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Results for “ELECTRIC STIMULATION”

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PubMed1999

Prevention of shoulder subluxation after stroke with electrical stimulation.

BACKGROUND AND PURPOSE: Subluxation is a significant problem in poststroke hemiplegia, resulting in pain and loss of function. Current treatments are not proved and not considered effective. It has been demonstrated that cyclical electrical stimulation of the shoulder muscles can reduce existing subluxation. The purpose of this study was to determine whether electrical stimulation could prevent subluxation in both the short and long terms. METHODS: A prospective, randomized controlled study was used to determine the efficacy of electrical stimulation in preventing shoulder subluxation in patients after cerebrovascular accidents. Forty patients were selected and randomly assigned to a control or treatment group. They had their first assessment within 48 hours of their stroke, and those in the treatment group were immediately put on a regimen of electrical stimulation for 4 weeks. All patients were assessed at 4 weeks after stroke and then again at 12 weeks after stroke. Assessments were made of shoulder subluxation, pain, and motor control. RESULTS: The treatment group had significantly less subluxation and pain after the treatment period, but at the end of the follow-up period there were no significant differences between the 2 groups. CONCLUSIONS: Electrical stimulation can prevent shoulder subluxation, but this effect was not maintained after the withdrawal of treatment.

Aged↗

PubMed2005

Electrical stimulation of the cochlear nerve in rats: analysis of c-Fos expression in auditory brainstem nuclei.

We investigated functional activation of central auditory brainstem nuclei in response to direct electrical stimulation of the cochlear nerve using c-Fos immunoreactivity as a marker for functional mapping. The cochlear nerve was stimulated in the cerebellopontine angle of Lewis rats applying biphasic electrical pulses (120-250 muA, 5 Hz) for 30 min. In a control group, bilateral cochlectomy was performed in order to assess the basal expression of c-Fos in the auditory brainstem nuclei. The completeness of cochlear ablations and the response of auditory brainstem nuclei to electrical stimulation were electrophysiologically verified. C-Fos immunohistochemistry was performed using the free floating method. In anaesthetized animals with unilateral electrical stimulation of the cochlear nerve, increased expression of c-Fos was detected in the ipsilateral ventral cochlear nucleus (VCN), in the dorsal cochlear nucleus bilaterally (DCN), in the ipsilateral lateral superior olive (LSO) and in the contralateral inferior colliculus (IC). A bilateral slight increase of c-Fos expression in all subdivisions of the lateral lemniscus (LL) did not reach statistical significance. Contralateral inhibition of the nuclei of the trapezoid body (TB) was observed. Our data show that unilateral electrical stimulation of the cochlear nerve leads to increased expression of c-Fos in most auditory brainstem nuclei, similar to monaural auditory stimulation. They also confirm previous studies suggesting inhibitory connections between the cochlear nuclei. C-Fos immunoreactivity mapping is an efficient tool to detect functional changes following direct electrical stimulation of the cochlear nerve on the cellular level. This could be particularly helpful in studies of differential activation of the central auditory system by experimental cochlear and brainstem implants.

Animals↗

PubMed1981

In vivo electrical stimulation alters sensitivity of the brain (Na+ + K+)ATPase toward inhibition by vanadate.

It has recently been shown that electrical stimulation of the brain cortex in vivo blocks invasion of cortical spreading depression (SD) into the stimulated area. The effect has been interpreted as a result of activating a K+ pumping mechanism that prevents the accumulation of this ion in the extracellular space to the high levels required for SD propagation. In the present experiments (Na+ + K+)ATPase activity was determined in the electrically stimulated region of the rat brain cortex. When ATP preparations containing vanadate were used as substrate, elevation of K concentration in the assay medium from 2 to 20 mM inhibited enzyme activity in homogenates from the normal cortex but not that from homogenates of the electrically stimulated cortical region. With vanadate-free ATP (Boehringer) as a substrate, slight stimulation by 20 mM K+ has been observed in both cases. Vanadate (0.25 microM) added to the assay medium containing Boehringer ATP and 20 mM K+ inhibited ATPase activity from the normal cortex but not that from the stimulated cortical area. Electrical stimulation may activate (Na+ + K+)ATPase at least partly by diminution of its susceptibility toward the inhibitory action of vanadate.

