Prevalence and clinical significance of epileptiform EEG discharges in a large memory clinic cohort.

BACKGROUND

Although EEG is not considered as standard in memory clinics, evidence indicates that epileptiform discharges are of value in diagnosing cognitive complaints as epilepsy.

OBJECTIVE

To determine prevalence and significance of epileptiform discharges in a memory clinic.

METHODS

1,674 consecutive patients underwent routine EEGs [mean age 66 years, diagnoses: Alzheimer disease (AD; n = 510), other dementia (n = 193), mild cognitive impairment (MCI; n = 225), subjective complaints (n = 368), and other disorders (n = 378)]. Database statistics, charts and EEG reports were reviewed.

RESULTS

Epileptiform discharges were present in 42 (3%) patients, of which 60% lacked clinical seizures. All discharges were focal and predominantly temporally localized. Epileptiform activity was not associated with a dementia diagnosis (2% in AD and 1% in other dementia vs. 2% in MCI, 2% in subjective complaints and 5% in other disorders, p = 0.07) or with lower Mini-Mental State Examination scores (p = 0.69). Two (diagnoses: AD, vascular dementia) of 20 patients with epileptiform activity without clinical seizures developed first seizures after 2 years.

CONCLUSION

In a memory clinic cohort, epileptiform discharges are rare, nonspecific and indicate a moderate risk of first-ever seizures in demented patients. These findings should be taken into account when routinely evaluating memory clinic patients with EEG.