Physiological and therapeutic effects of high frequency electrical pulses

Efficacy of cranial electrotherapy stimulation in patients with burning mouth syndrome: a randomized, controlled, double-blind pilot study

Background

The Burning mouth syndrome (BMS) is a chronic pain syndrome characterized by a burning sensation in the oral mucous membranes. The etiology and pathophysiology of BMS is largely unexplained. To date, there is no evidence-based treatment strategy for BMS. Cranial electrical stimulation (CES) represents a non-invasive treatment option with a low side effect profile that is approved for the treatment of pain, depression, anxiety disorder and insomnia. It has shown efficacy in studies for chronic pain such as fibromyalgia and neuropathic pain after spinal cord injury. This study aimed to investigate the therapeutic effectiveness of CES in combination with local transcutaneous electrical nerve stimulation (TENS) as an adjunct therapy in patients with BMS compared to sham stimulation.

Methods

This randomized, double-blind, sham-controlled pilot study enrolled 22 patients, aged 18 years and over, with the diagnosis of BMS meeting the ICHD-3 criteria from August 2020 to June 2021. The study duration was 4 weeks (28 days) per participant. After randomization, the active group participants (n = 11) received a 100 μA CES treatment for 60 min a day whereas the devices in the Sham group did not emit electricity. Simple linear regression was used to determine whether the interventions promoted significant differences in pain intensity.

Results

The linear regression showed that the period of stimulation significantly predicted decrease in the intensity of pain in the active group [β = -0.036; t(26) = -7.219; p < 0.001] as in the sham group [β = -0.026; t(26) = -2.56; p < 0.017]. With the applied cutoff of 30% pain reduction within the stimulation period, both the active and sham groups had 36% responders (n = 4) (Fisher's exact test, p = 1.00). In both groups (active stimulation and sham group), a significant decrease in the intensity of pain, somatic symptoms and an improvement in sleep quality over the study period was observed. Subjects reported no adverse events during the study.

Conclusion

Although CES is an easily applicable and safe therapeutic option for chronic facial pain, active stimulation was not superior to sham stimulation. Among other reasons, this could be due to the short double-blinded treatment period, duration of the daily stimulation session or the small sample size.

Effects of cranial electrotherapy stimulation on improving depressive symptoms in people with stress: A randomized, double-blind controlled study

BACKGROUND

Cranial electrotherapy stimulation (CES) is a form of neurostimulation that delivers alternating microcurrent via electrodes on the head. We investigated the effectiveness of CES in reducing stress.

METHODS

Participants who experienced subjective stress combined with subclinical depression or insomnia were recruited based on interviews and questionnaires. The subjects were randomly assigned to the active CES or sham groups and asked to use the device for 30 min twice a day for three weeks. Psychological rating scales, quantitative electroencephalography (QEEG), and serial salivary cortisol levels were measured before and after the intervention.

RESULTS

Sixty-two participants (58 females, mean age = 47.3 ± 8.2 years) completed the trial. After intervention, the depression scores improved significantly to a nearly normal level (Beck depression inventory-II, 31.3 ± 11.6 to 10.8 ± 7.2, p < 0.001) in the CES group, which were greater improvement compared to the sham group (p = 0.020). There were significant group-by-visit interactions in absolute delta power in the temporal area (p = 0.033), and theta (p = 0.038), beta (p = 0.048), and high beta power (p = 0.048) in the parietal area. CES led to a flattening of the cortisol slope (p = 0.011) and an increase in bedtime cortisol (p = 0.036) compared to the sham group.

LIMITATIONS

Bias may have been introduced during the process because device use and sample collection were self-conducted by participants at home.

CONCLUSIONS

CES can alleviate depressive symptoms and stress response, showing a potential as an adjunctive therapy for stress.

Comparison of the effects of cranial electrotherapy stimulation and midazolam as preoperative treatment in geriatric patients: A CONSORT-compliant randomized controlled trial

BACKGROUND

Although midazolam is widely administered as an anxiolytic premedication, it may cause over-sedation and hypoxia in geriatric patients. Cranial electrotherapy stimulation (CES) is a nonpharmacological device with anxiolytic effect. This study compared the effects of CES and midazolam as a preoperative treatment in geriatric patients.

