![]() ![]() The impairments related to focal IEDs appear to be related to duration and location. ![]() 19 Although earlier work correlated longer generalized 3-Hz spike and slow wave discharges to memory impairment, especially in children and young adults, 19,20 IEDs can be shorter in duration and focal in origin and location. 11-18 The term transient cognitive impairment (TCI) was created to explain the correlation with lapses of cognition during IED seen on EEG. 10 Although IEDs are classically considered asymptomatic, there is some evidence they are related to brief lapses in cognitive function. 7-9 A following hyperpolarization phase, or the after-going slow wave, is thought to be mediated by GABA. An IED is a large synchronous burst of neuronal activity thought to be preceded by a paroxysmal depolarization shift (PDS) related to α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPA)- and N-methyl-D-aspartate (NMDA) channel-mediated calcium conductance. These pathological discharges are frequently seen in-between seizures and occur in and around the seizure-onset zone. ![]() People with epilepsy frequently have interictal discharges (IED) or epileptic sharp or spike and slow waves seen on EEG. 5,6 Although patients with abnormal brain imaging findings were excluded in these studies, it is unclear if EEG findings were present prior to neuropsychologic testing. Although, at the time of diagnosis, people with epilepsy have been shown to exhibit negative mood and anxiety, 6 which could contribute to some of the memory deficits observed, 2 studies found no relationship between mood and neuropsychologic test results. These results are consistent with prior studies 2-4 however, in all studies, some individuals had experienced 1 or more generalized tonic-clonic seizures before neuropsychologic testing. Performance did not significantly differ among those with partial vs generalized vs unclassified epilepsy. 5 After adjusting for age, sex, and education, people with newly diagnosed epilepsy had worse performance on a finger-tapping task with the dominant hand, poor motor speed on the Adult Memory and Information Processing Battery, poor word recall on the Rey Auditory Verbal Learning Test, and poor story recall. 2-5 A study assessed 155 people with a newly diagnosed and untreated seizure disorder without known neuropathology with a battery of neuropsychologic testing. ![]() Memory Impairment Before Epilepsy DiagnosisĪ number of studies indicate that some memory impairment can precede the diagnosis of epilepsy. In this review, we discuss the possible reasons for memory impairments in people with intractable epilepsy. It is unclear if memory impairments remain stable over time or worsen as seizures become more intractable. 1 Factors that contribute to memory impairments include antiseizure medications (ASM), underlying causes of seizures, psychosocial factors, and effects of recurrent seizures. Memory impairment is among the largest contributors to poor quality of life for those with epilepsy. Frequently, people who report no or minimal memory problems perform poorly on certain neuropsychologic tests, whereas patients with multiple memory complaints might perform at, or above average levels recorded for typical people of the same age and education. Correlations between self-reported complaints and neuropsychologic test results are low. People with intractable epilepsy are frequently in denial of the severity of their memory impairments and frequently are seen for neuropsychologic testing only at the urging of family and friends. It is challenging to ascertain the degree and nature of memory complaints based only on self or family report, and many factors contribute to this challenge. Individuals with epilepsy frequently complain of memory impairment. ![]()
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