Clinically unsuspected cerebral infarction revealed by computed tomography scanning in late onset epilepsy

Cerebral small vessel disease increases risk for epilepsy: a Mendelian randomization study

BACKGROUND

Despite previous research suggesting a potential association between cerebral small vessel disease (CSVD) and epilepsy, the precise causality and directionality between cerebral small vessel disease (CSVD) and epilepsy remain incompletely understood. We aimed to investigate the causal link between CSVD and epilepsy.

METHOD

A bidirectional two-sample Mendelian randomization (MR) analysis was performed to evaluate the causal relationship between CSVD and epilepsy. The analysis included five dimensions of CSVD, namely small vessel ischemic stroke (SVS), intracerebral hemorrhage (ICH), white matter damage (including white matter hyperintensity [WMH], fractional anisotropy, and mean diffusivity), lacunar stroke, and cerebral microbleeds. We also incorporated epilepsy encompassing both focal epilepsy and generalized epilepsy. Inverse variance weighted (IVW) was used as the primary estimate while other four MR techniques were used to validate the results. Pleiotropic effects were controlled by adjusting vascular risk factors through multivariable MR.

RESULT

The study found a significant association between SVS (odds ratio [OR] 1.117, PFDR = 0.022), fractional anisotropy (OR 0.961, PFDR = 0.005), mean diffusivity (OR 1.036, PFDR = 0.004), and lacunar stroke (OR 1.127, PFDR = 0.007) with an increased risk of epilepsy. The aforementioned correlations primarily occurred in focal epilepsy rather than generalized epilepsy on subgroup analysis and retained their significance in the multivariable MR analysis.

CONCLUSION

Our study demonstrated that genetic susceptibility to CSVD independently elevates the risk of epilepsy, especially focal epilepsy. Diffusion tensor imaging may help screen patients at high risk for epilepsy in CSVD. Improved management of CSVD may be a significant approach in reducing the overall prevalence of epilepsy.

Identification of factors associated with new-onset vascular disease in patients admitted for video-EEG monitoring: A longitudinal cohort study

OBJECTIVE

People with epilepsy are at a higher risk of developing vascular disease. Understanding the risk factors in observational studies is hampered by the challenge in separating epilepsy-related risk and treatment-related risk, and uncertainty in the epilepsy diagnosis. This study aimed to identify factors associated with risk of subsequent vascular disease in patients with video-EEG monitoring (VEM) confirmed epilepsy.

METHODS

We included patients with a diagnosis of epilepsy and nonepileptic disorders between January 1, 1995, and December 31, 2015. Incident cardiovascular, cerebrovascular, and peripheral vascular disease was determined by linkage to a state-wide hospital admissions database between 1st July 1994 and 28th February 2018. Incidence was compared with the general population.

RESULTS

1728 patients (59.7% female, median age 35 years) underwent VEM, and were followed up for a median of 9.2 years (range 2.2-22.9 years). Eight-hundred and thirty -two were diagnosed with epilepsy and 896 nonepileptic disorders. The incidence of cerebrovascular disease was higher in both patients with epilepsy (incidence rate ratio [IRR] 1.78, p = 0.001) and with nonepileptic disorders (IRR 1.61, p < 0.001) than in the general population. Patients who took valproic acid (VPA) were at a lower risk of vascular disease than those taking enzyme-inducing antiseizure medications (EIASM, subdistribution hazard ratio [SHR] 0.42, p = 0.013), and those taking neither VPA nor EIASM (SHR 0.47, p = 0.03). There was no difference in the incidence of vascular disease between patients with epilepsy and those without epilepsy (SHR 0.94, p = 0.766). Factors associated with increased risk included age (SHR 1.04, p < 0.001), male sex (SHR 1.50, p = 0.017), and smoking (SHR 1.68, p = 0.017).

SIGNIFICANCE

In this study, both patients with epilepsy and without epilepsy had increased vascular risk. This suggests that the increased risk may be in part due to factors not directly related to epilepsy, such as EIASM use and vascular risk factors.

Effect of late-onset epilepsy on cognitive functioning in patients with small vessel disease

RATIONALE

Late-onset epilepsy (LOE) often has underlying cerebrovascular cause and has been associated with neurocognitive deficits and dementia. Nevertheless, the interplay between these factors has not been studied thus far. Hence, we conducted a retrospective cross-sectional study aimed to explore how unprovoked epileptic seizures along with vascular-related factors contribute to neurocognitive impairments in patients with cerebral small vessel disease.

