Reduced inhibition within primary motor cortex in patients with poststroke focal motor seizures

Antiepileptic drugs for the primary and secondary prevention of seizures after stroke

BACKGROUND

Seizures after stroke are an important clinical problem and may result in poor outcomes. The indications of antiepileptic drugs (AEDs) for seizure prophylaxis after stroke remain unclear. This is an updated version of the Cochrane Review previously published in 2014.

OBJECTIVES

To assess the effects of AEDs for the primary and secondary prevention of seizures after stroke. For primary prevention, we aimed to assess whether AEDs reduce the likelihood of seizures in people who have a stroke but do not have a seizure. For secondary prevention, we aimed to assess whether AEDs reduce the likelihood of further seizures in people who have a stroke and at least one post-stroke seizure.

SEARCH METHODS

We searched the following databases on 9 March 2021: Cochrane Register of Studies (CRS Web), MEDLINE (Ovid, 1946 to March 08, 2021). CRS Web includes randomised or quasi-randomised controlled trials from PubMed, Embase, ClinicalTrials.gov, the World Health Organisation International Clinical Trials Registry Platform (ICTRP), the Cochrane Central Register of Controlled Trials (CENTRAL), and the Specialised Registers of Cochrane Review Groups including Epilepsy and Stroke. We also checked the reference lists of articles retrieved from these searches.

SELECTION CRITERIA

We selected randomised and quasi-randomised controlled studies that recruited participants with a clinical diagnosis of stroke, either ischaemic or haemorrhagic. We excluded studies that only recruited participants with subarachnoid haemorrhage, subdural haemorrhage, extradural haemorrhage, or other non-stroke diagnoses such as tumour- or infection-related infarction or haemorrhage. We also excluded studies that recruited only participants who had undergone neurosurgery. We included participants of all ages suffering any seizure type who were assigned to AEDs or placebo groups.

DATA COLLECTION AND ANALYSIS

In accordance with standard methodological procedures expected by The Cochrane Collaboration, two review authors independently assessed trials for inclusion before evaluating trial risk of bias and extracting relevant data. The primary outcome assessed was the proportion of participants who experienced seizures in the follow-up period. We presented results as summary risk ratios (RRs) with 95% confidence intervals (CIs) for dichotomous outcomes and mean differences (MDs) with 95% CIs for continuous outcomes. Where we had sufficient data, we calculated random-effects (Mantel-Haenszel) meta-analyses for dichotomous outcomes; otherwise, we reported results narratively. We used the I2 statistic to analyse statistical heterogeneity. We planned to use funnel plots to assess publication bias in meta-analyses with at least 10 included studies. We used the GRADE approach to assess the certainty of the evidence.

MAIN RESULTS

Two studies with a total of 856 subjects were included. AEDs were not shown to be effective in primary prophylaxis of post-stroke seizure (RR 0.65, 95% CI 0.34 to 1.26; 2 studies, 856 participants; moderate-certainty evidence). The first study was a randomised double-blind study comparing valproic acid with placebo for primary seizure prevention up to one year after stroke. The study included 72 adults with intracerebral haemorrhage. There was no difference in the risk of post-stroke seizures (RR 0.88, 95% CI 0.35 to 2.16) or of death (RR 1.20, 95% CI 0.40 to 3.58). The second study was a substudy on the use of diazepam in acute stroke. It was a randomised double-blind study, comparing a three-day diazepam treatment versus placebo for primary seizure prevention up to three months after stroke in 784 adults with acute stroke. There was no evidence of a difference in the risk of post-stroke seizures for all stroke or subgroups of haemorrhagic or ischaemic stroke (RR for all stroke 0.47, 95% CI 0.18 to 1.22). In a subgroup analysis of anterior circulation cortical infarcts, primary prophylaxis with diazepam was associated with a reduced risk of post-stroke seizures (RR 0.21, 95% CI 0.05 to 0.95). Risks of mortality did not differ between the diazepam and the placebo group at two weeks (RR 0.84, 95% CI 0.56 to 1.26) and three months follow-up (RR 0.95, 95% CI 0.72 to 1.26). We assessed both studies to be at a low overall risk of bias. Using the GRADE approach, we assessed the overall certainty of the evidence as low to moderate.

AUTHORS' CONCLUSIONS

There is insufficient evidence to support the routine use of AEDs on the primary and secondary prevention of seizures after stroke. Further well-conducted studies are warranted for this important clinical problem.

Pathogenesis of seizures and epilepsy after stroke

Stroke is the most frequent cause of secondary epilepsy in the elderly. The incidence of cerebral stroke is increasing with the extension of life expectancy, and the prevalence of post-stroke epilepsy (PSE) is rising. There are various seizure types after stroke, and the occurrence of epilepsy is closely related to the type and location of stroke. Moreover, the clinical treatment of post-stroke epilepsy is difficult, which increases the risk of disability and death, and affects the prognosis and quality of life of patients. Now seizure and epilepsy after stroke is more and more get the attention of the medical profession, has been more and more researchers have devoted to seizures after stroke and PSE clinical and basic research, and hope to get a scientific and unified guideline, to give timely and effective treatment, but the exact pathophysiologic mechanism has not yet formed a unified conclusion. It has been found that ion channels, neurotransmitters, proliferation of glial cells, genetics and other factors are involved in the occurrence and development of PSE. In this review, we discuss the pathogenesis of early-onset epileptic seizures and late-onset epilepsy after stroke, in order to provide a basis for clinicians to understand the disease, and expect to provide ideas for future exploration.

