Adult-onset Still's disease presenting with generalized seizures in the absence of macrophage activation syndrome: a case report with review of the neurological literature

Abstract

Adult-onset Still’s disease (AOSD) is a rare systemic autoinflammatory disorder characterized by quotidian fever, arthritis, rash, and marked hyperferritinemia. Neurological manifestations are uncommon, and generalized seizures are exceptionally rare, particularly in the absence of macrophage activation syndrome (MAS). An 18-year-old man presented with one month of high-grade fever, migratory polyarthralgia, cervical and axillary lymphadenopathy, mild hepatosplenomegaly, and two generalized tonic-clonic seizures preceding diagnosis. Laboratory evaluation showed neutrophilic leukocytosis (21,300/mm³), elevated ESR and CRP, transaminitis, and serum ferritin >2,000 ng/mL. Electrolytes were normal. Blood and urine cultures, HIV testing, tuberculosis evaluation, echocardiography, thoracic CT, and lymph-node cytology were unremarkable. NCCT brain showed no structural lesion, and there was no clinical or laboratory evidence of MAS. After exclusion of infectious, autoimmune, and malignant causes, the patient fulfilled Yamaguchi criteria for AOSD. Treatment with prednisolone (1 mg/kg/day), methotrexate, and levetiracetam resulted in rapid resolution of fever and improvement in arthralgia. Generalized seizures may rarely be the presenting manifestation of AOSD even without MAS or demonstrable CNS pathology. In patients with unexplained seizures accompanied by persistent systemic inflammation and marked hyperferritinemia, AOSD should be considered after exclusion of infectious, autoimmune, and structural neurological causes; early immunosuppressive therapy is associated with favorable outcomes.