Marchiafava–Bignami disease mimicking acute corpus callosum infarction associated with chronic shochu consumption

Background: Marchiafava-Bignami disease (MBD) is a rare alcohol-related disorder that predominantly affects the corpus callosum. Because MBD frequently demonstrates diffusion restriction on magnetic resonance imaging (MRI), it can closely mimic acute ischemic stroke (AIS), posing a diagnostic challenge in image-driven acute stroke evaluation. Early recognition is crucial, as timely thiamine therapy may result in complete clinical and radiologic recovery. Case Description: A 38-year-old man with long-standing daily consumption of shochu, a Japanese distilled spirit, developed vertigo and vomiting on awakening, followed by mild right lower extremity weakness on day 5. MRI performed at a local clinic on day 6 revealed a diffusion-restricted lesion confined to the splenium of the corpus callosum, and corpus callosum infarction was initially suspected. On admission, the patient was fully conscious and exhibited horizontal gaze-evoked nystagmus with very mild right-sided weakness. MRI identified a splenial lesion of the corpus callosum exhibiting high signal intensity on diffusion-weighted imaging with corresponding low apparent diffusion coefficient values, accompanied by mild hyperintensity on T2-weighted and fluid-attenuated inversion recovery images. Given the patient's young age, absence of vascular risk factors, and the splenial distribution of the lesion, AIS was considered unlikely. Following consultation with a neurologist, MBD was suspected based on the patient's history of chronic alcohol consumption, and intravenous vitamin supplementation, including thiamine, was initiated. Neurological symptoms improved rapidly, and follow-up MRI on hospital day 8 demonstrated complete resolution of the splenial lesion. The patient was discharged without neurological sequelae on hospital day 10. Conclusion: A diffusion-restricted splenial lesion in patients with a history of chronic alcohol consumption and without vascular risk factors should prompt consideration of MBD rather than a reflexive diagnosis of AIS. Careful integration of imaging findings with clinical context is essential for identifying reversible stroke mimics and ensuring timely, appropriate treatment.