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PubMed1990

Electrical stimulation: current concepts and indications.

The use of electrical stimulation in fracture management is increasing. Electrical stimulation has been found to offer a reasonable means of treatment for nonunions that have failed to respond to previous bone grafting over an extended period of time. The effective use of electrical stimulation devices requires an understanding of the various principles and concepts employed by the four types of stimulators currently available. While the exact mechanism of electrically-induced osteogenesis is uncertain, current theories indicate that several factors probably are involved and more than one mechanism may be responsible. There are significant differences in the clinical applications of the various types of electrical stimulators. Whether these differences are significant from a practical standpoint remains to be seen.

Animals↗

PubMed1989

Excitatory and inhibitory influences on bladder activity elicited by electrical stimulation in the pontine micturition center in the rat.

Electrical stimulation at various sites in the dorsal pontine tegmentum in urethane anesthetized rats modulated activity of the urinary bladder as well as efferent firing on bladder postganglionic nerves. Electrical stimulation (0.2 ms 50 Hz, 5-20 V or 30-150 microA, 2-5 s train duration) using a microelectrode (tip diameter, 10-20 microns) in an excitatory area located rostral and medial to the locus coeruleus evoked short latency (less than 2 s) large amplitude (greater than 20 cm H2O) bladder contractions and increased firing on the bladder postganglionic nerves. Stimulation at sites adjacent to the excitatory area inhibited bladder postganglionic nerve firing and bladder activity. Inhibitory responses were evident as either a decrease in intravesical pressure, an increased interval between bladder contractions, or an interruption or elimination of bladder contractions. The threshold intensity for excitation using a large electrode (2-4 V) was slightly higher than that for inhibition (1.5-2 V). The optimum sites for evoking bladder contractions were located in and close to the laterodorsal tegmental nucleus (LDT) and in the periaqueductal gray just dorsal or dorsolateral to the LDT. The extent of the area that induced bladder contractions was 0.5-1.2 mm in diameter in each rat when a microelectrode was employed for electrical stimulation. Electrical stimulation in the optimum site for evoking bladder contractions induced relatively little striated muscle activity and produced no short-latency blood pressure changes. The longer latency blood pressure changes associated with a spontaneous bladder contraction were still present following a stimulation of the dorsolateral pons. These data are consistent with the view that neurons in the dorsal pontine tegmentum play an important role in the regulation of urine storage as well as urine release.

Action Potentials↗

PubMed2002

Cutaneous electrical stimulation of acupuncture points may enhance gastric myoelectrical regularity.

BACKGROUND/AIM: Cutaneous electrical stimulation has been reported to be as effective as electroacupuncture. The aim of this study was to test whether cutaneous electrical stimulation had the same effect as electroacupuncture to enhance the regularity of myoelectrical activity. METHODS: Fifteen healthy male volunteers were enrolled for this study. Electrogastrography (EGG) was performed for 30 min at the baseline, 30 min during electroacupuncture or cutaneous electrical stimulation, and for an additional 30 min thereafter. RESULTS: During 3 Hz of electroacupuncture on the Zusanli point, there was a significant increase in the percentage of normal frequency. The percentage of normal frequency in the post-acupuncture period was also increased, but it was not statistically significant when compared to the baseline. There was a significant decrease in the tachygastric and bradygastric rhythm during electroacupuncture on the Zusanli points. There were similar changes of EGG parameters with cutaneous electrical stimulation on the Zusanli points. The percentage of normal frequency during cutaneous electrical stimulation increased significantly. However, the percentage of normal frequency in the post-cutaneous electrical stimulation period was similar to the baseline. There was a significant decrease in the percentage of tachygastric rhythm during cutaneous electrical stimulation on the Zusanli points. However, there was no significant change in the percentage of bradygastric rhythm during and after the cutaneous electrical stimulation periods. CONCLUSIONS: The effect of cutaneous electrical stimulation on the percentage of normal frequency and tachygastria is similar to electroacupuncture. Nonetheless, the changes of the percentage in bradygastria are not significant.

