Six-Year Follow-Up of Neurocognitive Effects in a Child After Seronegative Anti-NMDAR Encephalitis with Ovarian Teratoma
Overview of the Case
A recent case study highlights the long-term neurocognitive outcomes in a pediatric patient diagnosed with probable anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis, despite negative antibody tests. The patient, an 11-year-old girl, experienced sudden neuropsychiatric symptoms, seizures, and abnormal movements. A mature ovarian teratoma was identified and surgically removed, supporting the diagnosis of a paraneoplastic autoimmune encephalitis.
Diagnosis and Treatment
Although both serum and cerebrospinal fluid (CSF) antibody tests returned negative results, these samples were collected late in the disease course and after immunotherapy had started, which may have influenced the findings. The clinical presentation, EEG monitoring, and positive response to corticosteroids and intravenous immunoglobulin reinforced the diagnosis of probable anti-NMDAR encephalitis.
Neuropsychological Findings at Six Years
Six years following the acute illness, formal neuropsychological evaluations revealed that the patient retained largely intact verbal comprehension skills. However, deficits were noted in executive function, attention, processing speed, and verbal memory. Additionally, the patient met diagnostic criteria for autism spectrum disorder, and her overall cognitive ability was assessed within the low average range.
Implications for Understanding Anti-NMDAR Encephalitis
This case underscores several important points: first, autoimmune encephalitis can occur without detectable antibodies, particularly when testing is delayed. Second, the developing brain is vulnerable to lasting cognitive effects from immune-mediated, paraneoplastic insults. Finally, comprehensive neuropsychological assessments may be more sensitive than imaging in identifying persistent cognitive challenges after encephalitis.
Considerations for Families and Clinicians
Families and healthcare providers should be aware that children recovering from anti-NMDAR encephalitis may experience subtle but significant cognitive and behavioral changes years after the initial illness. Ongoing neuropsychological monitoring can help detect and address these challenges to support optimal development.
Limitations and Cautions
As a single case report, these findings cannot be generalized to all patients with anti-NMDAR encephalitis. The negative antibody results and the presence of autism spectrum disorder complicate interpretation, as preexisting neurodevelopmental vulnerabilities may also contribute to the cognitive profile. Further research is needed to clarify long-term outcomes in seronegative cases.
For more detailed information, see the original publication: Neurocognitive sequelae following seronegative anti-NMDA receptor encephalitis with ovarian teratoma in a pediatric patient: A six-year follow-up case report.
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