On the cerebro-protective effects of caroverine, a calcium-channel blocker and antiglutamatergic drug: double-blind, placebo-controlled, EEG mapping and psychometric studies under hypoxia

EEG Beta-Band Spectral Entropy Can Predict the Effect of Drug Treatment on Pain in Patients With Herpes Zoster

BACKGROUND

Medication is the main approach for early treatment of herpes zoster, but it could be ineffective in some patients. It is highly desired to predict the medication responses to control the degree of pain for herpes zoster patients. The present study is aimed to elucidate the relationship between medication outcome and neural activity using EEG and to establish a machine learning model for early prediction of the medication responses from EEG.

METHODS

The authors acquired and analyzed eye-closed resting-state EEG data 1 to 2 days after medication from 70 herpes zoster patients with different drug treatment outcomes (measured 5-6 days after medication): 45 medication-sensitive pain patients and 25 medication-resistant pain patients. EEG power spectral entropy of each frequency band was compared at each channel between medication-sensitive pain and medication-resistant pain patients, and those features showing significant difference between two groups were used to predict medication outcome with different machine learning methods.

RESULTS

Medication-sensitive pain patients showed significantly weaker beta-band power spectral entropy in the central-parietal regions than medication-resistant pain patients. Based on these EEG power spectral entropy features and a k-nearest neighbors classifier, the medication outcome can be predicted with 80% ± 11.7% accuracy, 82.5% ± 14.7% sensitivity, 77.7% ± 27.3% specificity, and an area under the receiver operating characteristic curve of 0.85.

CONCLUSIONS

EEG beta-band power spectral entropy in the central-parietal region is predictive of the effectiveness of drug treatment on herpes zoster patients, and it could potentially be used for early pain management and therapeutic prognosis.

EEG Power Spectral Analysis of Abnormal Cortical Activations During REM/NREM Sleep in Obstructive Sleep Apnea

Objective: To characterize electroencephalogram (EEG) power in different frequency bands during rapid eye movement (REM) sleep and non-rapid eye movement (NREM) sleep in patients with obstructive sleep apnea (OSA). Methods: Retrospective data on 151 patients were collected and divided into three groups: primary snoring group (AHI < 5/h), mild-moderate OSA group (6 ≤ AHI < 30/h), and severe OSA group (AHI ≥ 30/h). EEG recordings in the frontal, central, and occipital regions were extracted from both REM and NREM sleep, to compute the normalized spectral power densities in the delta, theta, alpha, sigma, beta, and gamma frequency bands, using Fast Fourier Transform. Correlations between the computed EEG power and PSG parameters were analyzed. Results: In NREM sleep, elevated normalized power spectral density (PSD) in the delta band was observed in the severe OSA group compared to the other two groups. In contrast, the PSD of the other frequency bands showed a corresponding decrease in the severe OSA group. In REM sleep, similar changes were observed in the frontal region. Delta band PSD was positively correlated with Apnea Hypopnea Index (AHI) (r = 0.33), longest time of apnea, oxygen desaturation index (ODI) (r = 0.34), percent sleep time below 90% SaO₂ (T90%) (r = 0.30), Arousal Index (ArI) (r = 0.29), and negatively correlated with N3%, minimum oxygen saturation (minSaO₂). Conclusion: Our findings provide neurophysiological evidence for pathological cortical activation during REM/NREM sleep, which may be associated with the arousals and cognitive impairments in OSA. The technique of power spectral analysis could prove a potentially useful tool in complementing traditional PSG parameters in assessing disease burden to guide therapeutic decisions.

The key role of daytime sleepiness in cognitive functioning of adults with attention deficit hyperactivity disorder

Background.

Adults with attention deficit hyperactivity disorder (ADHD) frequently suffer from sleep problems and report high levels of daytime sleepiness compared to neurotypical controls, which has detrimental effect on quality of life.

Methods.

We evaluated daytime sleepiness in adults with ADHD compared to neurotypical controls using an observer-rated sleepiness protocol during the Sustained Attention Response Task as well as electroencephalogram (EEG) slowing, a quantitative electroencephalographic measure collected during a short period of wakeful rest.

Results.

We found that adults with ADHD were significantly sleepier than neurotypical controls during the cognitive task and that this on-task sleepiness contributed to cognitive performance deficits usually attributed to symptoms of ADHD. EEG slowing predicted severity of ADHD symptoms and diagnostic status, and was also related to daytime sleepiness. Frontal EEG slowing as well as increased frontal delta were especially prominent in adults with ADHD. We have validated and adapted an objective observer-rated measure for assessing on-task sleepiness that will contribute to future sleep research in psychology and psychiatry.

Conclusions.