Secondary effects on brain physiology caused by focused ultrasound-mediated disruption of the blood-brain barrier

Focused ultrasound (FUS) combined with microbubbles is a non-invasive method for targeted, reversible disruption of the blood-brain barrier (FUS-BBB opening). This approach holds great promise for improving delivery of therapeutics to the brain. In order to achieve this clinically important goal, the approach necessarily breaks a protective barrier, temporarily, which plays a fundamental role in maintaining a homeostatic environment in the brain. Preclinical and clinical research has identified a set of treatment parameters under which this can be performed safely, whereby the BBB is disrupted to the point of being permeable to normally non-penetrant agents without causing significant acute damage to endothelial or neuronal cells. Much of the early work in this field focused on engineering questions around how to achieve optimal delivery of therapeutics via BBB disruption. However, there is increasing interest in addressing biological questions related to whether and how various aspects of neurophysiology might be affected when this fundamental protective barrier is compromised by the specific mechanisms of FUS-BBB opening. Improving our understanding of these secondary effects is becoming vital now that FUS-BBB opening treatments have entered clinical trials. Such information would help to safely expand FUS-BBB opening protocols into a wider range of drug delivery applications and may even lead to new types of treatments. In this paper, we will critically review our current knowledge of the secondary effects caused by FUS-BBB opening on brain physiology, identify areas that remain understudied, and discuss how a better understanding of these processes can be used to safely advance FUS-BBB opening into a wider range of clinical applications.

Seizures in patients with a phaeochromocytoma/paraganglioma (PPGL): A review of clinical cases and postulated pathological mechanisms

The purpose of this work was to expound on the postulated pathological mechanisms through which pheochromocytoma/paraganglioma (PPGL) can cause seizures by conducting a comprehensive review of ten cases and several pathogenic mechanisms. The goal was to enhance awareness amongst doctors and researchers about patients with PPGL presenting with seizures. This would help decrease the risk of misdiagnosis and mismanagement in future clinics. Additionally, this review was written with the purpose to attract more attention to etiological explorations, particularly concerning rare causes of seizures, which is consistent with the idea that League Against Epilepsy (ILAE) has emphasized in the new version of the ILAE position paper published in 2017. It is of great importance to keep in mind the fact that seizures can constitute an atypical presentation of PPGL and to establish early diagnosis and accurate cure for these patients, especially in the presence of paroxysmal hypertension or other suggestive symptoms of PPGL.

Hypertension, seizures, and epilepsy: a review on pathophysiology and management

BACKGROUND

Epilepsy and hypertension are common chronic conditions, both showing high prevalence in older age groups. This review outlines current experimental and clinical evidence on both direct and indirect role of hypertension in epileptogenesis and discusses the principles of drug treatment in patients with hypertension and epilepsy.

METHODS

We selected English-written articles on epilepsy, hypertension, stroke, and cerebrovascular disease until December, 2018.

RESULTS

Renin-angiotensin system might play a central role in the direct interaction between hypertension and epilepsy, but other mechanisms may be contemplated. Large-artery stroke, small vessel disease and posterior reversible leukoencephalopathy syndrome are hypertension-related brain lesions able to determine epilepsy by indirect mechanisms. The role of hypertension as an independent risk factor for post-stroke epilepsy has not been demonstrated. The role of hypertension-related small vessel disease in adult-onset epilepsy has been demonstrated. Posterior reversible encephalopathy syndrome is an acute condition, often caused by a hypertensive crisis, associated with the occurrence of acute symptomatic seizures. Chronic antiepileptic treatment should consider the risk of drug-drug interactions with antihypertensives.

CONCLUSIONS

Current evidence from preclinical and clinical studies supports the vision that hypertension may be a cause of seizures and epilepsy through direct or indirect mechanisms. In both post-stroke epilepsy and small vessel disease-associated epilepsy, chronic antiepileptic treatment is recommended. In posterior reversible encephalopathy syndrome blood pressure must be rapidly lowered and prompt antiepileptic treatment should be initiated.

The Progress of Epilepsy after Stroke

BACKGROUND

Epilepsy is the second most common disease caused by multiple factors and characterized by an excessive discharge of certain neurons in the nervous system. Cerebrovascular disease, including stroke, is viewed as the most common cause of epilepsy in the elderly population, accounting for 30%-50% of the newly diagnosed cases of epilepsy cases in this age group.

METHODS

Data were collected from Web of Science, Medline, Pubmed, Scopus, through searching of these keywords: "Stroke" and "epilepsy".

RESULTS

Depending on the underlying cerebrovascular disease, 3%-30% of patients after stroke may develop post-stroke epilepsy (PSE), which has a negative effect on stroke prognosis and the quality of life.

CONCLUSION

In this review, we summarized new aspects emerging from research into PSE, including definition, epidemiology, risk factors, mechanism, accessory examination and treatment strategies for post-stroke epilepsy, which will enrich our knowledge of this disorder.

Prospects of modeling poststroke epileptogenesis

This Review describes the current status of poststroke epilepsy (PSE) with an emphasis on poststroke epileptogenesis modeling for testing new therapeutic agents. Stroke is a leading cause of epilepsy in an aging population. Late-onset "epileptic" seizures have been reported in up to 30% cases after stroke. Nevertheless, the overall prevalence of PSE is 2-4%. Rodent models of stroke have contributed to our understanding of the relationship between seizures and the underlying ischemic damage to neurons. To understand whether acutely generated stroke events lead to a chronic phenotype more closely resembling PSE with recurrent seizures, a limited variety of approaches emerged in early 2000s. These limited methods of causing an occlusion in mice and rats show different infarct size and neurological deficits. The most often employed procedure for inducing focal ischemia is the middle cerebral artery occlusion. This mimics the pathophysiology seen in humans in terms of extent of damage to cortex and striatum. Photothrombosis and endothelin-1 models can similarly evoke episodes of ischemic stroke. These models are well suited to studying mechanisms and biomarkers of epileptogenesis or optimizing novel drug discoveries. However, modeling of PSE is tedious, is highly variable, and lacks validity; therefore, it is not widely implemented in epilepsy research. Moreover, the relevance of ischemic models to specific forms of human stroke remains unclear. Stroke modeling in young male rodents lacks clinical relevance to elderly populations and especially to women, likely as a result of sex differences. Nevertheless, because of the neuronal damage and epileptogenic insult that these models trigger, they are helpful tools in studying acquired epilepsy and prophylactic drug therapy. © 2016 Wiley Periodicals, Inc.

