Clinical correlates of midline spikes. An analysis of 21 patients.

Twenty-one children had interictal EEGs showing spikes located at the Fz, Cz, and Pz electrodes; their EEGs were compared with those of age-matched children referred to our laboratory (group 1, 63 children) and children with C3 and C4 spikes (group 2, 41 children). Midline spikes correlated well with a history of seizures (91% vs 73% in group 1 and 76% in group 2) and neurologic abnormality (38% vs 29% in group 1 and 22% in group 2). No patient had progressive neurologic disease or brain tumor. There are two different possible mechanisms in the genesis of midline spikes. In the majority of children, midline spikes may represent generalized epileptiform abnormalities; in a small subgroup, they may be analogous to C3 and C4 spikes and be generated by a cortical epileptogenic focus.