Herpes Simplex Type 2 Encephalitis After Craniotomy: Case Report and Literature Review

Unexplained Progressive Neurological Deficits after Corpus Callosotomy May Be Caused by Autoimmune Encephalitis: A Case of Suspected Postoperative Anti-NMDAR Encephalitis

The main causes of anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis are ovarian teratoma and herpes simplex virus (HSV) encephalitis. We present a rare case of suspected anti-NMDAR encephalitis caused by corpus callosotomy (CC). An 18-year-old woman with Lennox-Gastaut syndrome underwent CC. Although left hemiplegic due to cerebral hemorrhage and impaired consciousness due to cerebral venous sinus thrombosis (CVST) appeared postoperatively, anticoagulant therapy quickly improved CVST and impaired consciousness. However, various unexplained symptoms such as insomnia, hallucination, impulsivity, impaired consciousness, and a new type of drug-resistant cluster seizures gradually developed over a 2-month period. Magnetic resonance imaging revealed the gradual extension of a hyperintense area from the right frontal lobe on fluid-attenuated inversion recovery images. Intravenous methylprednisolone pulse was initiated from postoperative day (POD) 74, followed by intravenous immunoglobulin (IVIg) therapy, although white blood cell counts were normal in all three cerebrospinal fluid (CSF) examinations. After IVIg therapy, the above unexplained symptoms promptly improved. On POD 103, antibodies against NMDAR were revealed in both the serum and CSF collected before these immunotherapies. The patient was transferred to a rehabilitation hospital due to residual left hemiplegia. Psychiatric symptoms and a new onset of drug-resistant seizures may be suggestive of postoperative anti-NMDAR encephalitis, even if CSF findings are mild.

[Reactivation of latent viruses in Neurology]

After establishing latent infection, some viruses can be reactivated by the alteration of host immunological conditions. First, we reviewed viruses that can cause neuronal damage by reactivation. Then we focused on the herpes simplex virus (HSV). The reactivation leads to neuronal damages through two possible mechanisms; "reactivation of a latent herpes virus" by which viruses can cause direct virus neurotoxicity, and "post-infectious immune inflammatory response" by which a focal reactivation of HSV leads to an inflammatory reaction. The former is radiologically characterized by cortical lesions, the latter is characterized by subcortical white matter lesions. We experienced a female, who underwent the right posterior quadrantectomy and then developed recurrent herpes encephalitis caused by herpes simplex reactivation, which pathologically demonstrated inflammation in the white matter, suggesting a post-infectious immune inflammatory response. The patient was successfully treated with immunosuppressants. The reactivation of the HSV is extremely rare in Japan. Neurologists should recognize this condition because this disorder will increase as epilepsy surgery gains more popularity.

Herpes simplex reactivation following neurosurgery: case report and review of the literature

Herpes simplex encephalitis is a common viral encephalitis associated with significant morbidity and mortality if not diagnosed and treated early. Neurosurgery may be an impetus for viral reactivation, either from direct nerve manipulation or high-dose steroids often administered during cases. The authors present the 40th known case of herpes simplex virus (HSV) encephalitis following 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 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.

Outcomes with acyclovir treatment in herpes simplex encephalitis after surgery for solid CNS tumors: a case report and systematic review of the literature

Background

Herpes simplex encephalitis (HSE) occurring within 30 days after neurosurgery for solid CNS tumors is underrecognized and underreported but remains important because of high morbidity and mortality. We present the case of a 41-year-old woman who had HSE after craniopharyngioma surgery, and delayed recognition and treatment led to a poor outcome. Subsequently, we review reported HSE cases after neurosurgery for solid CNS tumors and describe outcomes after treatment with and without acyclovir.

Methods

A literature search was performed for cases meeting the above criteria. Information was gathered regarding patient demographics, tumor types, symptoms, diagnostic workup, therapy, and outcomes.

Results

Eighteen cases were studied. Encephalopathy, fever, and seizures were the most common symptoms. A majority of patients (78%) received IV acyclovir, with a 79% survival rate with treatment. Mortality rate was 100% in untreated cases. The median time to starting acyclovir was 17 postoperative days (range, 8-53 days). Most patients received steroids, but its use was not associated with a specific outcome.

Conclusions

HSE may develop following neurosurgical resection, and the threshold for suspicion of this condition should be extremely low in a patient who shows compatible symptoms (encephalopathy, fever, or seizures) or does not recover as planned. Moreover, in case of suspicion of HSE, acyclovir should be promptly started until infection can be definitely ruled out. A delay in diagnosis of HSE and failure to treat may result in severe morbidity as well as mortality. This observation may warrant further study.

Herpes Simplex Encephalitis: an Update

PURPOSE OF REVIEW

The goal of this review is to provide an update on current thinking regarding herpes simplex encephalitis (HSE), emphasizing new information about pathogenesis, diagnosis, and immune responses. Specific questions to be addressed are the following: (1) Is there a genetic predisposition to HSE? (2) What clinical approaches have the greatest impact on improving the long-term outcomes in patients with HSE? And (3) are there immune-mediated mechanisms that may account for relapsing HSE?

RECENT FINDINGS

Toll-like receptor 3 (TLR 3) plays an important role in innate immune responses, including generation of interferons. Multiple single-gene errors in TLR 3 interferon pathways have recently been described in children that result in increased susceptibility to HSE. Conversely, studies in both animal models and humans indicate that both cytolytic viral replication and immune-mediated responses (including cytotoxic T lymphocytes and immune mechanisms mediated by TLR 2) contribute to the pathology of HSV, suggesting possible new therapeutic approaches. In terms of treatment, data clearly indicate that a longer duration between onset of symptoms and initiation of effective antiviral therapy correlates directly with less favorable clinical outcome. Recurrent or relapsing HSE may occasionally occur, but recent observations indicate that many instances of "relapsing HSE", especially in children, are more often anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis triggered by the antecedent HSV infection. Innate immune responses are critical for defense against HSV; genetic defects in this system may predispose patients to HSE. During acute HSE, exuberant immune responses may contribute to the CNS pathology, suggesting that selective immunosuppressive therapy, coupled with potent antiviral drugs, may eventually play a role in the therapeutic management of HSV. While overall clinical outcomes of HSE remain suboptimal, the initiation of high-dose acyclovir therapy as early as possible in the course of the illness provides the best chance for a patient to survive with minimal neurologic damage. Distinguishing relapsing HSE from autoimmune anti-NMDAR antibody encephalitis is critically important because therapeutic approaches will be very different.

Nosocomial herpes simplex encephalitis: A challenging diagnosis

Herpes simplex encephalitis (HSE) is a rare disease, but it is the most common form of sporadic encephalitis. HSE is transmitted through direct contact and developing nosocomial HSE is rarely reported in the literature. Nosocomial HSE is difficult to diagnose due to its non-specific clinical features. In this article, we present a case of nosocomial HSE that was responsible for grave consequence. We also explore its causes, outcome, and give recommendations to avoid such fatal occurrence. We stress on strict adherence to the standard precautions and preventive control measures.