Anti-NMDA receptor encephalitis
Anti-NMDA receptor encephalitis is a type of brain inflammation caused by antibodies. Early symptoms may include fever, headache, and feeling tired. This is then typically followed by psychosis which presents with false beliefs (delusions) and seeing or hearing things that others do not see or hear (hallucinations). People are also often agitated or confused. Over time, seizures, decreased breathing, and blood pressure and heart rate variability typically occur. In some cases, patients may develop catatonia.
| Anti-NMDA receptor encephalitis | |
|---|---|
| Other names | NMDA receptor antibody encephalitis, anti-N-methyl-D-aspartate receptor encephalitis, anti-NMDAR encephalitis |
| A schematic diagram of the NMDA receptor | |
| Specialty | Neurology |
| Symptoms | Early: Fever, headache, feeling tired, psychosis, agitated Later: Seizures, decreased breathing, blood pressure and heart rate variability |
| Complications | Long term mental or behavioral problems |
| Usual onset | Over days to weeks |
| Risk factors | Ovarian teratoma, unknown |
| Diagnostic method | Specific antibodies in the cerebrospinal fluid |
| Differential diagnosis | Viral encephalitis, acute psychosis, neuroleptic malignant syndrome |
| Treatment | Immunosuppresive medication, surgery |
| Medication | Corticosteroids, intravenous immunoglobulin (IVIG), plasma exchange, azathioprine |
| Prognosis | Typically good (with treatment) |
| Frequency | Rare |
| Deaths | ~4% risk of death |
About half of cases are associated with tumors, most commonly teratomas of the ovaries. Another established trigger is herpesviral encephalitis, while the cause in others cases is unclear. The underlying mechanism is autoimmune, with the primary target being the GluN1 subunit of the N-methyl D-aspartate receptors (NMDAR) in the brain. Diagnosis is typically based on finding specific antibodies in the cerebral spinal fluid. MRI of the brain is often normal. Misdiagnosis is common.
Treatment is typically with immunosuppresive medication and, if a tumor is present, surgery to remove it. With treatment, about 80% of cases have a good outcome. Outcomes are better if treatment is begun earlier. Long-term mental or behavioral problems may remain. About 4% of those affected die from the condition. Recurrence occurs in about 10% of people.
The estimated number of cases of the disease is one in 1.5 million people per year. The condition is relatively common compared to other paraneoplastic disorders. About 80% of those affected are female. It typically occurs in adults younger than 45 years old, but it can occur at any age. The disease was first described by Josep Dalmau in 2007.