Focal seizure propagation in the intracranial EEG.

INTRODUCTION: intracranial EEG offers a unique opportunity to study epileptic seizures in humans. Seizure propagation has not been extensively studied. We aimed to compare the propagation of focal seizures with onset in different brain regions. METHODS: seven zones were defined as medial frontal (MF), dorsolateral frontal (DLF), orbitofrontal (OF), medial temporal (MF), lateral temporal (LT), parietal (P) and occipital (O). Routes and times of ipsilateral (IPT) and contralateral (CPT) propagation as well as ictal frequency in onset zone and propagation zone were compared. RESULTS: forty patients had 112 seizures. (Mean and median number of seizures per zone was 16 and 15). Preferred routes of propagation, based on ictal onset, were: MF to contralateral MF; DLF to ispilateral temporal lobe; OF to contralateral OF and ispilateral temporal lobe; MT to contralateral MT; LT to ispilateral MT and OF and contralateral LT and MT; P to ispilateral temporal lobe, DLF and O; O to ipsilateral MT. IPT and CPT varied markedly between zones. Ictal onset frequency was faster than propagated frequency. CONCLUSION: seizure propagation varies according to onset zone possibly following major pathways. This needs confirmation. The findings could aid in the interpretation of symptoms and EEG and may result useful for future treatment using brain stimulation or disconnective surgery. The limitations are clearly stated.

Levetiracetam: a practical option for seizure management in elderly patients with cognitive impairment.

Cognitive impairment and seizures are common in our aging population. Anticonvulsant treatment is problematic due to sedation, cognitive slowing, and behavioral changes. Levetiracetam has favorable pharmacokinetics, good efficacy in elderly individuals, a favorable side effect profile, and lacks major drug interactions. We conducted a prospective, uncontrolled, phase 4, open label, 12-week study of levetiracetam to better profile its efficacy, safety, and impact on cognitive/behavioral status in 24 cognitively impaired, elderly individuals. In total, 69% were seizure free for the duration of the study; the remaining participants had satisfactory seizure control. Fatigue was the most common side effect (5 participants). Significant overall improvements were observed for the Folstein's Mini-Mental State Examination and the Alzheimer's Disease Assessment Scale-Cognitive. No significant changes were seen in behavioral or functional measures. Levetiracetam is an effective antiepileptic drug in elderly individuals with cognitive impairment. At 3 months, participants who remained on levetiracetam showed excellent cognitive tolerability.

Treatment and management of epilepsy in the elderly demented patient.

Epilepsy and seizures are more frequent in the elderly population than in any other age group. The number of individuals older than 65 is constantly increasing, and dementia is a process that predominantly affects this age group. Several studies have shown that dementia is an important risk factor for developing seizures and epilepsy. Seizure semiology in the elderly demented might differ from that of younger age groups and diagnosis can be complicated further by the variety of other causes of transient changes of alertness and behavior that affects these patients. The pharmacokinetic changes of antiepileptic drugs in the elderly make this group a major therapeutic challenge. Side effects and drug interactions play a major role in the choice of antiepileptic agents. This review intends to summarize the existing data to see whether this can help guide the clinician in the treatment and management of epilepsy in the elderly patient with dementia. Nonpharmacologic therapeutic options are also briefly considered.

Do skull base lesions and their surgical treatment cause epileptic seizures?

OBJECTIVES: Few reports exist on the risk of seizures with skull base lesions and their surgical treatment. PATIENTS AND METHODS: All patients referred for surgery of a skull base lesion at George Washington University Hospital from January 1998 to August 1999 were reviewed. After excluding patients with other risk factors 136 patients were included. RESULTS: No seizures were reported before or after surgery, but 59 patients (43%) were taking anticonvulsants. Only 17 (12.5%) had EEG. Four of these showed no abnormalities, 2 were abnormal without sharp waves and 11 had sharp waves (an increase compared to the general population). Most sharp waves affected the temporal lobe on the side of surgery. All EEGs were performed less than 4 months after surgery. CONCLUSION: This study does not indicate that seizures are common in this patient group, but there was an increased amount of epileptiform activity on EEG and many patients were taking AED. A prospective study with systematic patient interviews, pre- and post-surgical EEG and a longer follow up is needed.

Corpus callosotomy in refractory idiopathic generalized epilepsy.