Acupuncture Points↗

PubMed2006

Decrease in anterior knee laxity by electrical stimulation of normal and reconstructed anterior cruciate ligaments.

We have investigated the changes in anterior laxity of the knee in response to direct electrical stimulation of eight normal and 45 reconstructed anterior cruciate ligaments (ACLs). In the latter, the mean time from reconstruction was 26.7 months (24 to 32). The ACL was stimulated electrically using a bipolar electrode probe during arthroscopy. Anterior laxity was examined with the knee flexed at 20 degrees under a force of 134 N applied anteriorly to the tibia using the KT-2000 knee arthrometer before, during and after electrical stimulation. Anterior tibial translation in eight normal and 17 ACL-reconstructed knees was significantly decreased during stimulation, compared with that before stimulation. In 28 knees with reconstruction of the ACL, in 22 of which the grafts were found to have detectable somatosensory evoked potentials during stimulation, anterior tibial translation was not decreased. These findings suggest that the ACL-hamstring reflex arc in normal knees may contribute to the functional stability and that this may not be fully restored after some reconstructions of the ACL.

Adolescent↗

PubMed2005

Modular transcutaneous functional electrical stimulation system.

A new multipurpose programmable transcutaneous electric stimulator, Compex Motion, was developed to allow users to design various custom-made neuroprostheses, neurological assessment devices, muscle exercise systems, and experimental setups for physiological studies. Compex Motion can generate any arbitrary stimulation sequence, which can be controlled or regulated in real-time using any external sensor or laboratory equipment. Compex Motion originated from the existing Compex 2 electric stimulator, manufactured by a Swiss based company, Compex SA. The Compex Motion stimulator represents a further evolution and expansion of the ETHZ-ParaCare functional electrical stimulation system. This stimulator provides all the advanced functional electrical stimulation (FES) application and control features and can be easily incorporated into any standard rehabilitation program. Compex Motion has successfully been applied as a neuroprosthesis for walking, reaching and grasping in more than 100 stroke and spinal cord injured patients. This system has also been used to strengthen muscles and to investigate muscle properties in able-bodied subjects. Compex Motion is a multipurpose FES system specially designed to promote sharing and exchanging of stimulation protocols, sensors, and user interfaces. To the best of our knowledge an FES system that has similar capabilities does not exist yet.

Adult↗

PubMed2006

Electrical stimulation therapies for spinal fusions: current concepts.

Electrical stimulation therapies have been used for more than 30 years to enhance spinal fusions. Although their positive effects on spinal fusions have been widely reported, the mechanisms of action of the technologies were only recently identified. Three types of technologies are available clinically: direct current, capacitive coupling, and inductive coupling. The latter is the basis of pulsed electromagnetic fields and combined magnetic fields. This review summarizes the current concepts on the mechanisms of action, animal and clinical studies, and cost justification for the use of electrical stimulation for spinal fusions. Scientific studies support the validity of electrical stimulation treatments. The mechanisms of action of each of the three electrical stimulation therapies are different. New data demonstrates that the upregulation of several growth factors may be responsible for the clinical success seen with the use of such technologies.

Animals↗

PubMed1983

Effects of electrical stimulation of the human olfactory mucosa.

Electrical stimulation of the human olfactory mucosa was performed by means of an electrode attached to a rhinoscope . Stimulation of the nasal mucosa did not evoke smell sensations, but suppressed smell sensations of presented odorants. When electrical stimulation followed the exposure to an odorant within a certain interval, the stimulus recalled the already faded sensation of the preceding odorant. Electrical stimulation without prior natural stimulation produced unpleasant sensations in 3 patients with a history of temporal lobe seizures and olfactory auras , but not in patients with primary, generalized or focal epilepsy.

Electric Stimulation↗

PubMed1979

Reactivity of isolated bovine facial vessels to electric stimulation and to drugs.

