25 How is epilepsy defined? Recurrent seizures, provoked or unprovoked, in the presence of an enduring alteration in the brain that predisposes for future seizures1 What is a seizure? A seizure is a transient event that has clinical manifestation attributable to a specific area of the brain and is associated with abnormal enhanced synchrony on the electroencephalogram1 What are the major descriptors used to qualify seizures? Generalized Clonic Tonic Atonic Myoclonic Tonic-clonic Absence Partial Simple Complex Unclassifiable2 What are the different classifications of epilepsy? • Focal: partial seizures, focal electroencephalogram abnormalities • Idiopathic: no identifiable cause, e.g., benign rolandic epilepsy • Cryptogenic/symptomatic: associated with lesions or presumed brain lesions, e.g., mesial temporal sclerosis, brain tumors • Generalized: generalized seizures, diffuse electroencephalogram abnormalities • Idiopathic: no identifiable structural cause; most are genetically determined, e.g., childhood absence epilepsy • Cryptogenic/symptomatic: originated in a definable brain lesion, e.g., West syndrome, Lennox Gastaut Why is it important to differentiate epileptic syndromes? The treatment and prognosis vary widely. What is the prognosis of people diagnosed with epilepsy? • 20 to 30% have excellent prognosis with spontaneous remission. • 60% reach long-term remission with treatment.3 • 30 to 40% will have persistent seizures with variable intensity despite treatment.4 Which diagnostic modalities are useful in epileptic patients? • Electroencephalogram (EEG) • MRI • Lumbar puncture • SPECT (single photon emission computed tomography) and PET (positron emission tomography) scans What is the utility of electroencephalogram (EEG)? • Aids in the diagnosis of epilepsy • Allows for characterization of the epileptic syndrome • Helps in the differential diagnosis of seizures • Guides therapy in specific situations, e.g., status epilepticus But a normal EEG does not preclude the diagnosis of epilepsy. Among epileptic patients, who should get an MRI of the brain? • Every patient with focal epilepsy (focal seizures or focal EEG abnormalities) • Patients with developmental, neurological, or neuropsychological deficits • All patients with adult-onset epilepsy • All patients being considered for epilepsy surgery • Any patient with significant changes in the pattern of seizures (implying a progressive lesion) • Refractory epilepsy CT head is an alternative to MRI in acute situations or when MRI is technically difficult.5,6 True or false: Every patient with seizures requires a lumbar puncture. False. A lumbar puncture is indicated in people with clinical suspicion of infection7 or neoplastic dissemination. When are SPECT and PET scans indicated in patients with epilepsy? SPECT and PET scans are useful in localizing foci for presurgical planning. When should anticonvulsants be started? Whenever the diagnosis of epilepsy is made. Single seizures do not always require treatment. What are the most important risk factors for recurrence after a single unprovoked seizure? • Underlying cause: symptomatic seizure • Abnormal EEG: epileptiform discharges • Abnormal neurological exam True or false: The use of anticonvulsants reduces the risk of recurrence after a single seizure.
Epilepsy
25.1 Basic Concepts
25.2 Diagnosis
25.3 Treatment
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