Conclusions: In summary, we present a new in vitro model to study the renal pathology of methylmalonic aciduria. Introduction: Stroke like episodes are a feature of inherited metabolic disorders, including propionic acidemia (PA) (1) . So far, it was unclear, whether these episodes are caused by cytotoxic or vasogenic edema (2) . Patient: At one week, PA was diagnosed in parallel through appearing symptoms and positive newborn screening. The boy is treated with a protein restricted diet, l-carnitine, ß-blockers and diuretics. At 4 years he had a prolonged gastroenteritis. Two weeks later he showed noticeable behavioural changes with regression, especially in speech, confusion and abnormal reaction to people and objects well known to him. EEG showed bilateral diffuse slowing of background activity with right-sided accentuation, and with sharp wave foci bilaterally over the temporo-occipital regions. Evaluation of T2-weighted images, T2 relaxation maps, diffusionweighted imaging (ADC maps) and T2-shine-through indicated the presence of cytotoxic edema in putamen and the cerebellum. After general anesthesia for imaging, EEG changes resolved. He recovered within some days.