The effects of electric stimulation on isometric force generation of isolated helical strips of bovine facial arteries (BFA) and veins (BFV) were investigated. Whereas BFA always contracted, electrically stimulated BFV showed a biphasic response, i.e. a small, transient contraction followed by an intense relaxation. The findings presented suggest a neurogenic response for the vasodilator component of BFV response to electric stimulation. Exogenous catecholamines and serotonin dilated the veins; the effects were antagonized by propranolol and dihydroergotamine, respectively. Dopamine-induced relaxations were only partially inhibited by propranolol; the residual relaxations were antagonized by chlorpormazine and haloperidol. Relaxations of the veins after electric stimulation or after administration of noradrenaline were accompanied by an increase of the cAMP content. In the BFA catecholamines, serotonin and histamine increased the tension, whereas isoprenaline was ineffective. Acetylcholine contracted the veins and relaxed the arteries; both effects were antagonized by atropine.

Acetylcholine↗

PubMed1987

Activation of periaqueductal grey pools of beta-endorphin by analgetic electrical stimulation in freely moving rats.

Electrical stimulation of the ventral midbrain periaqueductal grey (PAG) elicited an antinociception (analgesia) in freely moving rats. Stimulated animals displayed a pronounced decrease in levels of immunoreactive (ir)-beta-endorphin (beta-EP) in the midbrain PAG. This depletion was selective in that: animals placed in the chamber and not stimulated revealed neither an analgesia nor an alteration in levels of ir-beta-EP. No change in levels of ir-beta-EP was detectable in other brain regions. Both stimulated rats and rats placed in the chamber and not stimulated revealed a rise in circulating ir-beta-EP: the magnitude of this rise did not, however, differ between these groups. Levels of ir-Met-enkephalin, ir-Leu-enkephalin and ir-dynorphin A were modified neither in the PAG nor in other CNS tissues. The data demonstrate that electrical stimulation of the midbrain PAG selectively influences (presumably activates) pools of beta-EP therein. Together with our finding that destruction of PAG-localized beta-EP neurones to block stimulation-analgesia, the data suggest that an activation of intrinsic pools of beta-EP underlies stimulation-produced analgesia elicited from the PAG in the rat.

Animals↗

PubMed2001

Electrical stimulation with bone and wound healing.

Electrical stimulation has been used to heal fractures and ulcers and reduce pain through modulation of local body processes. It has been recognized that mechanical forces and bioelectricity have an intimate relationship in influencing the production of bone. Science has developed techniques to affect change in the electrical charge of fractures to positively affect the healing process. Electrical stimulation, through invasive and noninvasive applications, has produced excellent results in the treatment of nonunions and ulcer care. A thorough review of the electrical properties of bone and soft tissue and the influence of electrical stimulation on healing is presented here.

Bone Diseases↗

PubMed2006

Electromotile hearing: acoustic tones mask psychophysical response to high-frequency electrical stimulation of intact guinea pig cochleae.

When sinusoidal electric stimulation is applied to the intact cochlea, a frequency-specific acoustic emission can be recorded in the ear canal. Acoustic emissions are produced by basilar membrane motion, and have been used to suggest a corresponding acoustic sensation termed "electromotile hearing." Electromotile hearing has been specifically attributed to electric stimulation of outer hair cells in the intact organ of Corti. To determine the nature of the auditory perception produced by electric stimulation of a cochlea with intact outer hair cells, guinea pigs were tested in a psychophysical task. First, subjects were trained to report detection of sinusoidal acoustic stimuli and dynamic range was assessed using response latency. Subjects were then implanted with a ball electrode placed into scala tympani. Following the surgical implant procedure, subjects were transferred to a task in which acoustic signals were replaced by sinusoidal electric stimulation, and dynamic range was assessed again. Finally, the ability of acoustic pure-tone stimuli to mask the detection of the electric signals was assessed. Based on the masking effects, it is concluded that sinusoidal electric stimulation of the intact cochlea results in perception of a tonal (rather than a broadband or noisy) sound at a frequency of 8 kHz or above.

Acoustics↗

PubMed2001

Comparing stimulation-induced pain during percutaneous (intramuscular) and transcutaneous neuromuscular electric stimulation for treating shoulder subluxation in hemiplegia.

