arthritisencephalitis

Arthritisencephalitis is a clinical syndrome involving concurrent inflammatory arthritis and encephalitis. The term is used in medical literature to describe patients who develop joint inflammation together with brain inflammation, often in the setting of autoimmunity, infection, or paraneoplastic processes. It is not a single disease but rather a descriptive syndrome identified in case reports and series.

Clinical features include arthritic symptoms—pain, swelling, warmth, and stiffness in joints—often symmetric; and neurologic symptoms such as confusion, altered consciousness, seizures, headaches, cognitive impairment, or focal neurologic deficits. Fever may be present.

Etiology is diverse. Autoimmune mechanisms are implicated, with antibodies targeting neural antigens or immune complexes, sometimes in the context of systemic autoimmune disease. Infections can trigger a post-infectious or parainfectious arthritis with CNS inflammation. Paraneoplastic mechanisms have been described in rare cases.

Diagnosis relies on integrated assessment. Neuroimaging (MRI) may show inflammatory changes; cerebrospinal fluid analysis often reveals pleocytosis and elevated protein; EEG may show abnormalities. Joint assessment and synovial fluid analysis, as well as comprehensive serologic testing for inflammatory arthritis and autoantibodies, help establish the diagnosis. Infections must be ruled out.

Treatment centers on immunomodulation and management of arthritis. First-line therapies include corticosteroids, intravenous immunoglobulin, or plasmapheresis. Refractory cases may require disease-modifying antirheumatic drugs or biologics. Treating an underlying trigger and supportive care, with multidisciplinary coordination, is common.

Prognosis varies. Early recognition and treatment improve outcomes, but relapses occur. The condition is rare, with most information derived from case reports and small series. Long-term follow-up is recommended to monitor CNS and joint symptoms and adjust therapy.