Seizures and Epilepsy in the Elderly Revisited

We wish to respond to a significant error, both of fact and attribution, in a review article recently published in the ARCHIVES.¹ In a section titled "Role of the EEG and Structural and Functional Imaging," the author states: "For example, slow focal activity with or without accompanying sharp waves from the temporal lobes (especially the left) that are increased by drowsiness is seen in as many as 40% of controls older than 60 years." This is a reference to an article written by us² but nowhere in this publication do we make such a statement. Independent of the incorrect attribution, the statement itself is seriously erroneous. The occurrence of intermittent focal slowing, especially in the left temporal region, was first reported by Silverman et al³ in 1955 and described in 43% of 90 healthy volunteers older than 60 years of age. However, more recent studies in which patients have been rigorously screened to ensure their normalcy suggest that this finding, when present, should be infrequent. Katz and Horowitz⁴ found intermittent focal slowing in 17% of 52 normal septuagenarians, but in no patient did it occupy more than 1% of the total record. In the study by Arenas et al,⁵ 18 of 50 normal subjects showed some minor slowing. However, this slowing occupied less than 1.8% of the total recording in all but 1 subject. Thus, slowing, especially in the left temporal region, is a minor feature of the normal elderly person's electroencephalogram. Bona fide sharp waves, as distinct from some of the benign epileptiform variants described in our article,² should never be considered normal and have an extremely high incidence of associated clinical seizures.⁶