Adenosine Triphosphatases↗

PubMed2001

Plasticity of bat's central auditory system evoked by focal electric stimulation of auditory and/or somatosensory cortices.

Recent findings indicate that the corticofugal system would play an important role in cortical plasticity as well as collicular plasticity. To understand the role of the corticofugal system in plasticity, therefore, we studied the amount and the time course of plasticity in the inferior colliculus (IC) and auditory cortex (AC) evoked by focal electrical stimulation of the AC and also the effect of electrical stimulation of the somatosensory cortex on the plasticity evoked by the stimulation of the AC. In adult big brown bats (Eptesicus fuscus), we made the following major findings. 1) Electric stimulation of the AC evokes best frequency (BF) shifts, i.e., shifts in frequency-response curves of collicular and cortical neurons. These BF shifts start to occur within 2 min, reach a maximum (or plateau) at 30 min, and then recover approximately 180 min after a 30-min-long stimulus session. When the stimulus session is lengthened from 30 to 90 min, the plateau lasts approximately 60 min, but BF shifts recover approximately 180 min after the session. 2) The electric stimulation of the somatosensory cortex delivered immediately after that of the AC, as in fear conditioning, evokes a dramatic lengthening of the recovery period of the cortical BF shifts but not that of the collicular BF shift. The electric stimulation of the somatosensory cortex delivered before that of the AC, as in backward conditioning, has no effect on the collicular and cortical BF shifts. 3) Electric stimulation of the AC evokes BF shifts not only in the ipsilateral IC and AC but also in the contralateral IC and AC. BF shifts are smaller in amount and shorter in recovery time for contralateral collicular and cortical neurons than for ipsilateral ones. Our findings support the hypothesis that the AC and the corticofugal system have an intrinsic mechanism for reorganization of the IC and AC, that the reorganization is highly specific to a value of an acoustic parameter (frequency), and that the reorganization is augmented by excitation of nonauditory sensory cortex that makes the acoustic stimulus behaviorally relevant to the animal through associative learning.

Acoustic Stimulation↗

PubMed2000

Effect of electrical stimulation on mandibular distraction osteogenesis.

This study was designed to examine whether the use of electrical stimulation during mandibular lengthening accelerates new bone formation. Twenty adult female rabbits weighing between 2800 g and 3200 g underwent left mandibular body osteotomy. After a 3 day latency period, an external fixation device was activated at a rate of 0.7 mm per day for 10 days. Direct current electrical stimulation of 10 microA was applied to 10 rabbit mandibles. Two of the screws were used as electrodes during the distraction phase. The other 10 rabbits (control group) were not stimulated. The device was then stabilized for periods of 10, 20, 30 and 60 days in both groups. The distraction segment was evaluated radiographically by assessing the proportion of bone mineral density using a dichroma scan. The amount of new bone formation was studied histologically with an image analyzer to evaluate the bone formation in the distraction gap. Histological examination showed that the new bone formation 10 and 20 days after distraction was greater in the electrical stimulation group than in the control group. Ten and 20 days after distraction, image analysis and analysis of bone mineral density in areas of newly formed bone indicated that there was a greater amount of new bone formation in the stimulation group than in the control group. The radiographic evaluation, however, did not demonstrate significantly different images between the stimulation group and the control group. Thirty and 60 days after distraction, no difference in the amount of new bone formation was noted in either the experimental or the control groups. These results indicate that electrical stimulation during gradual distraction promotes new bone formation in the early retention period in a rabbit model.

Absorptiometry, Photon↗

PubMed2003

[The effect of fastigial nucleus electrical stimulation on the therapeutic window of opportunity for intervention of focal cerebral ischemia].

