We used the (133)xenon method to assess cerebral blood now (CBF) durin
g generalized spike-wave discharges in a patient with an uncommon form
of generalized epilepsy with persistent spike-wave discharges. CBF me
asurements were made under four conditions with repeated measures: nor
mal EEG, continuous theta state, continuous spike-wave state at rest,
and continuous spike-wave discharges during performance of a cognitive
activation task. CBF was mildly reduced (5.7%) during the theta state
and decreased further (12%) in the spike-wave state. Although globall
y diminished, CBF was less decreased in the frontal lobes and more dec
reased in the parietal lobes during spike-wave discharges. CBF increas
ed to baseline levels during the cognitive activation task. The decrea
se in CBF suggested that the generalized spike-wave discharges caused
a net decrease in cortical metabolic demand and neuronal activity. The
differences in lobar CBF during spike-wave discharges may reflect lob
ar disparities in neuronal firing patterns. The theta state noted is n
ovel and intermediate between normal and spike-wave.