These findings indicate that the cognitive performance deficits routinely attributed to ADHD and often conceptualized as cognitive endophenotypes of ADHD are largely due to on-task sleepiness and not exclusively due to ADHD symptom severity. Daytime sleepiness plays a major role in cognitive functioning of adults with ADHD.

The analgesic effect of pregabalin in patients with chronic pain is reflected by changes in pharmaco-EEG spectral indices

AIM

To identify electroencephalographic (EEG) biomarkers for the analgesic effect of pregabalin in patients with chronic visceral pain.

METHODS

This was a double-blind, placebo-controlled study in 31 patients suffering from visceral pain due to chronic pancreatitis. Patients received increasing doses of pregabalin (75mg-300mg twice a day) or matching placebo during 3 weeks of treatment. Pain scores were documented in a diary based on a visual analogue scale. In addition, brief pain inventory-short form (BPI) and quality of life questionnaires were collected prior to and after the study period. Multi-channel resting EEG was recorded before treatment onset and at the end of the study. Changes in EEG spectral indices were extracted, and individual changes were classified by a support vector machine (SVM) to discriminate the pregabalin and placebo responses. Changes in individual spectral indices and pain scores were correlated.

RESULTS

Pregabalin increased normalized intensity in low spectral indices, most prominent in the theta band (3.5-7.5Hz), difference of -3.18, 95% CI -3.57, -2.80; P= 0.03. No changes in spectral indices were seen for placebo. The maximum difference between pregabalin and placebo treated patients was seen in the parietal region, with a classification accuracy of 85.7% (P= 0.009). Individual changes in EEG indices were correlated with changes in pain diary (P= 0.04) and BPI pain composite scores (P= 0.02).

CONCLUSIONS

Changes in spectral indices caused by slowing of brain oscillations were identified as a biomarker for the central analgesic effect of pregabalin. The developed methodology may provide perspectives to assess individual responses to treatment in personalized medicine.

Quantitative spectral analysis of vigilance EEG in patients with obstructive sleep apnoea syndrome: EEG mapping in OSAS patients

INTRODUCTION

Sleep disruption and blood gas abnormalities, observed in patients with obstructive sleep apnoea (OSA) syndrome, prevent sleep-related restorative processes and induce chemical or structural central nervous system cellular injury. The aim of the study was to determine electroencephalogram (EEG) alterations related to the severity of OSA in patients with OSAS and the effect of the nasal continuous positive air pressure (nCPAP) treatment.

MATERIALS AND METHODS

Polysomnography and vigilant EEGs were performed in subjects with possible OSA. The mean relative power was calculated for delta, theta, alpha and beta frequency bands. Thirty subjects without and 131 with OSA participated in this study. In 29 male patients with severe OSA, quantitative EEGs were re-evaluated after 6 months of CPAP treatment.

RESULTS

Compared to subjects without OSA, patients with severe OSA showed an increase in relative theta and delta power (occipital, temporal and parietal areas). Six months of nCPAP treatment improved daytime sleepiness of OSA patients. EEG demonstrated a decrease in alpha (frontal, central and temporal areas) and theta (frontal areas) relative power. However, beta relative power was increased mainly in central, and delta relative power, in all brain areas.

DISCUSSION

In conclusion, EEG slowing was observed in OSA patients. CPAP treatment improved daytime sleepiness of OSA patients in contrast to the alterations in alpha (decreased) and delta (increased) relative power suggesting a possible persistent brain dysfunction.

The central nervous system effects, pharmacokinetics and safety of the NAALADase-inhibitor GPI 5693

AIM

The aim was to assess the central nervous system (CNS) effects, pharmacokinetics and safety of GPI 5693, an inhibitor of a novel CNS-drug target, NAALADase which is being evaluated for the treatment of neuropathic pain.

METHODS

This was a double-blind, placebo-controlled, exploratory study in healthy subjects receiving oral GPI 5693 single ascending doses of 100, 300, 750, 1125 mg with a placebo treatment randomly interspersed. An open-label, parallel extension examined the effects of food and sex on the pharmacokinetics of 750, 1125 and 1500 mg doses. Blood samples were collected for pharmacokinetic and biochemical/haematological safety analysis, vital signs, ECG and adverse event checks were performed regularly up to 48 h postdose. Postdose CNS effects were assessed using eye movements, adaptive tracking, electroencephalography (EEG), body sway and Visual Analogue Scales (VAS).

