Subacute herpes simplex encephalitis presenting as relapsing encephalitis

Subacute Herpes Simplex Type 1 Encephalitis: Case Report With Literature Review

INTRODUCTION

The typical herpes simplex viral encephalitis (HSVE) course is an acute illness, less commonly it may present as a chronic course, mainly in children, and rarely may it be subacute. Subacute HSVE is rarely described in the literature being reported 4 times only.

CASE REPORT

We here report 2 cases of subacute HSV1 encephalitis diagnosed based on cerebrospinal fluid polymerase chain reaction and magnetic resonance imaging findings and review the literature trying to find any specific clinical, laboratory, radiologic diagnostic or prognostic criteria regarding this subacute form of HSVE.

CONCLUSION

There is subacute form of HSVE and should be suspected with any subacute febrile illness with nonspecific cognitive impairment even in the absence of focal neurological symptoms and in cases with rapidly progressive dementia. This form has similar radiologic finding and good response to acyclovir but carry even better prognosis than that the acute HSVE.

[A case of herpes simplex virus encephalitis recurring after a seven-year interval]

In January 2008, a 59-year-old man with a history of diabetes mellitus was admitted to our hospital with herpes simplex virus (HSV) encephalitis of his right temporal lobe, which was diagnosed by PCR testing of his cerebrospinal fluid (CSF). He was treated with intravenous acyclovir for three weeks and made a full recovery. On discharge, his CSF was negative for HSV on PCR testing. Seven years later, in March 2015, the man was readmitted to our hospital with fever, disorientation, and nominal dysphasia. Diffusion-weighted MRI of his head revealed a high-intensity area in his left temporal lobe. Testing of his CSF revealed a moderately increased monocyte count and HSV on PCR testing, so he was diagnosed with recurrent HSV encephalitis. He was treated with intravenous acyclovir for three weeks. On discharge, his CSF was negative for HSV on PCR testing, but he had mild residual amnesia. There have been few reports of HSV encephalitis with viral reactivation recurring after a long remission period in adults. This case illustrates the need for prolonged follow up of individuals with HSV encephalitis in order to detect recurrences.

Clinical Neuropathology practice guide 4-2013: post-herpes simplex encephalitis: N-methyl-Daspartate receptor antibodies are part of the problem

Classic herpes simplex virus encephalitis (HSVE) is an acute viral infection that usually follows a monophasic disease course; however some patients, mainly children, experience a relapse within weeks or months after the initial event. In a subset of these patients a viral reactivation is unlikely because the CSF PCR for HSV is negative, repeated MRI does not show new necrotic lesions, and the symptoms are refractory to antiviral therapy. These patients often develop choreoathetosis variably accompanied by behavioral changes and seizures, and a postinfectious immune-mechanism has been postulated. Recent studies demonstrated that 7% of patients with HSVE harbor NR1 N-methyl-D-aspartate receptor (NMDAR) IgG antibodies. Moreover, a child with post-HSVE choreoathetosis was found to have NMDAR antibodies; the patient did not improve with antiviral therapy but recovered after aggressive immunotherapy. Based on these findings, evidence is increasing that a subgroup of post-HSVE represents a separate disease entity, which in fact is anti-NMDAR encephalitis. Patients with relapsing HSVE or prolonged atypical symptoms, who have negative CSF PCR for HSV should routinely be tested for NMDAR IgG antibodies in CSF and serum. It is important to be aware of this differential diagnosis because patients respond to immunotherapy.

The case for immunomodulatory approaches in treating HSV encephalitis

HSV encephalitis (HSE) is the most prevalent sporadic viral encephalitis. Although safe and effective antiviral therapies and greatly improved noninvasive diagnostic procedures have significantly improved outcomes, mortality (~20%) and debilitating neurological sequelae in survivors remain unacceptably high. An encouraging new development is that the focus is now shifting away from the virus exclusively, to include consideration of the host immune response to infection in the pathology underlying development of HSE. In this article, the authors discuss results from recent studies in experimental mouse models, as well as clinical reports that demonstrate a role for exaggerated host inflammatory responses in the brain in the development of HSE that is motivating researchers and clinicians to consider new therapeutic approaches for treating HSE. The authors also discuss results from a few studies that have shown that immunomodulatory drugs can be highly protective against HSE, which supports a role for deleterious host inflammatory responses in HSE. The impressive outcomes of some immunomodulatory approaches in mouse models of HSE emphasize the urgent need for clinical trials to rigorously evaluate combination antiviral and immunomodulatory therapy in comparison with standard antiviral therapy for treatment of HSE, and support for such an initiative is gaining momentum.

Relapsing herpes simplex encephalitis resulting in Kluver-Bucy syndrome

Relapsing herpes simplex encephalitis (HSE) rarely occurs after acyclovir treatment. We treated a patient with relapsing HSE of the contralateral temporal lobe, resulting in Klüver-Bucy syndrome, after a full-dose acyclovir treatment. This case suggests that physicians should consider sudden behavioral and emotional changes after HSE treatment as a possible indication of relapsing HSE, as well as possible temporal lobe epilepsy, and the need to administer longer acyclovir treatment for select patients.