The clinical and radiographic features of eastern equine encephalitis: A single-center retrospective case series.

Rationale: This case series aims to describe the clinical and radiographic findings associated with eastern equine encephalitis (EEE) virus.

Patient Concerns: Patients in this series presented with a variety of neurological symptoms, including altered mental status, seizures, and focal neurological deficits. Common initial concerns included confusion, hemiparesis, fever, and flu-like symptoms. In all cases, the progression of neurological symptoms prompted urgent medical evaluation and hospitalization.

Diagnoses: Diagnosis of EEE was confirmed in all 4 patients by detection of EEE-specific IgM antibodies in cerebrospinal fluid. Cerebrospinal fluid studies also showed elevated protein, red blood cells, normal or high glucose, and elevated white blood cells with lymphocytic or neutrophil predominance. Magnetic resonance imaging showed T2 hyperintensities in the basal ganglia, thalamus, and cortical regions. Two cases showed encapsulation as evidence by a hyperintense ring around the basal ganglia or thalamus. Electroencephalogram findings ranged from normal, focal irritability, and spikes to nonconvulsive status epilepticus. Clinical and/or electrographic evidence of seizure was seen in all 4 cases.

Interventions: All patients received supportive care, including anticonvulsant therapy, often using levetiracetam. Two patients were treated with high-dose intravenous methylprednisolone and one with intravenous immunoglobulin (IVIG) to modulate the immune response. Empiric antibiotics and antivirals were initiated in most cases until the diagnosis of EEE was confirmed. Two patients required intubation and mechanical ventilation, one of which was due to seizure activity and nonconvulsive status epilepticus.

Outcomes: We report a 1/4 (25%) mortality rate. The average hospital stay among survivors was 10 days. Two-fourth (50%) required intubation and mechanical ventilation. Two patients were discharged to rehabilitation facilities, one patient recovered fully with resolution of magnetic resonance imaging abnormalities at follow-up, and one patient experienced a fatal outcome after the family opted to withdraw care due to a poor prognosis.

Lessons: This case series underscores the importance of maintaining a high clinical suspicion of EEE in patients with acute neurological symptoms, especially in endemic areas. Early diagnosis and treatment are crucial, but the variability in presentation and imaging findings complicates this process. Early use of high-dose steroids can improve outcomes.