Steroid-Responsive Parkinsonism and Encephalopathy: A Case Report

Area of Science:

• Neurology
• Immunology

Background:

• Autoimmune encephalitis (AE) is a group of immune-mediated disorders affecting the central nervous system.
• While typically presenting with seizures and cognitive decline, AE can manifest with diverse neurological symptoms.

Observation:

• A 71-year-old man developed rapidly progressive parkinsonism and encephalopathy with flu-like symptoms.
• Cerebrospinal fluid (CSF) showed lymphocytic pleocytosis and elevated protein, but neural antibody and infectious workups were negative.
• Brain MRI was initially unremarkable.

Findings:

• The patient's parkinsonism and encephalopathy significantly improved with prednisone treatment and relapsed upon tapering.
• CSF abnormalities also resolved with prednisone, indicating an autoimmune process.
• This case demonstrates subacute parkinsonism as an uncommon presentation of seronegative autoimmune encephalitis.

Implications:

• Physicians should consider autoimmune encephalitis in patients with acute or subacute parkinsonism, even with negative antibody tests.
• This case underscores the expanding spectrum of autoimmune neurology and the importance of considering seronegative AE.
• Early recognition and treatment with immunotherapy can lead to significant clinical improvement in these rare AE presentations.