METHODS

Twenty-seven patients with LOE aged > 60 years with concomitant cerebral small vessel disease (cSVD) and a matched group of cSVD without epilepsy were cognitively assessed. Demographic, clinical, and vascular information were obtained and vascular burden score was calculated for each patient. Multiple linear regression models were used to explore the relationship between epilepsy and cognitive measures adjusting for demographic and vascular risk factors.

RESULTS

Compared with cSVD, cSVD-LOE group showed a poorer performance on verbal memory measures, visuomotor tracking and speed processing and phonetic fluency. In the multiple regression analysis, the presence of epilepsy was found to be the major predictor for verbal memory dysfunction, specifically in verbal short recall (p = 0.008) and verbal learning (p < 0.001). No interactions between vascular burden and epilepsy were found.

CONCLUSION

Patients who had cSVD with concurrent LOE showed poorer performance on memory function compared with patients with cSVD without epilepsy, and they showed a different cognitive profile from that typically manifested by patients with cSVD. The presence of epilepsy, but not seizure localization nor vascular burden, was the major contributor to the decrease in verbal memory.

Vascular risk factors as independent predictors of neurocognitive impairments in patients with late-onset epilepsy who have small-vessel disease

RATIONALE

Late-onset epilepsy is often accompanied by underlying cerebrovascular disease and has been associated with neurocognitive deficits even dementia, but the interrelation between them remains unknown. In this study, we aimed to explore the contribution of vascular-related and epilepsy-related factors on neurocognitive outcomes in a sample of late-onset epilepsy with history of cerebral small vessel disease.

METHODS

In this retrospective cross-sectional study, a comprehensive neurocognitive assessment was performed in 25 patients aged >60 years with one or more unprovoked seizures and history of small-vessel disease. Raw scores of cognitive tests were transformed in T-scores and were grouped in 6 cognitive domains. Regression models were performed to explore the contribution of vascular risk factors (diabetes mellitus, arterial hypertension, dyslipidemia, and smoking habit) and epilepsy-related factors (drug-resistance, number of antiepileptic drugs, age at epilepsy onset, and epileptic focus localization).

RESULTS

Diabetes (p = 0.03) and smoking habit (p = 0.05) were the best independent factors to predict attention performance; diabetes also predicted visual memory function (p = 0.02); gender was related to verbal memory performance (p = 0.04) and speed processing (p = 0.02). Age at onset predicted that executive function (p = 0.05); age (p = 0.01) and gender (p = 0.03) were the major contributors to language performance. Epilepsy-related variables did not predict any cognitive outcomes.

CONCLUSIONS

Vascular risk factors and sociodemographic characteristics were the best predictors of cognitive outcomes in a sample of late-onset epilepsy with cerebral small-vessel disease. Epilepsy did not show influence on cognitive function. Longitudinal studies are necessary to clarify the relationship between vascular risk factors and epilepsy on progression of cognitive deterioration in patients with late-onset epilepsy. This article is part of the Special Issue "Seizures & Stroke".

New onset epilepsy in the elderly: clinical, radiological and electroencephalographic features and treatment responses

OBJECTIVE

To evaluate new onset epilepsy characteristics, etiology, radiological and electroencephalographic features and to document treatment response in the elderly.

METHODS

This was a retrospective study carried out in King Fahd Medical City, Riyadh, Kingdom of Saudi Arabia, from 2010 to 2013. Medical records were searched to recruit patients. Hundred and nineteen patients were enrolled who fulfill the inclusion criteria. Clinical data with respect to seizure semiology, etiology, electroencephalographic findings, radiological findings, co-morbidities, and anti-epileptic drug (AED) therapy were assessed.

RESULTS

Cerebrovascular disease was the most common etiology, followed by occult cerebrovascular disease (oCVD). Focal onset seizures were the most common clinical presentation in this group of cohort. Electroencephalogram (EEG) showed generalized slowing in majority of patients (45.5%), with 21.8% interictal epileptiform activity. Patients required lower doses of AEDs to control seizures, gain better seizure control. Common co-morbidities were hypertension and diabetes mellitus.

CONCLUSION

Patients presenting with LOE, should have search for any other cerebrovascular risk factors. Further research is needed to determine the prevalence of oCVD in LOE, and to investigate whether addressing cerebrovascular risk factors in this cohort of patients can reduce the incidence of stroke.