RESULTS

CNS effects were mainly observed after the 1125 mg dose, showing a significant decrease of adaptive tracking performance, VAS alertness and VAS mood, and an increase of EEG occipital alpha and theta power. Gastro-intestinal (GI) adverse effects were frequent at higher doses. No clinically significant changes in vital signs or ECG were noted during any of the treatments. The therapeutically relevant concentration range (950-11 100 ng ml(-1)) as determined from animal experiments was already reached after the 300 mg dose. C(max) after the 300 mg and 750 mg dose was 2868 and 9266 ng ml(-1) with a t(1/2) of 2.54 and 4.78 h, respectively. Concomitant food intake (with the 750 mg and 1125 mg doses) reduced C(max) by approximately 66% and AUC by approximately 40%. With concomitant food intake, the dose-normalized C(max) also decreased significantly by -5.6 (CI: -2.6 to -8.7) ng ml(-1) mg(-1). The pharmacokinetic variability was largest after the 300 mg and 750 mg dose, resulting in a SD of approximately 50% of the C(max).

CONCLUSION

NAALADase inhibition with GPI 5693 was safe and tolerable in healthy subjects. Plasma concentrations that were effective in the reversal of hyperalgesia in the chronic constrictive injury animal model of neuropathic pain were obtained at doses of 300, 750 and 1125 mg in the fasted state. Comcomitant food intake reduced C(max) and AUC. CNS effects and GI AEs increased in incidence over placebo only at the 1125 mg dose.

Caroverine inhibits the conditioned place aversion induced by naloxone-precipitated morphine withdrawal in rats

Comparable to the anti-craving compound acamprosate, caroverine reduces alcohol withdrawal symptoms by an antagonism at ionotropic glutamate receptors and a blockade of calcium channels. The present study examines the effect of caroverine in a craving model, in which acamprosate has proved effective before. A place aversion was induced by a conditioned morphine withdrawal by administration of the opioid antagonist naloxone (0.1 mg/kg, s.c.) 5-6 days after the subcutaneous implantation of a morphine pellet in rats. Testing in the drug-free state, the acquisition of a conditioned aversion against the naloxone-associated cues was inhibited by pretreatment with caroverine (5 mg/kg, i.p.). This result corroborates the involvement of excitatory glutamate and calcium in the development of conditioned withdrawal and craving. It offers further evidence for the hypothesis that these neuronal systems are altered during withdrawal in a similar way by ethanol and opiates.

Pharmacologic Manipulation of the Labyrinth with Novel and Traditional Agents Delivered to the Inner Ear

We describe the methodology and rationale behind the delivery of therapeutic medicines to the inner ear. The inner ear has long been impervious to pharmacologic manipulation. This is most likely the result of a protective mechanism called the blood-labyrinth barrier, whose function closely resembles that of the blood-brain barrier. This protective barrier impedes the clinician's ability to treat inner ear diseases with systemically administered medications. Since 1935, otolaryngologists have attempted to manipulate the inner ear with transtympanically injected medicines. Success has varied widely, but medicinal ablation of vestibular function can be achieved in this manner. Unfortunately, the auditory system is also at great risk from any medicine that is delivered to the inner ear via the middle ear. Over the past 10 years, significant improvements in drug delivery have allowed for more “titratable” treatment, which has reduced (but not eliminated) the risk of permanent hearing loss. In this article, we discuss both novel and time-tested methods of delivering medicines to the inner ear. We also review the classes of medications that alter inner ear function and the attendant risks of such treatments.

The antioxidant activity of caroverine

Caroverine, 1-(2-diethylaminoethyl)-3-(p-methoxy benzyl)-1,2-dihydro-2-quinoxalin-2-on-hydrochloride, is a class B calcium-channel-blocker and antiglutamatergic agent with significant effects on the brain function. Caroverine exhibits competitive AMPA antagonism, and at higher concentrations, noncompetitive NMDA antagonism. In clinical practice caroverine is used as a spasmolytic and otoneuroprotective agent. Since reactive oxygen species are supposed to be involved in the pathogenesis of inner ear diseases in which caroverine shows beneficial effects, the present study aimed to investigate the antioxidant properties of caroverine. Lipid peroxidation of liposomal membranes was suppressed in the presence of caroverine. In order to understand the mechanism of this antioxidant action of caroverine, we determined the rate constants both for a possible reaction with superoxide (O(2)(.-)) radicals from xanthine/xanthine oxidase and for a possible reaction with hydroxyl (.OH) radicals in Fenton system. Using a defined chemical reaction model O(2)(.-) scavenging was found to occur at a rather low rate constant only (3 x 10(2)M(-1)s(-1)). Thus, a reaction of caroverine with O(2)(.-) radicals is of marginal significance. In contrast, the reaction of caroverine with .OH radicals occurs at an extremely high rate constant (k=1.9 x 10(10)M(-1)s(-1)). The strong antioxidant activity of caroverine is therefore based both on the partial prevention and highly active scavenging of hydroxyl radicals.

