Depression in complex partial seizures. Electroencephalography and cerebral metabolic correlates

We sought to determine whether the frequency of depressive disorders among patients with complex partial seizures is associated with the laterality of ictal onset or the laterality of interictal cerebral hypometabolism.

Fifty-three patients with medically intractable complex partial seizures were assessed for history of interictal depressive disorders meeting strict Diagnostic and Statistical Manual of Mental Disorders, Revised Third Edition (DSM-III-R), criteria with use of a modification of the Structured Clinical Interview for DSM-III-R. All subjects underwent video-electroencephalographic telemetry and fludeoxyglucose F18 positron emission tomographic scanning. The main outcome measure was the frequency of a history of major depressive episodes (MDEs) in subjects with left-sided vs right-sided ictal onset and in subjects with left-sided vs right-sided temporal lobe hypometabolism.

Thirty-three subjects (62%) had a history of interictal depressive disorders, 16 (30%) of whom met criteria for one or more MDEs. More of those with left-sided ictal onset had a history of depression. Thirty-six subjects had definite unilateral temporal lobe hypometabolism demonstrated by positron emission tomographic scanning. More of those with left temporal lobe hypometabolism had a history of MDEs, and the combination of left temporal lobe hypometabolism and high-degree hypometabolism was strongly associated with a history of MDEs. Furthermore, among those with right temporal lobe hypometabolism, more of those with high-degree hypometabolism had a history of MDEs.

Laterality of ictal onset and degree of interictal temporal lobe hypometabolism may be interdependent factors that contribute to the risk of depressive disorder in patients with complex partial seizures.