METHODS

Eighty patients, under the age of 65 to 79 years, undergoing general anesthesia were randomly assigned into midazolam premedication group (M group, n = 40) or CES pretreatment group (CES group, n = 40). The patients in the M group were intramuscularly injected with midazolam (0.07 mg/kg) 30 minutes before receiving general anesthesia. The patients in the CES group received 20 minutes of CES pretreatment on the day before and on the morning of the surgery.

RESULTS

In the preoperative holding area, the anxiety score (P = .02) and the sedation score (P < .001) were significantly lower in the CES group compared with those in the M group. The oxygen saturations at the preoperative holding area and the operating room were significantly higher in the CES group than those in the M group (P < .001).

CONCLUSION

CES pretreatment relieved preoperative anxiety with less risk of over-sedation and respiratory depression than midazolam premedication in geriatric patients.

Effects of electrostatic therapy on nighttime sleep and daytime symptoms in patients with chronic insomnia: Evidences from an open label study

INTRODUCTION

Transcranial electric stimulation (TES) is a neuromodulation approach that applies low-intensity electrical current to the brain and has been proposed as a treatment for insomnia. Electrostatic therapy is a kind of TES and people do not have a feeling of electrical stimuli when the voltage of static electricity is lower than 2,000 volts. However, no studies have examined the effects of electrostatic therapy on objective sleep and daytime symptoms in patients with insomnia.

MATERIALS AND METHODS

Thirty chronic insomnia patients were included. All patients received a 6 week electrostatic therapy and three comprehensive assessments including two consecutive polysomnography (PSG) and daytime symptoms assessments, at pre-treatment, 3 week and 6 week of treatment. Insomnia Severity Index (ISI) was used to assess the severity of insomnia. Multiple sleep latency test (MSLT), Epworth Sleepiness Scale (ESS), and Flinders Fatigue Scale (FFS) were used to assess objective and self-reported daytime sleepiness and fatigue, respectively. Attention network test (ANT) was used to assess attention levels.

RESULTS

Total ISI scores decreased significantly at 3 weeks (p < 0.001) and 6 weeks (p < 0.001) after initiation of treatment. Furthermore, objective total sleep time (TST, p = 0.020) and sleep efficiency (SE, p = 0.009) increased and wake time after sleep onset (p = 0.012) decreased significantly after 6 weeks electrostatic therapy. Regarding daytime symptoms, ESS and FFS scores decreased significantly at 3 weeks (ESS, p = 0.047; FFS, p = 0.017) and 6 weeks (ESS, p = 0.008; FFS, p = 0.003) after initiation of treatment. Moreover, executive control improved significantly from pre-treatment to 3 weeks (p = 0.006) and 6 weeks (p = 0.013) and altering network improved significantly at 6 weeks (p = 0.003) after initiation of treatment. Secondary analyses showed that TST and SE improved significantly after electrostatic therapy in insomnia patients who slept < 390 min (all p-value < 0.05). However, no significant changes regarding TST and SE were observed in insomnia patients who slept ≥ 390 min.

CONCLUSION

Electrostatic therapy improves both nighttime sleep and daytime symptoms in patients with chronic insomnia. The effect on objective sleep appears to be stronger in patient with objective short sleep duration. Electrostatic therapy might be a therapeutic choice for insomnia patients with difficulty maintaining sleep and not responding to behavioral treatments.

CLINICAL TRIAL REGISTRATION

[www.clinicaltrials.gov], identifier [ChiCTR2100051590].

A meta-analysis of cranial electrotherapy stimulation in the treatment of depression

BACKGROUND

Depression rates have reached historic highs, with 49% of Americans reporting unabating symptoms and signs of depression, representing a 12% increase compared to the same time in 2019. With depression as a moderating factor for suicide, the need for efficacious treatments for depression has never been more pronounced. Although the armamentarium of the psychiatrist seems impressive having multiple medications and psychotherapy options, with guidelines for combination and augmentation treatments; many patients do not improve or are not suitable candidates for the usual, customary and reasonable (UCR) depression treatments. The use of various forms of brain stimulation technology as a complementary or alternative treatment for depression is growing and is expected to be part of the armamentarium of most psychiatrists by 2030. One form of brain stimulation, available in a phone sized prescription device, is cranial electrical stimulation (CES) which has been used as a treatment for depression since the 1970s. We have conducted two meta-analyses of CES research for depression separating randomized controlled trials (N = 5) from non-randomized studies on interventions (N = 12). For the double-blind RCTs 100 μA was used for 1 hour per day as 100 μA is a subsensory level of current so identical sham treatment devices could be used.

