Encephalitis associated with anti-mGluR5 antibodies

Area of Science:

• Neurology
• Immunology
• Oncology

Background:

• Autoimmune encephalitis presents with diverse neurological symptoms.
• Anti-metabotropic glutamate receptor 5 (mGluR5) encephalitis is a rare neurological disorder.
• Ophelia syndrome is a previously described presentation of anti-mGluR5 encephalitis.

Purpose of the Study:

• To describe a case of anti-mGluR5 encephalitis with an atypical presentation.
• To emphasize the diagnostic challenges and the importance of specific antibody testing.
• To highlight the association between autoimmune encephalitis and underlying malignancies.

Main Methods:

• Clinical case presentation of a 30-year-old woman with neurological symptoms.
• Cerebrospinal fluid (CSF) and serum analysis, including cell counts, protein, and glucose levels.
• Magnetic Resonance (MR) imaging of the brain.
• Immunological assays: commercial cell-based assays (CBAs), tissue-based assays, and specific CBAs for anti-mGluR5 antibodies.

Main Results:

• The patient exhibited visual hallucinations, nystagmus, memory impairment, and mutism.
• CSF analysis revealed pleocytosis and altered glucose levels.
• Brain MR imaging showed limbic, extra-limbic, and brainstem involvement.
• Tissue-based assays showed neuropil staining, and serum and CSF CBAs for anti-mGluR5 antibodies were positive.
• The patient was later diagnosed with Hodgkin's lymphoma.

Conclusions:

• Anti-mGluR5 encephalitis has a broader clinical spectrum than previously characterized.
• Commercial cell-based assays may be insufficient for diagnosing rare autoimmune encephalitis.
• Tissue-based assays followed by serum and CSF antibody testing are crucial for accurate diagnosis.
• Autoimmune encephalitis can be paraneoplastic, associated with underlying cancers like Hodgkin's lymphoma.