Bronchial effects of cryoballoon ablation for atrial fibrillation

BACKGROUND

Damage to extracardiac structures, including the esophagus and phrenic nerve, is a known complication of cryoballoon ablation (CBA) during pulmonary vein (PV) isolation for atrial fibrillation (AF). Other adjacent structures, including the pulmonary bronchi and lung parenchyma, may be affected during CBA at the PV ostia.

OBJECTIVE

The purpose of this study was to prospectively study the bronchial effects of CBA in humans undergoing CBA for PV isolation.

METHODS

Ten patients undergoing CBA for AF under general anesthesia were enrolled in an institutional review board-approved prospective observational study. Real-time bronchoscopy was performed during cryoablation of PVs adjacent to pulmonary bronchi to monitor for thermal injury. Patients were followed for the development of respiratory complaints postprocedure.

RESULTS

In 7 of 10 patients (70%) and in 13 of 22 freezes (59%), ice formation was visualized in the left mainstem bronchus during CBA in the left upper PV. Ice formation was not seen in the right mainstem bronchus during right upper PV CBA. The average time to ice formation was 89 seconds. There was no significant difference (P = -.45) in average minimum balloon temperature during freezes with ice formation (-48.5°C) and freezes without ice formation (-46.3°C). No patients went on to develop respiratory complications.

CONCLUSION

Unrecognized ice formation occurs frequently in the left mainstem bronchus during CBA for AF. This information helps explain the source of cough and hemoptysis in some patients who undergo CBA. The long-term consequences of this novel finding and the implications for procedural safety are unknown.

Increased risk of epilepsy in biopsy-verified celiac disease: a population-based cohort study

OBJECTIVES

Celiac disease (CD) is associated with several neurologic disorders but it is unclear whether CD is associated with epilepsy. We therefore investigated whether biopsy-verified CD is associated with epilepsy.

METHODS

Cohort study. Using biopsy report data from all Swedish pathology departments (n = 28), we identified individuals with CD who were diagnosed from 1969 to 2008 (Marsh 3: villous atrophy). Through Cox regression, we calculated hazard ratios (HRs) for epilepsy (defined as a diagnosis of epilepsy in the Swedish National Patient Register) in 28,885 individuals with CD and 143,166 controls matched for age, sex, calendar period, and county.

RESULTS

Individuals with CD were at an increased risk of future epilepsy (HR = 1.42; 95% confidence interval [CI] = 1.24-1.62) (272 individuals with CD had a diagnosis of epilepsy vs an expected 192). The absolute risk of future epilepsy in patients with CD was 92/100,000 person-years (excess risk = 27/100,000 person-years). This risk increase was seen in all ages, including children with CD. The HR for having at least 2 interactions with health care due to epilepsy was 1.41 (95% CI = 1.19-1.66). When we restricted epilepsy to those with both a diagnosis of epilepsy and an independent record of antiepileptic drug prescriptions, CD was associated with a 1.43-fold increased risk of epilepsy (95% CI = 1.10-1.86).

CONCLUSION

Individuals with CD seem to be at a moderately increased risk of epilepsy.

Pregnancy registries in epilepsy: a consensus statement on health outcomes

Most pregnant women with epilepsy require antiepileptic drug (AED) therapy. Present guidelines recommend optimizing treatment prior to conception, choosing the most effective AED for seizure type and syndrome, using monotherapy and lowest effective dose, and supplementing with folate. The Epilepsy Therapy Project established the international Health Outcomes in Pregnancy and Epilepsy (HOPE) forum to learn more about the impact of AEDs on the developing fetus, particularly the role of pregnancy registries in studying AED teratogenicity. The primary outcome of interest in these registries is the occurrence of major congenital malformations, with some data collected on minor malformations. Cognitive and behavioral outcomes are often beyond the timeframe for follow-up of these registries and require independent study. The HOPE consensus report describes the current state of knowledge and the limitations to interpretations of information from the various sources. Data regarding specific risks for both older and newer AEDs need to be analyzed carefully, considering study designs and confounding factors. There is a critical need for investigations to delineate the underlying mechanisms and explain the variance seen in outcomes across AEDs and within a single AED.

Heart rate variability in patients with untreated epilepsy

BACKGROUND

Several studies have reported reduced heart rate variability (HRV) in patients with chronic epilepsy under treatment with antiepileptic drugs. This impairment in cardiac autonomic control might be of relevance in relation to the risk of sudden unexpected death in patients with chronic refractory epilepsy. Little information is, however, available on HRV in untreated patients with newly diagnosed epilepsy.

METHODS

We used spectral analysis to assess HRV based on 24h ambulatory EKG recordings in 22 consecutive untreated patients with epilepsy (15 with localization-related, 4 with generalized idiopathic and 3 with undetermined epilepsy). The HRV in these patients was compared with 22 age and sex matched healthy controls.

RESULTS

When analysing the full 24h recordings, there were no significant difference between the patients and the controls in any of the analyzed measures of HRV: standard deviation of RR-intervals (P=0.191), total power (P=0.170), very low frequency power (P=0.329), low frequency power (LF) (P=0.161), high frequency power (HF) (P=0.186) and the LF/HF ratio (P=0.472). The results were very similar for daytime and nighttime recordings.

CONCLUSION

Our results suggest that there is no major effect of epilepsy as such on HRV in patients with untreated epilepsy. It should be emphasized that this study assessed newly diagnosed patients and that the results may not be applicable to patients with chronic epilepsy.

Therapeutic monitoring of antiepileptic drugs for epilepsy

BACKGROUND

The aim of drug treatment for epilepsy is to prevent seizures without causing adverse effects. To achieve this, drug dosages need to be individualised. Measuring antiepileptic drug levels in body fluids (therapeutic drug monitoring) is frequently used to optimise drug dosage for individual patients.

OBJECTIVES

To review the evidence regarding the effects of therapeutic drug monitoring upon outcomes in epilepsy.

SEARCH STRATEGY

We searched the Cochrane Epilepsy Group Specialised Register (September 2006), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2005, Issue 4), MEDLINE (January 1966 to April 2005) and EMBASE (1974 to May 2005). No language restrictions were imposed. We checked the reference lists of retrieved articles for additional reports of relevant studies.

SELECTION CRITERIA

Randomised controlled trials comparing the outcomes of antiepileptic drug monotherapy guided by therapeutic drug monitoring with drug treatment without the aid of therapeutic drug monitoring.

DATA COLLECTION AND ANALYSIS

We based this review on published aggregate data. The main outcomes measured were the proportions of patients achieving a 12-month remission from seizures, reporting adverse effects, and being withdrawn from the treatment they had been randomised to receive.

