OBJECTIVE

To delineate the characteristics of stroke-like episodes (SLEs) in patients with adult-onset neuronal intranuclear inclusion disease (NIID) and to compare these characteristics with those of patients with MELAS.

METHODS

Twenty-three adult-onset NIID patients who presented with acute or subacute brain disorders and 13 late-onset MELAS patients were enrolled in the study. Patients with NIID were categorized into the SLEs group and the encephalopathy-like episodes (ELEs) group according to the associated stroke-like lesions (SLLs) findings. Clinical characteristics were compared between the SLEs group and the ELEs group among NIID patients and between NIID patients with SLEs and MELAS patients.

RESULTS

Eleven (47.8%) NIID patients who manifested acute or subacute brain disorders had detectable associated SLLs and were categorized into SLEs group. SLEs patients were more likely to report fever, headache, and seizures instead of sleep disorders than ELEs patients. Four (36.4%) NIID patients with SLEs absence of diagnostic or suggestive NIID imaging features. The clinical manifestations, laboratory test results, and neuroimaging and muscle biopsy histological features of NIID patients with SLEs majorly overlapped with those of late-onset MELAS patients. Older age at the first SLE (OR [95% CI], 1.203 [1.045-1.384]), symptoms of movement disorders on admission (OR [95% CI], 9.625 [1.378-67.246]), and white matter hyperintensity in corpus callosum (OR [95% CI], 16.00 [1.542-166.46]) associated with the NIID diagnosis in patients with SLEs.

INTERPRETATION

NIID patients with SLEs exhibit evident features of mitochondrial disorders. Interventions aimed at mitochondrial dysfunction might be a promising therapeutic approach for treating this disease.