OBJECTIVE: To investigate the effect of cerebellar fastigial nucleus (FN) electrical stimulation on the therapeutic window of opportunity for intervention of focal cerebral ischemia. METHODS: Thirty-five healthy male Wistar rats were divided into focal cerebral ischemia/reperfusion group (I/R group, undergoing ischemia by embolism of middle cerebral artery for 3, 6 or 8 hours and then undergoing reperfusion for 24 hours, thus subdivided into I/R 3 hours, 6 hours, and 8 hours subgroups of 5 rats), focal cerebral ischemia/reperfusion plus FN electrical stimulation group (I/R-FN group, n = 15, undergoing FN electrical stimulation followed by focal cerebral ischemia/reperfusion as in the I/R group), and sham operation group (n = 5). Twenty-four hours after the reperfusion or sham operation, the rats were killed. The brain slices underwent Nissl's staining. Two slices of each rat were examined to observe the neuronal number and morphology, and the status or Nissl's staining, and make a scoring of the affected somatosensory cortex. RESULTS: The survival rates of neurons of the I/R 3, 6 and 8 hours subgroups 3.2% +/- 11.3%, 2.6% +/- 4.5% and 3.8% +/- 3.2% respectively without a significant difference between any 2 subgroups (all P > 0.05). The scores of these 3 subgroups all reached the highest grade (4.0 +/- 0.0). The neuron survival rate of the I/R FN 3 hours subgroup was 64.2% +/- 11.3%, significantly higher than those or other I/R subgroup at the same time point (all P < 0.01), however, the neurons being obviously shrunken. The score of the I/R FN 3 hours subgroup 2.1 +/- 0.2, significantly lower than that of the I/R 3 hours subgroup (P < 0.01). The neuron survival rate of the I/R FN 6 hours subgroup was 32.8% +/- 6.5%, significantly higher than that of the I/R 6 hours subgroup (P < 0.05), however, the neurons being shrunken and irregular in shape. The score of the I/R FM subgroup was 3.0 +/- 0.0, significantly lower than that of the I/R 6 hours subgroup (P < 0.05). The I/R FN 8 hours subgroup showed a neuron survival rate of 4.1% +/- 3.5%, not significantly different from that of the I/R 9 hours subgroup (P > 0.05), and the same score as that of the I/R 8 hours subgroup. The sham operation group showed a survival rate of neurons of 96.9% +/- 17.3% and a score of 0.00 +/- 0.00. CONCLUSION: FN electrical stimulation prolongs the therapeutic window of opportunity for intervention of focal cerebral ischemia. The complete recovery of survived neurons may need further interventions.

Animals↗

PubMed2002

Electrical stimulation induced lumbar medial branch referral patterns.

STUDY DESIGN: Fluoroscopically guided, minimum threshold electrical stimulation of the right first, second, third, and fourth lumbar medial branches and the fifth lumbar dorsal ramus in each of eight healthy test subjects was performed. The stimulation thresholds and referral patterns were recorded. A composite drawing of the referral patterns was created. The composite drawings were compared to documented referral patterns already published by other authors. OBJECTIVE: To determine the referral patterns of the lumbar medial branches and the fifth lumbar dorsal ramus. HYPOTHESIS: The lumbar medial branch referral patterns created by minimum threshold electrical stimulation may differ from those obtained after zygapophysial joint (Z-joint) injections. SUMMARY OF BACKGROUND DATA: Lumbar Z-joint referral patterns have been identified following provocative Z-joint injections. There are no reports of lumbar medial branch referral patterns. METHODS: The right L1 through L4 medial branch of the posterior primary ramus and the right L5 dorsal ramus in each of eight healthy volunteer males (n=40), without a history of back pain, were electrically stimulated under fluoroscopic imaging. All subjects were blinded to the level of stimulation, and each individual mapped out the referral area on a human line drawing at the time of each stimulus. The referral patterns after electrical stimulation and the stimulation thresholds were recorded. These referral patterns were compared to referral patterns recorded during provocative Z-joint injections by other authors. CONCLUSION: All of the subjects' mapped referral sites coincided with each other, creating a well defined composite drawing. These referral zones are different than those reported after injection of the lumbar Z-joint, which may have clinical and therapeutic implications. These referral maps may provide the clinician with additional insight when evaluating a patient with lumbar, flank, or gluteal pain of undetermined etiology.

Journal Article↗

PubMed2004

Maximizing muscle force via low-cadence functional electrical stimulation cycling.