MAIN RESULTS

Only one study met the inclusion criteria for the review. In this open study, 180 patients with newly-diagnosed, untreated epilepsy were randomised to treatment with the antiepileptic drug selected by their physician either with or without therapeutic drug serum level monitoring as an aid to dosage adjustments. The antiepileptic drugs used were carbamazepine, valproate, phenytoin, phenobarbital and primidone. A 12-month remission from seizures was achieved by 60% of the patients randomised to therapeutic drug monitoring (intervention group) and by 61% in the control group. A total of 56% in the intervention group and 58% in the control group were seizure free during the last 12 months of follow up. Adverse effects were reported by 48% in the intervention group and 47% of the control group patients. Of those randomised to therapeutic drug monitoring, 62% completed the two-year follow up compared with 67% of the control group.

AUTHORS' CONCLUSIONS

We found no clear evidence to support routine antiepileptic drug serum concentration measurement with the aim of reaching predefined target ranges for the optimisation of treatment of patients with newly-diagnosed epilepsy with antiepileptic drug monotherapy. However, this does not exclude the possible usefulness of therapeutic drug monitoring of specific antiepileptic drugs during polytherapy, in special situations or in selected patients, although evidence is lacking.

Valproate effects on kinetics of lamotrigine in pregnancy and treatment with oral contraceptives

In eight women treated with lamotrigine monotherapy, the lamotrigine dose/plasma concentration (D/C) ratio increased by 295% from baseline outside pregnancy to midgestation, whereas in six women treated with lamotrigine in combination with valproate, the increase was only 60%. No difference in lamotrigine D/C ratio was found between users and nonusers of oral contraceptives comedicated with valproate. Valproate seems to reduce the induction of lamotrigine metabolism associated with pregnancy or use of contraceptives.

Role of valproate across the ages. Treatment of epilepsy in adults

A workshop was held in Göteborg in June 2005 to discuss the place of valproate in treating adult epilepsies. Consensus positions were developed on the epilepsy types for which the drug is most suitable and the use of valproate in women of child-bearing age, in men and in patients with psychiatric comorbidity. Valproate was considered to be effective across a broad variety of epilepsy syndromes and seizure types and should be considered a suitable choice for first-line monotherapy of juvenile myoclonic epilepsy and other idiopathic generalized epilepsies. The use of valproate by women of child-bearing age is associated with potential harm to the foetus. A conservative approach to treatment is recommended in these patients whereby alternative antiepileptic drugs should be proposed to women planning pregnancies wherever satisfactory seizure control can be thereby maintained. In cases where valproate is used during pregnancy, either because the pregnancy was unplanned or because alternative treatment options of equivalent efficacy are unavailable, appropriate counselling, precautionary measures and monitoring should be provided. The evidence for an impact of valproate on male reproductive health is equivocal and considerations of male fertility should not be taken into account in deciding whether to prescribe valproate to men. Valproate can be proposed safely to patients with comorbid psychiatric disease or underlying psychiatric vulnerability.

Epilepsy as a risk factor for cancer

AIM

Epilepsy and long term use of antiepileptic drugs have been suggested to be associated with an increased risk of cancer. The authors therefore set out to analyse previous diagnosis of epilepsy as a risk factor for certain cancer forms in a case control study.

METHODS

Incident cases of leukaemia, lymphoma, myeloma, and pancreatic cancer were identified from the Swedish Cancer Registry 1987-99, a total of 52 861 cases. Controls (n = 137 485) were randomly selected from the Swedish Population Registry stratified on age, sex, and year of cancer diagnosis. Cases and controls were linked to the Swedish Hospital Discharge Registry for 1969-99 to identify individuals with first time hospital discharge for epilepsy.

RESULTS

While an epilepsy diagnosis the same year as a cancer diagnosis carried an increased risk of non-Hodgkin's lymphoma (OR = 2.89, 95% CI 1.89 to 4.41), Hodgkin's disease (OR = 4.77, 95% CI 1.77 to 13.30), leukaemia (OR = 2.55, 95% CI 1.50 to 4.32), acute myeloid leukaemia (OR = 3.65, 95% CI 1.68 to 7.93), and pancreatic cancer (OR = 2.05, 95% CI 1.22 to 3.45), the authors found no support for an association between discharge with a diagnosis of epilepsy two years or more before the diagnosis of cancer and an increased risk of any of the types of cancer included in this analysis. The lack of association was also evident for individuals with an epilepsy diagnosis preceding malignancy/reference year by >10 years.

CONCLUSIONS

Clinical examinations prompted by seizure onset probably mainly explain the observed association between epilepsy diagnoses the year before a cancer diagnosis. However, these results lend no support to the suggestion that epilepsy, and presumably long term exposure to antiepileptic drugs, is associated with an increased risk of the types of cancer included in the present study.

No apparent effect of surgery for temporal lobe epilepsy on heart rate variability

BACKGROUND

Impaired cardiac autonomic function may contribute to the risk of sudden unexpected death in epilepsy (SUDEP). Clinical observations indicate that successful epilepsy surgery is associated with a reduced risk of SUDEP. However, in a previous study we found impaired cardiac control pre-surgically in patients with poor outcome of surgery, indicating an a priori lower risk in responders to epilepsy surgery. We have now examined the effect of surgery on cardiac autonomic control in the same patients.

METHODS

We used 24 h EKG recordings to assess heart rate variability (HRV) by spectral analysis in 21 consecutive patients after temporal lobe epilepsy surgery. The HRV was compared with healthy controls, with pre-surgical HRV in the same patients, and analyzed in relation to seizure control 1 year after surgery.

RESULTS

The patients with poor outcome after surgery had significantly lower SD of RR-intervals, total power, very low frequency power and low frequency power than matched healthy controls. The patients with favorable outcome did not differ from the controls, and the postoperative HRV was not different from HRV before surgery in any of the patient groups.

CONCLUSION

We could not demonstrate any effect on HRV of temporal lobe epilepsy surgery in these patients. The observed lower HRV in the poor outcome group was present already before epilepsy surgery as previously reported. Although our results need confirmation in a larger study, the observations suggest that the increased risk of SUDEP in patients failing epilepsy surgery may be due to a common factor predisposing to surgical failure, impaired HRV as well as to an increased risk of SUDEP.

Preoperative heart rate variability in relation to surgery outcome in refractory epilepsy

BACKGROUND

Epilepsy patients may have an impaired autonomic cardiac control, which has been associated with an increased incidence of sudden unexpected death among people with epilepsy (SUDEP). The risk of SUDEP is particularly high among epilepsy surgery candidates with refractory epilepsy. This risk seems to be reduced after successful surgery but whether this is an effect of surgery or reflects pre-existing differences between good and poor responders is under debate.