Structural and physiological MRI correlates of occult cerebrovascular disease in late-onset epilepsy

Late-onset epilepsy (LOE), with onset after 50 years of age, is often attributed to underlying occult cerebrovascular disease. LOE is associated with a three-fold increase in subsequent stroke risk, therefore it is important to improve our understanding of pathophysiology. In this exploratory study, we aimed to determine whether established structural magnetic resonance imaging markers and novel physiological imaging markers of occult cerebrovascular disease were more common in patients with LOE than age-matched controls.

Sixteen patients with LOE (mean age ± SD: 67.6 ± 6.5 years) and 15 age-matched control subjects (mean age: 65.1 ± 3.9 years) underwent a 3 T MRI scan protocol. T₁-weighted images and T₂-weighted fluid attenuated inversion recovery (FLAIR) images were used to determine cortical grey matter volume and white matter hyperintensity (WMH) volume respectively, whilst multiple delay time arterial spin labelling (ASL) images were collected at rest and during a hypercapnic challenge. Cerebral blood flow (CBF) and arterial arrival time (AAT) were calculated from ASL data under both normocapnic and hypercapnic conditions. Cerebrovascular reactivity was also calculated for both CBF and AAT relative to the change in end-tidal CO₂.

Patients with LOE were found to have significantly lower cortical volume than control subjects (33.8 ± 3.8% of intracranial volume vs. 38.0 ± 5.5%, p = 0.02) and significantly higher WMH volume (1339 ± 1408 mm³ vs. 514 ± 481 mm³, p = 0.047). Baseline whole brain AAT was found to be significantly prolonged in patients with LOE in comparison to control subjects (1539 ± 129 ms vs. 1363 ± 167 ms, p = 0.005). Voxel-based analysis showed the significant prolongation of AAT to be predominantly distributed in the frontal and temporal lobes. Voxel-based morphometry showed the lower cortical volume to be localised primarily to temporal lobes. No significant differences in CBF or cerebrovascular reactivity were found between the two groups. Baseline whole brain AAT and cortical volume differences persisted upon further analysis to take account of differences in smoking history between patients and control subjects.

These findings suggest that occult cerebrovascular disease is relevant to the pathophysiology of LOE.

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LOE patients were found to have increased WMHs and reduced GM volume on MRI imaging in comparison to HC.

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Baseline arterial arrival time was significantly longer in LOE patients than HC.

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Baseline cerebral blood flow did not differ between LOE patients and HC.

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Cerebrovascular reactivity did not differ between LOE patients and HC.

Stroke after adult-onset epilepsy: a population-based retrospective cohort study

BACKGROUND

Earlier studies indicate a higher risk of subsequent stroke in PWE aged ≥60. However, little is known of the incidence of subsequent stroke in people with epilepsy (PWE) aged 35 through 60. We determined the risk factors that increase the incidence of stroke following adult-onset epilepsy in a large statewide population over a 10-year period.

METHODS

South Carolina hospital discharge and emergency department (ED) data from 2000 to 2011 were used. The study was limited to persons aged ≥35years without prior stroke. Cases included patients diagnosed with epilepsy who were hospitalized or visited the ED. Controls were people with an isolated fracture of the lower extremity without any history of epilepsy or seizure disorders, presumed to approximate the health status of the general population. Epilepsy, fracture, stroke, and comorbid conditions were ascertained by diagnostic codes from health-care encounters. Only persons having stroke occurring ≥6months after the onset of epilepsy or after the first clinical encounter for controls were included. Cox proportional hazards modeling was performed to determine the risk of stroke.

RESULTS

There were 21,035 cases with epilepsy and 16,638 controls who met the inclusion criteria. Stroke incidence was 2.5 times higher following adult-onset epilepsy (6.3%) compared with controls (2.5%). After adjusting for comorbidities and other factors, cases with epilepsy showed a 60% higher risk of stroke (HR=1.6; 95% CI: 1.42-1.80) compared with controls. Nearly half of the strokes in cases with epilepsy occurred in those with first diagnosis between ages 35 and 55. Somatic comorbidities associated with increased risk of stroke were more prevalent in cases with epilepsy than controls yet similar in both groups with stroke. Risk of stroke increased with increasing age in both groups. However, the risk of stroke in cases with epilepsy increased faster and was similar to that in controls who were ≥10years older.

