After most complex partial and all tonic-clonic seizures, memory is impaired for a period of time. What is the relationship between the time of seizures and the development of memory problems?
- Is it coincidence that memory problems are common between seizures (this period of time is called 'interictal) ?
- Do postictal (period after the seizure) symptoms predict future interictal symptoms?
- For example, changes in mood and thoughts that occur after a seizure (for example postictal psychosis) may evolve into interictal psychosis, or symptoms that occur between seizures.
- Personal observation also suggests that the same may happen with mood. Even without a prior history of depression, people who have periods of depression right after a seizure may be at risk for developing depression years later unrelated to the time of the seizures.
- Can treatment of seizures and postictal symptoms help prevent psychosis, depression or memory problems?
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For years, memory impairment was recognized as the most common interictal disorder.
- Patients complain of impaired recall for recently learned information, especially details and names.
- Partial seizures arising from the left temporal lobe affect mainly verbal memory, and right temporal seizures impair recently acquired visual, spatial, and geographic memory.
- Although patients with temporal lobe epilepsy show memory impairments on 30-minute delayed-recall tests, longer delays demonstrate even greater impairment.
- Just like other cognitive disorders, several factors contribute to interictal memory problems, including:
- Structural lesions (physical abnormalities in the brain, such as a stroke, scar, tumor, etc)
- Neuronal dysfunction or loss (brain cells don't work right or there is a loss of brain cells in that area)
- Interictal epileptiform discharges (seizure discharges seen on EEG between the time of witnessed seizures)
- Recurrent seizures
- Antiepileptic drugs (Smith,1988; Devinsky,1995; Drane & Meador, 1996)
- Interictal hypometabolism in medial temporal memory structures (this finding on certain brain scans is a marker that an area of the brain is not functioning normally and can be associated with impaired memory)
Treatment of interictal memory disorders
- Improving seizure control, reducing or eliminating AEDs that affect cognition (e.g., phenobarbital, topiramate), and improving sleep habits help memory in some patients.
- Pragmatic approaches include use of visual imagery, lists and schedules (displayed prominently), learning to take simple and clear notes, small portable notepads organized by topic, carrying important telephone numbers and addresses, and use of alarms as reminders. These strategies often fail to fulfill the needs of higher-functioning patients with demanding jobs.
- No medications are proven to enhance memory in patients with epilepsy.
- Studies on dietary supplements and herbal products to treat memory have shown mixed results. Most of the studies have been done in older people or those with Alzheimer's disease or other dementias. Since some of these can also have dangerous side effects, it is important for people with epilepsy to talk to their epilepsy team before considering any over-the-counter or prescribed supplements or herbal products.
- Romberg H. A manual of the nervous diseases of man. Sieveking EH, trans-ed. London, England: Sydenham Society, 1853:203.
- Smith DB. Anticonvulsants, seizures and performance. In: Trimble MR, Reynolds EH, eds. Epilepsy, behaviour and cognitive function. New York: Wiley, 1988:67–78.
Reproduced and adapted with permission from Orrin Devinsky, M.D. and Epilepsia.