A comparison of clinical findings, neuroimaging, and outcomes in immunocompromised versus immunocompetent patients with HSE suggests important differences.

Herpes simplex encephalitis (HSE) is a very serious disease with an incidence of 1 in 250,000 to 1 in 500,000. With the introduction of new and more potent immunosuppressive therapies, HSE is seen more often with an atypical presentation. In this retrospective case-control review of adult patients with HSE diagnoses, researchers compared features and outcomes in 14 patients who were immunocompromised and 15 who were immunocompetent.

Clinical features, magnetic resonance imaging (MRI), and cerebrospinal fluid (CSF) findings were different in the two groups. Fewer immunocompromised patients had prodromal symptoms (29% vs. 80%) and focal deficits (about 28% vs. 73%). Mean time between symptom onset and presentation to the hospital was shorter in the immunocompromised group (3.4 vs. 4.9 days). Whereas all immunocompetent patients had mononuclear cells in the CSF and one had no CSF pleocytosis, three immunocompromised patients had polymorphonuclear predominance and another three had normal profiles. Whereas all immunocompetent patients had MRI abnormalities in the temporal lobe, immunocompromised patients tended to have more diffuse cortical involvement, with cerebellar and brainstem compromise in some. Two of the immunocompromised patients and none of the immunocompetent patients had recurrent HSE, and 5 of the 14 immunocompromised patients died, versus 1 of the 15 immunocompetent patients. Similar numbers of patients in each group completed a 21-day treatment with acyclovir (30 mg/kg/day). Five immunocompetent patients completed a 14-day course.

Comment: Although this study is limited by its retrospective nature and its size, this is the largest published series on HSE in immunocompromised patients and the first to compare the presentation in immunocompromised and immunocompetent states. The findings should raise awareness of the potential increased risk, atypical presentations, and worse outcomes among immunocompromised patients. Early recognition of the disease is critical, because delay in treatment may be associated with severe morbidity and mortality. Early diagnosis and administration of acyclovir is associated with a better outcome.

Source: Journal Watch Neurology