METHODS

We used spectral analysis to analyze prospectively heart rate variability (HRV) preoperatively in 21 consecutive patients with temporal lobe epilepsy who were planned for epilepsy surgery. The presurgical HRV based on ambulatory 24 hours EKG recordings was analyzed in relation to seizure control at 1 year after surgery.

RESULTS

Patients had significantly lower SD of RR-intervals, total power, very low frequency power and low frequency power than matched healthy controls. Patients with good outcome of surgery (Engel class I; n = 11) did not differ from their controls while those with poor outcome (Engel class II-IV; n = 10) had significantly lower power in all domains than those with a favorable outcome.

CONCLUSIONS

Measurements of heart rate variability preoperatively indicate that patients with a poor outcome of surgery have a more pronounced impairment of sympathetic as well as parasympathetic cardiac control than those with good outcome. Reduced heart rate variability may be associated with an increased risk of sudden unexpected death among people with epilepsy (SUDEP). Good surgery candidates may a priori have a lower risk of SUDEP.

Knowledge, attitudes and smoking behavior among Lao doctors

The aim of this study was to describe the knowledge, attitudes and smoking behavior among doctors at Mahosot University Hospital in Lao PDR. A cross-sectional, descriptive study used a self-administered anonymous questionnaire. The study population comprised 164 doctors. Answers were retrieved from 151 (92%) of the doctors. The prevalence of smoking among male doctors was 35%, 16% smoked daily and 19% occasionally. None of the female doctors reported to have ever smoked. Out of the five diseases related to smoking, 5% of the doctors recognized all and 10% recognized only one. Doctors were significantly more likely to advise patients with symptoms related to smoking. However, approximately one in two doctors reported that they did not always counsel smokers with severe smoking related symptoms to stop smoking. Almost all doctors, independent of smoking behavior, perceived tobacco prevention to be important. The findings indicate a lack of comprehensive knowledge on tobacco related issues. Most doctors expressed a positive attitude towards tobacco prevention. An effort is needed to get doctors in Lao PDR to stop smoking engage in smoking assation support.

Psychomotor development in preschool children exposed to antiepileptic drugs in utero

The aim of this study was to assess psychomotor development with the Griffiths' test in preschool children exposed to antiepileptic drugs (AED) in utero. The study sample consisted of 76 children exposed to AED in utero and 71 unexposed children. The children (exposed and unexposed) have since birth been included in a population-based longitudinal follow-up study of children born to women with meticulously treated epilepsy during pregnancy, initiated in 1985. In total, 67 exposed and 66 unexposed children were tested with the Griffiths' test, which consists of 6 subsets: locomotor function, personal and social behaviour, hearing and speech, eye and hand coordination, performance, and practical reasoning. There was no significant difference in the global scores of the Griffiths' test between the two groups of children. Children exposed to phenytoin in utero (n = 16) showed a significant but subtle reduction in the scores for locomotor development compared with the unexposed children (mean scores: 98 vs 106: 95% confidence interval for the difference in mean scores: -14.0 to -0.4). There was no such difference for the children exposed to carbamazepine in utero (n = 35). The exposed children had significantly fewer siblings (p < 0.01). A significant number of the mothers with AED treatment had no higher level of education than compulsory school (p < 0.01). No other differences in socioeconomic status were observed between the groups.

CONCLUSION

The subtle delay in locomotor development evaluated with the Griffiths' test at 4.5-5 y of age in children exposed to phenytoin may indicate a subtle influence on psychomotor development, which may be more obvious at school age: thus, larger studies and further follow-up are warranted.

Risk of extremity fractures in adult outpatients with epilepsy

PURPOSE

To study the incidence of extremity fractures in a group of adult patients with epilepsy attending an outpatient clinic compared with the incidence of fractures in the general population in the same geographic area.

METHODS

We selected 177 consecutive adult patients with epilepsy attending the outpatient clinic at the Department of Neurology at Karolinska Hospital in Stockholm in 1995. This study population was matched with an Injury Registry to identify those epilepsy patients who during 1991 through 1995 attended the emergency department for an extremity fracture. The observed number of fractures in the epilepsy group was compared with the corresponding number of expected cases based on regional fracture rates. Relative-risk estimates for fractures were calculated with respect to the duration of epilepsy, mono- or polytherapy, and history of tonic-clonic seizures.

RESULTS

Twenty (11%) of 177 patients sustained 23 fractures that prompted a visit to the emergency department. The incidence of fractures in the epilepsy patients was 23.8/1,000 person-years. The overall Standardized Morbidity Ratio (SMR) was 2.39 (95% CI, 1.52-3.59). A significantly higher risk for fractures was thus found in patients with epilepsy. Risk factors were age 45 years or older, male sex, and occurrence of generalized seizures. It also was found that the relative risk of fractures was higher during the first and second year compared with >or=5 years after diagnosis (RR, 3.71; 95% CI, 1.20-11.48).

CONCLUSIONS

Our results highlight the risk of fractures in outpatients with epilepsy. In this patient group, 43% of the fractures were definitely or possibly seizure related. Males 45 years or older are a particular risk group. Special attention is required for this group of patients who are at higher risk for fractures. The risk is apparently higher in the first 2 years after diagnosis, although potential bias in ascertainment of fracture incidents in our study may have underestimated the long-term risk for fractures.

[Malformations in the offspring of pregnant women with epilepsy. Presentation of an international registry of antiepileptic drugs and pregnancy (EURAP)]

The interaction between epilepsy and pregnancy has been studied for many years; nonetheless the risk associated with individual antiepileptic drug has not been adequately characterized up to date. Moreover, virtually nothing is known about the possible human teratogenicity of the newer antiepileptic drugs. Because of the complexity of the mechanisms involved, the crucial evidence needed can only come from very large population based studies, and a collaborative European multicentre investigation has been set up to this purpose. Specific objectives include the evaluation of the risk of major foetal malformations and of delay in prenatal growth following exposure to antiepileptic drugs, assessment of the pattern of congenital abnormalities associated with older and newer antiepileptic drugs and their combinations, and identification of possible relationships with dosage and with a variety of other risk factors. All women exposed to antiepileptic drugs at the time of conception are eligible for entry. The protocol is purely observational and does not entail any change in prescribing pattern or management policies, which are left to the discretion of the treating physician. Data obtained during prospective monitoring for up to 1 year after birth are regularly collected in especially designed forms and entered into Regional Registries prior to transfer to a Central European Registry of Antiepileptic Drugs and Pregnancy (EURAP). Evaluations of incidence and prevalence of teratogenic endpoints will be based exclusively on cases enrolled before foetal outcome is known and in any case not after the 16th week of pregnancy. Cases enrolled after birth, after the 16th week of pregnancy or after prenatal diagnosis will only be reported descriptively. The study is being implemented gradually in 19 countries in Western and Eastern Europe. Wide participation from interested physicians is essential for the achievement of the study objectives, which are expected to lead to important advances in pre pregnancy counselling and overall clinical management of women with epilepsy.