OBJECTIVE: This study investigated the effect of pedal cadence upon torque production, power output and muscle fatigue rates during functional electrical stimulation evoked cycling in spinal cord injured individuals. SUBJECTS: All subjects had complete thoracic spinal cord injuries T4-T9 (ASIA A) and had been functional electrical stimulation training regularly for at least 6 months. METHODS: One trial (n = 8) examined a low vs high pedal rate (20 and 50 rev x min(-1)) upon isolated muscle fatigue over 5 minutes. A second trial (n = 9) investigated the effect of cadence (15 vs 50 rev x min(-1)) upon performance during 35-minutes of functional electrical stimulation evoked cycling. RESULTS: Peak torque produced by left quadriceps decayed significantly faster at the higher pedal cadence, indicating a higher rate of muscle fatigue. Functional electrical stimulation cycling over 35 minutes also revealed that peak and average torques were significantly greater at the lower cadence. From 15 minutes onwards, power output was significantly higher at 50 rev x min(-1) FES-cycling, compared with 15 rev x min(-1). CONCLUSION: The higher muscle forces observed during low cadence functional electrical stimulation cycling should offer improvements over traditional pedalling velocities for training leg strength in individuals with spinal cord injury.

Adult↗

PubMed2004

Pressor effects of electrical stimulation of medial prefrontal cortex in unanesthetized rats.

The medial prefrontal cortex (MPFC) is involved in central nervous system (CNS)-mediated cardiovascular modulation. We compared the cardiovascular effects of electrical stimulation (EE) of the MPFC in unanesthetized rats to those observed after stimulation of the same area in urethane-anesthetized rats. Electrical stimulation (35, 106, 177, 247, 318, and 389 microA rms/10 sec, 60-Hz sine wave) of the MPFC of urethane-anesthetized rats caused depressor responses of stimulus-related intensity. The cardiovascular response to electrical stimulation of the MPFC in unanesthetized rats was characterized by stimulus-related pressor responses. No significant heart rate changes were observed during the EE period in any case. The pressor response to electrical stimulation (106 microA rms/10 sec, 60-Hz sine wave) of the MPFC was not affected by intravenous pretreatment with the vasopressin antagonist dTyr(CH(2))(5)(Me)AVP (50 microg/kg, intravenously), by hypophysectomy, or by intravenous pretreatment with the angiotensin II antagonist losartan (1 mg/kg, intravenously). The pressor response was blocked by intravenous pretreatment with the ganglionic blocker mecamylamine (2 mg/kg, intravenously) but was not affected by adrenal demedullation, thus suggesting involvement of the neural component of the sympathetic nervous system without a major involvement of its hormonal component. Our results confirmed the occurrence of depressor responses after electrical stimulation of the MPFC in urethane-anesthetized rats and evidenced that only pressor responses are observed after its stimulation in unanesthetized rats. The fact that the pressor response to the stimulation of the MPFC was blocked by a ganglioplegic suggests that the MPFC has functional excitatory actions over the sympathetic nervous system.

Adrenal Medulla↗

PubMed2002

Electrical stimulation for the treatment of rheumatoid arthritis.

BACKGROUND: Electrical stimulation is one of several rehabilitation interventions suggested for the management of rheumatoid arthritis (RA) to enhance muscle performance. OBJECTIVES: To assess the effectiveness of electrical stimulation for improving muscle strength and function in clients with RA. SEARCH STRATEGY: We searched MEDLINE, Embase, Healthstar, Sports Discus, CINAHL, the Cochrane Controlled Trials Register, the PEDro database, the specialized registry of the Cochrane musculoskeletal group and the Cochrane field of physical and related therapies up to January 2002 according to the sensitive search strategy for RCTs designed for the Cochrane Collaboration. The search was complemented with handsearching of the reference lists. Key experts in the area were contacted for further articles. SELECTION CRITERIA: All randomized controlled trials (RCTs) and controlled clinical trials (CCTs), case-control and cohort studies comparing ES against placebo or another active intervention in patients with RA were selected, according to an a priori protocol. No language restrictions were applied. DATA COLLECTION AND ANALYSIS: Two independent reviewers determined the studies to be included based on a priori inclusion criteria. Data were independently abstracted by the same two reviewers, and checked by a third reviewer using a pre-developed form. The same two reviewers, using a validated scale, independently assessed the methodological quality of the RCTs and CCTs. The data analysis was performed using Peto Odds ratios. MAIN RESULTS: Of the two relevant studies that were identified in the literature, only one RCT met the inclusion criteria. This RCT compared the effects of two electrostimulation (ES) protocols on hand function in general and on the performance of the first dorsal interosseous muscle in particular, in 15 patients with RA and secondary disuse atrophy of the first dorsal interosseous of the dominant hand. The results showed that ES had significant benefit when compared to a control no treatment group in terms of muscle strength and fatigue resistance of the first dorsal interosseous. Most favourable results were obtained by using a patterned stimulation derived from a fatigued motor unit of the first dorsal interosseous in a normal hand rather than a fixed 10 Hz stimulation frequency. Side effects of the ES application were not reported. REVIEWER'S CONCLUSIONS: ES was shown to have a clinically beneficial effect on grip strength and fatigue resistance for RA patients with muscle atrophy of the hand. However, these conclusions are limited by the low methodological quality of the trial included. More well-designed studies are therefore needed to provide further evidence of the benefits of ES in the management of RA.

