Epilepsy: contemporary perspectives on evaluation and treatment

Prevalence of Side Effects Treatment with Carbamazepine and Other Antiepileptics in Patients with Epilepsy

OBJECTIVE

This paper reveals the studies of carbamazepine monitoring in the manifestation of side effects during clinical use. It is important to realize that these ranges are derived statistically, with most patients who have high levels suffering side effects and some with poor control having low levels. Broadly, the newer agents have advantages of lower risk of side effects and less drug interaction. At the presence they are more expensive than the, than "older" agents. Current recommendations and practice are to use newer agents as second line drugs, although in some countries there are gaining favour as potential first line agents.

METHODS

In the study 91 patients with epilepsy were involved from which 53 or 58.2% were female and 38 or 41.8% were male with no great significant difference between two genders (X(2)=2.47, P=0.116). However, according to the study results female patients had slightly greater prevalence of epilepsy than man. Average age of epileptic patients was 23.2 years (SD ± 16.4 years), in the range 1-66 years. Patient distribution was present within all age-groups, but 59.4% of all patients were up to 20 years old. The highest prevalence of epilepsy was in the group age 6-15 years old: 33.0%. There were also children 1 - 5 years old with 7 or 7.7% of the patients, and the patients older than 60 years with 4 or 4.4% of the patients. Patient distribution according to the age and gender results with no female patient over 60 year old and more female patients in the age group 1-5 years. However statistically this did not produce a highly significant difference (T-test= 0.72, P=0.437) between average age according to the gender. The average age of the female gender was 22.1 year (SD ± 14.2 years), with the range 2-55 years, while the average age of the male patients was 24.6 year (SD ±19.2 years), with the range 1-66 years.

CONCLUSION

Unwanted side effects of antiepileptic drugs analyzed in the study are frequent, but not so severe as to be life threatening. Treatment of epilepsy with these three drugs (carbamazepine, ac.valproic and phenobarbitone) would be the first choice of treatment, with the best safety and efficacy. Application of this therapy is rarely compromised because of the appearance of unwanted side effects. Replacement or termination of therapy may be applied if actual therapy is not adequate for the management of epileptic attacks.

Electrical stimuli in the central nervous system microenvironment

Electrical stimulation to manipulate the central nervous system (CNS) has been applied as early as the 1750s to produce visual sensations of light. Deep brain stimulation (DBS), cochlear implants, visual prosthetics, and functional electrical stimulation (FES) are being applied in the clinic to treat a wide array of neurological diseases, disorders, and injuries. This review describes the history of electrical stimulation of the CNS microenvironment; recent advances in electrical stimulation of the CNS, including DBS to treat essential tremor, Parkinson's disease, and depression; FES for the treatment of spinal cord injuries; and alternative electrical devices to restore vision and hearing via neuroprosthetics (retinal and cochlear implants). It also discusses the role of electrical cues during development and following injury and, importantly, manipulation of these endogenous cues to support regeneration of neural tissue.

Anticonvulsant activity of alcoholic extract of bark of Pinus roxburghii Sarg

OBJECTIVE

To study the anticonvulsant activity of alcoholic extract of bark of Pinus roxburghii Sarg. (AEPR) used in Indian traditional medicine system in treating convulsion.

METHODS

Anticonvulsant activity was evaluated by maximal electroshock (MES) and pentylenetetrazole (PTZ)-induced seizures in Wistar albino rats. In the MES model, 150 mA current for 0.2 s was given through ear electrodes to induce convulsions in rats. The duration of tonic extension of hind limb was used as the end point, namely, prevention or decrease in the duration of hind limb extension was considered as a protective action. In the PTZ model, the anticonvulsant property of AEPR was assessed by its ability to delay the onset of myoclonic spasm and clonic convulsions produced by intraperitoneal administration of PTZ.

RESULTS

In the MES-induced seizure model, AEPR in doses of 300 and 500 mg/kg body weight reduced all the phases of convulsion significantly (P<0.01). Standard drug phenytoin at a dose of 25 mg/kg significantly reduced flexion phase (P<0.01) and abolished all phases of convulsion. In the PTZ-induced seizure model, the administration of the extract at doses of 300 and 500 mg/kg 30 min prior to injection of PTZ significantly delayed the onset of clonic seizure (P<0.01). AEPR at the dose of 100 mg/kg body weight could not exert any significant protective effect on PTZ-induced convulsions. Standard drug diazepam at a dose of 4 mg/kg showed much delayed onset of clonic seizure.

CONCLUSION

The study suggests that AEPR would be effective against generalized tonic-clonic and partial seizures. Thus AEPR possesses anticonvulsant property against MES- and PTZ-induced seizures in Wistar rats. However, further research is in progress to isolate the compound responsible for its activity.