Teratogenesis with antiepileptic drugs: practical management of young women with epilepsy

Children born to mothers who take antiepileptic drugs during pregnancy have a 2-4 fold increased risk for birth defects and also a risk of growth retardation and possibly impaired psychomotor development. Despite their teratogenic effects, antiepileptic drugs are used during pregnancy because uncontrolled epileptic seizures are considered more hazardous to the fetus than the drug therapy. The aim is to maintain seizure control with the appropriate drug given in monotherapy at the lowest effective dosage. These issues have implications for the management of young women with epilepsy in general, since major changes in drug therapy and other attempts to reduce the teratogenic risks should be accomplished before conception in order to be effective and safe.

Harnessing the clinical potential of antiepileptic drug therapy: dosage optimisation

For patients with epilepsy, effective seizure control is the most important determinant of good quality of life. To achieve this, antiepileptic drug (AED) dosages should be individualised to maximise therapeutic benefit and to avoid most--if not all--adverse effects. Several studies suggest that, in routine clinical practice, dosage individualisation is often suboptimal. This may lead to patients receiving unnecessarily large dosages. Conversely, it may lead to patients switching to an alternative therapy (when clinical response is deemed insufficient), without exploration of the full dosage range. Indeed, dosage optimisation--which should involve consideration of the treatment setting and individual patient characteristics--can be a complicated process requiring skill and patience. In general neurological practice, most AEDs should be started at a low dosage and gradually titrated upwards. Starting dosages are similar in most types of epilepsy; however, if a rapid onset of therapeutic action is required, phenytoin, phenobarbital (phenobarbitone), levetiracetam and gabapentin are probably the best tolerated AEDs for starting at full dosage. The initial target maintenance dosage of an AED should be based on the dose-response profile of the drug, and on specific patient characteristics. Usually, the lowest effective daily dose expected to provide seizure control should be used, although various factors (e.g. stage and severity of epilepsy, pharmacokinetic and pharmacodynamic considerations, attitude of the patient) will markedly influence dosage selection. If seizures are not controlled on the initial target dose, the dosage should be increased gradually until complete seizure control is achieved or intolerable adverse effects occur. In most patients who fail to respond to the initially prescribed drug, switching to another AED (monotherapy) is the best option. Combination therapy may be appropriate for patients unresponsive to 2 or more sequential monotherapies. Therapeutic drug monitoring (measurement of serum drug concentrations) is useful in various settings, such as when drug interactions are expected, toxicity is suspected, or when AEDs with nonlinear pharmacokinetics (e.g. phenytoin, carbamazepine) are used. No indications currently exist for routine therapeutic drug monitoring of the newer AEDs. In summary, dosage regimens of AEDs should be assessed regularly, and adjusted if necessary, so that patients can derive optimal therapeutic benefit. For patients considered 'difficult to treat' (i.e. those in whom seizures remain incompletely controlled after several attempts at treatment), referral to a specialist is recommended.

Antiepileptic drug therapy and its management in sudden unexpected death in epilepsy: a case-control study

PURPOSE

Because frequent seizures constitute a major risk factor for sudden unexpected death in epilepsy (SUDEP), the treatment with antiepileptic drugs (AEDs) may play a role for the occurrence of SUDEP. We used data from routine therapeutic drug monitoring (TDM) to study the association between various aspects of AED treatment and the risk of SUDEP.

METHODS

A nested case-control study was based on a cohort consisting of 6,880 patients registered in the Stockholm County In Ward Care Register with a diagnosis of epilepsy. Fifty-seven SUDEP cases, and 171 controls, living epilepsy patients, were selected from the cohort. Clinical data including data on TDM were collected through medical record review.

RESULTS

The relative risk (RR) of SUDEP was 3.7 (95% CI, 1.0-13.1) for outpatients who had no TDM compared with those who had one to three TDMs during the 2 years of observation. RR was 9.5 (1.4-66.0) if carbamazepine (CBZ) plasma levels at the last TDM were above and not within the common target range (20-40 microM). High CBZ levels were associated with a higher risk in patients receiving polytherapy and in those with frequent dose changes. Although the subgroup of patients with high CBZ levels was small (six cases of 33 with CBZ therapy), and the result should be interpreted with caution, no similar associations were demonstrated for phenytoin plasma levels and risk of SUDEP. No association was found between SUDEP risk and within-patient variation in AED levels over time.

CONCLUSIONS

Polytherapy, frequent dose changes, and high CBZ levels as identified risk factors for SUDEP all point to the risks associated with an unstable severe epilepsy. It is unclear whether high CBZ levels per se represent a risk factor or just reflect other unidentified aspects of a severe epilepsy. Our results, however, prompt further detailed analyses of the possible role of AEDs in SUDEP in larger cohorts and suggest that reasonable monitoring of the drug therapy may be useful to reduce risks.

Cost minimization analysis of antiepileptic drugs in newly diagnosed epilepsy in 12 European countries

A recent United Kingdom cost minimization analysis (CMA) of four antiepileptic drugs (AEDs) used to treat newly diagnosed adult epilepsy demonstrated that a new drug, lamotrigine (LTG), incurred higher costs than carbamazepine (CBZ), phenytoin (PHT), and valproate (VPA), whose costs were similar. This analysis took account of each drug's side-effect and tolerability profile. The present analysis investigated the costs of treatment with LTG, CBZ, PHT, and VPA in 12 European countries. Data were derived from published sources and from a panel of locally based experts. When no published data were available, estimates were obtained using expert opinion by a consensus method. These data were incorporated into a treatment pathway model, which considered the treatment of patients during the first 12 months after diagnosis. The primary outcome considered was seizure freedom. Randomized controlled trials demonstrate that the drugs considered are equally effective in terms of their ability to achieve seizure freedom, and thus the most appropriate form of economic evaluation is a CMA. These trials provided data on the incidence of side effects, dosages, and retention rates. The economic perspective taken was that of society as a whole and the analysis was calculated on an "intent-to-treat" basis. Only direct medical costs were considered. In each country considered, LTG was twofold to threefold more expensive than the other drugs considered. A sensitivity analysis demonstrated that varying each of the assumptions (range defined by expert panels) did not significantly alter the results obtained.

