Focal and/or lateralized polymorphic delta activity. Association with either 'normal' or 'nonfocal' computed tomographic scans
D. W. Marshall, R. L. Brey and M. W. Morse
Department of Neurology, Wilford Hall, USAF Medical Center, Lackland AFB, TX 78236-5300.
Focal continuous polymorphic delta activity (PDA) is classically taught to
be associated with destructive lesions of cerebral white matter. One
hundred patients with focal or lateralized continuous PDA recorded by an
electroencephalogram who also had computed tomographic (CT) scans of the
head performed at approximately the same time were studied. Thirty-three
percent had normal or "nonfocal" abnormalities on their CT scans. Most of
these had a history of either seizures (51%) or transient cerebral
ischemia/stroke (27%); however, a wide variety of causes were possible.
This high percentage of patients with focal continuous PDA without
corresponding CT scan lesions supports the concept that the
electroencephalogram is a physiologic study that is complementary to
anatomic imaging techniques.
