Meningoencephalitis due to Spotted Fever Rickettsioses, Including Rocky Mountain Spotted Fever.

Background: The spotted fever rickettsioses (SFR), including Rocky Mountain spotted fever, are tick-borne infections with frequent neurologic involvement. High morbidity and mortality make early recognition and empiric treatment critical. Most literature on SFR meningoencephalitis predates widespread magnetic resonance imaging (MRI) utilization. To better understand the contemporary presentation and outcomes of this disease, we analyzed clinical and radiographic features of patients with SFR meningoencephalitis.

Methods: Patients were identified through hospital laboratory-based surveillance or through the Tennessee Unexplained Encephalitis Study. Cases meeting inclusion criteria underwent medical records review and, when available, independent review of the neuroimaging.

Results: Nineteen cases (11 children, 8 adults) met criteria for SFR meningoencephalitis. Rash was significantly more common in children than adults (100% vs 50%, respectively), but other clinical features were similar between the 2 groups. Cerebrospinal fluid pleocytosis and protein elevation were each seen in 87.5% of cases, and hypoglycorrhachia was present in 18.8% of cases. The "starry sky" sign (multifocal, punctate diffusion restricting or T2 hyperintense lesions) was seen on MRI in all children, but no adults. Ninety percent of patients required intensive care unit admission and 39% were intubated. Outcomes were similar between adults and children, with only 46% making a complete recovery by the time of discharge.

Conclusions: SFR meningoencephalitis is a life-threatening infection. The clinical presentation varies between adults and children based on the presence of rash and brain MRI findings. The starry sky sign was ubiquitous in children and should prompt consideration of empiric treatment for SFR when present.