Distribution of valproate to subdural cerebrospinal fluid, subcutaneous extracellular fluid, and plasma in humans: a microdialysis study

We sought to study the time course of the distribution of valproate (VPA) to subdural cerebrospinal fluid (CSF) in relation to subcutaneous extracellular fluid (ECF) and plasma after a single oral dose and to study the distribution to these three compartments under steady-state conditions. Microdialysis was used to estimate unbound VPA concentrations in subdural CSF and subcutaneous ECF, and blood samples were drawn for estimation of total and unbound VPA plasma concentrations in four patients with drug-resistant partial epilepsy undergoing presurgical evaluation with subdural EEG monitoring. Three patients were given a single oral dose of VPA, and one patient was receiving regular VPA treatment. VPA was analyzed by gas chromatography with flame ionization detection. The distribution of VPA to subdural CSF was rapid (Tmax, 3.5 h in two patients and 5.5 h in one patient) and subject to a minor delay in all three patients compared with that in the subcutaneous tissue ECF (Tmax, 2.5 h in all three patients), which in turn exhibited no evidence of a distribution delay compared with plasma. Subdural CSF levels of VPA were slightly lower than subcutaneous ECF levels (mean ratio, 0.78) and unbound plasma levels (mean ratio, 0.91). VPA rapidly enters the subdural CSF in unbound concentrations marginally lower than those obtained in subcutaneous ECF and plasma. These findings provide a pharmacokinetic rationale for acute administration of VPA. The good correlation between VPA concentrations in subcutaneous ECF and subdural CSF indicates that estimation of unbound VPA concentrations in subcutaneous tissue using microdialysis sampling has the potential to be useful for monitoring purposes.

Gabapentin versus vigabatrin as first add-on for patients with partial seizures that failed to respond to monotherapy: a randomized, double-blind, dose titration study. GREAT Study Investigators Group. Gabapentin in Refractory Epilepsy Add-on Treatment

PURPOSE

Our objective was to compare the efficacy and safety of gabapentin and vigabatrin as first-line add-on treatment in patients with partial epilepsy.

METHODS

This was a multicenter, double-blind, randomized dose titration study. After baseline assessment and randomization, the dose could be increased if seizures persisted and reduced if side effects occurred. Health-related quality of life was assessed at baseline and at the end of the study. By a protocol amendment post hoc, all randomized patients were offered a standardized perimetry examination at the end of the study. Improvement rate was the proportion of patients with a reduction of seizure frequency of at least 50% during an 8-week period without any adverse events causing withdrawal.

RESULTS

One hundred two patients were randomized and analyzed on an intent-to-treat basis. The improvement rate was 48% in the gabapentin group and 56% in the vigabatrin group. The improvement rate, when per protocol criteria were fulfilled, was 57% in the gabapentin group and 59% in the vigabatrin group. The proportion of seizure-free patients was 31% in the gabapentin group and 39% in the vigabatrin group. There was no difference in quality-of-life scores between the groups. Perimetry after termination of the study on 64 patients showed abnormal results in 3 of 32 patients in the vigabatrin group.

CONCLUSION

Approximately one third of the patients in both groups became seizure-free. Although no major differences were seen in terms of the improvement rate between the groups, equivalence between the two drugs was not found.

Assessing risk to benefit ratio in antiepileptic drug therapy

Assessment of risk to benefit ratio in patients with epilepsy is crucial in determining the need for treatment, the choice of drugs and the use of monitoring tools such as laboratory tests and other investigations. Active epilepsy per se carries significant risks in terms of increased mortality, susceptibility to psychopathology and physical injury, and reduced quality of life as a result of restricted lifestyle, stigma and prejudice. By preventing the occurrence of seizures, antiepileptic drugs (AEDs) attenuate or eliminate altogether seizure-related risks, but other risks may arise due to the side effects of the drugs, all of which have a relatively narrow therapeutic index. While there are no major differences in the degree of efficacy between AEDs which are effective in any given seizure type, side effect profiles differ considerably from one agent to another and represent a major factor in determining choice of treatment. Assessment of risk to benefit ratio should also take into consideration patient-specific factors such as type and severity of the epilepsy, age, sex, childbearing potential, medical and drug history, associated disease, use of concomitant medication (including the contraceptive pill) and the prospected patient's compliance. In some benign epilepsy syndromes, such as idiopathic partial epilepsy with centro-temporal spikes, the risk of side effects from AEDs may outweigh potential benefits in terms of seizure control, and treatment is generally not indicated. At the opposite end of the spectrum, the serious morbidity and mortality associated with severe epileptic encephalopathies, such as the Lennox-Gastaut syndrome, justifies aggressive treatment even with drugs associated with a relatively high risk of life threatening side effects such as felbamate. The present article will provide an overview of specific risks associated with epilepsy and with the various drugs used for its treatment, and will attempt to evaluate the complex balance between these risks and therapeutic benefits in different categories of patients.

Body dimensions of infants exposed to antiepileptic drugs in utero: observations spanning 25 years

PURPOSE

To investigate the influence of maternal antiepileptic drug (AED) treatment on pregnancy duration, birth weight, body length, head circumference, and intrauterine growth in infants exposed in utero to antiepileptic drugs in Sweden between 1973-1997, with 963 singleton infants.

METHODS

Data collected from (a) 1973-1981 (record linkage between a hospital discharge register and a medical birth register); (b) 1984-1995 (prospectively collected information in one defined catchment area with two delivery hospitals); and (c) 1995-1997 (medical birth register data). Observed numbers of infants below a defined size for body measurements compared with expected numbers calculated from all births in Sweden after stratification for year of birth, maternal age, parity, and education or smoking habits in early pregnancy. Standard deviation scores estimated with same stratification procedures.

RESULTS

Fraction of monotherapy exposures increased from approximately 40% to approximately 90% from 1973 to 1997. Significantly increased numbers of infants with small body measurements found in exposed group. Negative influence on body dimensions decreased over time. More marked effects found in infants exposed to polytherapy. In monotherapy, only infants exposed to carbamazepine consistently showed reduction in body dimensions. Significant effect on gestational age in girls and on number of small for gestational age (<2 SD) in boys.

CONCLUSIONS

Polytherapy with antiepileptic drugs and negative influence on body dimensions decreased. In monotherapy, only carbamazepine has a negative influence on body dimensions in this study.

Lamotrigine in pregnancy: pharmacokinetics during delivery, in the neonate, and during lactation

PURPOSE

To investigate the pharmacokinetics of lamotrigine (LTG) during delivery, during the neonatal period, and lactation.

METHODS

High-performance liquid chromatography was used to determine plasma and milk levels of LTG in nine pregnant women with epilepsy treated with LTG, and plasma levels in their 10 infants. Samples were obtained at delivery, the first 3 days postpartum, and at breast-feeding 2-3 weeks after delivery.