RATIONALE: A small percentage of patients with idiopathic generalized epilepsy (IGE) do not respond to medical therapy. Generalized tonic-clonic (GTC) seizures are especially debilitating and can be associated with severe injuries. The benefit, safety and effect of corpus callosotomy (CC) in patients with IGE have not been studied. METHODS: We reviewed patients with presumed IGE who underwent CC between 1991 and 2000. Criteria for selection included history, examination, brain imagining, interictal and ictal EEG. All patients had refractory and debilitating tonic-clonic seizures (GTCS) and had failed four or more antiepileptic drugs. Seizure frequency was calculated per month over the last year and pre-operative baseline was compared to last follow-up using paired t-tests. IQ, executive function, language and verbal, non-verbal memory and quality of life (QOL) was compared before and after surgery. Serial EEGs after surgery were reviewed. RESULTS: There were nine patients (seven men), mean age 37.9 (range: 22-49), mean IQ 87.3 (range: 75-107). All had anterior CC. Mean follow-up time was 5.4 years (range: 0.6-10.3 years). One patient died from sudden death in epilepsy 9 months after surgery. There was a significant reduction of GTC seizures from 6.3 to 1.1 (p<0.005). Four patients had more than 80% and eight more than 50% reduction. Of five patients with absence seizures, two became seizure free and one had more than 80% reduction and two worsened slightly, and of three with myoclonic seizures one had more than 90% reduction. One patient had completion of the CC with improvement of myoclonus and absence seizures, but not of GTC seizures and suffered a disconnection syndrome. Another had right frontal focal resection without improvement after new seizures of focal onset. Cognitive testing showed a good outcome (improved or no change) in all cognitive domains. Post-surgical EEG showed new focal slowing and sharp waves. There was no change in QOL. CONCLUSION: CC can be effective in reducing GTC, absence and myoclonic seizures in patients with refractory IGE. These findings suggest that interhemispheric communication of the cerebral cortices plays an important role in the generation of seizures in IGE. Anterior CC appears safe while complete callosotomy has a risk of disconnection syndrome.

Subjective somnolence relates mainly to depression among patients in a tertiary care epilepsy center.

Many patients with epilepsy complain of decreased energy and somnolence. There is increased awareness that comorbidity, especially depression, plays an important role in determining the quality of life for patients with epilepsy. We set out to determine how subjective somnolence is affected by depression, age, hours of sleep, sleep apnea, seizure frequency, and numbers of antiepileptic drugs and central nervous system drugs. A questionnaire and chart review were used to investigate patients in a tertiary referral center. We found that subjective somnolence was prominent and that it relates mainly to depression, less to obstructive sleep apnea, and not to the other variables. Further investigation is needed into the relationship between depression and subjective somnolence in patients with epilepsy.

How long do most seizures last? A systematic comparison of seizures recorded in the epilepsy monitoring unit.

PURPOSE: More information is needed regarding how long seizures typically last, since this influences treatment decisions. Seizure type and other factors could influence seizure duration. METHODS: Data were collected from a random sample of patients being evaluated with continuous video and scalp EEG. Seizure duration was defined as time from early sign of seizure (clinical or EEG) until the end of seizure on EEG. Seizures were categorized as simple partial (SPS), complex partial (CPS), secondarily generalized tonic-clonic (SGTCS), primary generalized tonic-clonic (PGTCS) and tonic (TS). SGTCS were divided into a complex partial part (SGTCS/CP) and a tonic-clonic part (SGTCS/TC). Median and longest duration of each seizure type in each individual were used. Comparisons of seizure types, first and last seizure, area of onset, and state of onset were performed. RESULTS: Five hundred seventy-nine seizures were recorded in 159 adult patients. Seizures with partial onset spreading to both hemispheres had the longest duration. SGTCS were unlikely to last more than 660 s, CPS more than 600 s, and SPS more than 240 s. PGTCS and TS had shorter durations, but the number of subjects with those two types was small. CPS did not differ in duration according to sleep state at onset nor side of origin. CONCLUSION: A working definition of status epilepticus in adults with cryptogenic or symptomatic epilepsy can be drawn from these data for purposes of future epidemiologic research. More information is needed for the idiopathic epilepsies and in children.

Value of non-invasive testing when there are independent bitemporal seizures in the scalp EEG.

We investigated the value of non-invasive data for predicting the outcome of intracranial EEG and anterior temporal lobectomy (ATL) (follow-up>1 year) in patients who have bitemporal independent seizures in the scalp EEG. No previous report has dealt with this patient group. Independent variables were duration of epilepsy, febrile seizures, interictal and ictal scalp EEG, ictal behavior, MRI, [18F]-fluorodeoxyglucose-PET (PET) and Wada test and dependent variables were surgical outcome (seizure free or not) and localized on intracranial EEG (finding all symptomatic seizures from one temporal lobe). Non-parametric statistics were used. Of 24 patients, 20 patients had IEEG, of which 12 were localized and 8 were not. Sixteen patients had ATL and, of these, 13 (81%) became seizure free and the remaining three improved. Lateralized findings on MRI and PET, a history of febrile convulsions and shorter duration of epilepsy were all associated with a focal onset on intracranial EEG, while there was a non-significant trend with ictal behavior. The non-invasive data did not predict surgical outcome. We conclude that some of these patients can do well with surgery. In most cases, intracranial EEG is necessary for localization of seizure focus, but if PET and MRI show focal abnormalities and there is a history of febrile convulsions no further evaluation could be needed. These findings need confirmation.

Electroencephalogram in the dementia workup.

Dementia is affecting an increasing proportion of the population in the developed world. It is important to reach a correct diagnosis of dementia, because this has implications on the treatment. The electroencephalogram (EEG) is, in general, not a sensitive test for detecting dementia and is not recommended in the standard workup of dementia. In spite of this, however, EEG is useful in patients with deteriorating mental status in whom dementia is suspected mainly to rule out delirium, depression, atypical complex partial seizures, and prion disease. An EEG also provides insight into the physiology of different dementia types. The EEG is most useful when interpreted within a well-defined clinical context, such as knowing the patient's degree of cognitive impairment. It is a noninvasive and inexpensive test, and the threshold should be low for ordering it. This article summarizes EEG findings with aging, different dementia types, and conditions masked as dementia.