Epilepsy in cerebrovascular diseases: Review of experimental and clinical data with meta-analysis of risk factors

OBJECTIVE

Seizures may occur in close temporal association with a stroke or after a variable interval. Moreover, epilepsy is often encountered in patients with leukoaraiosis. Although early post-stroke seizures have been studied extensively, less attention has been paid to post-stroke epilepsy (PSE) and to epilepsy associated with leukoaraiosis (EAL). The aim of this paper is to review data concerning pathophysiology, prognosis, and treatment of PSE and EAL.

METHODS

We performed an extensive literature search to identify experimental and clinical articles on PSE and EAL. We also conducted a systematic review of risk factors for PSE and EAL among eligible studies.

RESULTS

PSE is caused by enhanced neuronal excitability within and near the scar. The role played by white matter changes in EAL remains to be elucidated. Meta-analysis showed that cortical involvement (odds ratio [OR] 3.71, 95% confidence interval [CI] 2.34-5.90, p < 0.001), cerebral hemorrhage (OR 2.41, 95% CI 1.57-3.70, p < 0.001), and early seizures (OR 4.43, 95% CI 2.36-8.32, p < 0.001) are associated with an increased risk of PSE. As regards EAL, no prospective, population-based studies evaluated the role of different variables on seizure risk. Studies about the management of PSE are limited. PSE is generally well controlled by drugs. Data about risk factors, prognosis, and treatment of EAL are lacking.

SIGNIFICANCE

Pathophysiology and risk factors are well defined for PSE but need to be elucidated for EAL. Management of PSE and EAL relies on the clinician's judgment and should be tailored on an individual basis.

Early predictors and prevention for post-stroke epilepsy: changes in neurotransmitter levels

Background: The purpose of this study was to identify predictors and preventative treatments for post-stroke epilepsy (PSE). Methodology: Eighty-four patients who had suffered a cerebrovascular insult (within 72 hours) were recruited and divided into two groups: an EP group (patients with seizures after stroke) and a NEP group (patients without seizures after stroke). The NEP group was then subdivided into three groups: a control group, a GABA (γ-aminobutiric acid) group (received GABA orally), and a CCB group (received calcium channel blocker nimodipine orally). Patient groups were compared by gender, age, past medical history, stroke type, number of lesions, and position and stroke severity (using Scandinavian stroke scale, SSS). Forearm venous blood was sampled, and high performance liquid chromatography (HPLC) was used to measure plasma levels of neurotransmitters and Ca²⁺. Patients then received 14 days of drug intervention. One month after drug withdrawal, GABA, glutamate (Glu) and Ca²⁺ concentrations in plasma were measured again. Results: The number of previous strokes, size of infarction, presence of multiple lesions, localization to the cortex, and SSS were statistically significant between the two groups (P < 0.05). In the EP group, the Glu concentration was greater and the Ca²⁺ concentration was lower than in the NEP group (P < 0.05). The results obtained after 1 month of therapy showed a reduction in Glu levels and an increase in GABA levels in the GABA group relative to the control NEP group (P < 0.05), while the CCB group showed a decrease in the concentration of Glu and an increase in the concentrations of GABA and Ca²⁺ relative to the NEP control group (P < 0.05). Conclusions: We identified susceptibility factors for PSE and demonstrated that GABA and calcium antagonists may have a therapeutic use in the early prevention of PSE.

A Meta-analysis of the Cortical Silent Period in Epilepsies

OBJECTIVE

The cortical silent period (CSP) following transcranial magnetic stimulation reflects GABAB-mediated inhibition in the primary motor cortex (M1) and could contribute to understand the pathophysiological substrates of epileptic conditions. Increased CSP duration has been reported in idiopathic generalized epilepsy (IGE) and in partial epilepsy (PE) involving the M1, although other studies yielded discordant findings. We used meta-analysis to systematically assess the consistency of CSP changes in untreated patients with epilepsies.

METHODS

Databases were searched for controlled studies evaluating the CSP in drug-naïve or drug-free patients with IGE or PE. For each study, the mean difference with 95% confidence intervals (CIs) between CSP duration obtained in patients and controls was calculated. The effect of motor threshold (MT) on the CSP duration has also been explored by meta-analysis and meta-regression.

RESULTS

Fourteen studies (267 patients and 234 controls) were included. A significant mean difference (14.16 ms, 95% CI, 1.20, 27.11 ms) was found, with longer CSP in patients than in controls. The mean difference was still greater (18.05 ms) if only the 202 IGE patients were analyzed. No MT difference emerged between patients and controls. Meta-regression showed no relationship between MT and CSP duration.

CONCLUSION

Meta-analysis confirms CSP modifications in epilepsies, with enhancement of this cortical inhibitory measure at least in most IGE patients. This provides rationale for further investigations aiming to verify the hypotheses that increased CSP reflects compensatory neural phenomena counteracting transition from the interictal to ictal state and that CSP variability reflects the pathophysiological heterogeneity of epileptic syndromes.