METHODS

Our literature review followed Cooper's Taxonomy of Literature Reviews that is appropriate for the behavioral and physical sciences and the PRISMA reporting guidelines. The evaluation of strengths and limitations of the research studies included in this report adheres to recommended published guidelines in the Cochrane Handbook for Systematic Reviews of Interventions, and in the Handbook of Research Synthesis and Meta-Analysis. We used the Cohen's d effect size summary metric in all analyses. Homogeneity of effect sizes within the fixed and random effects models are reported. Meta-analyses were performed using the Compressive Meta-Analysis, version 3 program.

RESULTS

The 5 RCTs represent a combined N of 242 and the 12 NRSIs represent 16 data sets with a combined N of 1173 for total of 1415 subjects across 17 studies. There were male and female subjects, from adolescents to 60 years old. The average effect for the 5 RCTs was calculated as d = -0.69 (i.e., the mean depression level at posttest for the active group was -0.69 standard deviations lower than the mean depression level for the sham group), a medium effect. The additional 12 NRSI studies analyzed show a small effect of d = -0.43 in favor of the active treatment group.

CONCLUSION

We conclude that CES has a small to medium significant effect in symptoms of depression across moderate to severe patients in civilian, military, veterans, advanced cancer and pediatric populations.

A Critical Review of Cranial Electrotherapy Stimulation for Neuromodulation in Clinical and Non-clinical Samples

Cranial electrotherapy stimulation (CES) is a neuromodulation tool used for treating several clinical disorders, including insomnia, anxiety, and depression. More recently, a limited number of studies have examined CES for altering affect, physiology, and behavior in healthy, non-clinical samples. The physiological, neurochemical, and metabolic mechanisms underlying CES effects are currently unknown. Computational modeling suggests that electrical current administered with CES at the earlobes can reach cortical and subcortical regions at very low intensities associated with subthreshold neuromodulatory effects, and studies using electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) show some effects on alpha band EEG activity, and modulation of the default mode network during CES administration. One theory suggests that CES modulates brain stem (e.g., medulla), limbic (e.g., thalamus, amygdala), and cortical (e.g., prefrontal cortex) regions and increases relative parasympathetic to sympathetic drive in the autonomic nervous system. There is no direct evidence supporting this theory, but one of its assumptions is that CES may induce its effects by stimulating afferent projections of the vagus nerve, which provides parasympathetic signals to the cardiorespiratory and digestive systems. In our critical review of studies using CES in clinical and non-clinical populations, we found severe methodological concerns, including potential conflicts of interest, risk of methodological and analytic biases, issues with sham credibility, lack of blinding, and a severe heterogeneity of CES parameters selected and employed across scientists, laboratories, institutions, and studies. These limitations make it difficult to derive consistent or compelling insights from the extant literature, tempering enthusiasm for CES and its potential to alter nervous system activity or behavior in meaningful or reliable ways. The lack of compelling evidence also motivates well-designed and relatively high-powered experiments to assess how CES might modulate the physiological, affective, and cognitive responses to stress. Establishing reliable empirical links between CES administration and human performance is critical for supporting its prospective use during occupational training, operations, or recovery, ensuring reliability and robustness of effects, characterizing if, when, and in whom such effects might arise, and ensuring that any benefits of CES outweigh the risks of adverse events.

Clinical effectiveness and cost minimisation model of Alpha-Stim cranial electrotherapy stimulation in treatment seeking patients with moderate to severe generalised anxiety disorder

BACKGROUND

Cranial electrotherapy stimulation (CES) is a well-tolerated neuromodulation treatment with demonstrated trial efficacy in anxiety disorders. The aim of the current study was to demonstrate its clinical and cost effectiveness during and after CES in people with generalised anxiety disorder (GAD) who had not responded to low intensity psychological treatment in a routine health service.

METHODS

Consecutive sample of eligible patients with GAD waiting for individual cognitive behaviour therapy (CBT) selected from two publicly funded services in England. They received 60 min per day Alpha-Stim CES for 6-12 weeks. Primary outcome was remission on the GAD-7 scale at 12 and 24 weeks. Cost effectiveness was examined using a cost minimisation model of direct health costs.

