EPILEPSY. Terminology and Classification. Seizure Brief disturbance of cerebral dysfunction due to abnormal synchronized neuronal electrical discharge “Provoked or acute symptomatic seizure” Identifiable temporary or permanent isolated condition that disrupts cerebral structure or function
Terminology and Classification • Seizure • Brief disturbance of cerebral dysfunction due to abnormal synchronized neuronal electrical discharge • “Provoked or acute symptomatic seizure” • Identifiable temporary or permanent isolated condition that disrupts cerebral structure or function • Drug (ETOH) withdrawal, acute head trauma, hypoglycemia, CVA • “Unprovoked seizure” • Cryptogenic: Occult cause other then genetic etiology • Idiopathic: no cause other than genetic predisposition • Epilepsy: recurrent uprovoked seizures • Epilepsy is considered to have occurred after the 2nd unprovoked event.
International Classification of Epilepsy • Partial seizures • Simple partial seizures (unimpaired consciousness) • Complex partial seizures (impaired consciousness) • Partial seizure evolving into Secondarily generalized • Generalized seizures (Primary seizure disorder) • Absence seizures • Tonic-Clonic seizures • Clonic seizures • Tonic seizures • Myoclonic seizures • Atonic seizures
EpidemiologyIncidence of 1st unprovoked seizuresOverall incidence: 60/100K person-years Hauser et al,Epilepsia 1993;34:453-468
Incidence of EpilepsyOverall incidence: 44/100K person-years Hauser et al, Epilepsia 1993;34:453-468
Proportion of all incidence cases of epilepsy by seizure type Hauser et al, Epilepsia 1993
Proportion of newly diagnosed epilepsy cases according to etiologic categories within age groups Hauser et al, Epilepsia 1993
Age-specific distribution of the incidence of first status epilepticus per year per 100K in Richmond, VA DeLorenzo et al, JCN 1995;12:316-325
Prevalence of Epilepsyage and sex Hauser et al, Epilepsia 1993
Diagnosis • Case 1: 22 y/o male with 3 episodes of abnormal behavior for the past 3 months witnessed by his wife. With the 1st 2 events, he suddenly felt “weird” in his stomach, few seconds later, stopped talking and was staring. No response when his name was called. He began to make lip smacking, chewing movements and fumbled with his shirt for a minute, following which became responsive but felt tired. Yesterday, he had similar spell, but after 15 seconds of staring and smacking movements with his mouth, he fell to the floor and had jerking of his trunk and all limbs. The jerking continued for 2 minutes; after that he fell into deep sleep. • What type of seizure does the patient have? • Based on the clinical manifestation, where is the neuroanatomic localization? • Identifying risk factors for epilepsy • Evaluation
Risk factors for epilepsy Febrile convulsion Perinatal insult CNS infection Mass lesion in the brain Family history of epilepsy Head injury (LOC >30min) Developmental delay History of CVA Focal neurological exam Laboratory Electrolytes Hypoglycemia Hepatic Renal dysfunction Drugs Toxins Alcohol CT MRI brain EEG Evaluating a patient with Epilepsy
EEG test • Emergent EEG: To rule out NCSE • Support diagnosis and localize seizure focus • Normal EEG during clinical spell suggest non-epileptic event • Normal EEG does not rule out epilepsy • ¼ of epileptics have normal EEG • Deep focus (hippocampus, parasagittal frontal cortex) • Incr diagnostic yield: SD, HV and photic stimulation • Focal slowing: Focal brain dysfunction
Non-epileptic physiological Syncope Arrhythmias Vasovagal Orthostatic hypotension Medication-induced Cerebrovascular: TIA/CVA Classic migraines Toxic-metabolic ETOH, hypoglycemia Non-epileptic psychogenic Conversion disorder Anxiety or panic disorder What other diagnosis should be considered when evaluating a patient with suspected seizure disorder?
Medical Treatment of Epilepsy • The patient with a single seizure • 50-70% will not have another seizure • 50% of untreated patient: 2nd seizure within 5 yrs. • The decision to treat should be based on the presence or absence of risk factors associated with recurrence • Abnormal NE, abnormal EEG • Partial seizure with or without secondary generalization • History of neurologic injury (CVA, hge, tumor) • Possible consequence of second seizure • Risk of injury for patients taking anticoagulation • Risk of the patient’s job requires driving.
General Principles of AED Management • Monotherapyis the goal • Selection of AED is based mainly on the seizure type • In emergent situationsloading doseis preferrable (Phenytoin, Valproic acid, PB) • “Start low and go slow”, when loading dose is notgiven. Therapeutic dose is guided by occurrence of breakthrough seizures or intolerable SE • Treatthe patient and not the drug level • The risk of dose-related symptoms and acute idiosyncratic SE is minimized by slow and cautious doseescalation. • Iftoxicity occurs during adjustment of AED, reduce dose by 25%, wait 2 weeks then increase again.
AED withdrawal/ discontinuation • Unprovoked seizures caused by neurologic illness (brain tumor) require continuous drug therapy. • If seizure-free for >2 years, re-evaluate. • Tapering considered if no factors associated with high recurrence risk (structural lesion, abnormal EEG, abnormal NE, severe epilepsy prior to being controlled). • Without risk: 25 % risk of having recurrence • 80% within 4 months, 90% within 1 year after • Driving and potentially dangerous activities should be prohibited during tapering of AED for at least 4 months.
Status epilepticus • Continuous seizure activity for at least 20 minutes • (+/-) impairment of consciousness. • The patient does not completely recover to baseline neurologic functioning between 2 or more seizures • Approx 12% of epileptics have SE as initial event. • 5 Major subtypes of SE • GCSE: Overt Generalized Convulsive SE (primary and secondary generalized seizure) • Subclinical or Subtle GCSE (frequently referred as Myoclonic status) • CPSE: Complex Partial SE • Absence SE (Petit Mal status) • Simple Partial SE (No impairment of consciousness)
Comparative Trial of initial IV treatment of GCSE Treiman et al, NEJM 1998;339:792-798
Management of Status Epilepticus Noseworthy 2003, Neurologic Therapeutics; page 326
Special issues in Epilepsy • CVA is the leading cause of epilepsy >60 y/o • Majority occurs within 3-12 months • Risk include cortical involvement, lobar hematomas close to the brain surface. • Women with epilepsy: 30% have increased risk seizure frequency during pregnancy. • Seizures poses more danger to the fetus than AED itself. Discourage patients from reducing or stopping AED during pregnancy. • 90% of epileptic women: Normal pregnancy/ deliver normal children. • Surgical treatment is more superior than medical treatment in medically intractable epilepsy. Referral to Epilepsy center • Ketogenic diet, high fat, low-protein and low-carbohydrate diet, starve the body, increase ketones, increase seizure threshold. • Report seizure patients to Dept ofHealth/DMV. • Advise them not to drive, avoid heights, swimming, weaponry, equipment that can potentially harm self or others