CONCLUSION

Adult-onset epilepsy at age 35 and older warrants consideration for occult cerebrovascular disease as an etiology of the epilepsy, which may also increase the risk of subsequent stroke. Somatic comorbidities frequently associated with epilepsy include comorbid conditions that share the same underlying pathology with stroke (i.e., hypertension, hyperlipidemia, myocardial infarction, diabetes, and arteriosclerosis). This increased risk of stroke in patients with adult-onset epilepsy should dictate the evaluation and management of stroke risk factors to prevent stroke.

Late-onset epilepsy and occult cerebrovascular disease

The interface between cerebrovascular disease (CVD) and epilepsy is complex and multifaceted. Late-onset epilepsy (LOE) is increasingly common and is often attributed to CVD, and is indeed associated with an increased risk of stroke. This relationship is easily recognizable where there is a history of stroke, particularly involving the cerebral cortex. However, the relationship with otherwise occult, subcortical CVD is currently less well established yet causality is often invoked. In this review, we consider the diagnosis of LOE in clinical practice--including its behaviour as a potential mimic of acute ischemic stroke and transient ischemic attack; evidence for an association between occult CVD and LOE; and potential mechanisms of epileptogenesis in occult CVD, including potential interrelationships between disordered cerebral metabolism and perfusion, disrupted neurovascular unit integrity, blood-brain barrier dysfunction, and inflammation. We also discuss recently recognized issues concerning antiepileptic drug treatment and vascular risk and consider a variety of less common CVD entities associated with seizures.

Late-onset seizures and risk of subsequent stroke: a systematic review

Otherwise unexplained late-onset seizures, conventionally defined as epileptic seizures occurring in subjects older than 60years and in the absence of disorders known to increase the risk of developing epilepsy, have been assumed to be, in most cases, of cerebrovascular origin. We systematically searched the literature to identify the evidence supporting the association between otherwise unexplained late-onset seizures/epilepsy and the risk of subsequent stroke. Most data from the literature indicate that cerebrovascular disease often underlies otherwise unexplained late-onset seizures/epilepsy. Patients presenting with seizures occurring for the very first time in late life and without clinically overt cerebrovascular disease should be considered as at increased risk of stroke. Consequently, these patients should be screened for the presence of vascular risk factors and treated accordingly. Such measures may greatly contribute to prevent strokes in these patients.

Continuous electroencephalographic monitoring in critically ill patients: indications, limitations, and strategies

OBJECTIVE

Continuous electroencephalography as a bedside monitor of cerebral activity has been used in a range of critically ill patients. This review compiles the indications, limitations, and strategies for continuous electroencephalography in the ICU.

DATA SOURCE

The authors searched the electronic MEDLINE database.

STUDY SELECTION AND DATA EXTRACTION

References from articles of special interest were selected.

DATA SYNTHESIS AND CONCLUSION

Electroencephalographically-defined suppression is routinely used as the basis for titration of pharmacologic therapy in refractory status epilepticus and intracranial hypertension. The increasing use of continuous electroencephalography reveals a clinically underappreciated burden of epileptiform and epileptic activity in patients with primary acute neurologic disorders, and also in critically ill patients with acquired encephalopathy. Status epilepticus is reported with continuous electroencephalography in 1% to 10% of patients with ischemic stroke, 8% to 14% with traumatic brain injury, 10% to 14% with subarachnoid hemorrhage, 1% to 21% with intracerebral hemorrhage, and 30% of patients following cardiorespiratory arrest. These figures underscore the importance of continuous electroencephalography in the critically ill. The interpretation of continuous electroencephalography in the ICU is challenged by electroencephalography artifacts and the frequent subtle differences between ictal and interictal patterns.

Prevalence and subtypes of radiological cerebrovascular disease in late-onset isolated seizures and epilepsy

BACKGROUND

Late-onset epilepsy (LOE), onset over 60, is often attributed to cerebrovascular disease (CVD), and is associated with increased stroke risk. We investigated the radiological prevalence of CVD in LOE.

METHODS

We undertook a retrospective case-control study of patients with LOE and age and sex-matched controls, also matched for imaging modality. Radiological CVD was recorded, with radiological findings by an experienced consultant neuroradiologist usi a structured proforma.