Arthritis, Rheumatoid↗

PubMed1987

Electrical stimulation of ventral versus dorsal mesencephalic tegmental areas in the conscious rat: effects on luteinizing hormone release.

This study examined the effect of electrical stimulation of the ventral mesencephalic tegmentum versus the dorsal tegmentum region on blood LH levels in freely moving, ovariectomized (OVX) rats, as well as in OVX, estrogen-primed rats. In OVX rats, electrical stimulation (with parameters of 30 Hz, 0.4-msec biphasic pulses, 50-100 microA and 10 s on/off for 1 h) of the ventral tegmentum region with the aim of activating the ventral noradrenergic tract (VNT) failed to affect the pulsatile pattern of blood LH levels characteristic of OVX animals. In sharp contrast, electrical stimulation of the dorsal tegmentum region inside the ascending dorsal noradrenergic tract (DNT) markedly inhibited pulsatile LH release in OVX rats; the mean blood LH levels during the 1-hour stimulation period were significantly decreased when compared with prestimulation control values. Electrical stimulation in the same region near but outside the DNT was ineffective. In OVX rats primed with estradiol benzoate, electrical stimulation in the ventral or dorsal tegmentum region failed to alter the low, nonpulsatile blood levels of LH. The results in OVX rats suggest that selective activation of the ascending noradrenergic fibres of the DNT but not the VNT can inhibit pulsatile LH release in the awake, freely moving animal. These data further support the possible existence of an inhibitory noradrenergic system in the modulation of LH release.

Animals↗

PubMedDate not supplied

Is electrical stimulation effective in reducing neuropathic pain in patients with diabetes?

Pulsed-dose electrical stimulation is evaluated as an analgesic modality in patients-with painful diabetic neuropathy. Using a knitted silver-plated nylon/dacron stocking electrode, patients were given electrical stimulation over the course of 1 month. Pain was measured weekly, using a 10-cm. visual analog scale. Pain measurements at the end of the 4-week therapy and at 1 month after complete discontinuation of therapy were significantly lower than at the initiation of therapy. The results of this pilot study suggest that nocturnal doses of pulsed-electrical stimulation may be effective in alleviating subjective, burning, diabetic neuropathic pain in a population consisting of patients with grossly intact protective sensation, relatively good distal vascular perfusion and less than ideal glucose control. To the authors' knowledge, this is the first analytic report of pulsed-dose electrical nerve stimulation delivered through a stocking electrode for treatment of symptomatic diabetic neuropathy in medical literature.

Adult↗

PubMedDate not supplied

Electrogastrographic impact of multi-site functional gastric electrical stimulation.

Microprocessor-controlled multi-site functional gastric electrical stimulation using synchronized higher frequency (above 25 Hz) bipolar voltages has been suggested as a possible new avenue towards efficient artificial control of gastric motility. However, the effect of this sequential stimulation on gastric electrical activity is unknown. Because of the substantial strength of the invoked sequential contractions, using implanted electrodes to assess gastric electrical activity (GEA) in experimental animals is difficult, if not impossible. Electrogastrography (EGG), the non-invasively obtained recording of GEA, provides an excellent opportunity to study the changes associated with the multi-site functional stimulation. In this study, we investigated 4 unconscious dogs with 4 circumferential sets of subserosally-implanted stimulating electrodes and 4 force transducers attached close to each stimulating electrode set at operation. The abdominal cavity of each dog was closed after the electrode implantations and 3 standard neonatal electrocardiographic electrodes were attached overlying the abdominal projection of the gastric axis. Two-channel EGG recordings were obtained for 1/2 h before any electrical stimulation and during 1/2 h of intensive sequential stimulation. Significant changes were observed in the EGG pattern during stimulation. These changes were quantified and compared to the basal recordings. Our findings indicate that the interrelation between spectral changes in cutaneous EGG and mechanical activity of the stomach could be far more complex than previously speculated.