Application of approximate entropy on dynamic characteristics of epileptic absence seizure

Electroencephalogram signals are time-varying complex electrophysiological signals. Existing studies show that approximate entropy, which is a nonlinear dynamics index, is not an ideal method for electroencephalogram analysis. Clinical electroencephalogram measurements usually contain electrical interference signals, creating additional challenges in terms of maintaining robustness of the analytic methods. There is an urgent need for a novel method of nonlinear dynamical analysis of the electroencephalogram that can characterize seizure-related changes in cerebral dynamics. The aim of this paper was to study the fluctuations of approximate entropy in preictal, ictal, and postictal electroencephalogram signals from a patient with absence seizures, and to improve the algorithm used to calculate the approximate entropy. The approximate entropy algorithm, especially our modified version, could accurately describe the dynamical changes of the brain during absence seizures. We could also demonstrate that the complexity of the brain was greater in the normal state than in the ictal state. The fluctuations of the approximate entropy before epileptic seizures observed in this study can form a good basis for further study on the prediction of seizures with nonlinear dynamics.

Stimulus driver for epilepsy seizure suppression with adaptive loading impedance

A stimulus driver circuit for a micro-stimulator used in an implantable device is presented in this paper. For epileptic seizure control, the target of the driver was to output 30 µA stimulus currents when the electrode impedance varied between 20 and 200 kΩ. The driver, which consisted of the output stage, control block and adaptor, was integrated in a single chip. The averaged power consumption of the stimulus driver was 0.24-0.56 mW at 800 Hz stimulation rate. Fabricated in a 0.35 µm 3.3 V/24 V CMOS process and applied to a closed-loop epileptic seizure monitoring and controlling system, the proposed design has been successfully verified in the experimental results of Long-Evans rats with epileptic seizures.

Myelin damage of hippocampus and cerebral cortex in rat pentylenetetrazol model

Epilepsy is a chronic neurological disorder characterized by spontaneous recurrent seizures, which also occur in demyelinating diseases of the central nervous system (CNS) with a higher prevalence. Meanwhile, demyelination occurrings have been occasionally observed in CNS of epilepsy patients, indicating an association between demyelination and epileptic seizures by an unknown mechanism. However, no confirmative experimental evidence has yet been given. Thus, by using a rat pentylenetetrazol model, electroencephalogram (EEG), Western blotting, enzyme-linked immunosorbent assay (ELISA) and immunohistochemistry, the present study provided direct evidence that myelin sheath damage in rat hippocampus and cerebral cortex started in the early stage of epileptic seizures induction and lasted with no further increase in severity in the development of epileptic seizures. It was illustrated that myelin sheath damage was not the result of oligodendrocyte destruction, but the autoantibodies against myelin basic protein (MBP) produced in peripheral circulation accompanied by increased permeability of blood-brain barrier (BBB) formed in the development of epileptic seizures. This study firstly provided experimental evidence for myelin sheath damage in PTZ-induced rat's epileptic seizures and further demonstrated that its possible cause was autoimmunoreaction.

Synthesis and preliminary screening of benzothiazol-2-yl thiadiazole derivatives for anticonvulsant activity

Various N-(5-chloro-6-substituted-benzothiazol-2-yl)-N'-(substituted phenyl)-[1,3,4]thiadiazole-2,5-diamines (5a-t) were designed and synthesized starting from substituted acetophenones. Structures of all the compounds were confirmed on the basis of spectral and elemental analyses. All the newly synthesized compounds were screened for their anticonvulsant activity and were compared with the standard drug phenytoin sodium. Interestingly, all the compounds showed protections against seizures in the range 50-100% indicative of the promising nature of the compounds against seizure spread. Compounds 5b and 5c showed complete protection against MES induced seizures.

Epilepsy surgery: perioperative investigations of intractable epilepsy

Recent advances in our understanding of the basic mechanisms of epilepsy have derived, to a large extent, from increasing ability to carry out detailed studies on patients surgically treated for intractable epilepsy. Clinical and experimental perioperative studies divide into three different phases: before the surgical intervention (preoperative studies), on the intervention itself (intraoperative studies), and on the period when the part of the brain that has to be removed is available for further investigations (postoperative studies). Before surgery, both structural and functional neuroimaging techniques, in addition to their diagnostic roles, could be used to investigate the pathophysiological mechanisms of seizure attacks in epileptic patients. During epilepsy surgery, it is possible to insert microdialysis catheters and electroencephalogram electrodes into the brain tissues in order to measure constituents of extracellular fluid and record the bioelectrical activity. Subsequent surgical resection provides tissue that can be used for electrophysiological, morphological, and molecular biological investigations. To take full advantage of these opportunities, carefully designed experimental protocols are necessary to compare the data from different phases and characterize abnormalities in the human epileptic brain.

Evaluation of a single seizure: guidelines for advance practice nurses

Deciding whether or not to treat a client after a single seizure can be challenging for the clinician. The risk of seizure recurrence is greatest in the first six months after the initial episode. The decision to treat a single seizure should be based on diagnostic and clinical findings that assess the client's risk for recurrence. When making treatment decisions, the clinician must consider the benefits and risks of single-seizure therapy. Careful consideration should be given to differential diagnosis, factors that induce symptomatic seizures and risk factors for epilepsy.

