CNS manifestations of cytomegalovirus infections: diagnosis and treatment

Infectious myelopathies

Every genus of microorganism, as well as prions, has been associated with disease of the spinal cord. The spectrum of pathogens resulting in myelopathy varies with the population. Myelopathy is uniquely associated with certain retroviruses, particularly HIV type 1 and human T-cell lymphotropic virus type I, but the myelopathies that occur with these viruses are chiefly limited to "at risk" populations. In the immunocompromised population, a diverse array of pathogens may cause spinal cord disease, especially viruses from the Herpesviridae family, most notably cytomegalovirus and varicella-zoster virus. The prototypical myelopathy resulting from bacterial infection is tabes dorsalis, but this disorder is vanishingly rare in the modern era. In developing countries, Mycobacterium tuberculosis and schistosomiasis remain significant causes of myelopathy.

CMV-associated encephalitis and antineuronal autoantibodies--a case report

Background

Human cytomegalovirus (CMV) is an ubiquitous pathogen capable of modulating the host immune system. Immune dysfunction is common during CMV infection and includes autoimmune phenomena. Here we focus on a case of primary CMV infection associated with encephalopathy in a patient with a rudimentary spleen. We discuss diagnostic challenges and immunological aspects as well as the hypothesis that CMV may break tolerance and induce potentially encephalitogenic autoantibodies.

Case presentation

A 33-year-old woman was admitted with features of encephalitis, rapidly progressing into a catatonic state. The patient tested negative for presence of herpes simplex virus DNA in cerebrospinal fluid (CSF), and had elevated liver enzymes and hepatomegaly at computed tomography scan (CT) examination. CT scan and magnetic resonance imaging (MRI) showed only a rudimentary spleen. Initially, serum was negative for anti-CMV IgM, but borderline for anti-CMV IgG by enzyme-linked immunosorbent assay. However, a more sensitive assay resulted in a positive specific IgM Western blot profile and low IgG avidity, suggesting primary CMV infection. Further, CMV DNA was retrospectively detected in a CSF sample collected at admission. We also detected antineuronal autoantibodies, which stained GAD-positive neurons in the hippocampus. The patient was treated by a combination of prednisone, intravenous immunoglobulins (IVIg) and antivirals, which resulted in a dramatic amelioration of the patient’s neurological status. One year after admission the patient exhibited a nearly complete recovery with mild deficits in attention and memory.

Conclusions

A possible reason for the critical course of CMV infection could be the lack of a functional spleen in this patient, a condition previously associated with severe CMV infection. Prompt treatment with antiviral drugs, steroids and IVIg was most likely important for the positive outcome in this case and should be considered for similar cases of severe primary CMV infection associated with immunopathological phenomena.

CMV central nervous system disease in stem-cell transplant recipients: an increasing complication of drug-resistant CMV infection and protracted immunodeficiency

We report on two patients with no active GVHD and on moderate doses of immunosuppressive drugs who unexpectedly developed fatal CMV meningoencephalitis after umbilical cord blood transplantation. A review of these two cases along with nine other cases of CMV central nervous system (CNS) disease after allogeneic SCT that were mostly reported within the last 8 years suggests that this severe complication of CMV infection may be increasing. CMV CNS disease after allogeneic SCT is a late-onset disease (median time of onset, 210 days) and is usually manifested as encephalitis in the absence of other sites of CMV disease. The development of CMV CNS disease is associated with risk factors (T-cell depletion, anti-thymocyte globulin, umbilical cord blood transplantation) that cause severe and protracted T-cell immunodeficiency (8 of 11 cases), a history of recurrent CMV viremia treated with multiple courses of preemptive ganciclovir or foscarnet therapy (11 of 11 cases), and ganciclovir-resistant CMV infection (11 of 11 cases). Despite therapy with a combination of antiviral drugs (ganciclovir, foscarnet and cidofovir), mortality is high (10 of 11 cases). Given this high mortality, extended prophylaxis with current or novel antiviral drugs and strategies to enhance CMV immunity need to be considered in high-risk patients.

