Dynamic thalamo-cortical perfusion changes in myoclonic-atonic seizures captured by ictal technetium-99m ethyl...

Ictal and interictal single-photon emission computed tomography (SPECT) has not been used to characterize myoclonic-atonic seizures. However, monitoring changes in cerebral blood flow (CBF) may help determine the pathogenetic mechanisms of this condition.

We evaluated myoclonic-atonic seizures using technetium-99m ethylene cysteinate dimer (ECD)-SPECT and ictal SPECT subtraction co-registered with magnetic resonance imaging (SISCOM).

A 3-year-old boy with normal development presented with truncal ataxia caused by acute cerebellitis at 1 year and 10 months, followed by atonic seizures at 2 years and 1 month and myoclonic-atonic seizures at 2 years and 6 months. Seizures could not be controlled by valproate, lamotrigine, or clonazepam. By 3 years of age, he experienced up to 40 myoclonic-atonic seizures per day, confirmed using ictal electroencephalography. Interictal electroencephalography showed diffuse spike-and-wave complexes. Ictal ECD-SPECT demonstrated increased CBF in the right precentral gyrus and temporal lobe and decreased CBF in both thalami. The patient was diagnosed with epilepsy with myoclonic-atonic seizures. Seizure control was achieved after adrenocorticotropic hormone therapy. Following treatment, interictal ECD-SPECT images demonstrated no difference in CBF between the left and right precentral gyri and temporal lobes, and resolution of hypoperfusion in both thalami. SISCOM revealed hyperperfusion in the right centroparietal region.

Adrenocorticotropic hormone therapy successfully treated myoclonic-atonic seizures and resolved bilateral thalamic hypoperfusion. Thalamic dysfunction may also be involved in myoclonic-atonic seizures. This case uniquely demonstrates CBF changes in the motor cortex and thalamus and provides insight into the mechanisms underlying myoclonic-atonic seizures.