Seizures in pediatric emergency and autoimmune encephalitis, an essential and challenging differential diagnosis: a case report

Case presentation: Three-years-old male attended with a generalized tonic-clonic seizure. No history of traumatic brain injury, fever or associated flu-like symptoms. Days before, aggressive behavior, slurred speech, visual hallucination. Only one previous tonic-clonic seizure, one month ago, without status epilepticus. Electroencephalogram (EEG): brush pattern extreme delta, cerebrospinal fluid (CSF) with IgG+ for herpes and normal brain magnetic resonance. This condition corroborates the diagnosis of autoimmune encephalitis, and pulse therapy was instituted empirically. He also required anticonvulsant drugs with improvement in epileptic seizures and wakefulness. However, also developed significant psychosis, agitation, extrapyramidal syndrome with dystonia and involuntary movement, and also required antipsychotic drugs. Diagnosis was confirmed with positive CSF for anti-N-methyl-D-aspartate receptor (anti-NMDAR). He remained hospitalized for 97 days, being discharged with hypotonia limited to bed, severe encephalitic condition and gastrostomy. Received eight pulse therapy cycles with complete improvement of neurological condition.

Discussion: Autoimmune encephalitis is characterized by antibodies production against neurons' surface and synaptic molecules. Herpes simplex-1 virus encephalitis seems to trigger anti-NMDAR as in this case. It is possibly underdiagnosed in developing countries in Latin America due to delay and scarcity of diagnostic methods. Manifestations include behavioral or psychiatric changes, dysautonomia and epilepsy. In this case, it's noted that neuropsychiatric encephalitic disorder was neglected by the family and initially by health professionals as well. EEG often changes and extreme delta brush pattern described in anti-NMDAR encephalitis supports this diagnosis. Pathogenic anti-NMDAR autoantibodies may be present in serum and CSF, the latter being chosen in this case for greater sensitivity. First-line therapy is performed with high doses of corticosteroids. Plasmapheresis and rituximab may be considered. Prognosis is usually good when therapy is instituted early.

Final comments: Recognizing autoimmune encephalitis is often difficult and late, although disorders can be severe and highly responsive to immunomodulatory therapies. Therefore, it's necessary to implement pulse therapy empirically, as soon as there is a diagnostic suspicion, both because it allows maximizing full recovery chances and diagnostic tests are generally time consuming little available.

 

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No conflict of interest has been declared by the author(s).

Publication History

Article published online:
18 September 2023