Neuropathological analysis of the brainstem and cerebral cortex lesions on epileptogenesis in hereditary dentatorubral-pallidoluysian atrophy

In order to investigate epileptogenesis in hereditary dentatorubral-pallidoluysian atrophy (DRPLA), we immunohistochemically examined the expression of neurotransmitters, neuropeptides, calcium-binding proteins and/or glutamate transporters in the brainstem and cerebral cortex in autopsy cases. The subjects comprised 14 cases of clinicopathologically confirmed DRPLA, including 7 cases of juvenile and 2 cases of early adult types with progressive myoclonus epilepsy (PME), 5 cases of late adult type without PME, and 10 age-matched controls. Serial sections of the brainstem and cerebral cortex were treated with antibodies to tyrosine hydroxylase, tryptophan hydroxylase, substance P, methionine-enkephalin, parvalbumin, calbindin-D28K, calretinin, and excitatory amino acid transporters. Although the size of the tegmentum was small, we failed to find any PME-specific brainstem changes in the expression of neurotransmitters, neuropeptides and calcium-binding proteins. The number of interneurons immunoreactive for calbindin-D28K and parvalbumin, markers of GABAergic inhibitory interneurons, were reduced throughout the cerebral cortex, but there was no significant difference in the density of immunoreactive neurons between DRPLA patients of each type. The expression of glutamate transporters was comparatively spared. The current study revealed an absence of PME-specific brainstem lesions and indicated a possible involvement of the reduced GABAergic interneurons in the cerebral cortex in formation of PME in DRPLA.