Non-convulsive status epilepticus revealing acute deterioration in AARS2 mutation-associated progressive leukoencephalopathy.

Nonconvulsive status epilepticus (NCSE) is defined as a condition of prolonged epileptiform activity on electroencephalography (EEG) accompanied by altered mental status without prominent motor manifestations. It is frequently underdiagnosed, particularly in patients with pre-existing cognitive impairment or neurodegenerative disorders [1, 2]. Reports describing NCSE in patients with AARS2-related leukoencephalopathy remain extremely limited. This case identifies NCSE as a potential cause of clinical deterioration in AARS2-related leukoencephalopathy and highlights the importance of considering NCSE in patients presenting with subacute neurological deterioration. A 41-year-old woman was admitted with progressive cognitive decline and social withdrawal that had markedly worsened over the preceding month. The patient initially developed slowly progressive memory impairment approximately 18 months before admission followed by gradual cognitive decline and increasing dependence in daily activities. During the month before hospitalization, her condition deteriorated more rapidly, with marked reduction in speech, impaired responsiveness, and behavioral changes. Because of this abrupt deterioration, EEG was performed and showed rhythmic frontal delta activity with superimposed sharp waves. These EEG findings, together with her altered mental status and the subsequent clinical and EEG response to antiseizure treatment, supported a diagnosis of NCSE. Following treatment, her consciousness and interaction improved markedly, with regression of the previously observed EEG abnormalities on follow-up recording. She had experienced a single generalized tonic-clonic seizure several months before admission. Antiseizure medication was prescribed following the seizure, but subsequently did not continue with the treatment. Her medical history revealed premature menopause at the age of 21 years and she was born to consanguineous parents. Brain magnetic resonance imaging showed bilateral patchy T2/FLAIR hyperintense lesions predominantly affecting the frontal and temporal white matter, together with corpus callosum thinning and cerebellar atrophy. Next-generation sequencing identified compound heterozygous variants in the AARS2 gene, and gynecological evaluation confirmed premature ovarian failure.