P3.G140: Pediatric Autoimmune Encephalitis: Navigating Limitations for Optimal Prognosis in Resource-Limited Settings

Introduction: Anti-NMDA receptor (anti-NMDAR) encephalitis is a rare autoimmune disorder with a prevalence of 0.8 cases per 100,000 individuals and a mortality rate of up to 15%. There is limited data about its prevalence in South America. Its diagnosis is challenging, requiring specific tests and a high clinical suspicion. Furthermore, its most common psychiatric clinical manifestations can be mistaken for normal adolescent behavior. Treatment can be difficult in low-income countries like Ecuador, as it requires multidisciplinary medical teams and access to special and expensive medications such as IVIG, monoclonal antibodies, cyclophosphamide as well as complex procedures like plasma exchange. We report a 15-year-old male with anti-NMDAR encephalitis, highlighting the importance of early recognition and prompt intervention addressing both the inflammatory aspect of the disease and the neuropsychiatric manifestations.

Case Description: A 15-year-old male presented to the ED after a generalized tonic-clonic seizure. Prior to admission, the patient reported orofacial dyskinesias, mood and sleep disturbances for four days. The patient presented with severely altered mental status, psychomotor agitation, and autonomic decompensation requiring management in ICU. A timeline representation of the clinical course and treatment is shown in Figure 1. The initial EEG showed a characteristic Delta-brush pattern (Image 1). The CSF analysis revealed pleocytosis, normal glucose and protein levels. Positive anti-NMDA antibodies in CSF and serum were reported after seven days. Prompt immunoregulatory therapy with methylprednisolone and intravenous immunoglobulin resulted in partial response. Subsequently, Rituximab was administered, yielding an excellent clinical response.

Discussion: The clinical presentation of Anti-NMDAR encephalitis encompasses several phases. Initially, there is a subacute prodromal phase characterized by non-specific symptoms such as fever, malaise and headache. This phase is followed by the emergence of neurological and psychiatric symptoms alongside autonomic dysfunction. Given the non-specific nature of these presentations, a high degree of clinical suspicion from pediatricians and primary care physicians is crucial, supported by tests with high specificity. In low-income countries, accessing the exact treatment recommended by current guidelines remains a challenge. For instance, first-line interventions typically involve corticosteroids, IV immunoglobulins, or plasmapheresis, with the latter being unavailable at the hospital where this patient was treated. Additionally, second-line therapy often requires rituximab and cyclophosphamide, with limited access to rituximab in Ecuador and other low- and middle-income countries. However, timely identification of symptoms enables the prompt initiation of targeted therapies, which can mitigate the impact on cognitive functions and prevent potential long-term sequelae. In this case, the patient achieved full recovery within three months.

Conclusion: This case underscores the significance of early recognition and intervention in the management of anti-NMDAR encephalitis. Despite challenges in accessing specific treatment options, favorable outcomes are attainable, especially with prompt diagnosis. Timely intervention reduces the risk of potential long-term neurological sequelae and improves overall prognosis.