[Cytomegalovirus and systemic lupus: severe infection and difficult diagnosis]

INTRODUCTION

There are a few reports only on cytomegalovirus (CMV) reactivation in lupus. Diagnosis of this infection is difficult and can be associated with of a poor outcome. We report three cases of infection with CMV that occurred in patients with lupus and review the literature.

CASE REPORTS

The three reported patients presented with fever, polyarthritis, myocarditis and enteritis. Lupus was longstanding and the patients were receiving corticosteroids or cyclophosphamide. There was no major CD4 lymphopenia. The diagnosis was obtained with the presence of antigenemia pp65. The outcome was favorable with antiviral therapy in two patients, while the remaining patient died. In the English literature, pulmonary and intestinal involvement seem frequent, and associated with poor prognosis.

CONCLUSION

In systemic lupus CMV infection is often serious and difficult to diagnose. Risk factors, treatment and prophylaxis remain to be evaluated in this population. The incidence of this infection could increase among patients receiving a biotherapy.

Central nervous system infections in immunocompromised patients: update on diagnostics and therapy

Infections of the central nervous system (CNS) are increasingly reported in patients with malignancies. Heavily immunocompromised patients like those after allogeneic stem cell transplantation (SCT) or previous T cell depleting treatment regimens (e.g. with fludarabine or alemtuzumab) are at highest risk for cerebral infections. The spectrum of causative organisms may vary greatly, depending on the underlying malignancy, its treatment and various other factors. Toxoplasma gondii and fungi are the leading causative organisms in patients after allogeneic SCT, but also viruses such as herpes simplex virus or JC virus may be detected in these patients. Definitive diagnosis of cerebral infection still remains a high challenge, although diagnostics have improved by the wide availability of imaging techniques and polymerase chain reaction in recent years. Novel therapeutic options are arising, particularly for fungal CNS infections. Here, we summarise aspects on epidemiology, clinical symptoms and prognosis of CNS infections in patients with malignancies. Additionally, we give an overview on the diagnostics and management of cerebral infections in these patients including evidence evaluation of efficacy of treatment.

Neuroimaging of herpesvirus infections in children

Six members of the herpesvirus family cause well-described neurologic disease in children: herpes simplex virus-1 (HSV-1), herpes simplex virus-2 (HSV-2), varicella-zoster (VZV), Epstein-Barr (EBV), cytomegalovirus (CMV), and human herpes virus-6 (HHV-6). When herpesviruses infect the central nervous system (CNS), the clinical presentation is non-specific and often confounding. The clinical urgency is often underscored by progressive neurologic deficits, seizures, or even death, and prompt diagnosis and treatment rely heavily on neuroimaging. This review focuses on the spectrum of cerebral manifestations caused by these viruses, particularly on non-congenital presentations. Recent advances in our understanding of these viruses are discussed, including new polymerase chain reaction techniques that allow parallel detection, which has improved our recognition that the herpesviruses are neurotropic and involve the CNS more often than previously thought. Evolving knowledge has also better elucidated viral neuropathology, particularly the role of VZV vasculitis in the brain, HHV-6 in febrile seizures, and herpesvirus reactivation in immunosuppressed patients. The virology, clinical course, and CNS manifestations of each virus are reviewed, followed by descriptions of neuroimaging findings when these agents infect the brain. Characteristic but often subtle imaging findings are discussed, as well as technical pearls covering appropriate use of MRI and MRI adjuncts to help differentiate viral infection from mimics.

Main adult herpes virus infections of the CNS

Herpes viruses are widely involved in human infectious diseases, and some are life threatening, such as CNS infections. These manifestations vary according to the type of virus involved and the immune status of the patient. This article will review the clinical manifestations (encephalitis, myelitis, meningitis and postinfectious encephalomyelitis), the diagnostic strategies and the presently used drugs (acyclovir, valacyclovir, ganciclovir, valgancyclovir, foscarnet and cidofovir). The review will also discuss drugs that are currently in the pipeline and that could be used in the future.

