Seronegative Autoimmune Encephalomyelitis with Area Postrema Symptoms.

Area of Science:

• Neuroimmunology
• Neurology

Background:

• Encephalopathy and longitudinally extensive myelitis present diagnostic challenges.
• Area postrema symptoms like intractable hiccoughs can help differentiate diagnoses.
• Neuromyelitis optica spectrum disorders and GFAP autoimmune encephalitis are known causes, but some cases are seronegative.

Observation:

• A previously healthy man in his 70s experienced headache, fever, confusion, seizure, and persistent hiccoughs.
• MRI showed brainstem involvement and extensive transverse myelitis.
• Initial CSF analysis revealed inflammation, but tests for AQP4, MOG, and GFAP antibodies were negative.

Findings:

• The patient showed a weak positive for serum GFAP-IgG after treatment, but CSF remained negative.
• Immunotherapy improved his condition, though significant lower limb weakness persisted.
• This suggests a seronegative encephalomyelitis syndrome with area postrema involvement.

Implications:

• Tanycytes, specialized glial cells in the area postrema, are hypothesized as a potential immune target in GFAP encephalitis.
• This case suggests glial cells beyond astrocytes may be involved in autoimmune neuroinflammation.
• Further research is needed to investigate the role of tanycytes in autoimmune neuroinflammation.