Biomedical subjects

J Overweg

Publications and source records attributed to J Overweg.

At least 19 recordsLinked to original sources

PubMed2000

A multicenter, randomized clinical study to evaluate the effect on cognitive function of topiramate compared with valproate as add-on therapy to carbamazepine in patients with partial-onset seizures.

PURPOSE: This study compares the cognitive effects of topiramate (TPM) with those of valproate (VPA) using efficacious doses of each drug when used as adjunctive therapy to carbamazepine (CBZ). A key question of the study is to what extent a more gradual introduction of TPM improves tolerability and prevents cognitive impairment. METHODS: The study is a multicenter, randomized, observer-blinded, parallel-group clinical trial with VPA or TPM given as first-line add-on therapy to steady-state treatment with CBZ. TPM is introduced at 25 mg and increased with weekly 25mg/d increments to a minimum dosage of 200 mg/d. The target dosage ranges from 200 to 400 mg/d for TPM and is 1800 mg/d for VPA. The study evaluates cognitive function changes from baseline to end point (after 20 weeks of treatment) and during titration (after 8 weeks of treatment). The primary outcome measure is the difference between the treatments (TPM versus VPA) in change from baseline to end point and change from baseline to titration, using a 95% confidence interval approach. RESULTS: For the 10 baseline-to-end point comparisons, one test measuring short-term verbal memory (Rey Auditory Verbal Learning Test) yields a statistically significant difference between the treatments (p = 0.02), showing worsening for TPM and improvement of scores for VPA. The 10 baseline-to-titration comparisons also show one statistically significant difference, again for a test measuring short-term memory (Recognition of Words; p = 0.04), showing a larger change in the negative direction for TPM. None of the mood tests or the test for subjective complaints shows statistically significant differences between the treatments, although more scores are in the negative direction for TPM during titration. CONCLUSION: Although the pattern of changes in the negative direction seems consistent with clinical information, the differences found between the treatments are small. An important finding of our study is that, when the results are compared with those of other studies, it is clear that gradual introduction of TPM can reduce the extent of cognitive impairment (with a maximum of about 0.6 SD).

Adolescent↗

PubMed1998

[Antiepileptics].

Despite introduction of new antiepileptic drugs the established drugs phenytoin, carbamazepine and valproate still provide the treatment of choice in most forms of epilepsy, being efficacious in approximately two-thirds of all newly referred patients. In 20-60% of patients resistant to treatment with the older drugs, a 50% reduction of seizure frequency can be achieved by adding ethosuximide, clobazam, vigabatrine, oxcarbazepine, lamotrigine, felbamate, tiagabine or topiramate to the classic treatment. The majority of the new drugs are free of the problematic enzyme induction of the older compounds, making monotherapy as well as combination therapy much easier. To what extent the new antiepileptic drugs are going to be used for the treatment of patients with epilepsy will depend on the analysis of cost and benefits. This will be based on efficacy, side effects, interactions and teratogenicity of these new compounds.

Anticonvulsants↗

PubMed1997

Prospective study of the prevalence of Alzheimer-type dementia in institutionalized individuals with Down syndrome.

Institutionalized patients with Down syndrome (n = 307) were monitored for 5 to 10 years prospectively to determine prevalence of Alzheimer-type dementia. Clinical signs, cognitive functioning, and EEGs were assessed. When possible, postmortem neuropathological examinations were conducted. Progressive mental and physical deterioration was found for 56 of the residents. Mean age at onset of dementia was 56 years. Prevalence increased from 11% between ages 40 and 49 to 77% between 60 and 69. All patients 70 and over had dementia. Neuropathological findings were consistent with clinical diagnosis. Use of a dementia checklist, cognitive skills inventory, and EEG reliably detected Alzheimer-type dementia at an early stage.

Adult↗

PubMed1996

Effect of epilepsy, seizures and epileptiform EEG discharges on cognitive function.

Patients with an established diagnosis of epilepsy were included in three groups on the basis of the absence (Group 2) or presence (Group 3) of epileptiform EEG discharges or subtle seizures (Group 4) during the cognitive assessment procedure. A separate age-matched non-epileptic control group (Group 1) was formed. Twenty-five patients were included in each of the four groups. Thus, a total of 100 patients were investigated. The patients were assessed with continuous 21-channel EEG and video-monitoring, combined with cognitive testing. The results show consistently lower performance on cognitive tests for Group 4, the group with subtle seizures. The difference with the control group was significant for the intelligence subtests and for the complex information processing test (p < 0.05). No transient cognitive impairment was found. The results are discussed in the light of possible factors that may be responsible for the lower test-scores in the patients of Group 4: both the ictal effects of the seizures themselves, postictal effects and the effects of the epileptiform EEG discharges may have had an impact on cognitive performance. Finally the absence of evidence for transient cognitive impairment in a group with frequent epileptiform EEG discharges is discussed in detail.

