The yield of routine EEG in geriatric patients: A prospective hospital-based study.

ABSTRACT

STUDY AIM: To study the yield of routine EEG in geriatric patients. PATIENTS AND METHODS: We examined standard EEG recordings of 701 patients aged 84.6±6.4 years. These were performed over a 15 month-period in a geriatric hospital. The majority of patients were hospitalized and 46.5% suffered from multiple medical problems. RESULTS: We found EEG abnormalities in 392/701 (56%) patients. These consisted of permanent diffuse slowing, either isolated (17.1%) or with intermixed epileptiform abnormalities (2.4%), focal slowing (15.4%), intermittent diffuse slowing (8.9%), triphasic waves (1.14%), periodic epileptiform discharges (0.57%), flat and inactive tracing (0.14%), status epilepticus (0.99%), seizures (0.42%), interictal epileptiform abnormalities (8.7%). Epileptiform abnormalities (both ictal and interictal) were observed in 92/701 (13.1%) patients. These were focal in the majority of cases (85.9%), most frequent in temporal regions (42%), followed by centroparietal (20.2%) and temporo-parieto-occipital carrefour regions (17.2%), but less frequent in frontal (6.3%) and occipital regions (3.8%). We found sleep activity without other EEG abnormalities in 13.7% of patients and subclinical rhythmic electrographic discharge in adult (SREDA) in 1% of cases. CONCLUSIONS: In this study, EEG abnormalities were very common, which reflects the high frequency of cerebral dysfunction in geriatric patients. These abnormalities are of various types, often suggestive of different aetiologies, and may be helpful in clinical management.