Ictal single photon emission computed tomographic study of myoclonic absence seizures

Epilepsy with myoclonic absences (EMAs) is a rare epileptic disorder characterized by a predominant type of seizures, myoclonic absences (MAs). The pathophysiology of MAs in patients with EMAs remains unknown. Here, we report the first characterization of the ictal phase of MAs by single photon emission computed tomography (SPECT).

We evaluated 1 male (Patient 1) and 1 female (Patient 2) patient with EMAs, aged 8 and 4years at first SPECT investigation, respectively. We performed ictal and interictal ^{99 m}Tc-ethyl cysteinate dimer (ECD) SPECT. We then generated images of subtraction ictal SPECT co-registered to MRI (SISCOM) from the interictal and ictal data to evaluate topographic changes in cerebral blood flow (CBF) during MAs as compared to the interictal state.

In Patient 1, the CBF increased in the perirolandic areas, thalamus, caudate nucleus, and precuneus, and decreased in the middle frontal gyrus and bilateral orbitofrontal regions. In Patient 2, CBF increased in the thalamus, putamen, and globus pallidus. In contrast to the CBF in Patient 1, CBF was decreased in the precuneus.

Using SPECT, we showed that, in addition to the thalamus and basal ganglia, the perirolandic cortical motor area is involved in MAs. We hypothesize that in MAs the blood perfusion in the perirolandic cortical motor area might have changed under the influence of the cortico-thalamic network oscillation features. The CBF properties observed by means of our SPECT procedure may represent key features of the pathophysiological mechanisms underlying MAs.