1 Epilepsy What is epilepsy? Epilepsy is a condition of recurrent seizures caused by an inherent brain abnormality. The underlying abnormality may result from a number of etiologies, including hereditary factors, developmental disorders, perinatal injury, infection, trauma, infarction, or neoplasm. What is the incidence of epilepsy? 5% of the population will suffer a single seizure at some time. In 0,5% of this will be recurrent. Most epileptics have few seizures and permanent or prolonged remission, the average duration is 10 years. What is the difference between partial and generalised seizures? Partial seizures start focally and have clinical and electroencephalographic changes that indicate onset from one brain region and in some cases one cerebral hemisphere. Generalised seizures begin in both hemispheres at the same time. What kind of partial seizures can you distinguish? 1. Simple partial seizure (motor, sensory) 2. Complex partial seizure What kind of generalised seizures can you distinguish? 1. absence (petit mal) 2. tonic seizures 3. clonic seizure 4. tonic/clonic seizure 2 5. akinetic seizure 6. infantile spasm What is Jacksonian motor seizure? A ‘march’of involuntary movement from one muscle group to the next. Movement is clonic (shaking) and usually begins in hand or face. What are the characteristics of alcohol withdrawal seizures? Chronic alcohol abuse may be associated with seizures during abstinence. Most seizures occur between 7 and 48 hours after the last drink. The seizures are usually generalised tonic-clonic, although multiple seizures or even status epilepticus may occur. A subset of patients with alcohol withdrawal seizures have epilepsy and require maintenance anticonvulsants. These patients usually have posttraumatic epilepsy. In patients with only alcohol withdrawal seizures, benzodiazepines appear to be the most efficacious therapy, whereas phenytoin does not appear to help. Differential diagnosis of epilepsy: syncope, hyperventilation, toxic and metabolic disturbances, cardiovascular disorders, sleep disorders, paroxysmal vertigo, transient global amnesia, 3 psychogenic seizures, psychiatric dissociative states. What percentage of persons with epilepsy will have an abnormal EEG during the interictal period? The answer depends on the type of epilepsy. One study found that only 35-40% of patients with the clinical diagnosis of epilepsy had interictal epileptiform activity on a single EEG. Most of these patients had partial seizures with or without secondary generalisation. Multiple EEGs could enhance the yield of positive EEGs to 60%. Untreated patients with absence seizures usually have an abnormal routine EEG. The diagnostic yield of EEG may also be increased by prolonged monitoring, including sleep. An important point is that epilepsy is a clinical diagnosis and cannot be ruled out by normal EEG. On what kind of epileptic patients should we perform CT or MRI scans? Patients with partial seizures or focal features on EEG should have CT or MRI scans to look for a brain lesion associated with their seizures. CT scans should be performed with intravenous contrast medium, particularly in adults, because structural lesions are often the cause of the seizures. Patients with clear-cut primary generalised epilepsy based on EEG and clinical features usually do not require CT or MRI scanning. When should antiepileptic treatment be initiated? People should be treated with antiepileptic medication when the clinician thinks that the person will probably have another seizure without treatment. The seizure type may help with this decision. For example, absence seizures are rarely isolated and so require therapy, whereas febrile seizures are often isolated and therapy is usually not indicated. Between 20% and 70% of people with an isolated unprovoked generalised tonic-clonic seizure will never have another seizure. Ideally, it would be best not 4 to treat these patients. Seizure recurrence is more likely if the patient has focal neurologic deficits, mental retardation, an EEG that demonstrates epileptiform abnormalities, or a structural brain lesion. In these patients it is reasonable to begin antiepileptic therapy. In patients with well-defined provocative etiology, it is best to treat the underlying process rather than the seizures themselves, particularly in clear-cut cases of alcohol withdrawal seizures and drug-induced seizures. What is the first choice of drug in partial seizures? Carbamazepine (600-1200 mg/die; serum level: 4-9 ug/ml.). What is the first choice of drug in generalised seizures? Valproic acid (800-1500 mg/die, serum level: 60-100 ug/ml.). How would you treat status epilepticus? 1. oxygenisation 2. vitamin B1 (100 mg) i.v., 100 ml 20% glucose i.v. 3. 0,2 mg/kg diazepam (it can be repeated after 5 minutes) or 2 mg clonazepam i.v. 4. 15-20 mg/kg phenytoin i.v. 5. 5 mg/kg phenytoin (max. dosage: 30 mg/kg) 6. fenobarbital 15-20 mg/kg i.v. 7. thiopental 100-200 mg i.v, anesthesia When should antiepileptic treatment be stopped? What are the risk factors for recurrence of seizures? Treatment should be stopped when it is the physician's opinion that the patient probably will not have seizures off medications and 24 months of seizure-free period can be proven. Certain seizure types and 5 benign epileptic syndromes will remit. Patients with absence seizures will usually "outgrow" their seizures and therapy will no longer be needed. Benign childhood epilepsy with centrotemporal spikes also remit. Recent studies have suggested that approximately one-third of adult patients and one-fourth of children who were seizure-free for 2 years will relapse following termination of antiepileptic medication. Risk factors for recurrence include: 1. Prolonged duration before seizures were controlled 2. High frequency of seizures before control 3. Neurologic abnormalities 4. Mental retardation 5. Complex partial seizures 6. Consistently abnormal EEGs What are the advantages of monotherapy? 1. In most situations controls seizures as well as two drugs. 2. Prevents interactions between antiepileptic medications. 3. Less expensive. 4. Improves compliance. What are the teratogenic risks of antiepileptic medications? All antiepileptic medications have teratogenic features. In general, a pregnant patient taking a single antiepileptic medication has a three-fold increased risk of birth defects. The teratogenic effects of antiepileptic medication are more likely when more than one medication is used. The physician should try to treat the patient with only one antiepileptic medication during pregnancy. A patient and her family 6 should know these potential effects, but rarely is pregnancy contraindicated because of antiepileptic therapy. When should patients be considered for epilepsy surgery? Approximately 20% of patients with epilepsy have seizures that are not completely controlled despite adequate antiepileptic therapy and good patient compliance. These patients should be considered for epilepsy surgery. Forms: Localized resections are effective in temporal lobe epilepsy and in forms of neocortical epilepsy due to well-circumscribed lesions, corpus callosum sections can abolish drop attacks, hemispherectomies or large multilobar resections can be beneficial in secondary generalised epilepsies.