Background/Purpose: Although recognized only 10 years ago, anti-N-Methyl-D-Aspartate receptor encephalitis (anti-NMDAR encephalitis) has become a leading cause of encephalitis with an identifiable etiology in pediatric patients₁. The clinical presentation of patients with this disorder is quite variable but typically involves acute onset of symptoms with a characteristic progression including movement disorders, psychiatric symptoms, autonomic instability and seizures₂. Despite efforts to fully understand this disorder, there continue to be gaps in our knowledge.

Methods: This was a retrospective chart review of patients admitted to a mid-sized tertiary pediatric hospital for medical or rehabilitative services with a diagnosis of anti-NMDAR encephalitis over a 41 month period. Only patients with laboratory evidence of anti-NMDAR encephalitis between the ages of 24 months and 18 years were included in this study.

Results: 12 patients met our inclusion criteria ranging in age from 2 years to 17 years of age with a median age of 9. These patients represent 12.5% of the patients with a diagnosis of encephalitis at our hospital during this time frame. 58% were female. Multiple ethnicities and socioeconomic backgrounds were represented. All but one patient presented with sudden onset of unexplained behavioral change from baseline. Mean time to diagnosis was 17 days. Eleven out of twelve patients had a minimum of 3 of the 8 characteristic symptoms noted in 90% of patients₃. One patient died of overwhelming sepsis while immunosuppressed. Only one patient was found to have an associated tumor. 41% of patients required a PICU admission. All of the patients required inpatient rehabilitation. 75% of patients required gastrostomy tube placement. 25% of patients have returned to baseline and another 16% demonstrated functional gains by the most recent follow up. Many are still in the initial 12-24 months of recovery so their outcomes are still undetermined. 3 of the 12 patients in our study had pre-existing cognitive deficits or propensity for them; these patients were noted to all have incomplete recovery.

Conclusion: Though previously described, anti-NMDAR encephalitis may be more common than we recognize. In this study we present 12 cases of anti-NMDAR encephalitis treated at a single center pediatric tertiary care institution. We found no correlation of time to diagnosis with ethnicity or socioeconomic status. Our series corroborates the current literature with most patients presenting with acute unexplained behavioral change. Many patients required intensive care management. Their recovery is prolonged and almost invariably requires inpatient rehabilitation and often gastrostomy tubes. This suggests that management at a tertiary care center and early physical medicine and rehabilitation consultation is recommended. Recovery for these patients is mixed, and though our study is too small to reach statistical significance, we did note a trend in patients with pre-existing cognitive deficits or propensity for them who seem to have diminished recovery compared to patients with no prior history suggesting the need for further research in this area.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/anti-n-methyl-d-aspartate-receptor-encephalitis-expanding-our-understanding-of-the-clinical-needs-of-pediatric-patients-with-this-complex-disorder/