Triphasic waves in Alzheimer's disease.

Clinical records and EEGs of 114 consecutive patients with clinical diagnosis of Alzheimer's disease have been reviewed. The EEGs of 15 patients (13%) contained triphasic waves. Triphasic waves were always atypical as they occurred singularly or in short bursts, and/or they had occipital predominance, and/or they were bilateral but asymmetrical. Triphasic waves, in all but one patient were recorded in a state of complete alertness. No statistically significant differences were found between the triphasic waves group and the other one, with respect to age, age at onset, illness duration, presence of seizures. Myoclonus was more frequent in patients with triphasic waves (p less than 0.01). Triphasic waves patients had a higher degree of dementia (p less than 0.01), both in cases with rapidly evolving disease and in subjects with relatively slow clinical course.