RESULTS

105 cases and 105 controls were studied, comprising 61 (58.1%) males, mean (±SD) age (years) 72.7±7.48 (cases), 72.4±7.02 (controls). 9 cases had isolated seizures rather than LOE. Imaging modality (in cases and controls) was CT in 59 and MRI in 46. Radiological CVD was more prevalent amongst cases (65.7%) than controls (33.3%) (p<0.0001, Chi-square), odds ratio 3.83 (95% CI 2.16-6.79). Large vessel disease (LVD) (single or multiple cortical or subcortical infarcts>1.5 cm) was present in 23 (21.9%) cases and 2 (1.9%) (p<0.001) controls, with small vessel disease (SVD) (periventricular or subcortical white matter lesions (WMLs), including leukoaraiosis (LA)) present in 52 (49.5%) cases (LA in 4) and 34 (32.3%) controls (LA in 0) (p<0.05). When WMLs were rated using a semiquantitative visual rating scale, a trend towards greater severity was observed amongst cases compared to controls.

CONCLUSIONS

Radiological CVD is significantly more prevalent in patients with LOE than controls, including signs of both LVD and SVD. SVD also appears to be of greater severity. Further studies are needed in this area.

Epilepsy in later life

Epilepsy is most likely to develop in later life. The burden of this disorder on health-care resources will rise further as the world's population continues to age. Making a secure diagnosis can be challenging because the clinical manifestations of seizures and the differential diagnoses and causes of epilepsy can be different in older individuals compared with younger individuals. Obtaining a reliable account of the events for accurate assessment is particularly important in guiding the appropriate choice and interpretation of investigations to arrive at the correct diagnosis. In older age, unique pharmacokinetic and pharmacodynamic changes occur. The use and selection of antiepileptic drugs is often further complicated by the presence of comorbidities, polypharmacy, and concomitant functional impairment, but there is a paucity of high-level clinical evidence on the effects of these factors as well as on the choice of treatment in the elderly. A comprehensive model of care should combine expertise in the diagnosis and treatment of epilepsy with effective assessment and management of the psychosocial effects to improve the prognosis in this vulnerable and poorly studied group of patients.

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.

Seizures and epilepsy in patients with lacunar strokes

BACKGROUND

The relation between seizures and small subcortical infarcts is uncertain. The present retrospective study investigates whether differences are observed between patients with and without seizures following a lacunar stroke.

PATIENTS AND METHODS

Thirty-seven patients with seizures and a prior history of a lacunar stroke were admitted to the Ghent University Hospital during 2000 and 2005. They were compared to 205 patients, admitted between 2002 and 2004, with an acute lacunar stroke and without epileptic spells on follow-up. Nine out of the 37 patients with seizures and 48 out of the 205 without seizures had a history of recurrent strokes.

RESULTS

No differences in vascular risk factors, distribution and frequency of the lacunes, degree of severity of the white matter changes and outcome were observed. On the Mini-Mental State Examination moderate to severe cognitive disturbances were observed in the seizure group and in some patients of the non-seizure group.

CONCLUSIONS

In the present study we found no evidence that seizures are directly induced by lacunar infarcts. The seizures appear to be part of a more global ongoing cerebral disorder probably leading to cognitive impairment.

Late-onset seizures as a predictor of subsequent stroke

BACKGROUND Cerebrovascular disease is thought to be a major cause of epilepsy in late life. We investigated the hypothesis that the onset of seizures after the age of 60 years in people with no history of overt stroke might be associated with an increased risk of subsequent stroke.

METHODS

Data were obtained from the UK General Practice Research Database on 4709 individuals who had seizures beginning at or after the age of 60 years, and on 4709 randomly selected controls with no history of seizures, matched for age, sex, and general practice. Individuals with a history of cerebrovascular disease, other acquired brain injury, brain tumour, drug or alcohol misuse, or dementia were not eligible for inclusion. Computerised patients' records were searched for subsequent diagnoses of stroke.

FINDINGS

Log-rank testing, adjusted for matching, showed a highly significant difference in stroke-free survival between the two groups (p<0.0001). With a Cox's model, we estimated that the relative hazard of stroke at any point for people with seizures compared with the control group was 2.89 (95% CI 2.45-3.41).

INTERPRETATION

Our findings show that the onset of seizures in late life is associated with a striking increase in the risk of stroke. Further research is warranted to assess the benefit of specific interventions to prevent stroke in patients with seizures.

[Acute repetitive giratory seizures as a manifestation of nonketotic hyperglycemia]

This 71 years old women without any history of epilepsy had diabetes mellitus. She was admitted for repetitive giratory seizures in relation with non-ketotic hyperglycaemia. The EEG showed right centro-parietal paroxysmal slow activity. Symptomatology disappeared within 48 hours after insulin therapy. One month later, she presented with a left hemiplegia in relation with a right sylvian infraction. The role of focal transitory ischaemia in connection with hyperglycaemia is discussed.

