Acute Viral Infections of the Central Nervous System in Immunocompetent Adults: Diagnosis and Management

Abstract

Patients with viral infections of the central nervous system (CNS) may present with a variety of neurological symptoms, most commonly dominated by either encephalitis or meningitis. The aetiological panorama varies in different parts of the world as well as over time. Thus, virological first-line diagnostics must be adapted to the current epidemiological situation and to the individual patient history, including recent travels. This review focuses on the diagnostics and treatment of viral CNS infections in the immunocompetent host from a Northern European perspective. Effective vaccines are available for viruses such as poliovirus and tick-borne encephalitis virus (TBEV) and for the childhood diseases morbilli (measles), rubella (German measles), parotitis (mumps) and varicella (chickenpox). However, cases do appear due to suboptimal immunization rates. In viral CNS infections, epidemiological surveillance is essential for establishing preventive strategies and for detecting emerging viruses. Knowledge of the possibilities and limitations of diagnostic methods for specific viral CNS infections is vital. A positive cerebral spinal fluid (CSF) polymerase chain reaction (PCR) finding is usually reliable for aetiological diagnosis. The demonstration of intrathecal antibody synthesis is useful for confirming the aetiology in a later stage of disease, hitherto sufficiently evaluated in herpes simplex encephalitis (HSE) and tick-borne encephalitis (TBE). Despite improved virological and differential diagnostic methods, aetiology remains unknown in about half of the cases with suspected viral encephalitis. Antiviral treatment is available chiefly for infections caused by herpesviruses, and acyclovir (aciclovir) is the drug of choice for empirical therapy in suspected viral encephalitis. However, randomized, controlled antiviral trials have only been conducted for HSE, while such studies are lacking in other viral CNS infections. Viral cytolysis and immune-mediated mechanisms may contribute to varying extents to neurological damage. Although the brain damage is believed to depend, to a varying degree, on the intrathecal host immune response, the use of corticosteroids in viral CNS infections is scarcely studied, as is specific treatment for neuroinflammation. Improved antiviral and immunomodulating treatment is desirable. Since neurological sequelae are still abundant, follow-up after severe viral CNS disease must include a neuropsychological assessment and an individually adapted rehabilitation plan.

Epidemiology, clinical characteristics, diagnosis and vaccination of tick-borne encephalitis: an overview

“…EE me tu lik vo re ran da ma vi du ti në ple o ci to zë [22], ku ri në ra to kia ið reikð ta kaip ki tais vi ru si niø me nin go en ce fa li tø at ve jais [23]. Ra dzi ðaus kie nës ir kt.…”

“…Ta èiau EEV tu ri ben dras an ti ge ni nes sri tis su ki tais fla vi vi ru sais (Gel to nosios karð ti nës vi ru su, Ja po nið ko jo en ce fa li to vi ru su, Dengës vi ru so 1-4 se ro ti pais), to dël ELI SA tes to me tu ga li re aguo ti ri ðan tys, bet ne neut ra li zuo jan tys an ti kû nai [23,25]. To kiais at ve jais svar bu nu sta ty ti spe ci fi nius EEV an ti kû -nus ir at lik ti neut ra li za ci jos tes tà [17].…”

“…Ki ta stu di ja nu statë, kad pa si skie pi ju siø jau nø ir vy res niø as me nø se ru me ap tik ti an ti kû nai ne si ski ria nei avi dið ku mu, nei funk ci niu ak ty vu mu (vi ru sà neut ra li zuo jan èiø ir jun gian èiø an ti kû nø san ty kiu), ski ria si tik an ti kû nø kie kis, ku ris vy res niø pacien tø krau jy je yra daug ma þes nis [46]. Ða lu ti niai abie jø vak ci nø po vei kiai yra pa na ðûs [23]. Jie daþ niau pa si reið kia po pir mo sios vak ci nos do zës [2].…”

Herpes Encephalitis Resulting in Neurologic Sequelae: Case Report

“…Yeterli klinik yanıt alınamayan olgularda tedavi süresini uzatmanın yararlı olduğu bildirilmektedir [2] . Ayrıca, mortalite ve morbiditenin önlen-mesinde erken tedavi son derece önemlidir [1][2][3] .…”

Kaposi’s varicelliform eruption in herpes simplex encephalitis

“…In adults, the majority of cases are caused by HSV-1, which is believed to represent the reactivation of latent HSV in situ within the central nervous system. The diagnosis of herpes simplex encephalitis is based on clinical features (a triad of fever, headache and an altered mental state), cerebrospinal fluid examination, and brain imaging [1]. HSV DNA detection by polymerase chain reaction using the cerebrospinal fluid has a sensitivity of 98 % and a specificity of 94-100 %.…”