Thalamic blood flow and EEG frequency band power during hyperventilation in idiopathic generalized epilepsy

Absence seizures in idiopathic generalised epilepsy (IGE) involve thalamo-cortical circuits. Hyperventilation (HV) is a standard technique to trigger epileptiform discharges and absence seizures in IGE. HV also increases electroencephalography (EEG) delta band power and decreases global cerebral blood flow (CBF). The relationships between HV, EEG band power, and regional CBF have not been investigated in the same patients at the same time. We compared the effects of hyperventilation between 13 individuals with IGE and 18 healthy controls on thalamic CBF assessed with pseudo-continuous Arterial Spin Labelling (pCASL) simultaneously to EEG frequency band power during three periods of hyperventilation interleaved with three periods of rest, normalised to each participants pre-HV values. Pre-HV, there were no differences between patients and controls. During the three rest periods combined, patients had higher normalised respiratory rates but no difference in CBF or EEG band power compared with controls. During HV, CBF decreases were similar in controls and IGE patients in cortical gray matter (37.1{+/-}1.3% in controls, 37.9{+/-}2.0% in patients) and basal ganglia (35.6{+/-}2.0% in controls, 33.3{+/-}2.3% in patients). In the thalamus, CBF decreased by 35.5{+/-}1.9% in controls, but only by 27.1{+/-}2.5% in patients (p=0.011). Delta band power increased by 42% in patients, but only by 27% in patients (p View larger version (58K): org.highwire.dtl.DTLVardef@12a5ebeorg.highwire.dtl.DTLVardef@b22944org.highwire.dtl.DTLVardef@b335dforg.highwire.dtl.DTLVardef@195c5e2_HPS_FORMAT_FIGEXP M_FIG C_FIG