Epilepsy in patients with multiple sclerosis: radiological-clinical correlations

PURPOSE

To determine potential mechanisms of epilepsy in patients with multiple sclerosis (MS).

METHODS

Among 402 patients with clinically and radiologically defined MS, including de novo cases, presenting to the Neurology Service, University Hospital of Dijon, we identified 17 with epileptic seizures (4.25%). Among them, the percentage with partial seizures (50%) was greater than that in the reference population.

RESULTS

In most of the patients with MS, plaques were localized in the frontal region, associated with frontal and callosal atrophy, a frontal syndrome, and severe disability status (as assessed by a standard scale). Magnetic resonance imaging (MRI) showed numerous subcortical plaques. Seizures generally were well controlled with antiepileptic drugs (AEDs).

CONCLUSIONS

Our data suggest that the subcortical plaques of MS underlie seizure activity in patients with MS and epilepsy.

Vascular determinants of epilepsy: the Rotterdam Study

PURPOSE

To investigate the relation between vascular determinants and epilepsy in an elderly population.

METHODS

This is a cross-sectional, community-based, case-control study. The total study population was comprised of 4,944 subjects, 65 of whom had epilepsy which conformed to International League Against Epilepsy (ILAE) criteria. Vascular determinants that were evaluated included a history of stroke or myocardial infarction, peripheral vascular disease, hypertension, serum total cholesterol and left ventricular hypertrophy. Multivariate logistic regression analysis was used to calculate prevalence odds ratios (OR), adjusted for age and gender, as a measure of the strength of the associations.

RESULTS

A history of stroke was strongly associated with lifetime epilepsy (OR 3.3; 95% CI [Confidence Interval] 1.3-8.5), as well as with late-onset epilepsy (OR 3.1; 95% CI 0.9-10.6). All vascular determinants were associated with lifetime epilepsy and late-onset epilepsy, with odds ratios >1. When stroke patients were excluded, the odds ratios were statistically significant for the relationships between total cholesterol and late-onset epilepsy (OR 1.3, 95% CI 1.0-1.6) and left ventricular hypertrophy and late-onset epilepsy (OR 2.9, 95% CI 1.0-8.6). Furthermore, presence of any of these vascular indicators was twice as common among subjects with late-onset epilepsy as compared with subjects without epilepsy (OR 2.0, 95% CI 0.9-4.2), and this was statistically significant when stroke patients were excluded (OR 2.1, 95% CI 1.0-4.7).

CONCLUSIONS

These results suggest that there may be a relationship between vascular factors and the risk of late-onset epilepsy, apart from the relationship that exists through clinically overt stroke.

Epidemiology of disabling neurological disease: how and why does disability occur?

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Anticonvulsant therapy in the elderly--a need for placebo controlled trials

Epileptic seizures are common in the elderly, yet data concerning the long-term clinical course and apparent impact of anticonvulsant therapy are scant. We studied 73 consecutive elderly patients with a diagnosis of seizures [remote symptomatic (52%), acute symptomatic (23%), progressive symptomatic (10%), cryptogenic (15%)] during a median period of clinical review of 33 (range 3-72) months. Sixty-seven patients received anticonvulsant drugs, 38 phenytoin (PHT), 21 carbamazepine (CBZ), 6 sodium valproate (VPA) and 2 phenobarbitone. Six patients were untreated with drugs and three of these had no further seizures over a median review period of 26 months. Forty-one (61%) treated patients remained seizure free and a further nine patients suffered less than three fits per year. Seventeen patients had poorer control (three to five seizures per year in six patients and more than five seizures per year in eleven patients). Mean daily dosage of anticonvulsants (PHT 248 mg, CBZ 320 mg, VPA 571 mg) and serum concentrations were modest. Anticonvulsant side effects were reported by 27% of all treated patients (22% of those who were seizure free). Both adverse effects and satisfactory seizure control were associated in the majority of patients with serum anticonvulsant concentrations at the lower limit or below recommended therapeutic ranges utilised in the young. This study suggests that placebo controlled studies are warranted to appraise the extent to which anticonvulsant drugs modify a generally favourable prognosis for seizure disorders in the elderly and to adequately define the benefit-risk ratio of such drugs.

