MELAS Syndrome

A 19-year-old short-statured man presents with sudden left hemianopia, headache, vomiting, and focal seizures. His mother and maternal aunt have diabetes mellitus and sensorineural hearing loss. Serum lactate is elevated at rest (4.5 mmol/L) with disproportionate rise on exercise. MRI brain shows a T2-hyperintense lesion in the left occipital lobe that does not respect vascular territories, with restricted diffusion and elevated lactate peak on MR spectroscopy. The EEG pattern marked **B** in the diagram is recorded over the affected occipital region. Based on this clinical presentation and EEG finding, what is the most appropriate acute management for the stroke-like episode?