A 22-year-old woman is brought to the emergency department by her family with complaints of bizarre behavior, jerky, dance-like movements of her arms and legs, mood swings, and difficulty speaking over the past 10 days. Initially, she had flu-like symptoms, but her condition rapidly progressed to agitation, paranoia, and eventually periods of unresponsiveness.
On examination:
She is restless and occasionally non-verbal.
Exhibits orofacial dyskinesias and choreiform limb movements.
No signs of meningeal irritation.
Vitals are stable.
CSF analysis shows mild lymphocytic pleocytosis.
MRI brain is unremarkable.
EEG shows diffuse slowing.
Urine drug screen is negative.
What is your top differential diagnosis? What rare but increasingly recognized condition could explain this presentation in a young female? What would be the next steps in confirming the diagnosis and managing the patient?
Top diagnosis: anti-NMDA receptor encephalitis.
Rare autoimmune disorder causing psychiatric and movement symptoms.
Confirm with anti-NMDA receptor antibodies in CSF/serum; manage with immunotherapy and tumor screening (ovarian teratoma).
This young woman most likely has anti-NMDA receptor encephalitis, a rare autoimmune condition that affects the brain and is more common in young females. It often starts with flu-like symptoms, followed by behavior changes, movement problems, and speech issues. The diagnosis can be confirmed by testing her CSF for anti-NMDA receptor antibodies. Treatment includes steroids, IVIG, or plasmapheresis, and checking for an ovarian tumor (teratoma), which should be removed if found.