Seizures in the acute stroke setting

Stroke is one of the leading causes of long-term disability. One in six people in the world will suffer a stroke in their lifetime, with the annual incidence about 117 per 100,000 person-years in developing countries. It has also been shown to be the cause of 10-15% of epilepsies, more prevalent in patients above 60 years of age. The incidence of early seizures in acute stroke ranges 3-33%, with 50-78% of the seizures occurring within the first 24 hours. Occurrence of seizures within 24 hours of stroke is associated with higher 30-day mortality, which may be a reflection of severe neuronal damage. Alteration in intracellular ion concentrations and hyper-excitability are thought to be etiologies for early seizures in acute stroke, and the increased stress on already vulnerable tissues may result in worsening of stroke symptoms. Early detection of seizures and subsequent effective treatment can prevent additional metabolic burden and damage to the blood-brain barrier, which may improve recovery and overall outcome. Clinical seizures can be recognized readily at bedside and lead to prompt medical intervention. In contrast, electrographic seizures with subtle or no clinical sign and non-convulsive status epilepticus (NCSE) may escape clinical observation and be left untreated. With the use of continuous electroencephalogram monitoring (cEEG), patients with electrographic seizures can be better identified and medically treated more quickly. In addition to electrographic seizures, the presence of isolated and periodic epileptiform patterns on electroencephalogram (EEG) suggests the need for medical treatment since up to 75% of these patients have been found to develop early post-stroke seizures. Newer anti-epileptic medications with intravenous formulation, together with traditional regimen and barbiturate, have shown promise in controlling early post-stroke seizures and possibly improving outcome.

CORTICAL EXCITABILITY AS A POTENTIAL CLINICAL MARKER OF EPILEPSY: A REVIEW OF THE CLINICAL APPLICATION OF TRANSCRANIAL MAGNETIC STIMULATION

Transcranial magnetic stimulation (TMS) can be used for safe, noninvasive probing of cortical excitability (CE). We review 50 studies that measured CE in people with epilepsy. Most showed cortical hyperexcitability, which can be corrected with anti-epileptic drug treatment. Several studies showed that decrease of CE after epilepsy surgery is predictive of good seizure outcome. CE is a potential biomarker for epilepsy. Clinical application may include outcome prediction of drug treatment and epilepsy surgery.

Antiepileptic drugs for the primary and secondary prevention of seizures after stroke

BACKGROUND

This is an updated version of the original Cochrane review published in 2010, Issue 1. Seizures after stroke are an important clinical problem, and they may be associated with poor outcome. The effects of antiepileptic drugs for the primary and secondary prevention of seizures after stroke remain unclear.

OBJECTIVES

We aimed to assess the effects of antiepileptic drugs for the primary and secondary prevention of seizures after stroke.

SEARCH METHODS

We searched the Specialised Registers of the Cochrane Epilepsy Group (12 August 2013) and the Cochrane Stroke Group (12 August 2013), the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library 2013, Issue 7), and MEDLINE (OVID, 1946 to 12 August 2013). We also checked the reference lists of articles retrieved from these searches.

SELECTION CRITERIA

Randomised and quasi-randomised controlled trials in which participants were assigned to treatment or control group (placebo or no drug).

DATA COLLECTION AND ANALYSIS

Two review authors independently screened all the titles, abstracts, and keywords of publications identified by the searches to assess their eligibility, and both review authors assessed their suitability for inclusion according to prespecified selection criteria. We included only one study for data collection and analysis.

MAIN RESULTS

We found only one trial that fulfilled the study inclusion criteria of comparison of the effects of an antiepileptic drug with placebo (or no drug) for the primary or secondary prevention of seizures after stroke. This was a prospective randomised, double-blind, placebo-controlled trial comparing valproic acid with placebo for primary prevention of seizures in 72 adults (over 18 years of age) with spontaneous non-aneurysmal, non-traumatic intracerebral haemorrhage; no statistically significant difference in outcome (seizure occurrence at one year) was demonstrated between groups.

AUTHORS' CONCLUSIONS

Currently, there is insufficient evidence to support the routine use of antiepileptic drugs for the primary or secondary prevention of seizures after stroke. Further well-conducted research is needed for this important clinical problem.

Poststroke epilepsy: occurrence, predictors and treatment

Although a well-known clinical phenomenon, there still remain some questions regarding the definitions, pathophysiology and epidemiology of early and late poststroke seizures and of poststroke epilepsy. Poststroke seizures and epilepsy constitute important complications in patients surviving a stroke. Several studies of the prevalence and possible predictors of poststroke seizures and epilepsy have been undertaken during the past few decades. Unfortunately, these studies have not consistently used the established definitions. There are only few studies concerning treatment of poststroke epilepsy in the elderly, especially regarding the effect of the newer antiepileptic drugs. The aim of this article is to give an overview of the latest studies of poststroke seizures, with special emphasis on poststroke epilepsy, by presenting data on occurrence, predictors and treatment. The results from the recent studies on both poststroke seizures (early and late) and poststroke epilepsy are quite consistent. Poststroke epilepsy appears to occur in 2-4% of patients. The most convincing predictors of late poststroke seizures and epilepsy and treatment options are discussed in this review.

Incidence and associations of poststroke epilepsy: the prospective South London Stroke Register

BACKGROUND AND PURPOSE

To describe the epidemiology and associations of poststroke epilepsy (PSE) because there is limited evidence to inform clinicians and guide future research.

METHODS

Data were collected from the population-based South London Stroke Register of first strokes in a multiethnic inner-city population with a maximum follow-up of 12 years. Self-completed forms and interviews notified study organizers of epilepsy diagnosis. Kaplan-Meier methods and Cox models were used to assess associations with sociodemographic factors, clinical features, stroke subtype, and severity markers.

RESULTS

Three thousand three-hundred ten patients with no history of epilepsy presented with first stroke between 1995 and 2007, with a mean follow-up of 3.8 years. Two-hundred thirteen subjects (6.4%) had development of PSE. PSE incidence at 3 months and 1, 5, and 10 years were estimated at 1.5%, 3.5%, 9.0%, and 12.4%, respectively. Sex, ethnicity, and socioeconomic status were not associations, but markers of cortical location, including dysphasia, visual neglect, and field defect, along with stroke severity indices at presentation, including low Glasgow Coma Scale, incontinence, or poor function on Barthel Index, were associated with PSE on univariate analysis. Young age was independently associated with PSE, affecting 10.7% of patients aged <65 years and 1.6% >85 years (P≤0.001) on 10-year estimates. Independent predictors of PSE also included visual neglect, dysphasia, and stroke subtype, particularly total anterior circulation infarcts. Dysarthria was associated with reduced incidence.

