Research articleRepeated misdiagnosis of a relapsed atypical anti-NMDA receptor encephalitis without an associated ovarian teratoma

- The differential diagnosis of anti-NMDAR encephalitis is broad and difficult.
- Repeated misdiagnosis can lead to serious sequelae.
- Non-organ specific antibodies may be byproducts of the autoimmune reaction in anti-NMDAR encephalitis.
- Mitochondrial encephalomyopathy should be highlighted as a differential diagnosis of anti-NMDAR encephalitis.

We present an atypical case of relapsed anti-NMDAR encephalitis in a young female patient without an associated ovarian teratoma. She presented with recurrent seizure attacks with muscle weakness, psychosis, dyskinesia, autonomic failure and insomnia. She was first misdiagnosed as mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS) then Hashimoto's encephalopathy due to diffuse cerebral lesions, elevated serum lactic acid concentration, increased amount of thyroid peroxidase and thyroglobulin antibodies in serum and diffuse lesions of the thyroid gland. Her final diagnosis was delayed for 6 months with the detection of anti-NMDAR antibodies in her CSF. After treatment, she had poor recovery with serious sequelae at 10-month follow-up. Noteworthy, MELAS should be highlighted as a differential diagnosis of anti-NMDAR encephalitis.