Abstract Number: Esoc2026a2432 Beyond the Diffusion Restriction; Adult Onset-Melas as Stroke Mimic

Background and aims Mitochondrial encephalomyopathy, lactic acidosis and stroke like episodes (MELAS) is a rare mitochondrial disorder presenting with recurrent stroke-like episodes which could mimic ischaemic infarct and presents a challenge in diagnosis and treatment. Methods 62 years old male had a wake-up onset of severe headache, left sided visual agnosia, and left homonymous hemianopia in 2021. At the time, CT angiography raised possibility of vertebral artery dissection or thrombosis with distal embolization; MRI head showed T2/FLAIR hyperintensity in right occipital and temporal cortex with restricted diffusion but lack of white matter involvement, and leptomeningeal enhancement; CSF examination was done to exlude encephalitis and only showed elevated Lactate. Given his background of type II diabetes mellitus, hypertension and family history of stroke in his younger brother, He was treated as Ischemic Stroke. Later on, he developed recurrent myoclonic seizures, and four years later he was readmitted with right sided hemianopia and expressive dysphasia. MRI head showed new T2/FLAIR hyperintensity in left temporal, and occipital cortex, sulcal effacement with restricted diffusion. Results His recurrent stroke-like episodes and MRI findings raised possiblilty of MELAS. Management was largely symptomatic with a focus on metabolic support and antiplatelet therapy. Conclusions The key features of MELAS are relapsing-remitting nature, seizures occurence, shifting pattern of lesions that favors occipital and temporal lobes, cortical diffusion restriction with sparing of white matter that doesn't follow vascular territory, CSF high lactate, and positive family history. Early diagnosis allows genetic counselling for family members, early adequate support to our patients and follow up. Conflict of interest Authors ( Wedad Mohamed, Ahmed Ali, Khin Zin) :Nothing to disclose Figure 1 - belongs to Methods Figure 2 - belongs to Results