True or false: Imaging findings reflect typical changes after partial status epilepticus.
False. The MRI features observed in the acute phase of partial status epilepticus are usually localized, bilateral and disappear after a few days.
True or false: There is no evidence of crossed cerebellar diaschisis.
Somehow both true and false. Assessment of acute crossed cerebellar diaschisis requires functional imaging, e.g. FDG-PET, CBF (cerebral blood flow) SPECT, CT perfusion, perfusion MRI. However, there is no evidence of long-standing crossed cerebellar diaschisis, reflected by normal cerebellar hemispheres. You could of course argue the odds for "long-standing" in a toddler without previous hospital admission or health issues.
Are patient symptoms right-sided of left-sided?
There is solely supratentorial and left-sided holohemispheric involvement, why patient symptoms only can be right-sided (which they were).
What is the most likely diagnosis?
Acute phase of hemiconvulsion-hemiplegia epilepsy syndrome.
Non-contrast MR head with TOF MRA performed 2 days after CT 3 days efter seizures.
Sulcal effacement of the left hemisphere with slight grey-white dedifferentiation on T1WI, sparing the deep nuclei. Associated diffuse panhemispheric hyperintense left white matter changes on DWI with signal loss on ADC and slightly increased signal on T2WI/FLAIR, indicating diffusion restriction consistent with cytotoxic edema. No significant mass effect. The affected areas are independent of vascular territories and there is striking sparing of the deep nuclei including the basal ganglia. No cerebellar involvement.
No gross or petechial intracranial hemorrhages. No vessel or flow abnormalities on TOF angiography, nor evidence of dissection. No focal abnormalities or atrophy, including contralateral cerebellar atrophy.
Conclusion
Patient history, clinical picture and imaging findings suggest hemiconvulsion-hemiplegia-epilepsy syndrome in the acute phase.