CONCLUSIONS

PSE is common, with risk continuing to increase outside the acute phase. Young age, cortical location, larger lesions, and hemorrhagic lesions are independent predictors.

[Neuropathology and etiology of focal epilepsy]

In 2010 the International League against Epilepsy published a new classification of epilepsies. A major advance of this classification system is the acknowledgment of a genetic or pathologic-anatomic basis of epilepsy as important predictors of outcome (cause matters). This applies in particular to structural-metabolic lesions, which were frequently recognized in surgical specimens obtained from patients with drug-resistant focal epilepsy, i.e. hippocampal sclerosis, glioneuronal tumors, focal cortical dysplasias, vascular malformations, ischemia, intracerebral hemorrhage, glial scars or inflammation. A better understanding and classification of the etiopathology as well as the underlying molecular mechanisms will help to anticipate and appreciate the clinical course of a disease as well as to develop new and targeted drug treatment. Surgically available human brain tissue will be most helpful to support this approach but will also need careful neuropathological evaluation with accurate classification systems and use of terminology.

Antiepileptic drugs for the primary and secondary prevention of seizures after stroke

BACKGROUND

Seizures after stroke are an important clinical problem, and they may be associated with poor outcome. The effects of antiepileptic drugs for the primary and secondary prevention of seizures after stroke remain unclear.

OBJECTIVES

We aimed to assess the effects of antiepileptic drugs for the primary and secondary prevention of seizures after stroke.

SEARCH STRATEGY

We searched the Specialised Registers of the Cochrane Epilepsy Group and the Cochrane Stroke Group (2 July 2009), the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library Issue 2, 2009), and MEDLINE (1950 to June, week 4, 2009). We also checked the reference lists of articles retrieved from these searches.

SELECTION CRITERIA

Randomised and quasi-randomised controlled trials in which patients were assigned to treatment or control group (placebo or no drug).

DATA COLLECTION AND ANALYSIS

Both review authors independently screened all the titles, abstracts, and keywords of publications identified by the searches to assess their eligibility, and both review authors assessed their suitability for inclusion according to pre-specified selection criteria. No study was included, hence no data analysis was performed.

MAIN RESULTS

We did not find any randomised controlled trials that have compared the effects of antiepileptic drugs with placebo (or no drug) for the primary or secondary prevention of seizures after stroke. We did, however, find three randomised controlled trials that have assessed the effects of several different antiepileptic drugs for the secondary prevention of post-stroke seizures. The first study was performed in older adults (mean age 72 years) with a mixture of diagnoses including stroke (comparing carbamazepine, lamotrigine and gabapentin); the second study was performed in children and younger adults (mean age 38 years) with a mixture of diagnoses including stroke (comparing carbamazepine, oxcarbazepine, lamotrigine, gabapentin and topiramate); and the third study was performed in stroke patients only (comparing carbamazepine and lamotrigine).

AUTHORS' CONCLUSIONS

Currently, there is insufficient evidence to support the routine use of antiepileptic drugs for the primary or secondary prevention of seizures after stroke. Further well-conducted research is needed for this important clinical problem.

Ischaemic stroke in adults and epilepsy

Stroke is an important cause of symptomatic epilepsy especially in the elderly. Seizures in the setting of stroke will furthermore worsen the prognosis of stroke. Studies show that the frequency of seizures in stroke ranges between 2.3% and 14%. Typically early seizures are defined as those that occur within 14 days of the stroke, and later seizures those that occur after this period. A number of risk factors have been identified like cortical involvement, size of the infarct and stroke severity. Status epilepticus can be a presenting symptom of acute stroke and can lead to increased mortality. Early seizures are risks for recurrent seizures though not for the development of epilepsy but late seizures do carry a higher risk. There are no clear cut guidelines for the treatment of seizures in stroke and hence treatment needs to be initiated in the context of the patient. The presence of co morbid conditions and the use of other drugs also complicate antiepileptic therapy, and the risk of drug interactions is a particular hazard in elderly patients on multiple co medication. Although hemorrhagic and ischaemic stroke can both result in epilepsy, this review focuses primarily the association of epilepsy and ischaemic stroke.

Motor cortical organization in an adult with hemimegalencephaly and late onset epilepsy

Hemimegalencephaly is a rare brain malformation whose physiology is largely obscure. In a single patient, we studied motor cortex using several transcranial magnetic stimulation variables testing cortical excitability, and mapping motor area. The megalencephalic hemisphere showed an enlargement of cortical motor map with abnormal axonal orientation and an excess spread of corticospinal excitation, associated with multiple defects of cortical inhibition. TMS gave new information on the anatomic/functional features and epileptogenesis in this complex and physiologically obscure syndrome.

[Seizures and epilepsies after stroke]

Epilepsies after stroke represent 20% of all adult-onset epilepsies and exhibit special characteristics with respect to diagnosis, treatment, and prognosis. Patients are frequently amnestic for their seizures the signs of which can be very subtle. Postictal pareses and confusional states can last for days, which further complicate diagnosis. Single seizures after stroke were reported in 2% to 10% of cases, and community-based studies found epilepsies in 3% to 4% of stroke patients. Analyses of subgroups identified epilepsy risks of 3% after ischemic infarction, 6% to 10% after intracerebral hemorrhage, and 9% after subarachnoid hemorrhage. Status epilepticus developed in less than 1% of stroke patients. Besides etiology, further risk factors for epilepsy comprise: remote seizures (latency >2 weeks, risk of recurrence >50%) more than early seizures (latency <2 weeks, risk of recurrence <50%), extent of stroke, cortical involvement, and degree of neurological deficit. The first appearance of seizures in patients older than 60 years represents a risk factor for future stroke with a hazard ratio of 2.89.There is currently no sufficient evidence for starting AED treatment before seizures occur. The benefit is still unclear of starting AED after a single early post-stroke seizure. Most authors recommend AED treatment after the second seizure but also after a first remote seizure because of the high risk of seizure recurrence in these situations. Possible pharmacokinetic interactions should be considered when choosing AED. Especially the first-generation AED carry the potential to interact with comedication, which is usually seen in stroke patients receiving substances such warfarin and salicylates. Only very few studies investigate specific AED exclusively in stroke patients. Lamotrigine and gabapentin have been successfully tested in these patients.

