Crossed cerebellar diaschisis in a COVID-19 patient with hemiconvulsion-hemiplegia syndrome: a case report and literature review

Crossed cerebellar diaschisis (CCD) is rare in patients with hemiconvulsion-hemiplegia syndrome (HHS). This report presents a novel and instructive case of CCD combined with HHS in a 7-month-old infant with coronavirus disease 2019 (COVID-19) and multisystem inflammatory syndrome in children (MIS-C). A previously healthy 7-month-old male infant presented with high-grade fever, frequent left-sided seizures, and subsequent left-sided paralysis. Diagnosed with COVID-19 and MIS-C, he exhibited critical hyperinflammation and multi-organ dysfunction. Brain magnetic resonance imaging (MRI) was pivotal, revealing unilateral cytotoxic edema in the right cerebral hemisphere and restricted diffusion in the contralateral cerebellum, confirming the diagnoses of HHS and CCD. Despite management with anticonvulsants and immunomodulation, his condition deteriorated rapidly, leading to death within 45 h. The pathophysiology is proposed to center on the MIS-C-triggered cytokine storm, which likely creates a substrate for excitotoxic injury and diaschisis. This case represents, to our knowledge, the first documented fatal instance of CCD associated with HHS in a pediatric patient with acute COVID-19 and MIS-C. It underscores the potential for severe neurological complications in this population and broadens the recognized spectrum of neurovascular injuries linked to COVID-19. The early detection of CCD in such settings may serve as a critical radiological marker for a high-risk disease course.