Epilepsy in the elderly
Brain CT shows right temporal lobe epilepsy with hypometabolism.
This is the first of a two-part series. Part 2 will appear in the May issue.
Epilepsy is one of the most common neurologic diseases, and although few primary-care practitioners realize it, the prevalence of epilepsy is highest among older adults, especially after age 65.1-3 In those older than 70, the incidence of epilepsy is nearly twice that of children,3 and in those aged 80 years and older, the disorder occurs three times more often than it does in the pediatric population. Among patients older than 75, 10% will experience a seizure and 3% will be diagnosed with epilepsy. Until recently, however, there has been very little information about epilepsy or seizures in older adults, the focus being on infants, children, and young adults.
Further, epilepsy manifests somewhat differently in older individuals, so it is often missed or misdiagnosed. Many believe that epilepsy always causes dramatic grand mal seizures, but the symptoms of seizures in older adults are often subtle and easily missed.
Many older patients with epilepsy present with complex partial seizures that have a higher recurrence rate than in the younger person.4 Most of the nearly 1% of the population that develops epilepsy has a family history, but in older adults, epilepsy frequently signifies cerebrovascular disease or malignancy. The intent of this series is to bring practitioners up to date on the identification, causes, and care of older adults with seizures.
Epilepsy is an attack of impaired neurologic function, usually combined with loss of consciousness and/or other paroxysmal motor, sensory, or autonomic phenomena. Epileptic seizures are produced by abnormal electrical excitation of brain tissue usually detectable as an abnormal pattern on an electroencephalogram (EEG).2 A single seizure occurrence does not connote epilepsy (e.g., a febrile seizure). Only seizures spanning a period of time and recurring repeatedly are considered epileptic seizures. The various types of epilepsy can be categorized by the clinical pattern produced (generalized, localized, unclassifiable, occurring in series or singly); the site, i.e., the lobe, of the epileptic focus; the EEG pattern; and the age of onset (Table 1).2
The most common seizure experienced by older adults (66.2%) is the complex partial seizure, which is sometimes called a temporal lobe seizure and is accompanied by impaired consciousness. The next most common seizure type in older patients is the secondarily generalized variety (33.8%), which may evolve to a generalized tonic-clonic seizure.5 Details about seizure types are available from the International League Against Epilepsy.
Non-epileptic seizures are less common than epileptic seizures and are not accompanied by abnormal electrical discharges in the brain.6 No cause has been identified, but non-epileptic seizures seem to be related to psychological distress and the patient's physical reaction to it. These seizures, which occur most often in younger adults, resemble epilepsy and are characterized by falling and shaking. They may also resemble petit mal or complex partial seizures, with loss of attention, staring into space, or sleeping at odd times.
Other non-epileptic seizures are associated with some toxic-metabolic disorders common in older adults,7 including hypoglycemia, hypocalcemia, hyponatremia, renal failure, and some medications, especially psychotropic drugs. While these seizures are often treated with anti-epileptic drugs (AEDs) acutely, they stop after the metabolic disorder is corrected.
Brain tumors, such as malignant gliomas and other metastatic tumors, are often associated with seizures.