Herpes Simplex and Herpes Zoster

Environmental triggers of multiple sclerosis

Multiple sclerosis is a chronic immune-mediated disease of the central nervous system that develops in young adults with a complex genetic predisposition. Similar to other autoimmune disease, HLA-DR and -DQ alleles within the HLA class II region on chromosome 6p21 are by far the strongest risk-conferring genes. Less robust susceptibility effects have been reported for non-MHC related genetic variants. Improvements in the design of epidemiological studies helped to identify consistent environmental risk-associations such as the increased susceptibility for MS in individuals with a history of infectious mononucleosis, a symptomatic primary infection with the human γ-herpesvirus Epstein-Barr virus (EBV). Sun exposure and serum vitamin D levels are emerging non-infectious environmental risk factors that may have independent roles. The analysis of environmental effects will likely expand in the next few years and will allow for the generation of testable hypotheses as to how environmental insults interact with genetic factors to jointly determine the susceptibility to MS. Insights gained from these studies might facilitate the development of prevention strategies and more effective treatments for MS.

Viral triggers of multiple sclerosis

Genetic and environmental factors jointly determine the susceptibility to develop Multiple Sclerosis (MS). Collaborative efforts during the past years achieved substantial progress in defining the genetic architecture, underlying susceptibility to MS. Similar to other autoimmune diseases, HLA-DR and HLA-DQ alleles within the HLA class II region on chromosome 6p21 are the highest-risk-conferring genes. Less-robust susceptibility effects have been identified for MHC class I alleles and for non-MHC regions. The role of environmental risk factors and their interaction with genetic susceptibility alleles are much less well defined, despite the fact that infections have long been associated with MS development. Current data suggest that infectious triggers are most likely ubiquitous, i.e., highly prevalent in the general population, and that they require a permissive genetic trait which predisposes for MS development. In this review article, we illustrate mechanisms of infection-induced immunopathologies in experimental animal models of autoimmune CNS inflammation, discuss challenges for the translation of these experimental data into human immunology research, and provide future perspectives on how novel model systems could be utilized to better define the role of viral pathogens in MS.

Entzündungen des Hirnstamms und des Kleinhirnbrückenwinkels

Inflammatory lesions of the brainstem and the cerebellopontine angle are often critical for the patient, because crucial neuronal and vascular structures are found in this region. The patient's prognosis mainly depends on rapid identification of the inflammation site and the radiological evaluation of the inflammation pathogenesis to develop therapeutic strategies. Therefore, cross-sectional imaging is complementary to laboratory and CSF analysis as well as biopsies. This article gives a survey of inflammatory lesions of the brainstem and the cerebellopontine angle.

Profound cerebrospinal fluid pleocytosis and Froin's Syndrome secondary to widespread necrotizing vasculitis in an HIV-positive patient with varicella zoster virus encephalomyelitis

Demonstration of the direct involvement of cranial blood vessels by varicella zoster virus (VZV) is facilitated by immunohistochemistry (IHC), in situ hybridization (ISH) and polymerase chain reaction (PCR) techniques. The extent to which an inflammatory vasculitis serves as the pathogenic mechanism for VZV encephalomyelitis (VZVE) is still, however, debated. Most VZVE patients are immunocompromised and show little inflammation, either pre-mortem in cerebrospinal fluid (CSF) or at autopsy. We describe an HIV-positive patient with a moderately depressed CD4 count (304) who presented with massively elevated CSF protein (1800 mg/dl), bloody CSF and pleocytosis (1300 white blood cells (WBC)/mm3). His CSF was positive for VZV DNA by PCR. He was treated with acyclovir and foscarnet, but died. At autopsy, an unusually widespread, inflammatory, transmural vasculitis caused by VZV affected meningeal vessels at virtually all brain stem and spinal cord levels, causing multiple subpial hemorrhages and necrosis. Virus DNA in multiple areas of brain, brainstem and spinal cord was readily revealed by PCR, but not by the presence of viral inclusions, IHC or ISH. This case, with a clinically confusing presentation for VZVE, illustrates the extensive, albeit infrequent, degree of necrotizing vasculitis and CSF abnormalities that VZV is capable of producing. Antiviral therapy may have inhibited VZV genome replication and subsequent antigen production, resulting in negative ISH and IHC studies, but generated increased VZV genomic fragments that were detectable by the more sensitive PCR technique.

Herpes zoster polyradiculopathy

Herpes zoster infection, resulting from reactivation of the dormant varicella zoster virus in the dorsal root ganglia, usually causes a painful dermatomal vesicular rash. Rarely, associated peripheral motor weakness is present, the mechanism of which is unclear. Three patients are reported who had focal limb muscle weakness associated with zoster infection. Physical and occupational therapy played a key role in motor function recovery of the patients, yet emphasis on the rehabilitation of postherpetic motor weakness is lacking in the literature. Physiatrists evaluating patients with limb muscle weakness following herpes zoster infection should be alert to this condition. The clinical syndrome of herpes zoster radiculopathy and the rehabilitation of these patients are discussed.

Antiviral IgM and IgG subclasses in varicella zoster associated neurological syndromes

The varicella zoster virus (VZV) and herpes simplex virus (HSV) IgGl-4 subclasses were compared in serum and cerebrospinal fluid (CSF) of 22 patients with VZV-associated neurological symptoms, 12 patients with HSV-associated neurological symptoms and 14 controls. The clinical syndromes of the VZV-associated diseases comprised meningo-encephalitis, myelitis, myelopathies and polyneuropathies, mostly with a favourable outcome. A characteristic finding was an intrathecal synthesis of VZV IgG1 and HSV-3. Commonly also IgG2 and 4 were seen in CSF of VZV patients. Their intrathecally synthesised HSV IgG was restricted to IgG1. VZV IgG3 occurred in serum and/or CFS together with VZV IgM in 14 cases and may be a marker of recent VZV replication. In patients with HSV-associated neurological disease, a multi-IgG subclass HSV response and concomitant VZV antibodies restricted to IgG1 was found. Intrathecal synthesis of both HSV and VZV IgG occurred in 20 patients. Detection of two or more VZV or HSV specific IgG subclasses synthesised intrathecally identified the aetiological agent in 19 of these 20 cases.

Guillain-Barré syndrome after varicella-zoster infection. Case report

The authors report a case of Guillain-Barrè syndrome (GBS) following a varicella infection in a 13 year-old boy. During his admission he developed respiratory insufficiency and dysautonomic events, as well as a severe sensitive peripheral neuropathy. Some aspects related to the etiology and pathogenesis of GBS are discussed.

Acute herpetic and postherpetic neuralgia: clinical review and current management

The pain of acute herpes zoster (HZ) may be severe, but it is usually transitory. A minority of patients, with the elderly at particular risk, go on to develop persistent, severe, often disabling pain called postherpetic neuralgia. Though the clinical features of these conditions are well known, the pathology of PHN is poorly described and the pathogenesis of the pain in both remains conjectural. During the past 60 years, an extraordinary number of pharmacological, anesthetic, and surgical therapies have been applied in an attempt to ameliorate the symptoms of acute herpes zoster, enhance its healing, prevent its transition to postherpetic neuralgia, and treat the pain of those with this complication. Relatively few treatments have been studied in a controlled manner, and fully reliable, safe, and effective therapeutic approaches for preventing and treating postherpetic neuralgia have not yet been found. This review summarizes current information on the epidemiology, clinical features, and pathology of herpes zoster and postherpetic neuralgia, and critically examines the accumulated experience with the various treatments. Guidelines for management are suggested.