Daytime sleepiness and EEG spectral analysis in apneic patients before and after treatment with continuous positive airway pressure

BACKGROUND

Obstructive sleep apnea syndrome (OSAS) is characterized by recurrent apneas during sleep, resulting in repetitive hypoxemic episodes and interruptions of the normal sleep pattern. A previous study showed EEG slowing (ie, a higher ratio of delta + theta frequencies to alpha + beta frequencies on EEG) during rapid eye movement (REM) sleep and wakefulness in untreated OSAS patients. STUDY AND OBJECTIVES: To determine whether EEG slowing is reversible with continuous positive air pressure (CPAP) treatment and to verify whether the persistence of excessive daytime sleepiness (EDS) is correlated with residual slowing of the EEG.

PATIENTS

Ten healthy subjects (9 men and 1 woman) and 14 patients with moderate-to-severe OSAS (13 men and 1 woman) were studied before and after 6 months of treatment with CPAP.

RESULTS

Untreated OSAS patients showed EEG slowing in frontal and central cortical regions during both wakefulness and during REM sleep compared to healthy control subjects. This EEG slowing was found to be independent of time spent with arterial oxygen saturation < 90%, severity of OSAS, or mean sleep latency as determined by the multiple sleep latency test. CPAP treatment was found to correct the EEG slowing for both REM sleep and wakefulness. Daytime sleepiness also greatly improved with treatment, but some degree of somnolence remained.

CONCLUSION

CPAP treatment was found to correct the EEG slowing that was observed in untreated OSAS patients. Persistent EDS may be related to persistent obesity after CPAP treatment.

Dose-dependent effects of Cerebrolysin on EEG and short-term memory of healthy volunteers during control and hyperventilation induced cerebral ischemia

Cerebrolysin, a peptidergic nootropic drug, was to be effective on learning and other cognitive functions in animal experiments as well as in clinical studies. Hyperventilation (HV) as a model of brain ischemia induces slowing of the EEG and cognitive impairment. The aim of this study was to examine the potential dose-dependent effects of Cerebrolysin on HV related EEG changes and short term memory during chronic (10 days) application and the time dependency of these effects. In this single centre, double blind, randomized, placebo-controlled, parallel group study 48 healthy males were enrolled and received either 100 ml placebo (NaCl) or Cerebrolysin (10 ml or 30 ml or 50 ml) in a volume of 100 ml (NaCl) for 10 days. EEG at baseline and during HV as well as the cognitive performance was evaluated at Day 1 (baseline, 15 min p.i., 2 h p.i., 4 h p.i., 8 h p.i., 24 h p.i.), Day 10 (baseline, 15 min p.i., 2 h p.i.,) and at day 11 (24 h. after the last infusion). The main effects found during the study can be summarized as follows: At baseline we found an increase of the EEG power ratio (PR) for the grouptrated with 10 ml Cerebrolysin. The effect was most pronounced at the parietal cortex. The effect started after 15 min, was most expressed at 2 h and was kept until 8 h. During HV we found a relative PR decrease of the group (10 ml Cerebrolysin) at 2 hours. For short term memory, there is a trend towards less effective word recall for the baseline situation during the first 4 hours for the placebo. This effect was not observed in the Cerebrolysin treated groups. If chronic effects are concerned, the PR increased over the parietal regions at 24 h for the groups treated with 10 and 30 ml Cerebrolysin. The effect remains at day 10 and 11. But at 10 and 11 days there was also a trend for a relative increase of the PR in the group treated with 50ml Cerebrolysin. Signs of overdosage occurred with the highest concentrations of Cerebrolysin. The events were only mild and caused no harm to the volunteers. The highest concentration caused a small but significant reduction of blood pressure. The effects could be interpreted as those of an atypical nootropic with anti-ischemic properties.

Infusional high-dose application of the calcium-channel-blocking and antiglutamatergic agent caroverine in the treatment of alcohol withdrawal (DSM-III-R 291.80)

In an open study, nineteen in-patients fulfilling the criteria for an alcohol withdrawal syndrome (DSM-III-R 291.80) were treated with intravenous caroverine (400 mg/12 h). Caroverine is a class B calcium-channel-blocker and antiglutamatergic agent with significant effects on the brain function. Caroverine exhibits competitive AMPA antagonism, and at higher concentrations, non-competitive NMDA antagonism. All rating scales showed a significant improvement from the start of the treatment throughout the whole study period (CIAW-Ar: P=0.0000; NGI 1: P=0.0000, NGI 2: P=0.0304; CGI 1: P=0.0000, CGI 2: P=0.0208, CGI 3: P=0.0003). The heart rate also stabilised from 111/min before treatment to 81/min after 12 h (P=0.0000). Caroverine was well tolerated, showed no sedative side effects, and no epileptic seizures were observed.