Adolescent↗

PubMed1996

Use of electroencephalography to detect Alzheimer's disease in Down's syndrome.

We studied the role of electroencephalography (EEG) in the diagnosis of Alzheimer-type dementia in patients with Down's syndrome. 197 patients with Down's syndrome were monitored for 5 to 8 years. Aspects of cognitive functioning were assessed twice yearly. EEGs were scored in a blind fashion, and changes in the EEG were compared to changes in cognitive functioning. When possible, a neuropathological post-mortem examination was performed. Cognitive functioning was drastically reduced in 29 patients. The dominant occipital rhythm became slower at the onset of the cognitive deterioration, and eventually disappeared. In 11 of these patients neuropathological examination showed a severe form of Alzheimer's disease. Changes in the frequency of the dominant occipital rhythm could distinguish between Alzheimer's disease or other causes as underlying the cognitive decline. Slowing of the dominant occipital rhythm seems to be related to Alzheimer's disease in patients with Down's syndrome, and the frequency of the dominant occipital activity decreases at the onset of cognitive deterioration. The EEG is thus an important tool in the clinical diagnosis of Alzheimer-type dementia in patients with Down's syndrome.

Adult↗

PubMed1995

Withdrawal of antiepileptic drugs (AEDs) in seizure-free patients, risk factors for relapse with special attention for the EEG.

When a patient has remained free from seizures for several years while taking antiepileptic drugs (AED) the question arises whether or not the medication can be withdrawn. Therefore it would be desirable to be able to identify reliably those patients who will remain seizure-free without treatment. Numerous variables might be of prognostic importance but our knowledge about the significance of demographic, genetic, aetiological, pathophysiological and treatment-related factors remains extremely poor. Although an abnormal inter-ictal EEG has been repeatedly cited as predictive of relapse during and after AED withdrawal, there is little evidence to support this view. There is a need for more precise individual prediction of risk but as long as patients with forms of epilepsy with widely varying prognosis are grouped together in AED withdrawal trials the outcome of these trials will never reach consensus about the relapse risk and about the possibility of predict relapse in individual patients.

Anticonvulsants↗

PubMed1995

Effect of sabeluzole (R 58,735) on memory functions in patients with epilepsy.

Sabeluzole, a new benzothiazol derivative, has shown positive effects on memory function in animals and in normal volunteers. The present study reports the results of sabeluzole, in memory-impaired patients with localization-related (partial) epilepsy. A randomized, double-blind placebo-controlled parallel-group design was used. A total of 38 patients entered a prospective baseline. Five patients dropped out from the study, thus 33 patients were randomly assigned to either a 12-weeks treatment with sabeluzole (n = 14) or placebo (n = 19). The treatment phase was preceded by a titration phase of 4 weeks to obtain serum levels of sabeluzole between 50 and 130 ng/ml. In order to maintain blindness, a sham titration was carried out in the placebo group. The number of 'responders', i.e. patients with a > 1 SD improvement on at least three of the memory tests was 9 out of 14 (64.3%) in the sabeluzole group and 7 out of 19 (36.8%) in the placebo group. This suggests a clinically relevant effect of sabeluzole. The analysis of the memory tests showed a statistically significant improvement with sabeluzole on the verbal long-term memory test. This could represent a specific drug effect and is in line with previous results of normal volunteer studies that also found improvement mainly restricted to the area of verbal long-term memory.

Adult↗

PubMed1994

Home EEG and video monitoring in epilepsy: first experiences.

In an out-patient epilepsy clinic methods were developed for mobile epilepsy diagnosis and treatment. One of the diagnostic facilities is long-term EEG/video monitoring at home. Method and first results are presented together with a case report of an 8-year-old boy with persistent seizures.

Child↗

PubMed1994

Cognitive side-effects of phenytoin compared with carbamazepine in patients with localization-related epilepsy.

