Ketogenic Diet-Mediated Immunomodulation for Prevention of Epilepsia Partialis Continua in Rasmussen's Encephalitis: Review and Case Study.

Introduction: Rasmussen's encephalitis (RE) is a rare immune-mediated neurological disorder characterized by refractory focal epilepsy, progressive neurological deficits, and unilateral cerebral atrophy. Although typically a pediatric disease, adult-onset cases account for fewer than 10% of reported diagnoses and remain poorly characterized. Early recognition and prompt immunotherapy are critical to limit irreversible neurological damage. Case Presentation: We report the case of a 46-year-old woman with adult-onset RE presenting with focal non-motor seizures and progressive cognitive impairment. Neuroimaging demonstrated progressive left hemispheric atrophy with hippocampal and mammillary involvement, while continuous electroencephalographic monitoring revealed persistent left frontotemporal epileptogenic activity. Cerebrospinal fluid analysis showed intrathecal antibody synthesis. Immunotherapy with oral tacrolimus was initiated, resulting in stabilization of cognitive decline and reduction of seizure frequency from approximately 30-40 to 15-20 episodes per day. Due to persistent seizures and intolerance to multiple antiseizure medications (ASMs), a classical ketogenic diet was introduced as adjunctive therapy, leading to an additional reduction in seizure frequency of approximately 50% 6 months after initiation, and subjective stabilization of cognitive symptoms despite minimal change in screening scores. Seizure control and clinical state have remained stable up to current follow-up, almost 5 years after combined treatment initiation. Conclusion: This case highlights the potential therapeutic benefit of combining immunomodulatory therapy with ketogenic dietary intervention in adult-onset RE. Beyond its established role in refractory epilepsy, ketogenic therapy may exert anti-inflammatory and neurometabolic effects through modulation of microglial activation, cytokine signaling, and cellular metabolism pathways implicated in RE pathogenesis. The combination of tacrolimus and a ketogenic diet was associated with substantial seizure reduction and stabilization of cognitive impairment in this patient with adult-onset RE. These findings suggest that ketogenic dietary therapy may represent a promising adjunctive therapeutic strategy alongside immunomodulatory treatment in this rare and challenging condition. Further studies are needed to clarify its role in disease progression and seizure control.