Motor Cortical Excitability in Patients with Poststroke Epilepsy

PURPOSE

To gain insight into the mechanisms underlying poststroke epilepsy (PSE), we evaluated motor cortical function in chronic stroke patients with (N = 18) and without (N = 18) PSE.

METHODS

We measured resting motor threshold (RMT), motor evoked potential (MEP) amplitudes, cortical silent period (CSP), intracortical inhibition (ICI), influenced by GABAergic neurotransmission, and intracortical facilitation (ICF), influenced by glutamatergic activity, to transcranial magnetic stimulation.

RESULTS

We found (1) larger MEP amplitudes and ICF, in the affected than unaffected hemispheres of patients in the PSE group but not in patients without epilepsy, and (2) comparably higher RMT and longer CSP in the absence of differences in ICI, H-reflexes or F-waves in the affected and unaffected hemispheres of both PSE and non-PSE patients.

CONCLUSIONS

Enhanced cortical excitability in the affected hemisphere, possibly related to increased glutamatergic activity, could be one of the mechanisms contributing to the development of poststroke epilepsy.

rTMS Reveals Premotor Cortex Dysfunction in Frontal Lobe Epilepsy

PURPOSE

Studies of motor cortex excitability provided evidence that focal epilepsies may alter the excitability of cortical areas distant from the epileptogenic zone. In order to explore this hypothesis we studied the functional connectivity between premotor and motor cortex in seven patients with frontal lobe epilepsy and seizure onset zone outside the premotor or motor cortex.

METHODS

Low-frequency subthreshold repetitive transcranial magnetic stimulation was applied to the premotor cortex and its impact on motor cortex excitability was measured by the amplitude of motor-evoked potentials in response to direct suprathreshold stimulation of the motor cortex.

RESULTS

Stimulation of the premotor cortex of the non-epileptogenic hemisphere resulted in a progressive and significant inhibition of the motor cortex as evidenced by a reduction of motor evoked potential amplitude. On the other hand, stimulation of the premotor cortex of the epileptogenic hemisphere failed to inhibit the motor cortex. The reduced inhibition of the motor cortex by remote areas was additionally supported by the significantly shorter cortical silent periods obtained after stimulation of the motor cortex of the epileptogenic hemisphere.

CONCLUSION

These results show that the functional connectivity between premotor and motor cortex or motor cortex interneuronal excitability is impaired in the epileptogenic hemisphere in frontal lobe epilepsy while it is normal in the nonepileptogenic hemisphere.

Stroke recovery can be enhanced by using repetitive transcranial magnetic stimulation (rTMS)

Post-stroke recovery is based on plastic changes in the central nervous system that can compensate the loss of activity in affected brain regions. In particular, monohemispheric stroke is thought to result in disinhibition of the contralesional unaffected hemisphere. Neurorehabilitation programs improve function partly by enhancing cortical reorganization. Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive way of producing potent changes in cortical excitability. Therefore, the application of rTMS was recently proposed to promote functional recovery in stroke patients, owing to the induced neuroplasticity. This review discusses the first clinical results that were obtained by rTMS in patients with post-stroke motor deficit, visuospatial neglect, or aphasia. These results are promising and depend on the site and frequency of stimulation. In summary, functional recovery might be obtained either when rTMS is applied at low-frequency (around 1 Hz) over the disinhibited, unaffected hemisphere in order to restore defective inhibition or when rTMS is applied at high-frequency (5 Hz or more) over the affected hemisphere in order to reactivate hypoactive regions. The overall procedure remains to be optimized, in particular regarding the number of rTMS sessions and the time of rTMS application after stroke. Cortical stimulation is an exciting perspective for improving functional recovery from stroke. Transient application of non-invasive transcranial stimulation during the time of the rehabilitation process will be preferable to the temporary implantation of epidural cortical electrodes, as recently proposed. Therefore, in the future, acute or recent stroke might be a major indication of rTMS in neurological practice.

Arm function after stroke: Neurophysiological correlates and recovery mechanisms assessed by transcranial magnetic stimulation

Transcranial Magnetic Stimulation has been used for over 20 years to investigate recovery of motor function in stroke patients. In particular, it has been used to quantify the extent of damage to the corticospinal output, reorganisation of the cortical representation of the affected body parts and excitability of intracortical and cortico-cortical circuitries in both hemispheres. In this review, we provide a detailed account of most of the published data with particular reference to methodological issues that affect their interpretation.

Long-term effects of stroke on neuronal rest activity in rolandic cortical areas

To understand the relationship between neuronal function and clinical state in the framework of stroke, the long-term poststroke rolandic spontaneous neuronal activity was studied by means of magnetoencephalography. Fifty-six patients who had suffered a unilateral stroke within the middle cerebral artery were enrolled. Median time since stroke was 2.8 years. In association with lesion features and clinical picture, total and relative band powers and the spectral entropy were analyzed in the affected (AH) and unaffected (UH) hemispheres in comparison with an age-matched control group. An increase of absolute and relative slow band powers and a reduction of relative fast band powers were found in patients' AH with respect to both UH and control values. Absolute delta band was higher than in controls also in UH. New findings were the increase of rolandic rest activity power also in the alpha band and the decrease of spectral entropy in AH with respect to both UH and control values. Moreover, our results in chronic stroke patients indicate frequency-selective alterations related to specific dysfunctions: global clinical status was mostly impaired in patients with larger lesions and increased total and slow band activity powers, whereas hand functionality was mostly disrupted in patients with subcortical involvement and reduction of high-frequency rhythms and spectral entropy. Total power increase and spectral richness decrease are in agreement with a higher synchrony of local neuronal activity, a reduction of the intracortical inhibitory network's efficiency, and an increase of neuronal excitability.