OBJECTIVE: To determine whether percutaneous (intramuscular) neuromuscular electric stimulation (perc-NMES) is less painful than transcutaneous neuromuscular electric stimulation (trans-NMES) for treating shoulder subluxation in hemiplegia. DESIGN: Double-blind, crossover trial. SETTING: University-affiliated tertiary care hospital. PARTICIPANTS: A convenience sample of 10 hemiplegic subjects with at least 1 fingerbreadth of glenohumeral subluxation. INTERVENTIONS: All subjects received 3 randomly ordered pairs of perc-NMES and trans-NMES to the supraspinatus and posterior deltoid muscles of the subluxated shoulder. Both types of stimulation were optimized to provide full joint reduction with minimal discomfort. MAIN OUTCOME MEASURES: Pain was assessed after each stimulation with a 10-cm visual analog scale (VAS) and the McGill Pain Questionnaire, using the Pain Rating Index (PRI) scoring method. Subjects were asked which type of stimulation they would prefer for 6 weeks of treatment. Wilcoxon's signed-rank test was used to compare median differences in VAS and PRI between perc-NMES and trans-NMES. RESULTS: Median VAS scores for perc-NMES and trans-NMES were 1 and 5.7, respectively (p = .007). Median PRI scores for perc-NMES and trans-NMES were 7 and 19.5, respectively (p = .018). Nine of the 10 subjects preferred perc-NMES to trans-NMES for treatment. CONCLUSION: Data suggest that perc-NMES is less painful than trans-NMES in the treatment of shoulder subluxation in hemiplegia.

Adult↗

PubMed1993

Axon termination conditions for electrical stimulation.

The cable model for electrical stimulation near the terminal of a passive fiber is derived for excitation by an arbitrary, time-varying, applied extracellular field. Unless the termination impedance is comparable to that of mammalian node of Ranvier, the end-conditions require the longitudinal intracellular current at the fiber terminal to be negligibly small. This requirement substantially alters the membrane potential profile from that obtained with a fiber of infinite length. Stimulation near the end of a fiber may result in lower thresholds and may reverse the anodal/cathodal threshold ratio obtained with stimulation in the mid-portion of the fiber. Chronaxie for stimulation near the terminal may be much smaller than at a distance from the terminal and the strength-duration curve may be nonmonotonic. These differences may have significant implications for any application of electrical stimulation where fiber terminations may play a role in the excitatory process.

Electric Stimulation↗

PubMed1998

Transmitter release and uptake evoked by the amphibian skin alkaloid, pumiliotoxin-B (PTX-B), in the electrically stimulated mouse vas deferens preparation (MVD).

Upon electrical stimulation three transmitters are known to be released from the adrenergic nerve terminals of the isolated MVD preparation: two motor transmitters (noradrenaline (NA) and ATP) acting synergistically to provoke twitch contraction, and an inhibitory transmitter, the peptide NPY. The frog alkaloid pumiliotoxin-B (PTX-B) displayed two opposite effects on the electrically stimulated MVD: at low concentrations (0.1-0.3 microM) it caused twitch depression, at higher concentrations (0.5-2 microM) there was a potent twitch stimulation. Transmitters and/or receptors involved in the depressive effect could not be clearly identified, although interference with NPY is possible. On the other hand, the potent twitch stimulation caused by PTX-B may be due to exaggerated release of the same transmitters (NA and ATP) involved in twitch stimulation produced by electrical stimulation. Opening by PTX-B of the Na+ channels on the membrane of the adrenergic nerve terminals causes activation of the amine pump facilitating re-uptake of not only endogenous NA but also of exogenous catecholamines.

Adrenergic alpha-Agonists↗

PubMed1992

[A physiological investigation of chronic electrical stimulation with scala tympani electrodes in kittens].