In continuation of an earlier study of our group (Neurology, 43 (1) (1993) 41-51), we present the results of an investigation of the adverse effects of carbamazepine versus phenytoin on cognitive function. Two groups of twenty-five patients are compared in an open, parallel group and non-randomized clinical investigation: a group of patients on carbamazepine (CBZ) monotherapy versus a group of similar size on phenytoin (PHT) monotherapy. The two groups do not show significant differences on variables that could confound the comparison of drug-specific adverse effects: age, gender, intelligence, type of epilepsy, seizure type, seizure frequency, EEG focus and age at onset of the epilepsy. All patients were investigated with a comprehensive neuropsychological test battery ('FePsy'), assessing the cognitive domains of 'speed factors', memory and attention. The results show lower performance in the PHT group compared to the CBZ group on all tests measuring motor speed. Additionally, there is evidence that PHT also affects the speed of central 'higher cortical' processing systems. Our investigation also shows slower performance in tasks that measure speed of information processing ('mental speed'). The other investigated areas, i.e. short-term memory, long-term (verbal and non-verbal) memory and selective attention, do not reveal statistically significant differences between the two groups. These results reconfirm that patients on PHT may suffer from cognitive side-effects even when the medication is sufficiently controlled and the drugs are given within the assumed therapeutical interval.

Adolescent↗

PubMed1992

Syncope or seizure? A matter of opinion.

We studied the diagnostic interpretation by physicians of written histories of 118 patients with a transient loss of consciousness. Considerable disagreement about a diagnosis of either syncope or seizure was found. Overall agreement was only 31%; an erroneous diagnosis was made in 16% of cases. We concluded that the diagnosis of a seizure after a single event is often too unreliable to justify early treatment.

Adolescent↗

PubMed1992

Memory complaints, memory disorders and focus localization in patients with partial epilepsy.

Our study aimed at analysing effects of epileptic foci on memory function in patients with partial epilepsy. Twenty-eight patients with spontaneous memory complaints and psychometrically established memory disorders were assessed by 21-channel electroencephalography recorded both during cognitive testing and during 99mTc-HMPAO single photon emission computed tomography (SPECT). Computed tomography (CT) was performed on the same day. None of the epilepsy-related factors (seizure type, seizure frequency, type of epilepsy, age at onset of the seizures, type of antiepileptic treatment) could be related directly to severity or type of memory impairment (classified into the categories 'global', 'verbal' and 'non-verbal'). Remarkably, this study found no significant relationship between EEG focus localization and severity of measured memory impairment. Most areas with hypoperfusion on the SPECT were found in the group with global (severe) amnesia, typically with a right frontal localization. Abnormalities on CT were predominantly found in the same group, however, with a right-sided parietal localization. An unanticipated finding was that the majority of temporal CT and SPECT lesions were found in the group with relatively better memory performance.

Adult↗

PubMed1992

Focus localization in patients with partial epilepsy with 99Tcm-HMPAO SPECT under continuous surface EEG monitoring.

Our study was aimed at determining the validity of 99Tcm-HMPAO single photon emission computed tomography (SPECT) in the localization of the epileptogenic focus by correlating this diagnostic method with other auxiliary investigations such as surface EEG and X-ray transmission computed tomography (CT). Twenty-eight patients with partial epilepsy and spontaneous memory complaints were assessed with a 21-channel EEG recorded during psychometric evaluation of the memory complaints and with a 12-channel EEG during 99Tcm-HMPAO SPECT. No significant agreement was observed for total focus localization by the two EEGs, CT or SPECT. The EEGs were highly reproducible. Frontal and temporal pathology on CT resulted in frontal and temporal cold spots on SPECT on the same side in six patients. In addition, SPECT demonstrated frontal, temporal or posterior temporal-inferior parietal cold spots in nine patients without accompanying pathology on CT. It is concluded that CT and SPECT may provide complementary anatomical and functional information, respectively, to the EEG. Furthermore, SPECT may be complementary to CT in visualizing functional deficits without an anatomical correlate. The value of SPECT studies in partial epilepsy may be improved by increasing the resolution of the SPECT system and by simultaneous EEG monitoring.

Adult↗

PubMed1992

Epilepsy care in The Netherlands.

In this article models of epilepsy care in the Netherlands are outlined. Mostly this care is aimed at people with uncontrolled epilepsy who may have suffered from the adverse effects of ignorance, prejudice and even discrimination. Many of these adverse factors should be avoidable in future as the educational programmes for people with epilepsy, professionals and the general public take full effect. Meanwhile there is a great deal that can be done to rehabilitate people whose seizures are a problem and whose social abilities fall short of the standards that are required for independent and self-fulfilling living in any society. The models of care described are very sophisticated and they have been developed over many years. They require well-trained and motivated staff and sometimes elaborate and expensive medical diagnostic equipment. But this should not put anybody off as the principles behind any model of care should be the same: Accurate diagnosis. Optimal drug and other treatment (this should be optimal treatment available in that country). Education of the patient and family about all aspects of epilepsy. Opportunity to share experiences. A multidisciplinary approach to identified problems (a multidisciplinary approach can be taken by one person, although a team of people from different disciplines is ideal.) Objectives agreed by all participants.

