[Neuronal intranuclear inclusion disease with prolonged impaired consciousness and status epilepticus: a case report]

Neuronal intranuclear inclusion disease (NIID) is a neurodegenerative disease presenting with various manifestations including dementia, weakness, transient impaired consciousness, encephalitis-like episodes and also epileptic seizures. However, the nature of epileptic seizures, focal or generalized onset, remains unclear. A man at age 76 was admitted to a local hospital due to febrile impaired consciousness lasting several days. During the hospital stay, a generalized convulsion occurred, and afterward he remained obtunded. He was transferred to our hospital for further treatment. One additional seizure occurred while on an ambulance to our hospital and two additional seizures shortly after the arrival, which indicated convulsive status epilepticus (SE). The ictal EEG showed low amplitude fast activity arising from the left centro-parietal area with an evolutionary pattern. The clinical concomitant was the contralateral versive seizure evolving to a bilateral convulsion. Inter-ictal epileptiform abnormalities seen on the tracings taken on later days consisted of brief potentially ictal rhythmic discharges (B(I)RDs) and frequent sharp waves recorded from both frontal areas. These findings along with the ictal discharges would indicate a multifocal epileptic disorder in this patient. Diffusion weighted images (DWIs) of this patient showed hyperintensity signals in the cortico-medullary junctions in the bilateral frontal and the left parietal regions. Skin biopsy revealed characteristic intranuclear inclusions, and hence the diagnosis of NIID was made. The regions of epileptic foci on EEG corresponded well to the hyperintensity areas in DWIs, which suggests the cerebral cortices near the DWI hyperintensity could be more hyperactive than other regions. This case report suggests that some of the prolonged impaired consciousness and the encephalitis-like episodes in NIID could be related to epileptic seizures and even non-convulsive SE or a post-ictal twilight state after an unwitnessed convulsion. This issue should be further studied for the appropriate treatment of episodic encephalopathy and epileptic seizures in NIID.