Brain plasticity in recovery from stroke: an MEG assessment

The aim of this paper was to deepen understanding about the role played by brain plasticity in obtaining clinical recovery. Eighteen patients, who had recovered partially or totally from dysfunctions due to a monohemispheric infarction within the middle cerebral artery territory, underwent magnetoencephalographic (MEG) recordings of rolandic areas cerebral activity both in rest state (spectral power properties) and in response to the electrical stimulation of the contralateral median nerve (M20 and M30 cortical sources). MEG evaluation was performed in acute (T0: mean 5 days from ischemic attach) and post-acute phase (T1: median 6 months). At T1, all the inter-hemispheric asymmetries were reduced for both spontaneous and evoked activity parameters with respect to T0. In post-acute phase, lower cortical excitability, higher delta and theta power and lower spectral entropy were associated to a worse clinical state. An unusual recruitment-as revealed by an excessive inter-hemispheric asymmetry of M20 cortical source position-correlated with higher level of clinical amelioration in the patients who showed a partial recovery. In addition to confirmative evidence that "normalization" of neural activity in both the affected and unaffected hemispheres subtends best clinical recovery, present data provide support to the positive role of cerebral plasticity phenomena--i.e. unusual neural recruitments--to regain lost functions in those patients unable to achieve total recovery.

Delayed transient worsening of neurological deficits after ischaemic stroke

BACKGROUND

Although the causes of stroke recurrence are well known, no particular study deals with the specific issue of late-onset transient worsening of the neurological deficit (TWND) after an ischaemic stroke.

PATIENTS AND METHODS

In this retrospective study the aetiology of the TWNDs in 101 patients was compared to the causes of transient ischaemic attacks (TIAs) in 115 patients. All patients had a full cardiovascular and neuroimaging examination according to current guidelines. An electroencephalogram (EEG) was performed when necessary. The diagnosis of inhibitory seizures was retained when the EEG showed periodic lateralized epileptiform discharges or intermittent rhythmic delta activities, or when the patient developed typical seizures afterwards.

RESULTS

Arterial hypertension and diabetes were more prevalent vascular risk factors in TWND patients. Small-vessel disease and inhibitory seizures were a more frequent cause of TWNDs than of TIAs. Extracranial large-vessel disease predominates in TIA patients. The global prevalence of cardiac diseases as cause of TIAs and TWNDs was the same, although severe ulcerous plaques of the aortic arch and patent foramen ovale with atrial septum aneurysm occurred more frequently in TWND patients.

CONCLUSIONS

The most frequent causes of late-onset TWNDs were different from those of TIAs. Apart from repeated neuroimaging of the brain, exhaustive cardiac investigations and EEG are mandatory in TWND patients.

Effects of carotid endarterectomy on motor evoked potentials elicited by transcranial magnetic stimulation

PURPOSE

To investigate the within 3 days effects of carotid endarterectomy (CEA) on functional status of the central motor system in patients with carotid stenosis by means of transcranial magnetic stimulation (TMS).

PATIENTS AND METHOD

We studied 30 consecutive patients, 20 males and 10 females with a mean age of 69.2+/-7.1 years, who underwent CEA for symptomatic carotid stenosis. All patients had suffered an ischemic attack 6 months prior to the operation. Two TMS studies, one before and one shortly after CEA were performed on both sides in each of the patients. Resting motor threshold, motor evoked potentials (MEP) amplitude at rest, MEP latency at rest and during contraction and silent period duration (SPD) were recorded and analyzed. Two groups of data were collected. Group 1 consisted of data from the operated side in all 30 patients. Group 2 consisted of data from the contralateral side and served as a control.

RESULTS

Motor resting thresholds were similar in the two groups. Intragroup pre and post CEA comparisons showed no difference in the operated group and significant increased threshold after CEA on the non-operated side. There was no significant difference of TMS intensity for maximal MEP in either side before or after CEA. Latency at rest and during voluntary contraction and amplitude at rest showed no significant differences between or within groups' comparisons. In group 1 SPD showed a statistically significant increase after CEA as opposed to baseline. In group 2 SPD showed a non significant increase after CEA.

CONCLUSION

In the absence of other MEP changes, our finding of prolonged SPD post-operatively suggests preferential influence of the inhibitory cortical circuits. The potential favorable effect of CEA in patients with hyperexcitability such as disabling spasticity after stroke should be further studied.

Bimanual recoupling by visual cueing in callosal disconnection

The cerebral control of bimanual movements is not completely understood. We investigated a 59-year-old, right-handed man who presented with an acute bimanual coordination deficit. Magnetic resonance imaging showed a lesion involving the entire corpus callosum, which was found on stereotactic biopsy to be an ischemic infarct. Paired-pulse transcranial magnetic stimulation indicated that the patient had a lack of interhemispheric inhibition, while intracortical inhibition in motor cortex of either side was normal. Functional magnetic resonance imaging showed activation of the left SMA, the bilateral motor cortex and anterior cerebellum during spontaneous bimanual thumb-index oppositions, which were uncoupled as evident from simultaneous electromyographic recordings. In contrast, when the bimanual thumb-index oppositions were cued by a visual stimulus, the movements of both hands were tightly correlated. This synchronized activity was accompanied by additional activations bilateral in lateral occipital cortex, dorsal premotor cortex and cerebellum. The data suggest that the visually cued movements of both hands were recoupled by action of a bihemispheric motor network.

The cortical silent period: intrinsic variability and relation to the waveform of the transcranial magnetic stimulation pulse

OBJECTIVE

To assess the variability of the duration of the contralateral cortical silent period (CSP) between individuals and to assess the effect of different transcranial magnetic stimulation (TMS) pulse waveforms.

