Destroyed cochleae had no spontaneous activity and showed even stronger phase-locking. Thresholds obtained using 0.2 ms per phase biphasic pulse stimuli were 60-350 microApp. Action potentials were found to be released with as little as 0.3 ms latency. The neuronal responses to any electric stimulus differed considerably from the responses to corresponding acoustic stimuli. Vestibular fibers were easily activated by electric stimulation.

Acoustic Stimulation↗
PubMed2003

C-Fos immunoreactivity mapping of the auditory system after electrical stimulation of the cochlear nerve in rats.

The aim of this study was to establish the use of c-Fos immunoreactivity as a marker for functional mapping in the auditory system in response to direct electrical stimulation of the cochlear nerve in the cerebellopontine angle. In rats the cochlear nerve was electrically stimulated with a biphasic current (120-250 microA, 5 Hz) for 30 min using a bipolar concentric Tungsten electrode. Bilateral cochlectomy was performed in a control group in order to investigate basal expression of c-Fos in the auditory brainstem nuclei. The response of auditory brainstem nuclei to electrical stimulation and the completeness of cochlear ablations were electrophysiologically verified. After the experiments, the animals were prepared for cryotomy and c-Fos immunohistochemistry. The results were morphologically analyzed and statistically compared among groups. In anesthetized animals with unilateral electrical stimulation of the cochlear nerve increased expression of c-Fos was detected in the ipsilateral ventral (VCN) and bilateral dorsal cochlear nucleus (DCN), whereas the VCN of the contralateral side revealed only few immunoreactive cells. In animals with bilateral cochlear ablation the number of c-Fos reactive cell nuclei representing basal expression was generally low in the VCN and DCN of both sides. Our data show that electrical stimulation of the cochlear nerve leads to increased expression of c-Fos in the cochlear nucleus. It also confirms bilateral connections between the cochlear nuclei. These experimental results suggest that c-Fos immunoreactivity mapping provides a powerful tool for functional investigations on the cellular level after direct electrical stimulation of the cochlear nerve. Future functional studies analyzing the effect of electrical stimulation of the central auditory system as performed by auditory brainstem implants could be investigated in detail by mapping c-Fos expression on cellular level.

Animals↗