RESULTS

At delivery, maternal plasma LTG concentrations were similar to those from the umbilical cord, indicating extensive placental transfer of LTG. There was a slow decline in the LTG plasma concentration in the newborn. At 72 h postpartum, median LTG plasma levels in the infants were 75% of the cord plasma levels (range, 50-100%). The median milk/maternal plasma concentration ratio was 0.61 (range, 0.47-0.77) 2-3 weeks after delivery, and the nursed infants maintained LTG plasma concentrations of approximately 30% (median, range 23-50%) of the mother's plasma levels. Maternal plasma LTG concentrations increased significantly during the first 2 weeks after parturition, the median increase in plasma concentration/dose ratio being 170%.

CONCLUSIONS

Our data demonstrate a marked change in maternal LTG kinetics after delivery, possibly reflecting a normalization of an induced metabolism of LTG during pregnancy. LTG is excreted in considerable amounts in breast milk (the dose to the infant can be estimated to >/=0.2-1 mg/kg/day 2-3 weeks postpartum), which in combination with a slow elimination in the infants, may result in LTG plasma concentrations comparable to what is reported during active LTG therapy. No adverse effects were observed in the infants, however.

Psychomotor development and minor anomalies in children exposed to antiepileptic drugs in utero: a prospective population-based study

The aim of this study was to assess psychomotor development, using Griffiths' test, and the incidence of minor anomalies at birth in children who had been exposed to antiepileptic drugs (AEDs) in utero. The study sample comprised 100 children of mothers who were treated with AEDs during pregnancy and 100 matched control children. Women with epilepsy were recruited from a pregnant urban population (450 000 inhabitants). The lowest possible dose of the fewest AEDs to maintain seizure control was used. Drug levels were controlled on a monthly basis. The children were assessed at 9 months of age. The study children had a significant increase in the number of minor anomalies (31 compared with 18 control children; odds ratio 2.4, CI 1.15 to 5.02, P=0.02 McNemars test), and an increased number of facial anomalies after carbamazepine exposure (11 compared with six control children). Drug exposure did not influence the Griffiths' score at 9 months of age. Even a meticulous AED treatment strategy during pregnancy increases the number of minor anomalies. However, treatment with AEDs does not necessarily influence short-term psychomotor development.

Mortality in epilepsy

Both community-based studies and reports from more selected epilepsy populations consistently reveal persons with epilepsy to have a mortality rate two to three times that of the general population. This increased rate is most pronounced in patients with remote symptomatic epilepsy, although many studies also report a significant excess mortality also among those with idiopathic epilepsy. The highest standardized mortality ratios (SMR) are seen in young age groups, mainly due to the low expected mortality in children, and during the first 5-10 years after diagnosis. Many of these observations suggest that the higher mortality is partly related to the underlying disorder causing epilepsy rather than a direct consequence of the seizures. For example, mortality in cerebrovascular diseases is increased, with SMRs ranging from 1.8 to 5.3 in the various studies. Deaths due to neoplasms, and in particular brain tumors, is also increased among patients with epilepsy. Accidents, status epilepticus, and sudden unexpected death (SUD) are more directly seizure-related causes of death. The incidence of such deaths vary considerably depending on the population being studied. While rare among patients with new-onset epilepsy, seizure-related deaths may account for up to 40% of all deaths in patients with chronic epilepsy. SUD is probably the most frequent seizure-related cause of death among young adults with epilepsy, with an SMR more than 20 compared with the general population. Seizure-induced autonomic cardiorespiratory effects have been suggested, but the mechanisms behind SUD are far from fully understood. It appears, however, that the risk of SUD is closely related to seizure frequency, being 40 times higher in patients who continue to have seizures than in those who are seizure-free.

Therapeutic monitoring of the new antiepileptic drugs

OBJECTIVE

To discuss the potential value of therapeutic drug monitoring (TDM) of the new antiepileptic drugs gabapentin, lamotrigine, oxcarbazepine, tiagabine, topiramate, vigabatrin and zonisamide.

METHODS

A review of studies of the relationship between plasma concentrations and effects of new antiepileptic drugs is provided. Furthermore, the potential value of TDM of these drugs is discussed in relation to their mode of action and their pharmacokinetic properties. The various methods that are available for analysing plasma concentrations of the new antiepileptic drugs are also briefly reviewed.

RESULTS

The available information on the relationship between plasma concentrations and effects of the new drugs is scarce. For most drugs, wide ranges in concentrations associated with seizure control are reported, and a considerable overlap with drug levels among non-responders and also with concentrations associated with toxicity is often noted. However, very few studies have been designed primarily to explore the relationship between drug plasma concentrations and effects. Consequently, there are no generally accepted target ranges for any of the new antiepileptic drugs. Although the available documentation clearly is insufficient, the pharmacological properties of some of the drugs, in particular lamotrigine, zonisamide and, possibly, oxcarbazepine, topiramate and tiagabine, suggest that they may be suitable candidates for TDM.

CONCLUSION

TDM of some of the new antiepileptic drugs may be of value in selected cases, although routine monitoring in general cannot be recommended at this stage. Further systematic studies designed specifically to investigate concentration-effect relationships of the new antiepileptic drugs are urgently needed.

Visual and ocular outcome in children after prenatal exposure to antiepileptic drugs

PURPOSE

To prospectively study the incidence of structural and/or functional ophthalmological abnormalities in the offspring to an unselected population of women with epilepsy, subjected to a well controlled antiepileptic drug (AED) treatment during pregnancy.

METHODS

Forty-three children prenatally exposed to antiepileptic drugs and 47 controls were included. Blinded ophthalmological examinations including fundus photography were performed at a median age of 7 years and 4 months.

RESULTS

No major eye anomalies were found except in one child in the exposed group who had nystagmus and low vision. The visual acuity was lower in the eye with lowest acuity among the exposed children (p < 0.05). No other significant difference was found between the two groups.

CONCLUSION

The results suggest that a well-controlled treatment with AEDs, preferably monotherapy, during pregnancy does not have any major adverse effects on the development of the eye and ophthalmological functions.

Estimation of topiramate in subdural cerebrospinal fluid, subcutaneous extracellular fluid, and plasma: a single case microdialysis study

PURPOSE

To estimate topiramate (TPM) concentrations in subdural cerebrospinal fluid (CSF), subcutaneous extracellular fluid (ECF), and plasma and to study the correlation of TPM concentrations in these three different compartments.

METHODS

In this single case study of a patient with drug-resistant partial epilepsy undergoing presurgical evaluation with subdural EEG monitoring, we used microdialysis to estimate concentrations of unbound TPM in CSF of the subdural space and ECF of abdominal subcutaneous tissue. Blood samples were drawn for estimation of TPM concentrations in plasma.

RESULTS

The correlation between unbound TPM concentrations in subdural CSF and abdominal subcutaneous ECF was good. The mean ratio of ECF/CSF TPM concentration was 0.93 (SD+/-0.03) and the correlation coefficient was 0.98. The mean ratio of ECF/total plasma TPM was 0.75 (SD+/-0.06), and the correlation coefficient was 0.99. The mean ratio of CSF/total plasma TPM was 0.81 (SD+/-0.06), and the correlation coefficient was 0.97.

