Ictal hyperperfusion patterns according to the progression of temporal lobe seizures

To investigate ictal hyperperfusion patterns during semiologic progression of seizures, the authors performed SPECT subtraction in 50 patients with temporal lobe epilepsy (TLE).

The patients were categorized into five groups according to semiologic progression during ictal SPECT (Group 1 had aura only; Group 2 had motionless staring with or without aura; Group 3 had motionless staring and then automatism with or without aura; Group 4 had motionless staring and then dystonic posturing with or without aura and automatism; and Group 5 had motionless staring, automatism, then head version and generalized seizures with or without aura and dystonic posturing).

In Group 1, three patients showed ipsilateral temporal hyperperfusion and two had bilateral temporal hyperperfusion with ipsilateral predominance. In Group 2, three patients (42.9%) showed bilateral temporal hyperperfusion with unilateral predominance and four patients (57.1%) revealed insular hyperperfusion of epileptic side. In Group 3, 15 patients (88.2%) showed bilateral temporal hyperperfusion with unilateral predominance and 12 patients (70.6%) revealed insular hyperperfusion. In Group 4, 11 patients (84.6%) showed basal ganglia hyperperfusion on the opposite hemisphere to the side of the dystonic posturing. In Group 5, there were multiple hyperperfusion areas in the frontal, temporal, and basal ganglia regions. However, the injection times of radiotracer in five groups were relatively short and similar.

The semiologic progression in TLE seizures were related to the propagation of hyperperfusion from ipsilateral temporal lobe to contralateral temporal lobe, insula, basal ganglia, and frontal lobe. Not only the radiotracer injection time but also semiologic progression after the injection was important to determine hyperperfusion pattern of ictal SPECT.