Abstracts

Rationale: Epilepsy is often challenging to diagnose in older adults. Adult-onset epilepsy is frequently missed in older persons, as their seizures are not always convulsive & may be misinterpreted as transient events caused by vascular disease, dementia, or medical illness. Epilepsy diagnosis is further hindered by insensitive objective clinical testing; MRI is frequently normal & routine clinical EEG has less than 50% sensitivity for epileptiform features. Chronic EEG recording has the highest sensitivity and specificity for epilepsy, & home ambulatory EEG has been shown to be both sensitive & inexpensive relative to other EEG tests. The purpose of this study was to begin to evaluate the efficacy of ambulatory EEG for epilepsy diagnosis in adults aged 65 or older. Methods: Ambulatory EEG studies (24-72 hours duration) performed between 1/1/2012 and 12/31/13 for twenty patients aged 65 or older in the VA Boston Healthcare System as part of their diagnostic workup after inconclusive routine EEG testing or to evaluate for spells concerning for subclinical seizure activity were analyzed retrospectively for the impact of ambulatory EEG results on epilepsy diagnosis & management. Epilepsy likelihood before & after ambulatory EEG testing was assessed via the epilepsy diagnosis grading system in Table 1. Results: The twenty older adults who underwent ambulatory EEG during the specified time-period were all male veterans & ranged in age from 65 to 83 years old. Ambulatory EEG results changed the epilepsy grade in 8/20 (40%) patients & effected a management change (resulted in or prevented ordering of additional testing, prevented or caused a changed in medical management) in 11/20 patients (55%). Regarding etiology of epilepsy: there were seven patients with epilepsy of unknown cause; four with posttraumatic epilepsy & radiographic evidence of focal cerebral injury; one with posttraumatic epilepsy without radiographic evidence of cerebral injury; and three with lesional epilepsy of non-TBI cause. Five were deemed not to have epilepsy. Fifteen patients had subjective complaints of cognitive impairment; information about subjective complaints was not available from two patients. Fourteen patients underwent formal neuropsychology testing, with twelve found to have cognitive deficits on testing. Conclusions: Ambulatory EEG can identify clinically relevant epileptic abnormalities in older adults & is tolerated by adults aged 65 & older. Ambulatory EEG recording has previously been shown to be superior to routine EEG in the detection of epileptic abnormalities. This superiority of ambulatory EEG appears to be due to three factors: (i) its longer duration compared to routine EEG; (ii) reliable capture of sleep; and (iii) its compatibility with routine home activities of daily living. Timely diagnosis of epilepsy in older adults is crucial, as seizures are a potentially treatable cause of cognitive decline in older adults. Based on these preliminary results, ambulatory EEG can play an important role in the timely diagnosis of epilepsy in adults aged 65 & older.