RESULTS

Of 161 patients recruited, 72 (44.7%) and 77 (47.8%) achieved remission on the GAD-7 at 12 and 24 weeks respectively with 122 (75.8%) receiving at least 6 weeks CES. Mean (sd) GAD-7 score at baseline significantly improved from 15.77 (3.21) to 8.92 (5.42) and 8.99 (6.18) at 12 and 24 weeks respectively (p < 0.001). 80 (49.7%) participants required further individual CBT. CES provided a saving of £540.88 per patient (95% CI -£327.12, £648.69).

LIMITATIONS

Participants were not randomised and there was no control group. Only 48 (29.9%) participants completed every assessment.

CONCLUSION

In patients with generalised anxiety disorder not responding to low intensity psychological treatment, 6-12 weeks daily Alpha Stim CES may be effective after treatment and 3 months later, thereby reducing the need for individual CBT and saving health costs.

Special Considerations and Assessment in Patients with Multiple Sclerosis

Multiple sclerosis is a progressive autoimmune neurologic disorder that may affect any region of the central nervous system. Spasticity in patients with multiple sclerosis can be debilitating and detrimental to the function and quality of life of patients. Treatment options include oral medications, chemodenervation, physical therapy, and modalities. Cannabinoids in the form of a delta-9-tetrahydrocannabinol/cannabidiol oro-mucosal spray has been shown to be effective in addressing spasticity in multiple sclerosis. Successful treatment of spasticity will be integrated, multimodal, and individualized.

Cranial electrotherapy stimulation affects mood state but not levels of peripheral neurotrophic factors or hypothalamic- pituitary-adrenal axis regulation

Cranial electrotherapy stimulation (CES) is reported to aid in relieving symptoms of depression and anxiety, though the mechanism underlying this effect remains unclear. Therefore, the present study aimed to evaluate changes in the hypothalamic-pituitary-adrenal (HPA) axis response and levels of neurotrophic factors, as well as changes in mood state, in patients undergoing CES therapy. Fifty healthy postmenopausal women were randomly assigned to either a Sham CES group (n = 25) or an Active CES group (n = 25). CES treatment was conducted in 20-minute sessions, three times per week for 8 weeks, using a micro current cranial electrotherapy stimulator. Blood samples were collected prior to and following the 8-week treatment period for measurement of cortisol, adrenocorticotropic hormone (ACTH), brain-derived neurotrophic factor (BDNF), and nerve growth factor (NGF) levels. Changes in mood state were also examined at the time of blood collection using the Profile of Mood States (POMS). No significant differences in cortisol, ACTH, BDNF, or NGF were observed between the two participant groups (p > 0.05) following the treatment period. However, those in the Active CES group exhibited significantly decreased Tension-Anxiety and Depression-Dejection scores on the POMS relative to pre-treatment scores (p < 0.05). Furthermore, Depression-Dejection scores following treatment were significantly lower in the Active CES group than in the Sham CES group (p < 0.05). No significant differences were observed in any other POMS scores such as Anger-Hostility, Vigor-Activity, Fatigue-Inertia, and Confusion-Bewilderment (p > 0.05). These results suggest that 8 weeks of CES treatment does not induce changes in blood levels of neurotrophic factors or HPA-axis-related hormones, though such treatment may be effective in treating symptoms of anxiety and depression.

A clinical trial of cranial electrotherapy stimulation for anxiety and comorbid depression

BACKGROUND

Anxiety disorders are among the most prevalent mental disorders and are usually treated with medication and/or psychotherapy. When anxiety disorders are accompanied with comorbid depression, this further complicates the treatment process. Medication compliance is a common problem due to adverse side effects and new and effective treatments that have minimal side effects are needed for the treatment of anxiety and depression. This study used a randomized, double-blind, sham controlled design to examine the effectiveness of CES as a treatment for anxiety disorders and comorbid depression in a primary care setting. The study was registered at clinicaltrials.gov, NCT01533415.

METHODS

One hundred and fifteen participants, age 18 years and over, with a primary diagnosis of an anxiety disorder were enrolled from February 2012 to December 2012 The Hamilton Rating Scale for Anxiety (HAM-A) and the Hamilton Depression Rating Scale17 (HAM-D17) were used for baseline and outcome measures at weeks one, three, and five. Response to treatment was defined as a reduction of ≥50% or more on these measures.

RESULTS

Analysis of covariance revealed a significant difference between the active CES group and the sham CES group on anxiety (p=0.001, d=0.94) and on depression (p=0.001, d=0.78) from baseline to endpoint of study in favor of the active CES group.