METHODS

In Expt. 1, CSP duration, and the motor-evoked potential (MEP) amplitude and area were measured in the first dorsal interosseous muscle (FDI) of 11 subjects on 3 separate occasions using a TMS intensity of 150% active motor threshold (AMT). In Expt. 2, the stimulation intensity was varied between 100% AMT and 150% AMT. In both sets of experiments, 3 types of TMS pulse were used: monophasic posterior-anterior (PA) induced current in the brain, monophasic anterior-posterior induced current (AP), and biphasic PA/AP stimulation.

RESULTS

Experiment 1: Between-subject variation in CSP duration was high. In addition, the duration after PA stimulation was significantly shorter than after AP or PA/AP stimulation. However, there was a good correlation between CSP duration and the area, or amplitude, of the MEP. This meant that calculating the ratio of duration/amplitude or duration/area reduced intersubject variability and eliminated differences between TMS pulses. Experiment 2: increasing stimulation intensity increased the mean value of all parameters, but with significantly lower values for PA than other forms of stimulation. The ratios of duration/amplitude or duration/area did not differ between current flow directions and were relatively constant for intensities 130-150% AMT.

CONCLUSIONS

Between-subject variation in the duration of the CSP is high. A given intensity of stimulation (expressed in %AMT) produces a shorter CSP for PA stimulation than for AP or PA/AP stimulation.

SIGNIFICANCE

If the ratio (CSP duration)/(MEP size) is calculated, then intersubject variability is reduced, and TMS pulse type differences are eliminated.

Poststroke Epilepsy

Seizures and status epilepticus can be a presenting feature of acute stroke. They may occur in its early (<7 days) clinical course or be a remote (>7 days) complication. Most seizures are single, either partial or generalised. Early and remote seizures seem to have different predictors and pathogenesis. Seizures are more frequent in severe and disabling strokes, haemorrhagic strokes and those with cortical involvement. The risk of epilepsy is higher for patients with early seizures, cortical infarctions and lobar haemorrhages and in dependent patients. Early or remote seizures do not have a significant influence on dependency or mortality, although seizures and status epilepticus can be a direct cause of death. Treatment can be started after a first or a recurrent seizure. Treatment options include phenytoin, carbamazepine, valproic acid (valproate sodium) and the new antiepileptic drugs (AEDs). New AEDs can be used to decrease the likelihood of drug interactions and adverse effects in patients who do not tolerate the classic AEDs and in treatment failures with classic AEDs. Large observational studies to define prognostic factors for poststroke seizures in specific stroke subtypes are needed. Randomised controlled trials of AED prophylaxis for acute and remote seizures are essential to improve the evidence level of current guidelines and recommendations.

Suprathreshold 0.3 Hz repetitive TMS prolongs the cortical silent period: potential implications for therapeutic trials in epilepsy

OBJECTIVE

To investigate the after-effects of 0.3 Hz repetitive transcranial magnetic stimulation (rTMS) on excitatory and inhibitory mechanisms at the primary motor cortex level, as tested by single-pulse TMS variables.

METHODS

In 9 healthy subjects, we studied a wide set of neurophysiological and behavioral variables from the first dorsal interosseous before (Baseline), immediately after (Post 1), and 90 min after (Post 2) the end of a 30 min long train of 0.3 Hz rTMS delivered at an intensity of 115% resting motor threshold (RMT). Variables under investigation were: maximal M wave, F wave, and peripheral silent period after ulnar nerve stimulation; RMT, amplitude and stimulus-response curve of the motor evoked potential (MEP), and cortical silent period (CSP) following TMS; finger-tapping speed.

RESULTS

The CSP was consistently lengthened at both Post 1 and Post 2 compared with Baseline. The other variables did not change significantly.

CONCLUSIONS

These findings suggest that suprathreshold 0.3 Hz rTMS produces a relatively long-lasting enhancement of the inhibitory mechanisms responsible for the CSP. These effects differ from those, previously reported, of 0.9-1 Hz rTMS, which reduces the excitability of the circuits underlying the MEP and does not affect the CSP. This provides rationale for sham-controlled trials aiming to assess the therapeutic potential of 0.3 Hz rTMS in epilepsy.

Neurophysiologic correlates of psychiatric disorders and potential applications in epilepsy

There is increasing interest in psychiatric assessment using neurophysiologic tools such as electroencephalography (EEG), magnetoencephalography (MEG), and transcranial magnetic stimulation (TMS). This is because these technologies have good temporal resolution, are relatively noninvasive, and (with the exception of MEG) are economical. Many different experimental paradigms and analysis techniques for the assessment of psychiatric patients involving these technologies are reviewed including conventional quantitative electroencephalography (QEEG), EEG cordance, low-resolution electromagnetic tomography (LORETA), frontal midline theta, midlatency auditory evoked potentials (P50, N100, P300), loudness dependency of the auditory evoked potential (LDAEP), mismatch negativity (MMN), contingent negative variation (CNV), and transcranial magnetic stimulation (TMS). Many of these neurophysiologic stimulus paradigms hold the promise of improving psychiatric patient care by improving diagnostic precision, predicting treatment response, and providing new phenotypes for genetic studies. Large cooperative multisite studies need to be designed to test and validate a few of these paradigms so that they might find use in routine clinical practice.

Transcranial magnetic stimulation and epilepsy

Epileptic conditions are characterized by an altered balance between excitatory and inhibitory influences at the cortical level. Transcranial magnetic stimulation (TMS) provides a noninvasive evaluation of separate excitatory and inhibitory functions of the cerebral cortex. In addition, repetitive TMS (rTMS) can modulate the excitability of cortical networks. We review the different ways that TMS has been used to investigate pathophysiological mechanisms and effects of antiepileptic drugs in patients with epilepsy and epileptic myoclonus. The safety of different TMS techniques is discussed too. Finally, we discuss the therapeutic prospects of rTMS in this field.