Seizures due to multiple sclerosis: seven patients with MRI correlations

The MRI data of seven patients with clinically definite multiple sclerosis who developed epileptic seizures are presented. Six of these cases demonstrated new or enhancing lesions. Cerebral biopsy in one of these lesions confirmed inflammation with myelin breakdown products. Lesions implicated in the causation of seizures involved the cortex or subcortical area. In one patient, a new lesion was associated with EEG abnormalities which resolved as the lesion reduced in size. In three patients epileptic activity was the only clinical manifestation of disease. Large, unresolving lesions tended to be associated with continuing seizures.

Supratentorial brain infarcts in adult-onset seizures; the Maastricht Epilepsy Case Register

We studied the frequency of supratentorial brain infarction as the cause of late-onset epilepsy in 680 patients with a first seizure after the age of 20, registered on an epilepsy register: 65 (10%) had seizures following a symptomatic supratentorial brain infarct. Brain infarction as the presumed cause of epilepsy was related to age at first seizure. A first seizure occurred within one year after brain infarction in 62%, and later than two years in 19%. Eight of 14 patients (57%) with an early seizure (< or = 2 weeks), and 28 of 41 patients (68%) with a first seizure later than two weeks post-stroke had seizure recurrences despite anti-epileptic treatment. Of 38 patients who underwent computed tomography head scan (CT), 32 (84%) had a cortical infarct, whereas six (16%) had one or more lacunar infarcts. This may indicate that lacunar infarction may be associated with post-stroke epilepsy. Using a detailed topographic brain atlas to localize the cortical infarcts, no 'specific epileptogenic' gyri could be identified. What factors predict future epilepsy in stroke patients need to be studied in prospective series of well-defined stroke subgroups.

Parietal and occipital lobe epilepsy: a review

There has been considerable recent interest in frontal lobe epileptic syndromes, and less attention paid to occipital and parietal epilepsies. The occipital and parietal lobes have arbitrary anatomical borders. The prinicpal seizure symptomatology includes somatosensory (paresthetic, painful, thermal, sexual, apraxia, disturbances of body image); visual (amaurotic, elementary and complex hallucinations, illusions) and other phenomena (anosognosia, apraxia, acalculia, alexia, aphemia, confusional states, gustatory, vertiginous, adversive, oculoclonic and eyelid flutter). The seizure symptoms are of varying localizing and lateralizing value and seizure discharges may spread rapidly and perceived symptoms may reflect secondary spread rather than the primary site of seizure onset. Recognized parietal and occipital epilepsy syndromes include benign epilepsy of childhood with centrotemporal spikes, benign epilepsy of childhood with parietal evoked spikes, benign occipital epilepsy of childhood, migraine/epilepsy syndromes, and epilepsy with bilateral occipital calcification. In addition, occipital and parietal epilepsy may be on the basis of any underlying structural lesion. There is frequently a poor correlation between clinical and EEG features. MRI and functional imaging often reveals underlying pathology. There have been no specific trials of different antiepileptic drugs for occipital and parietal seizures. Surgical treatment has its place, with attention to the risk of causing a fixed neurological deficit.

Incidence of epilepsy and unprovoked seizures in Rochester, Minnesota: 1935-1984

The incidence of epilepsy and of all unprovoked seizures was determined for residents of Rochester, Minnesota U.S.A. from 1935 through 1984. Age-adjusted incidence of epilepsy was 44 per 100,000 person-years. Incidence in males was significantly higher than in females and was high in the first year of life but highest in persons aged > or = 75 years. Sixty percent of new cases had epilepsy manifested by partial seizures, and two thirds had no clearly identified antecedent. Cerebrovascular disease was the most commonly identified antecedent, accounting for 11% of cases. Neurologic deficits from birth, mental retardation and/or cerebral palsy, observed in 8% of cases, was the next most frequently identified preexisting condition. The cumulative incidence of epilepsy through age 74 years was 3.1%. The age-adjusted incidence of all unprovoked seizures was 61 per 100,000 person-years. Age- and gender-specific incidence trends were similar to those of epilepsy, but a higher proportion of cases was of unknown etiology and was characterized by generalized onset seizures. The cumulative incidence of all unprovoked seizures was 4.1% through age 74 years. With time, the incidence of epilepsy and of unprovoked seizures decreased in children and increased in the elderly.