Efficacy of antiviral compounds in human herpesvirus-6-infected glial cells

The beta-herpesvirus human herpesvirus-6 (HHV-6) is becoming increasingly recognized as an important pathogen in immunocompromised patients, particularly in post bone marrow transplant (BMT). Reactivation of latent HHV-6 resulting in encephalitis has been reported in BMT and stem cell transplant (SCT) patients. The development of HHV-6 encephalitis can be a fatal complication, the frequency of which is increasing likely due to improved diagnosis with quantitative polymerase chain reaction (PCR) of cerebrospinal fluid. There are currently no antiviral compounds approved for HHV-6, nor have any controlled clinical trials been conducted. The frequency and severity of HHV-6 encephalitis in both immunocompetent and immunocompromised patients necessitates studies on the usefulness of currently available anti-viral compounds. The authors compared the antiviral efficacy of four drugs currently used for cytomegalovirus (CMV) infection, a beta-herpesvirus sharing homology with HHV-6. In HHV-6A- and HHV-6B-infected T cells, acyclovir, ganciclovir, foscarnet, and cidofovir exhibited antiviral activity consistent with that published in other studies. In HHV-6-infected human astrocytes (U251), however, only foscarnet and cidofovir exhibited antiviral activity and this effect was restricted to infection with HHV-6 variant A. In pathological brain sections from patients with neurological disorders such as multiple sclerosis and epilepsy, HHV-6 has been localized to glial cells. Determination of antiviral activity in human glial fibrillary acidic protein (GFAP)-positive astrocytes of currently used antiviral compounds is essential for potential treatment of HHV-6 and neurological disorders. Our data highlight the necessity for further study of antiviral compound in HHV-6-infected glial cells as well as the development of more selective compounds for HHV-6.

Viral myelitis: An update

Viral infections of the central nervous system are uncommon but are important in the differential diagnosis of acute myelopathy. Acute viral myelitis can present as acute flaccid paralysis (poliomyelitis) or neurologic dysfunction due to involvement of the white matter. The latter usually affects only part of the transverse expanse of the spinal cord and manifests as asymmetric motor and sensory symptoms. When both halves of the spinal cord are affected, the entity is referred to as acute transverse myelitis and patients exhibit uniformly symmetric weakness, sensory loss, and urinary bladder involvement. Acute flaccid paralysis is due to cytolytic infection of anterior horn cells. When the involvement is mainly white matter, virus-specific and autoimmune host cellular immune responses are believed to contribute to spinal cord damage. Acute flaccid paralysis is caused by polioviruses-1, -2, and -3; coxsackieviruses A and B; enterovirus-71; and flaviviruses, including West Nile virus. Involvement of spinal cord white matter may be associated with infection by many different viruses; however, in most cases a specific viral cause is never determined. Chronic myelitis may be due to either direct infection of the spinal cord by human T-cell lymphotrophic virus-1 (HTLV-1), or a metabolic disturbance due to HIV-1 infection in AIDS patients; no other human virus is known to chronically infect the spinal cord without involvement of the brain. The principal treatment is antiviral drugs immediately upon virus isolation or the identification of a viral sequence by PCR and, when indicated, high doses of methylprednisolone.

Encephaloradiculomyelitis associated to HHV-7 and CMV co-infection in immunocompetent host

An active co-infection with CMV and HHV-7 has been never described in immunocompetent patients. The authors describe a case of encephaloradiculomyelitis in an immunocompetent man. Polymerase chain reaction (PCR) performed on cerebrospinal fluid (CSF) showed positivity for DNA of Cytomegalovirus (CMV) and Herpes-virus type 7 (HHV-7), whereas the same test applied on peripheral blood mononuclear cells gave negative result. These results are highly supportive of an infection of the central and peripheral nervous systems, caused by CMV and HHV7. Such viral co-infection has only been described in immune-depressed patients with CMV disease, in which HHV-7 was supposed to act as a cofactor, enhancing clinical manifestations. The same mechanism is presumably responsible for the development of encephaloradiculomyelitis clinical signs in the present case. This is the second case in which DNA of HHV-7 has been found in the CSF of an adult immunocompetent patient. This novel observation suggests that the search for viral DNA in the CSF should be performed also in immunocompetent patients.

