Herpes simplex encephalitis

Excerpt The development of methods for cultivation of viruses and of improved antigens makes possible improved etiologic identification in some of the encephalitides. It is increasingly recognized ...


Epidemiology
Estimated incidence of HSE: 1 in 750,000 to 1 million persons/yr. Equally distributed between males and females, in all races, in all ages (over 33%of cases occur in children 6 mos to 18 yrs), throughout the year 1) .

Presentation
Patients are often confused and disoriented at onset, and progress to coma within days.

Diagnosis
Herpes simplex encephalitis diagnosis.
Brain biopsy see Brain biopsy for Herpes simplex encephalitis.

Differential diagnosis
There are a few cases reported in the literature in which a diagnostic dilemma between was raised between herpes simplex encephalitis and brain glioma, and a definitive diagnosis was difficult to be obtained When confronted with confounding data that can pose a diagnostic dilemma between HSV encephalitis and glioma, brain biopsy and PCR of CSF samples could be able to verify the definite diagnosis 2) .

Complications
Intracerebral hemorrhage and ischemic stroke are increasingly recognized complications of central nervous system (CNS) infection by herpes simplex virus (HSV).
Hauer et al. found distinct pathogenesis, cause, and outcome for HSV-related cerebral hemorrhage and infarction. Vessel disruption within a temporal lobe lesion caused by HSV-1 is the presumed mechanism for hemorrhage, which may potentially have a fatal outcome. Brain ischemia is mostly related to multifocal cerebral large vessel vasculitis associated with HSV-2, where the outcome is more favorable 3) .

Treatment
Herpes simplex encephalitis treatment

Case series
Basaran et al. aimed to explore distinctive clinical and laboratory features of HSV-1 encephalitis. All of the adult patients with viral encephalitis hospitalized between 2011-2017 were enrolled, including 16 patients with HSV-1 encephalitis and 51 patients non-HSV-1 viral encephalitis. The determination of viruses in cerebrospinal fluid was performed by PCR tests. Female sex, hyponatremia, and abnormalities in MRI were independently associated with HSV-1 encephalitis (p < 0.05 for each). In particular, hyponatremia (< 135 mEq/L) was found in nine patients with HSV-1 encephalitis (56.3%) and 10 patients with non-HSV-1 viral encephalitis (19.6%) (p = 0.005). As serum sodium is determined easily and quickly in clinical practice, the presence of hyponatremia among patients with viral encephalitis could be helpful for the early diagnosis of HSV-1 encephalitis before cerebrospinal fluid PCR results were available. Moreover, the presence of positive findings in MRI could further support the diagnosis. This is the first study that compared the serum sodium levels among patients between HSV-1 and non-HSV-1 viral encephalitis. We thus propose the diagnostic value of hyponatremia for HSV-1 encephalitis 4) .

Case reports
McLaughlin et al. presented the 40th known case of herpes simplex virus (HSV) encephalitis following the neurosurgical intervention and review the previously reported cases. In their review, the authors observed positive HSV polymerase chain reaction (PCR), which had initially been negative in several cases. In cases in which there is a high suspicion of HSV, it may be prudent to continue antiviral therapy and retest CSF for HSV PCR. Antiviral therapy significantly reduces mortality associated with HSV encephalitis 5) .
A case of a 78-year-old woman with no known prior history of HSVE and declining mental status eleven days after posterior C3-T1 decompression and instrumented fusion following resection of an intradural extramedullary tumor confirmed to be meningioma on final pathology. Reactivation of HSV-1 encephalitis was suspected to be the underlying cause of her symptoms, though MRI scans of the brain for HSVE were negative. The patient reacted positively to a 21-day treatment of acyclovir and was discharged with a neurological status comparable to her preoperative baseline. This case contributes to the literature in that it is the first reported instance of HSVE reactivation after intradural cervical spinal surgery with negative MRI findings.
Heller et al. recommended utilizing multiple tests, including PCR, EEG, and MRI, for postoperative neurosurgery patients that have decreased mental status in order to quickly and correctly diagnose/treat patients who are HSVE positive. Clinicians should consider the possibility of receiving false-negative results from PCR, CSF, EEG, or MRI tests before terminating treatment for HSVE reactivation 6) . 2020/07/04 16:34 Herpes simplex encephalitis Operative Neurosurgery -https://operativeneurosurgery.com/ A 74-year-old man with a history of herpes simplex encephalitis suffered recurrent seizures. Brain magnetic resonance imaging revealed a mass lesion and resection was performed. A polymerase chain reaction using a brain biopsy specimen was positive for HSV DNA; thus, the patient was diagnosed with HSV-associated granulomatous encephalitis. After administering acyclovir, the patient showed improvement. HSV can cause granulomatous encephalitis in adults, and acyclovir can be used for its treatment 7) .