CONCLUSIONS

CES significantly decreases anxiety and comorbid depression. Subjects reported no adverse events during the study.

Is β endorphin related to migraine headache and its relief?

BACKGROUND

Low β endorphin level in serum and cerebrospinal fluid (CSF) has been reported in migraine. The basis of pain relief in migraine by repetitive transcranial magnetic stimulation (rTMS) may be related to β endorphin (BE), which has not been evaluated. It is proposed to measure plasma β endorphin level in migraine patients and the change in β endorphin level following rTMS, and to correlate these changes with migraine relief.

METHODS

Twenty-five patients with migraine diagnosed as per International Headache Society criteria and 20 gender- and age-matched controls were included. Their clinical characteristics including duration of migraine, its frequency, severity and functional disability, triggers, allodynia and number of analgesic used were noted. Plasma β endorphin level was estimated before and after the third rTMS session. rTMS was delivered on the hot spot of right abductor digiti minimi on alternate days for 3 days and each session consisted of 600 pulses at 10 Hz. The clinical response was noted weekly for 1 month and correlated with β endorphin level.

RESULTS

The median age of the patients was 35 (20-50) years and 19 were females. Eight patients had episodic and 17 chronic migraine. β endorphin level was significantly lower in migraine (4.35 ± 2.29 ng/ml) compared to controls (6.68 ± 2.93 ng/ml). β endorphin level was lower in chronic compared to episodic migraine (3.74 ± 2.20 versus 5.65 ± 2.02 ng/ml). Following rTMS, the headache frequency, severity, functional disability and analgesic intake significantly reduced on the seventh day of rTMS and remained significant until the fourth week compared to the baseline. The clinical improvement was associated with increase in β endorphin level (4.35 ± 2.29 versus 6.58 ± 3.33 ng/ml).

CONCLUSION

It can be concluded from this study that the basal plasma β endorphin level was low in migraine patients, especially in chronic migraine. The improvement in migraine after rTMS was associated with increase in β endorphin level.

Cranial electrotherapy stimulation for treatment of anxiety, depression, and insomnia

Cranial electrotherapy stimulation is a prescriptive medical device that delivers a mild form of electrical stimulation to the brain for the treatment of anxiety, depression, and insomnia. It is supported by more than 40 years of research demonstrating its effectiveness in several mechanistic studies and greater than 100 clinical studies. Adverse effects are rare (<1%), mild, and self-limiting, consisting mainly of skin irritation under the electrodes and headaches. Often used as a stand-alone therapy, because results are usually seen from the first treatment, cranial electrotherapy stimulation may also be used as an adjunctive therapy.

A randomized, double-blind trial of transcranial electrostimulation in early Parkinson's disease

We studied the effects of noninvasive transcranial electrical stimulation on the motor and psychological symptoms of early Parkinson's disease. Twenty-three subjects were treated with 10 days of placebo versus active treatment and then followed for 14 weeks. Baseline off medication Unified Parkinson's Disease Rating Scale parts I-III was 29.4 ± 10.0. The primary end point, Unified Parkinson's Disease Rating Scale in week 2 following treatment, reduced by 5.3 ± 9.7 for those in active treatment and 7.7 ± 4.8 for those receiving placebo (not significant). Similarly, no significant differences were seen in the Hamilton Anxiety Scale, Geriatric Depression Scale, and Epworth Sleepiness Scale over the duration of the study. The treatment was well tolerated without device-related adverse events. Despite the negative study, nonpharmacological approaches should continue to be pursued in Parkinson's disease, as they are generally well received by patients.

Why do some promising brain-stimulation devices fail the next steps of clinical development?

Interest in techniques of noninvasive brain stimulation (NIBS) has been growing exponentially in the last decade. Recent studies have shown that some of these techniques induce significant neurophysiological and clinical effects. Although recent results are promising, there are several techniques that have been abandoned despite positive initial results. In this study, we performed a systematic review to identify NIBS methods with promising preliminary clinical results that were not fully developed and adopted into clinical practice, and discuss its clinical, research and device characteristics. We identified five devices (transmeatal cochlear laser stimulation, transcranial micropolarization, transcranial electrostimulation, cranial electric stimulation and stimulation with weak electromagnetic fields) and compared them with two established NIBS devices (transcranial magnetic stimulation and transcranial direct current stimulation) and with well-known drugs used in neuropsychiatry (pramipexole and escitalopram) in order to understand the reasons why they failed to reach clinical practice and further steps of research development. Finally, we also discuss novel NIBS devices that have recently showed promising results: brain ultrasound and transcranial high-frequency random noise stimulation. Our results show that some of the reasons for the failure of NIBS devices with promising clinical findings are the difficulty to disseminate results, lack of controlled studies, duration of research development, mixed results and lack of standardization.