Animals↗

PubMed1984

An investigation into the mechanism of cardiovascular responses elicited by electrical stimulation of locus coeruleus and subcoeruleus in the cat.

Electrical stimulation of locus coeruleus (LC) and subcoeruleus (SC) elicited an increase in heart rate (HR) and blood pressure (BP). Adrenergic neurone blockade in the posterior hypothalamus with guanethidine and also bilateral adrenalectomy completely blocked the LC stimulation induced cardiovascular responses. The cardiovascular responses elicited by electrical stimulation of SC were, however, unaffected by the former and only partially inhibited by the latter. It is suggested that the LC stimulation-evoked rise in HR and BP is mediated by catecholamine release from the adrenal medulla due to an activation of the hypothalamic-adrenal axis. The cardiovascular responses elicited by stimulation of SC are mainly due to activation of the sympathetic preganglionic neurones and are further augmented by the adrenal catecholamine release.

Adrenal Medulla↗

PubMed2002

Electrical stimulation of substantia nigra pars reticulata is anticonvulsant in adult and young male rats.

Electrical stimulation of deep brain structures has been used for pain relief and treatment of refractory Parkinson's disease. Recently, stimulation of the subthalamic nucleus or anterior nuclei of the thalamus was introduced for the treatment of refractory epilepsy when other treatments failed. The substantia nigra pars reticulata (SNR) is another crucial site involved in the control of seizures. We studied the effects of continuous electrical stimulation of the SNR as a function of age in male rats. Adult [postnatal day (PN) 60] and young (PN 15) rats with electrodes symmetrically implanted in the SNR were used. The rats were stimulated with continuous constant current pulses (130 Hz) and simultaneously challenged with flurothyl to induce seizures. Control rats had the electrodes implanted but were not stimulated. High-frequency electrical stimulation of the SNR had anticonvulsant effects in both age groups. However, we identified age-specific features: In PN 60 rats, both unilateral and bilateral stimulation of the anterior region of the SNR produced anticonvulsant effects against clonic seizures, while stimulation of the posterior region of the SNR was ineffective. Stimulation of either SNR region had no effects on tonic-clonic seizures. In PN 15 rats, irrespective of the stimulation site within the SNR, bilateral stimulations of the SNR produced anticonvulsant effects against both clonic and tonic-clonic flurothyl-induced seizures, while unilateral stimulation was without effect. The data suggest that the SNR may be a candidate site for deep brain stimulation for the treatment of epilepsy.

Age Factors↗

PubMed2001

Effects of electrical stimulation of the Gasserian ganglion on regional cerebral blood flow after induced subarachnoid hemorrhage in pigs evaluated by 99mTc-HMPAO-SPECT.

It could be demonstrated that cervical spinal cord stimulation increases cerebral blood flow. The effects of electrical stimulation of the trigeminal ganglion in the acute phase of SAH in pigs were investigated. The experiments were carried out on 11 domestic pigs divided in two groups (group I: SAH [n = 5]; group II: SAH and trigeminal stimulation [n = 6]). In all animals a native SPECT was performed. The Gasserian ganglion was exposed for inserting the stimulation electrode. SAH was induced by injecting 10 ml autologous blood through a catheter placed in the suprasellar cistern. 30 minutes after SAH-induction electrical stimulation was started for two hours in group II (2.8-4.5 V, 50 Hz, 300 microseconds). 99mTc-HMPAO (400-540 MBq) was injected intravenously 110 minutes later. In group I 99mTc-HMPAO was applied after the same time interval. 80 minutes later SPECT was performed. Data were processed to calculate the uptake of radioactivity (%/kg tissue weight). The mean values were calculated for the different groups: native animal examination (%/kg tissue weight): 0.6343; group I: 0.468; group II: 0.6533. Comparing the mean values a highly significant difference between group I and group II (p < 0.01) and between native examination and group I (p < 0.01) could be found. No statistical significance could be detected on comparing the left/right-ratio in any ROI. The electrical stimulation of the Gasserian ganglion leads to a significantly increased uptake of 99mTc-HMPAO after induced SAH. Maybe the stimulation of the Gasserian ganglion constitutes a new therapeutic modality treating disturbed rCBF after SAH.

