Nonconvulsive Status Epilepticus in MELAS Syndrome Without Stroke-Like Lesions: A Case Report
Maria Jose Jaramillo-Arrázola1, Carmela Fawcett1, Andres Ricaurte-Fajardo1, Juan Felipe Vargas Ruiz1, Gabriela Revelo Urbano1, Daniel Nariño Gonzalez1
1Department of Neuroscience, Pontificia Universidad Javeriana
Objective:
To describe a case of nonconvulsive status epilepticus (NCSE) in a patient with MELAS syndrome occurring in the absence of new stroke-like lesions, highlighting the role of mitochondrial dysfunction and metabolic instability in epileptogenesis.
Background:
Mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS) is a multisystem disorder predominantly caused by the m.3243A>G mutation in the MT-TL1 gene. Epileptic seizures are frequent and often coincide with acute stroke-like lesions; however, NCSE without radiologic correlates is rare and may reflect intrinsic neuronal bioenergetic failure rather than vascular pathology.
Design/Methods:
Not applicable
Results:
A 22-year-old woman with molecularly confirmed MELAS (m.3243A>G, 30% heteroplasmy) and homozygous MTHFRC677T mutation presented with focal seizures progressing to NCSE after intermittent discontinuation of L-arginine supplementation. Continuous EEG showed 2–3 Hz rhythmic spike– and polyspike–wave discharges in the right temporo-parieto-occipital region with anterior propagation, lasting 12–15 seconds, resolving after intravenous midazolam. Brain MRI demonstrated chronic occipital and lingual gyrus gliosis without new diffusion- or FLAIR-restricted lesions. Antiseizure therapy was optimized with brivaracetam and clobazam, and metabolic therapy with L-arginine and citrulline was reinstated.
The patient achieved full clinical and electrographic recovery without new neurological deficits. The episode was attributed to metabolic decompensation secondary to nitric oxide deficiency following L-arginine withdrawal.
Conclusions:
This case broadens the clinical spectrum of mitochondrial epilepsy, showing that NCSE may occur in MELAS without structural lesions. These findings support metabolic dysfunction as a direct mechanism of epileptogenesis. Sustained nitric oxide precursor therapy and continuous EEG monitoring are essential to prevent recurrence and irreversible neuronal injury.
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