Atteintes du système nerveux central et infection par le VIH-1

Central nervous system complications are common in HIV-1 infected patients and occur either as a result of concomitant immunosuppression (opportunistic infections, lymphoma and tumors), as a primary manifestation of HIV infection, or as an adverse effect of therapy (immune restoration and toxicity). These complications contribute largely to patient morbidity and mortality. In the era of highly active antiretroviral therapy (HAART) these disease states have changed in presentation, outcome and incidence. We review in detail the epidemiology, pathogenesis, clinical features, diagnosis, and management of these disorders.

[Central nervous system infections in HIV patients in the era of high activity antiretroviral treatment]

Although the incidence of most central nervous system infections in HIV+ patients has decreased after the introduction of the modern antiretroviral treatments, they are still a major cause of morbidity and mortality. New technologies in molecular biology and neuroradiology establish the diagnosis in many cases and have decreased the need for cerebral biopsy. Prognosis has improved substantially after the introduction of high activity antiretroviral treatment; more active treatments are needed, however, for infections as PML or citomegalovirus encephalitis because of their still unacceptably high mortality.

Factors affecting delivery of antiviral drugs to the brain

Although the CNS is in part protected from peripheral insults by the blood-brain barrier and the blood-cerebrospinal fluid barrier, a number of human viruses gain access to the brain, replicate within this organ, or sustain latent infection. The efficacy of antiviral drugs towards the cerebral viral load is often limited as both blood-brain interfaces impede their cerebral distribution. For polar compounds, the major factor restricting their entry lies in the tight junctions that occlude the paracellular pathway across these barriers. For compounds with more favourable lipid solubility properties, CNS penetration will be function of a number of physicochemical factors that include the degree of lipophilicity, size and ability to bind to protein or red blood cells, as well as other factors inherent to the vascular and choroidal systems, such as the local cerebral blood flow and the surface area available for exchange. In addition, influx and efflux transport systems, or metabolic processes active in both capillary endothelial cells and choroid plexus epithelial cells, can greatly change the bioavailability of a drug in one or several compartments of the CNS. The relative importance of these various factors with respect to the CNS delivery of the different classes of antiviral drugs is illustrated and discussed.

Comparison of nested PCR and real time PCR of Herpesvirus infections of central nervous system in HIV patients

Background

Molecular detection of herpesviruses DNA is considered as the reference standard assay for diagnosis of central nervous system infections. In this study nested PCR and real time PCR techniques for detection of Herpes simplex virus type 1 (HSV-1), Cytomegalovirus (CMV) and Epstein-Barr virus (EBV) in cerebrospinal fluid of HIV patients were compared.

Methods

Forty-six, 85 and 145 samples previously resulted positive for HSV-1, CMV and EBV by nested PCR and 150 randomly chosen negative samples among 1181 collected in the period 1996–2003 were retrospectively reassessed in duplicate by real time PCR and nested PCR.

Results

Samples giving positive results for CMV, HSV-1 and EBV with nested PCR were positive also with real time PCR. One of the negative samples resulted positive for HSV and one for EBV. Real time PCR showed comparable sensitivity and specificity vs nested PCR.

Conclusion

Real time PCR proved to be a suitable method for diagnosis of herpesvirus infections in CNS, showing comparable sensitivity and being less time consuming than nested PCR.

Update on neuroimaging in infectious central nervous system disease

PURPOSE OF REVIEW

Neuroimaging constitutes an important component in the diagnosis of the underlying infectious agents in central nervous system infection. This review summarizes progress in the neuroimaging of infectious central nervous system disease since January 2003. It focuses on imaging of viral encephalitis, including that caused by exotic and emerging viruses, and on imaging in immunodeficient patients.

