Herpes simplex encephalitis: A new type of "ICU-acquired infection"?

Abstract

Purpose: Although it is a well-known disease, the occurrence of Herpes simplex encephalitis (HSE) during a hospital stay may render the diagnosis particularly challenging. The objective of this report is to alert clinicians about the diagnostic pitfalls arising from hospital-developed HSE.

Materials and methods: Clinical observation of one patient.

Case report: An 87-year-old male was admitted to the Intensive Care Unit (ICU) because of respiratory failure due to an exacerbation of myasthenia gravis. After corticoids and azathioprine treatment, his clinical condition improved, allowing weaning from mechanical ventilation. One month after admission, while still hospitalized in the ICU, the patient developed fever and confusion. In the context of confounding factors, HSE was not suspected before a convulsive status epilepticus occurred, resulting in a significant delay in treatment. Diagnosis was confirmed by PCR-analysis in the cerebrospinal fluid. Serological status confirmed reactivation of prior herpes simplex infection. The patient died one week after the onset of confusion.

Conclusions: Hospital-"acquired" HSE must be suspected in case of new neurologic symptoms associated with fever, even in ICU-hospitalized patients. The diagnosis is made even more difficult by nonspecific symptoms due to previous diseases, leading to an even more severe prognosis in those vulnerable patients.

Keywords: Electrophysiology; Herpes simplex Encephalitis; Herpes simplex reactivation; ICU acquired Infection; Immunosuppression; Infectious disease; Intensive care; Intensive care medicine; Neurology; Neurosurgery.

Figure 1

EEG recordings of epileptic and periodic discharges. 1A. September 20th at 6.30 a.m.: Status epilepticus: Continuous rhythmic spike-wave activity prevailing on the right hemisphere with left hemispheric propagation and a minor attenuation by propofol. 1B. September 20th at 10 p.m.: Within 16h, substantial changes were visible on EEG, which now showed unreactive right paroxysmal fronto-central spikes waves of short periodicity and left fronto-temporal monomorphic periodic delta activity in favor of HSE. Midazolam had no effect on the periodic pattern. 1C. September 21st: Slow monomorphic bi-hemispheric periodic subdelta complexes, unreactive to external stimuli, indicating very advanced stages of HSE.

Figure 2

MRI (September 20th at 9 p.m.). High signal intensity lesions in Diffusion (A,B,C) and in T2 fluid-attenuated inversion recovery (FLAIR) (D) sequences in the bilateral temporal, frontal lobes and cingular gyri.