Ambulatory Care↗

PubMed1991

Transient loss of consciousness: the value of the history for distinguishing seizure from syncope.

We studied 94 consecutive patients (age 15 or over) to investigate which aspects of the history and clinical findings help to distinguish seizures from syncope and related conditions. Clonic movements or automatism observed by an eyewitness classified an event as a seizure. The seizure group consisted of 41 patients and the syncope group of 53 patients. The likelihood ratio was used to calculate the predictive power of single findings and logistic regression to analyse combinations of findings. The best discriminatory finding was orientation immediately after the event according to the eyewitness and the age of the patient in the absence of an eyewitness report (P less than 0.001). We found a seizure five times more likely than syncope if the patient was disoriented after the event and three times more likely if the patient was less than 45 years of age. Nausea or sweating before the event were useful to exclude a seizure. Incontinence and trauma were not discriminative findings.

Adolescent↗

PubMed1991

Syncope or seizure? The diagnostic value of the EEG and hyperventilation test in transient loss of consciousness.

In a prospective study of consecutive patients (age 15 or over) with transient loss of consciousness 45 patients had a history of seizure and 74 patients had a history of syncope. All patients had an EEG, ECG, laboratory tests and a hyperventilation test and were followed for an average of 14.5 months. Epileptiform activity in the interictal EEG had a sensitivity of 0.40 and a specificity of 0.95 for the diagnosis of a seizure. Epileptiform activity nearly doubled the probability of a seizure in doubtful cases. If no epileptiform activity was found, this probability remained substantially the same. The hyperventilation test had a sensitivity of 0.57 and a specificity of 0.84 for the diagnosis of syncope. A positive test increased the probability of syncope half as much in doubtful cases. A negative test did not exclude syncope. Laboratory tests were not helpful except for an ECG which was helpful in elderly patients.

Adolescent↗

PubMed1990

Quantitative analysis of 18/FDG-PET in the presurgical evaluation of patients suffering from refractory partial epilepsy. Comparison with CT, MRI, and combined subdural and depth. EEG.

CT, MRI, 18/FDG-PET and Depth. EEG, performed with subdural and depth electrodes were part of the presurgical evaluation in 22 patients. Statistical analysis of 18/FDG-PET was performed to compare cerebral utilization of glucose to that of normal age matched controls. The findings of CT, MRI, and quantitative analysis of PET are compared with those of ictal Depth. EEG. A positive correlation between CT and Depth. EEG was obtained in 23% of the patients and between MRI and Depth. EEG. in 50%. For both imaging techniques a negative correlation was found in 5%. Regional abnormalities were found with quantified PET in 95% of the patients and were concordant with Depth. EEG. for side of onset in 77% of the patients and for lobe of onset in 59%. A possibly false localising PET result for lobe of onset was obtained in 8 patients (36%). Limitations of PET were most apparent in patients with regional mesiolimbic or bilateral seizure onset. A favourable outcome of surgery was associated usually with positive convergence of both methods. PET may be a valuable contribution to the research and management of partial complex epilepsy, but at present cannot be considered a reliable alternative to invasive EEG methods in patients without clear unilateral focus localization on surface EEG.

Adolescent↗

PubMed1990

Single-dose efficacy evaluation of loreclezole in patients with photosensitive epilepsy.

Photosensitivity can be used as a model in short-term studies for assessing the efficacy of new antiepileptic drugs in man. As a quantitative measure of photosensitivity, the photosensitivity range is employed. This is the range between the highest and the lowest flash rate producing a photoparoxysmal response (generalized paroxysmal activity on the EEG). An efficacious new antiepileptic drug should, like all currently available antiepileptic drugs, reduce the photosensitivity range. Single-dose administration of 100-150 mg of loreclezole resulted in a decreased photosensitivity in all patients tested. This effect was attributable to loreclezole as no acute interactions with valproic acid could be demonstrated. The rapid onset of activity indicates that loreclezole readily passes the blood-brain barrier. The doses applied were very well tolerated.

Adult↗

PubMed1990

Neuropsychological aspects of learning disabilities in epilepsy.

Cognitive impairment is regarded as the link between epileptic conditions and the inability to learn in school. The neuropsychological approach to learning disabilities in epilepsy, therefore, first concentrates on analyzing the differential effects of epileptic factors on cognitive function. The impact of seizure activity, localization of epileptogenic foci, and antiepileptic treatment on cognitive functioning can be evaluated based upon the results of continuous assessment with a computerized neuropsychological test system. Second, learning disabilities may be evaluated on observations made during classroom performance. Three issues seem to predominate in learning studies among disabled children with epilepsy: test-retest variability, deterioration, and the supposed specificity of the learning disabilities.

Adolescent↗