MELAS Stroke-Like Episodes and Challenges in Diagnosis via Imaging Techniques

Introduction Mitochondrial encephalopathy with lactic acidosis and stroke‐like episodes (MELAS) is a rare mimic of ischemic stroke. Stroke‐like lesions can cross vascular territories, appear normal on early MRI, and overlap clinically with post‐ictal phenomena in patients prone to seizures. Mtehods/Case Description A 17‐year‐old male with MELAS and epilepsy presented with generalized tonic‐clonic seizures followed by perception of shadows in his left visual field. This resolved with antiseizure medication and evolved into transient left homonymous hemianopia. Routine EEG was normal, MRI showed only chronic basal ganglia calcifications, and IV arginine was started for possible metabolic stroke. Persistent deficit with reported improvement after medication led to continuous EEG, which revealed right occipital subclinical seizures and abundant discharges that evolved into ictal‐interictal continuum despite multiple antiseizure loads and ketamine drip. While awake, visual fields were testable. The persistent hemianopia raised concern for either post‐ictal changes from active EEG abnormalities or a stroke‐like MELAS episode. Repeat MRI on day 8 showed new right occipital T2/FLAIR and DWI hyperintensity with ASL hyperperfusion, consistent with a metabolic stroke‐like event. The patient was placed in burst suppression, continued on high‐dose IV arginine, later transitioned to oral, and gradually weaned off antiseizure medications. Seizures ceased and the hemianopia resolved. Results This case highlights three diagnostic challenges: Early MRI can be normal in MELAS stroke‐like episodes; repeat imaging is useful. Clinical distinction between post‐ictal deficits and metabolic strokes is difficult, particularly with occipital lesions, as stroke‐like lesions can mimic or trigger seizures. Radiographic differentiation between seizure‐related and metabolic stroke lesions is challenging, as both may show hyperperfusion. Conclusion In MELAS, intermittent focal deficits after seizure even with negative initial imaging, warrant repeat MRI and/or continuous EEG. image Initial MRI : unremarkable image Day 8 MRI: Metabolic stroke