CONCLUSIONS

Assuming a protein binding of TPM of approximately 13%. it is concluded that, based on nine microdialysis samples from a single subject, TPM levels in the CSF at the cortical surface are approximately the same as the unbound plasma levels. Additional patients should be studied to confirm the results.

Paradoxical GH response to TRH during status epilepticus in man

Information on GH in relation to epilepsy is sparse, and to our knowledge there is no information on GH levels during status epilepticus in man. We studied GH in serum in six patients during status epilepticus, and in a control group of six seizure-free patients with epilepsy, before and after injection of TRH. The baseline GH values before TRH administration were within the normal range in all patients. After injection of TRH all patients with status epilepticus showed a paradoxical peak-shaped increase of GH to at least twice their baseline levels within 45 min after the injection (median basal GH value 1.5 mU/l and median peak GH value 6. 5 mU/l, mean increase 330%). No uniform reaction to TRH was observed in the control group (median basal GH value 2.7 U/l and median of the highest value within 45 min 5.2mU/l). A paradoxical peak reaction of GH to TRH was significantly more frequent in the status epilepticus group compared with the control group (P=0.008, Fisher exact probability test). TRH is not considered a GH-releasing hormone in humans during normal conditions, but a paradoxical response of GH to TRH, similar to that observed during status epilepticus, has been reported in various other pathological conditions, such as acromegaly, liver cirrhosis, mental depression and hypothyroidism. Our results of GH release after TRH administration in patients with status epilepticus suggest an altered regulation of GH as a result of the long-standing epileptic activity.

Risk factors for sudden unexpected death in epilepsy: a case-control study

BACKGROUND

Sudden unexpected death is substantially more common in people with epilepsy than in the general population. Our objective was to investigate the association between some clinical variables and sudden unexpected death in epilepsy (SUDEP) to identify risk factors.

METHODS

This nested case-control study was based on a cohort of people aged between 15 and 70 years, who, during 1980-89, had been admitted to and discharged with a diagnosis of epilepsy from any hospital in the county of Stockholm. The study population was followed up through the National Cause of Death Register until Dec 31, 1991. Cases were individuals who had died, with a diagnosis of epilepsy registered on the death certificate, and who after review of medical and necropsy records were found to meet our SUDEP criteria. Three control participants, who were living epilepsy patients matched for age and sex, were selected from the same cohort for each case. All medical records were examined. Clinical data were collected and analysed on a predesigned protocol.

FINDINGS

57 SUDEP cases were included, of whom 91% had undergone necropsy. The relative risk of SUDEP increased with number of seizures per year. The estimated relative risk was 10.16 (95% CI 2.94-35.18) in patients with more than 50 seizures per year, compared with those with up to two seizures per year. The risk of SUDEP increased with increasing number of antiepileptic drugs taken concomitantly--9.89 (3.20-30.60) for three antiepileptic drugs compared with monotherapy. Other major risk factors were early-onset versus late-onset epilepsy (7.72 [2.13-27.96]), and frequent changes of antiepileptic drug dosage compared with unchanged dosage (6.08 [1.99-18.56]). The association between SUDEP risk and early onset, and SUDEP risk and seizure frequency, was weaker for female than for male patients, whereas frequent dose changes showed a stronger association in female patients.

INTERPRETATION

Our data suggest that SUDEP is a seizure-related event, although the pathophysiological substrate that predisposes individuals to SUDEP may be established at an early age, and there may be some sex differences. Improvement of seizure control and possibly the avoidance of polytherapy may be ways to reduce the risk of SUDEP.

Monotherapy trials with the new antiepileptic drugs: study designs, practical relevance and ethical implications

Traditional randomized clinical trials for the monotherapy assessment of antiepileptic drugs (AED) involve allocation of newly diagnosed patients to long-term treatment with different AEDs in order to determine remission rates and side effect profile. Apart from being time-consuming, however, these trials are unlikely to show significant differences in seizure control between the various drugs, which may lead some regulatory agencies to argue that remission rates could be related to the natural history of the disease rather than to efficacy of the administered drugs. To circumvent this problem, a number of innovative designs for the monotherapy assessment of new AEDs have been developed in recent years. They all share the common feature of being aimed at demonstrating a difference in response rate over a short treatment period between a high dosage of a new AED and some form of suboptimal treatment (placebo or low-dose active control). Patients allocated to suboptimal treatment show unacceptable seizure control more rapidly than patients on high-dose active treatment and therefore they exit the trial at a faster rate: evidence of antiepileptic activity is therefore based on demonstration of differences in rate of deterioration rather than improvement. These trials are conducted with titration schedules, dosages and durations of treatment which are totally unrelated to optimal use of the same AEDs in routine clinical practice. No comparative data with an established reference agent are provided, and allocation of patients to suboptimal treatment raises serious ethical concerns. For these reasons, justification for the continued implementation of these trials is questionable. Randomized long-term comparative trials should be considered the gold-standard for the monotherapy assessment of new AEDs. A review of the literature, however, reveals that long-term trials with new AEDs completed to date had significant shortcomings in their design, including excessively rigid or inappropriate dosing schedules, enrollment of patients with heterogeneous seizure disorders, low statistical power and insufficient duration of follow-up. Because these studies are usually aimed at addressing regulatory requirements, the information obtained cannot be meaningfully applied to routine clinical practice. Large longer-term randomized comparative trials using more pragmatic approaches are highly needed to determine the real value of first-line therapy with new AEDs in patients with well defined seizure disorders.

Valproate monotherapy in juvenile myoclonic epilepsy: dose-related effects on electroencephalographic and other neurophysiologic tests

A neurophysiologic test battery (consisting of a 24-hour, seven-channel electroencephalogram [EEG], EEG spectral analysis, multiple sleep latency test, visual evoked potentials, critical flicker fusion, and visual contrast sensitivity) was administered twice to 16 patients with juvenile myoclonic epilepsy (JME) in a double-blind, randomized, crossover study comparing two daily doses of sodium valproate (VPA), 1000 mg and 2000 mg. Clinical observation time was 6 months for each dose. Mean total VPA concentration during low-dose treatment was 470.4 mmol/L and during high-dose treatment was 700.0 mmol/L. Ten patients had seizures during low-dose treatment, but only three of these showed spike-wave activity on EEGs. During high-dose treatment, nine patients had seizures; five of these had spike-wave activity. EEG power spectrum did not change between doses. The other tests also showed no change between doses. Our results suggested that EEG and our selection of other neurophysiologic tests were of limited value for monitoring seizure frequency and clinical effects of VPA.