Cranial electrical stimulation: potential use in reducing sleep and mood disturbances in persons with dementia and their family caregivers

Family caregivers of persons with dementia and their care recipients frequently experience sleep and mood disturbances throughout their caregiving and disease trajectories. Because conventional pharmacologic treatments of sleep and mood disturbances pose numerous risks and adverse effects to elderly persons, the investigation of other interventions is warranted. As older adults use complementary and alternative medicine interventions for the relief of sleep and mood disturbances, cranial electrical stimulation, an energy-based complementary and alternative medicine, may be a viable intervention. The proposed mechanism of action and studies that support cranial electrical stimulation as a modality to reduce distressing symptoms are reviewed. Directions for research are proposed.

The effect of physical therapy on beta-endorphin levels

Beta-endorphin (betaE) is an important reliever of pain. Various stressors and certain modalities of physiotherapy are potent inducers of the release of endogenous betaE to the blood stream. Most forms of exercise also increase blood betaE level, especially when exercise intensity involves reaching the anaerobic threshold and is associated with the elevation of serum lactate level. Age, gender, and mental activity during exercise also may influence betaE levels. Publications on the potential stimulating effect of manual therapy and massage on betaE release are controversial. Sauna, mud bath, and thermal water increase betaE levels through conveying heat to the tissues. The majority of the techniques for electrical stimulation have a similar effect, which is exerted both centrally and--to a lesser extent--peripherally. However, the parameters of electrotherapy have not yet been standardised. The efficacy of analgesia and the improvement of general well-being do not necessarily correlate with betaE level. Although in addition to blood, increased brain and cerebrospinal fluid betaE levels are also associated with pain, the majority of studies have concerned blood betaE levels. In general, various modalities of physical therapy might influence endorphin levels in the serum or in the cerebrospinal fluid--this is usually manifested by elevation with potential mitigation of pain. However, a causal relationship between the elevation of blood, cerebrospinal fluid or brain betaE levels and the onset of the analgesic action cannot be demonstrated with certainty.

The Role of the Craniospinal Nerves in Mediating the Antinociceptive Effect of Transcranial Electrostimulation in the Rat

Transcranial electrostimulation (TES) has been reported to elicit significant analgesia, but its mechanism of action has not been elucidated. In a recently introduced clinically relevant rat model of TES we have validated and characterized the TES antinociceptive effect, suggesting involvement of the sensory nerves of the rat's scalp in mediating that effect. In this study, we have further investigated the role of the craniospinal nerves by attempting to block the TES antinociceptive effect with local anesthetic injected under the TES electrodes. We also applied different transcutaneous electrical nerve stimulation modalities through the TES electrodes and compared the elicited antinociceptive effect to that of TES. The antinociceptive effect was assessed by measuring nociceptive thresholds in the tail-flick latency test in awake, unrestrained male rats. Data were analyzed by one-way analysis of variance followed by the Bonferroni t-test. The TES antinociceptive effect was significantly reduced after local anesthetic injection, and administration of 100 Hz transcutaneous electrical nerve stimulation was, over time, capable of eliciting the same degree of antinociceptive effect as TES. We conclude that sensory craniospinal nerves play a critical role in mediating the TES antinociceptive action and offer a hypothesis on the underlying mechanism(s) responsible for this action.

Decreased dynorphin A (1–17) in the spinal cord of spastic rats after the compressive injury

Spasticity in rat hindlimbs was induced by compressing cervical spinal cord with a wax ball. Ashworth score and H-reflex were measured 1 week after the surgery. The results showed that: (1) muscle spasm was detected in the hindlimbs a week after the operation and maintained at least 8 weeks, (2) in the spastic animals, dynorphin A (1-17)-ir decreased significantly in thoracic and lumbar segments of the spinal cord and (3) peripheral administration of kappa receptor agonist U50488H and electrical stimulation at 100 Hz effectively relieved the muscle spasm. Our data supported the note that the reduction of endogenous dynorphin A (1-17) might play an important role in the pathogenesis of spinally induced muscle spasticity and the replenishment of its shortage might relieve the spasticity.