An evaluation of antiepileptic drug therapy in nursing facilities

OBJECTIVES

To describe the prescribing and use of antiepileptic drug (AED) therapy in nursing facility residents.

DESIGN

A retrospective, multicenter drug use evaluation.

SETTING

A total of 85 nursing facilities (average size, 119 beds) in five states.

PARTICIPANTS

1132 residents of the total 10,168 residents screened were prescribed at least one AED.

MEASURES

Demographic information, primary indication for AED, comorbid conditions, prescribing physician's specialty, concomitant medications, and AED dosage regimen information were collected. Laboratory tests obtained in the most recent 6 months and seizure occurrence and seizure-related diagnostic assessments made in the most recent 3 months were also recorded.

RESULTS

Of 1132 residents receiving AED therapy, 892 (78.8%) were prescribed AED therapy for a seizure-related diagnosis although 86% of seizure types were unspecified. Another 215 residents (19.0%) were prescribed AEDs for nonseizure diagnoses, and 25 (2.2%) had no indication for AED therapy. AEDs most frequently prescribed were phenytoin (56.8%), carbamazepine (23.0%), phenobarbital (15.6%), and valproic acid (13.1%). For residents with a seizure diagnosis, the most frequently prescribed monotherapy agents were phenytoin (52.0%), carbamazepine (12.2%), and phenobarbitol (7.1%). Almost 25% of residents with a seizure diagnosis took a combination of AEDs; more than 50% of all combinations included phenobarbital. About 9% of residents with a seizure diagnosis had one or more documented seizures during a 3-month review period.

CONCLUSION

Among the substantial percentage of residents treated with AEDs, the lack of diagnosis of seizure type has serious implications for the choice of AED therapy. Opportunities exist for prescribing physicians, consultant pharmacists, and nursing staff to improve the medical management of nursing facility residents with seizures and of others receiving AEDs.

Nonobstetric conditions causing hypoxia during pregnancy: asthma and epilepsy

Nonobstetric medical emergencies of hypoxia may be difficult to recognize in pregnant patients whose normal physiologic condition is altered by the pregnant state. Keys to early recognition of hypoxia in pregnancy may result in appropriate medical interventions for treatment of asthma and seizures that minimize ill effects to mother and fetus. Preventive measures and patient education are important to reducing the incidence of emergencies such as status asthmaticus and status epilepticus.

Seizures in lung transplant recipients

PURPOSE

We wished to assess organ transplant recipients, who incur a significant risk for seizures.

METHOD

We reviewed 85 lung transplants performed in 81 patients at the University of North Carolina hospitals between 1991 and 1994. All patients were reviewed for age, reason for transplant, detailed description of seizures, neurological examination, medications, and laboratory results, including cyclosporine level, EEG, and brain imaging.

RESULTS

Eighteen of 81 (22%) patients experienced seizures. Patients aged < 25 years had the greatest risk of seizures and 15 of the 18 patients had cystic fibrosis. Sixteen of the 18 (89%) patients, by history, had partial-onset seizures. Eleven of the 18 (61%) patients had seizures < or = 10 days after initiation of intravenous methylprednisolone for allograft rejection. Two patients had seizures associated with sustained hypertension: 1 of these patients was simultaneously being treated for rejection. Four patients had strokes (1 before transplant) and seizures. Two patients were receiving imipenem. Magnetic resonance imaging (MRI) of the brain demonstrated areas of increased T2 signal in 8 of 9 patients.

CONCLUSIONS

Our findings demonstrate multiple etiologies for seizures in our transplant recipients. However, we believe that patients, especially those aged < 25 years, being treated with intravenous methylprednisolone for rejection may be at increased risk of seizures. We hypothesize that the focal loss of blood-brain barrier (BBB) may play a significant role in the development of partial seizures in lung transplant recipients.

High doses of carbamazepine for refractory partial epilepsy

Forty-eight patients with partial seizures were analysed during treatment with 1200 mg/d or more of carbamazepine (CBZ). Thirty-three were on monotherapy and fifteen on polytherapy. The other drugs were kept unchanged in the patients on polytherapy. The dose of CBZ was increased if no control was observed and the patient had no side effects. The doses used ranged between 1200 and 1900 mg/day (1200 mg/day, n = 18; 1300 mg/day, n = 1; 1400 mg/day, n = 7; 1600 mg/day, n = 9; 1700 mg/day, n = 4; 1800 mg/day, n = 8; 1900 mg/day, n = 1). Anticonvulsant plasma levels were taken to confirm patient compliance. The average plasma level was 9.6 ug/mL. The period of follow up varied from 3 to 96 months (M = 25.6). Seizure's control was observed in 7 (14.48%) patients taking 1200 mg/day and in 2 (4.16%) patients taking 1400 mg/day of CBZ. Thirty-nine patients did not show any control (81.21%). Ten patients (20.81%) had signs of intoxication. When patients have no improvement with 1400 mg/day, it is difficult to obtain any control despite the use of higher doses of CBZ, which frequently expose the patient to significant side effects.