A physiological investigation of cochlear electrical stimulation was undertaken in six two-month-old kittens. The scala tympani electrodes were implanted and electrically stimulated using biphasic balanced electrical pulses for periods of 1000-1500h in four ears. Four ears received implants for same period but without electrical stimulation. The other two ears served as normal control. The results indicated: 1) Chronic electrical stimulation of the cochlea within electrochemically safe limits did not influence the hearing of kittens and the normal delivery of impulses evoked by acoustic and electrical signals on the auditory brainstem pathway. 2) The wave shapes of EABRs were similar to those of ABRs. The amplitudes of EABRs showed a significant increase following chronic electrical stimulation, resulting in a leftward shift in the input/output function. The absolute latencies and interwave latencies of waves II-III, III-IV and II-IV were significantly shorter than those of ABRs. These results imply that there was no adverse effect of chronic electrical stimulation on the maturing auditory systems of kittens using these electrical parameters and the mechanism of electrical hearing should be further studied.

Animals↗

PubMed2000

Subdural air limits the elicitation of compound muscle action potentials by high-frequency transcranial electrical stimulation.

High-frequency transcranial electrical stimulation was performed in 8 patients undergoing surgery in the sitting position. Following the opening of the dura of the posterior fossa changes in compound muscle action potentials were observed. These changes were not attributable to surgical manoeuvres at the brain stem or spinal cord, or to anaesthetic changes. In all these cases intraoperative fluoroscopy of the skull revealed a subdural air collection underneath the stimulation electrodes. Such a subdural air collection, not infrequent in patients operated on in the sitting position, limits the application of high-frequency transcranial electrical stimulation as a monitoring technique. It remains unclear if this effect is due to the increasing distance between scalp and cortex and the insulating effect of subdural air, or due to displacement of the motor cortex. The practical importance of this report is derived from the increasing application of intraoperative motor pathway monitoring.

Adult↗

PubMed1981

Depressant action of chlordiazepoxide on cardiovascular and respiratory changes induced by aversive electrical stimulation of the brain.

1. Electrical stimulation of the dorsal periaqueductal gray matter (DPAG), an aversive area of the rat brain, increased the mean blood pressure of awake rats as well as of animals anesthetized with urethane. 2. In the anesthetized rats, increases in heart rate and in breath rate were also induced by DPAG stimulation. 3. Chlordiazepoxide, a benzodiazepine, decreased the blood pressure rise caused by aversive stimulation of the brain in the awake rat. 4. Chlordiazepoxide elicited the same effect in urethane-anesthetized rats. In addition, the hyperpnea induced by electrical stimulation of the dorsal periaqueductal gray matter was also decreased by the drug. 5. The pressor response to intravenous noradrenaline was not affected by chlordiazepoxide. 6. These results suggest that benzodiazepines attenuate the neurovegetative changes accompanying emotion by depressing brain systems that integrate emotional behavior.

Animals↗

PubMed1990

The use of electrically stimulated skeletal muscle to pump blood.

Electrically stimulated skeletal muscle can be used in many ways to pump blood. The important physiological characteristics of skeletal muscle for use in a cardiac assist role are presented. The force developed by a twitch and tetanic contraction are quantitated and the considerations in the choice of the stimulus applied to the innervating motor nerve are discussed. The importance of stimulus frequency and duration of the stimulus train are presented in terms of the stroke volume produced by skeletal muscle contracting around a pouch. The effect that preload has on pouch stroke volume and muscle blood flow are demonstrated. Finally an example is given in which cardiac output is augmented by an untrained, electrically stimulated, canine rectus abdominis muscle wrapped around a pouch connected between the apex of the left ventricle and the aorta. In this study, the augmentation in cardiac output was measured when the skeletal muscle was contracted after each second, third, and fourth ventricular contraction. The augmentation was 46% +/- 4, 31% +/- 7, and 25% +/- 4, respectively, for the three contraction regimens. Although electrically stimulated skeletal muscle can be used as a power source to assist the failing heart, the optimum application is yet to be discovered. Important considerations in selecting the optimal application are preload, stimulus train duration, train rate, and muscle blood flow.

Abdominal Muscles↗