Geriatric epilepsy: a review

After the turn of the century, the proportion of population over 60 years of age is expected to be over 20%. Recent epidemiologic studies show a higher incidence of new-onset epilepsy in the population over 60 years of age compared with preceding decades of life. The predominant seizure type in up to 80% of these new cases of epilepsy is simple and complex partial manifestation. This paper reviews the literature documenting the increased incidence of partial seizures in the aging population, explores the known etiologies of new-onset epilepsy, and uses five case vignettes presenting with complex partial symptomatology.

Transient occlusion of rat carotid arteries decreases susceptibility to pilocarpine seizures

Bilateral clamping of the carotid arteries (BCCA) for 24 min protects animals against convulsive effects of intraperitoneal injection of 300 mg/kg of pilocarpine when administered 14 days after surgery. Electrographic recordings from hippocampus, frontal cortex, striatum and substantia nigra demonstrate that (1) no spontaneous spiking activity is caused by the BCCA when observed for up to 10 days after surgery, (2) spiking activity can only be recorded in limbic structures but not in the frontal cortex after systemic administration of pilocarpine. These observations suggest that the propagation of seizure activity from subcortical limbic structures to the neocortex is affected by BCCA.

Seizures of unknown origin after the age of 50: vascular risk factors

To investigate the possible etiologic factors of late onset seizures of unknown origin, 50 consecutive patients whose seizures started after age 50 and who had a normal CT, were screened. The seizures in this group were generalized in 70% and infrequent. The hypothesis that late-onset seizures of unknown origin were frequently due to microinfarcts, was evaluated by comparing the frequency of arterial hypertension, coronary heart disease, peripheral vascular disease, carotid bruits, diabetes mellitus and smoking in these patients with appropriate control groups. The results showed that the frequencies of these cardiovascular risk factors were similar to those of sex and age-matched controls and much lower than in a comparable series of patients whose seizures followed a stroke, or patients with stroke but not seizures. These data suggest that subclinical cerebrovascular disease is probably not a frequent etiology of late-onset epilepsy of unknown origin. The cause of these seizures remains to be elucidated.

Epileptic seizures in thrombotic stroke

Epileptic seizures due to thrombotic cerebral infarction were studied in 118 patients. The occurrence of seizures had a bimodal distribution with one peak period within 2 weeks and another peak period from 6 to 12 months after stroke. Four patients had seizures preceding stroke, while 23 patients without a history of previous stroke had "silent infarct" on the CT scan. Fifteen patients (13%) had status epilepticus. Simple partial seizures occurred in 56% of patients, complex partial seizures in 24% and generalized tonic-clonic seizures in 4%. Epilepsy developed in 35% of patients with early seizures and in 90% of patients with late seizures.

EEG and CT findings in poststroke epilepsy

The present study was undertaken to assess the diagnostic value of CT in patients with poststroke epilepsy, related to EEG in revealing the factors contributing to the development of epileptic fits. The EEG and CT results were evaluated in 50 patients with poststroke epilepsy and compared with those of 50 patients without epilepsy after stroke. Cortical and extensive lesions involving the cortex were more frequent among patients with poststroke epilepsy. Sparing of certain parts of cerebral cortex was observed within vasogenic lesion. This type of change was only found in the poststroke epilepsy group and may be responsible for development of epileptic fits. It seems that CT has a higher diagnostic value than EEG in evaluating the risk of development of poststroke epilepsy.

The natural history of late-onset epilepsy secondary to vascular disease

Twenty-nine patients with late-onset epilepsy were followed prospectively for a mean period of 4.9 years; 14 had CT evidence of occult cerebral infarction and 15 had normal scans. The prognosis was similar in the 2 groups; 57% and 53% respectively became seizure-free. One patient in each group had a myocardial infarction and one patient with occult cerebrovascular disease had a stroke. A separate study was made of the prognosis of 24 patients with epilepsy following stroke (mean follow-up 5.9 years). Twelve of 12 patients with seizure onset within 2 weeks of the stroke became seizure-free, compared with 7/12 with more delayed onset. Late-onset epilepsy has a favourable prognosis, and excellent control should be expected if seizures commence within 2 weeks of stroke.

Status epilepticus in the elderly: etiology, seizure type and outcome

We have studied status epilepticus among 342 patients who had their first seizures after the age of 60 years. One hundred and two patients (30%) had status epilepticus. Cerebrovascular disease (35%) was the leading cause of status, followed by head trauma (21%), multifactorial etiology (11%), metabolic disorders (10%), brain tumors (8%) and CNS infection (2%). The etiology of status remained undetermined in 13 patients (13%). The majority (80%) had partial status or generalized status with focal onset. Overall mortality was 35%.