A 36-year-old female with no clear past medical history other than possible mood disorder presented after three days of decreased level of consciousness. Associated symptoms included body aches, fever, chills, nausea, vomiting, and headaches. The patient had been suffering from flu-like symptoms two weeks prior to presentation and was treated with antibiotics. The patient became progressively confused with accompanying visual hallucinations, memory deficits, and episodes of exuberance alternating with episodes of agitation. The patient’s mother reported a family history of bipolar disorder, though the patient had never exhibited such symptoms in the past.
Upon presentation, the patient’s vital signs were stable other than elevated blood pressure. She appeared agitated with a labile mood. She did not have nuchal rigidity or meningeal signs. CBC, CMP, urine toxicology, and urinalysis were unremarkable. Lumbar puncture was performed. The CSF was clear and colorless with the following values: WBC 92/μL (99% lymphocytes and 0% neutrophils), RBC 0/μL, glucose 49 mg/dL, and protein 61 mg/dL.
The patient’s CSF was negative for West Nile virus, herpes simplex virus, and enterovirus by PCRs, and cryptococcal antigen. However, the fluid was positive for NMDA receptor IgG. She was diagnosed with anti-NMDAR (N-methyl-D-aspartate receptor) encephalitis and was treated with IV methylprednisolone and plasmapheresis resulting in improvement of her mental status and functional capacity prior to discharge to a rehabilitation facility.
Discussion:
Anti-NMDA receptor encephalitis is a potentially fatal but treatable form of non-infectious encephalitis. It is caused by autoantibodies targeted against the NR1 subunit on the NMDA receptors in the brain. Patients typically present with viral-like symptoms, followed by psychiatric manifestations and finally neurologic decline. The affected patient population is typically composed of young females, however cases are also seen in young children and men. Anti-NMDA encephalitis is commonly associated with teratomas and therefore may also be considered a paraneoplastic syndrome. Diagnosis is made by identification of NMDA receptor antibodies in serum or CSF. Prompt initiation of immunotherapy (steroids and IVIG or plasma exchange) and tumor removal (if applicable) is the cornerstone of therapy. Patients require close monitoring and coordination between multiple specialties in the hospital for favorable outcomes and prevention of long-term neurological sequelae.
Conclusions:
Anti-NMDA receptor encephalitis is an under-diagnosed autoimmune disorder characterized by a constellation of neurologic and psychiatric symptoms. Hospitalists should consider anti-NMDA receptor encephalitis in patients with psychiatric manifestations coupled with symptoms of encephalitis. Prompt recognition and treatment of this disease can result in a dramatic recovery for affected patients.