Factors associated with the employment problems of people with established epilepsy

The employment experiences of 245 respondents with epilepsy as their main diagnosis were examined as part of a study into the rehabilitation needs of an epilepsy outpatient clinic. It was found that 9% of the sample was unemployed and a further 16% were in receipt of a disability pension. Patients with seizures in remission were more likely to be employed and less likely to have experienced job problems, to feel limited by the epilepsy or to experience stigma. Job problems per se were experienced by 35% of the population. Of those with uncontrolled seizures, 50% had had job problems; however, 22% thought that their current employment situation had not been unduly influenced by epilepsy. It was those respondents who were younger or who were diagnosed early with epilepsy who were most likely to perceive their current situation as a result of having epilepsy. The survey suggests that unemployment is not the major problem it was once thought to be but that discrimination at work is a more serious problem which could lead to under-employment and restricted career development. Career planning should be instigated early and employment services should include information, practical advice and emotional support.

The perceived rehabilitation needs of a hospital-based outpatient sample of people with epilepsy

A postal survey was carried out to identify the perceived epilepsy rehabilitation needs of a hospital-based outpatient population. A response rate of 70% resulted in 245 patients being surveyed. Data showed that 65% of the total sample wanted more rehabilitation assistance and that 27% required substantial contact with the rehabilitation services. The most common request was for more medical information both via written material and telephone contact with a specially trained epilepsy nurse. Approximately one in six patients would like to attend a course on how to live with epilepsy. Access to a psychologist was most often requested during the first year following diagnosis and demand for courses on how to live with epilepsy was highest in the second to fourth year following diagnosis. Requests for social worker assistance were associated with employment issues. Frequency of seizures, duration of epilepsy and age were significant variables in relation to demands for rehabilitation resources. The general conclusions are that (1) the minimum standards of a rehabilitation service should include greater access to medical information via a variety of authoritative sources; and (2) that team-based resources are wanted by a substantial proportion of the population in relation to specific and definable problems, which would involve intensive input from psychologists and social workers.

Postmortem changes in blood concentrations of phenytoin and carbamazepine: an experimental study

Observations of low postmortem blood concentrations of antiepileptic drugs in cases of sudden unexpected death in epilepsy (SUDEP) have led to the assumption that noncompliance may play a role in SUDEP. However, the reliability of postmortem drug levels has been questioned. The purpose of this study was to analyze possible postmortem changes in blood concentrations of carbamazepine (CBZ) and phenytoin (PHT). New Zealand white rabbits were fed with PHT or CBZ until assumed steady state. A blood sample was then drawn for determination of serum and whole blood concentrations of CBZ and PHT, after which the rabbits were killed and stored at 6 degrees C. A further blood sample for drug analysis was obtained 72 hours after death. Antemortem serum concentrations of CBZ were not significantly different from whole blood concentration 72 hours after death. In contrast, antemortem whole blood concentrations of PHT were only 65% of the corresponding serum concentrations, and postmortem PHT blood levels were even lower, being 35% of antemortem serum concentrations. In conclusion, blood concentrations of CBZ seem to be stable during 72 hours after death under these experimental conditions. However, postmortem PHT concentrations should be interpreted with caution and low postmortem concentrations do not necessarily imply a poor compliance.

Validation of microdialysis sampling for subcutaneous extracellular valproic acid in humans

This article is the second in a series of studies aimed at monitoring valproic acid pharmacokinetics in patients with epilepsy by subcutaneous microdialysis. In the current study, a detailed investigation on healthy volunteers is made of the relationship between total concentrations in plasma, free concentrations in plasma, and dialysate concentrations. Particular emphasis is put on validating that the in vivo recovery under standard conditions (30 mm dialyzing membrane and 0.5 microl/minute perfusion rate) is sufficiently close to 100%. It was found that the recovery was very close to 100% at 0.5 microl/minute and by in vitro studies it could be excluded that valproic acid binds to the dialysis equipment. The correlation between unbound plasma concentrations and microdialysis concentrations of valproic acid was acceptable (r = 0.80), and they did not differ systematically from one another. It is concluded that microdialysis can be used to sample subcutaneous extracellular valproic acid in a clinical setting giving reliable estimates of the unbound concentration in plasma.

Valproate as monotherapy for juvenile myoclonic epilepsy: dose-effect study

Sodium valproate enteric-coated tablets were used in this double-blind, randomized, cross-over study of 16 patients with juvenile myoclonic epilepsy comparing 1000 mg and 2000 mg VPA daily in b.i.d. administration with 6 months of observation on each dose. Myoclonic, absence, and generalized tonic-clonic seizures were registered separately. Subjective side-effects were monitored, and a computerized neuropsychologic test battery was performed on each dose. There was no significant difference in seizure frequency between the two doses. Only 25% of the patients were seizure free throughout the study despite concentrations well within the normally proposed therapeutic range for VPA. During the higher dose, 37.5% of the patients had an improved seizure control, but 25% of the patients had an increase in seizure frequency compared to the lower dose. However, there was no correlation between VPA concentrations and subjective side-effects or neuropsychologic test results. Our observations point out the possibility that the common strategy of increasing plasma levels in difficult-to-treat patients until side effects occur should perhaps be reconsidered, but this suggestion needs further confirmation.

Heart rate variability in patients with epilepsy

Autonomic function was studied by the use of spectral analysis of heart-rate variability in patients with epilepsy in relation to type of epilepsy and anti-epileptic drug therapy. A total of 21 patients with juvenile myoclonic epilepsy (JME) and 21 with temporal lobe epilepsy (TLE) were included; 18 patients were treated with carbamazepine (CBZ), 16 with valproate (VPA) and seven with phenytoin (PHT). One healthy drug free control, matched for age and sex, was selected for each patient. Patients and controls underwent an ambulatory 24 h EKG. Heart-rate variability was analyzed in time and frequency domains. Patients with TLE had significantly lower S.D. of the RR-intervals, lower low frequency power and a lower low frequency/high frequency power ratio than their controls. A lower low frequency/high frequency power ratio was the only significant difference between the JME patient group and their controls. Treatment, however, may have had a considerable influence on the heart rate variability in the epilepsy patients. Patients on CBZ had significantly lower S.D. of RR-intervals, low frequency power and a low frequency/ high frequency power ratio than did their matched healthy drug free controls. The ratio of low frequency/high frequency power was also lower in patients on VPA compared with their controls, but apart from that no differences could be demonstrated between this treatment group and the controls. In conclusion, patients with epilepsy appear to have an altered autonomic control of the heart, with a reduction in some heart-rate variability measures, suggesting a decreased sympathetic tone, which may be related to the drug therapy or the epilepsy as such. Further studies are warranted to explore these changes and their possible relevance for sudden death in epilepsy.