Spinal 5-HT(2) and 5-HT(3) receptors mediate low, but not high, frequency TENS-induced antihyperalgesia in rats

Transcutaneous electrical nerve stimulation (TENS) is a form of non-pharmacological treatment for pain. Involvement of descending inhibitory systems is implicated in TENS-induced analgesia. In the present study, the roles of spinal 5-HT and alpha(2)-adrenoceptors in TENS analgesia were investigated in rats. Hyperalgesia was induced by inflaming the knee joint with 3% kaolin-carrageenan mixture and assessed by measuring paw withdrawal latency (PWL) to heat before and 4 h after injection. The (1). alpha(2)-adrenergic antagonist yohimbine (30 microg), (2). 5-HT antagonist methysergide (5-HT(1). and 5-HT(2). 30 microg), one of the 5-HT receptor subtype antagonists, (3). NAN-190 (5-HT(1A), 15 microg), (4). ketanserin (5-HT(2A), 30 microg), (5). MDL-72222 (5-HT(3), 12 microg), or (6). vehicle was administered intrathecally prior to TENS treatment. Low (4 Hz) or high (100 Hz) frequency TENS at sensory intensity was then applied to the inflamed knee for 20 min and PWL was determined. Selectivity of the antagonists used was confirmed using respective agonists administered intrathecally. Yohimbine had no effect on the antihyperalgesia produced by low or high frequency TENS. Methysergide and MDL-72222 prevented the antihyperalgesia produced by low, but not high, frequency TENS. Ketanserin attenuated the antihyperalgesic effects of low frequency TENS whereas NAN-190 had no effect. The results from the present study show that spinal 5-HT receptors mediate low, but not high, frequency TENS-induced antihyperalgesia through activation of 5-HT(2A) and 5-HT(3) receptors in rats. Furthermore, spinal noradrenergic receptors are not involved in either low or high frequency TENS antihyperalgesia.

Agents physiques antalgiques

Analgesic electrotherapy is now based on more consistent scientific data; the biological action of the electric current, of the electromagnetic radiations and of the mechanical vibrations is better approached. But the randomized control trials still provide contradictory results concerning the analgesic efficiency of the cryotherapy, the TENS, the pulsed electro-magnetic fields, the ultrasound and laser therapy, the shock waves; iontophoresis, short waves, microwaves, infrasound vibrations are very few investigated. The analgesic electrotherapy cannot be recommended nor prohibited; physical agents represent only therapeutic options. On the basis of the scientific data and of their personal experience, the therapists can use them. More controlled clinical investigations of higher methodological levels are still required.

Cognitive impairment in patients with chronic pain: the significance of stress

This review article examines the role of emotional distress and other aspects of suffering in the cognitive impairment that often is apparent in patients with chronic pain. Research suggests that pain-related negative emotions and stress potentially impact cognitive functioning independent of the effects of pain intensity. The anterior cingulate cortex is likely an integral component of the neural system that mediates the impact of pain-related distress on cognitive functions, such as the allocation of attentional resources. A maladaptive physiologic stress response is another plausible cause of cognitive impairment in patients with chronic pain, but a direct role for dysregulation of the hypothalamic-pituitary-adrenocortical axis has not been systematically investigated.

A study of the effects of cranial electrical stimulation on attention and concentration

There have been several anecdotal accounts that cranial electrical stimulation (CES) enhances attention and the ability to learn new tasks in a normal population, but only one published investigation confirms that CES improves attention using the Alpha Stim CES (Madden and Kirsch, 1987). The purpose of this study was to corroborate the findings of Madden and Kirsch, using more precise measures of attention, such as a Continuous Performance Test (CPT). A pretest and posttest CPT was given to two groups using the LISS CES device. The control group consisted of twenty-one subjects who received the placebo treatment. The experimental group of thirty-one subjects received twenty minutes of CES. Four measures of the CPT show significant gains in attention: Number of Hits, p =.010 Hit RT ISI Change, p =.016, Risk Taking, p =.055; and Attentiveness, p =.054. Based on subjects who demonstrated improvement by one standard deviation on two different measures of the CPT, thirty-one percent of the experimental group improved versus four percent of the control group. The use of CES as a method of increasing attention is a promising area that requires further investigation.