Animals↗

PubMed1988

Hyperglycemia induced by electrical stimulation of lateral part of dorsal parabrachial nucleus.

Electrical stimulation of the lateral part of the dorsal parabrachial nucleus (PBD) induces hyperglycemia by enhancing glucagon secretion and suppressing insulin secretion in rats. The mechanism of this effect in the light period was examined by use of blockers of the autonomic nervous system. Hexamethonium, a ganglion blocker, and propranolol, a beta-adrenergic blocker, markedly inhibited the hyperglycemic response to stimulation of the lateral part of the PBD (LPBD). In contrast, phenoxybenzamine, an alpha-adrenergic blocker, and atropine methylnitrate, a muscarinic blocker, had no effect. Because previous studies showed that bilateral lesions of the suprachiasmatic nucleus (SCN) eliminated hyperglycemia induced by intracranial injection of 2-deoxy-D-glucose and that blinding largely suppressed the hyperglycemia, the effects of these two treatments on hyperglycemia induced by electrical stimulation of the LPBD were examined. SCN lesions abolished the hyperglycemic response but did not affect the hyperglucagonemic response. Results 4 wk after orbital enucleation were similar to those after SCN lesions. These findings suggest that the SCN and a beta-adrenergic mechanism are involved in the hyperglycemic response to LPBD stimulation.

Animals↗

PubMedDate not supplied

Effect of impulse duration on patients' perception of electrical stimulation and block effectiveness during axillary block in unsedated ambulatory patients.

BACKGROUND AND OBJECTIVES: Chronaxie of the motor-neurons (A-alpha) is shorter than that of the sensory A-delta and C neurons. Therefore, a short current impulse should elicit a painless muscle twitch. This randomized, double-blind study of patients having ambulatory axillary block by multiple neurostimulations compared patients' perception of electrical stimulation, latency, and quality of analgesia and the incidence of adverse effects. METHODS: In group S (short impulse, n = 44) 0.1-ms-current impulses were used and in group L (long impulse, n = 43) 0.3-ms impulses were used. Initial amplitude was 2 mA. Local anesthetic was injected near the 4 terminal nerves (musculocutaneous, median, ulnar, radial) after reaching a target amplitude between 0.1 and 0.5 mA. Patients were specifically requested to categorize sensation of electrical stimulation "electric shocks" as follows: no discomfort, discomfort, pain. Pain was then quantified on a visual analog scale (VAS). Surgically ineffective blocks were supplemented after 30 minutes. A patient was defined as ready for surgery (complete block) when analgesia was present in all areas distal to the elbow. RESULTS: There were no significant differences between groups in quali- and quantitative assessments of electrical stimulation. Eight patients (18%) in either group described the sensation as "strange or funny." Eight patients in group S and 13 (30%) in group L reported discomfort during stimulation. Twenty-eight patients (64%) in S group and 22 (52%) in L group experienced pain. Median VAS (0 to 100) of this pain was 21 and 24, respectively. Block performance time was 9 minutes in L group and 11 minutes in S group (P < .001), but the latency of analgesia was 23 minutes for both groups and the times to achieve complete block were, therefore, similar: 32 minutes in L group and 34 minutes in S group (not significant [NS]). Nine group S and 8 group L patients required supplementary blocks (NS). The incidence of vessel punctures and accidental intravascular injections were also similar in both groups. CONCLUSIONS: This study did not confirm our hypothesis that short-current impulses (0.1 ms) make neurostimulation of peripheral nerves painless, by selectively depolarizing motor-neurons. Longer impulses (0.3 ms) shorten block performance time, probably by easier location of the nerves, but the clinical relevance of this finding is doubtful.

Adolescent↗