RECENT FINDINGS

Diffusion-weighted imaging has been shown to be superior to conventional magnetic resonance imaging for the detection of early signal abnormalities in herpes simplex virus encephalitis but also in enterovirus 71 encephalitis and in West Nile encephalitis. Several studies defined the pattern of magnetic resonance imaging signal changes in endemic diseases such as West Nile encephalitis, Murray Valley encephalitis, enterovirus 71 encephalitis and Japanese encephalitis, but also in encephalitides due to ubiquitous viruses such as measles virus and Lyssavirus (rabies). In patients with HIV infection, apparent diffusion coefficient ratios obtained by diffusion-weighted imaging were significantly greater in lesions due to Toxoplasma encephalitis than in primary central nervous system lymphomas.

SUMMARY

The diagnosis of unclear infectious central nervous system diseases remains a challenge. More recent magnetic resonance imaging techniques, such as diffusion-weighted imaging and magnetic resonance spectroscopy, provide additional helpful information. However, the mainstay of diagnosis remains the detection of viral DNA or serological markers of specific infectious agents within the cerebrospinal fluid.

Cerebral mass lesion due to cytomegalovirus in a patient with AIDS: case report and literature review

Cytomegalovirus (CMV) disease in acquired immunodeficiency syndrome (AIDS) patients most commonly presents as chorioretinitis and gastro-intestinal infection. Neurological involvement due to CMV may cause several clinical presentations: polyradiculitis, myelitis, encephalitis, ventriculo-encephalitis, and mononeuritis multiplex. Rarely, cerebral mass lesion is described. We report a 39 year-old woman with AIDS and previous cerebral toxoplasmosis. She presented with fever, seizures, and vulval ulcers. Her chest X-ray showed multiple lung nodules, and a large frontal lobe lesion was seen in a brain computed tomography scan. She underwent a brain biopsy through a frontal craniotomy, but her condition deteriorated and she died in the first postoperative day. Histopathological studies and immunohistochemistry disclosed CMV disease, and there was no evidence of cerebral toxoplasmosis, bacterial, mycobacterial or fungal infection. CMV disease should be considered in the differential diagnosis of cerebral mass lesion in AIDS patients. High suspicion index, timely diagnostic procedures (surgical or minimally invasive), and proper utilization of prophylactic and therapeutic medication could improve outcome of these patients.

Opportunistic infections of the CNS in patients with AIDS: diagnosis and management

The CNS is the second most commonly affected organ in patients with AIDS. Many opportunistic infections may involve the brain, but the four most frequent conditions are toxoplasmosis, progressive multifocal leukoencephalopathy (PML), cryptococcosis and cytomegalovirus infection. Although the incidence of these infections among patients with AIDS has decreased in the past years as a consequence of the introduction of highly active antiretroviral therapy (HAART), they remain a major cause of morbidity and mortality in this patient group. This article summarises the clinical manifestations, diagnostic procedures and management strategies for these four conditions. The clinical manifestations are nonspecific and depend on the type and location of the lesions. In clinical practice, the diagnosis of these entities is made with noninvasive methods. Imaging studies, especially magnetic resonance imaging, are very useful for the diagnosis of toxoplasmic encephalitis and PML, although their usefulness for the diagnosis of cryptococcal meningitis and cytomegalovirus infections is lower. The presence of multiple ring-enhancing lesions with surrounding oedema and mass effect is characteristic of toxoplasmosis. The response to antitoxoplasmic therapy, which is usually observed within the first 2 weeks, is also used for diagnostic purposes. Molecular methods applied to the CSF are essential for the diagnosis of PML and cytomegalovirus infections. In addition, the quantification of viral DNA of both JC virus (the causative agent of PML) and cytomegalovirus has prognostic implications and may serve to evaluate the response to therapy. Cryptococcosis may be easily diagnosed by CSF stains and cultures, as well as by the detection of the cryptococcal capsular polysaccharide antigen in the blood and, especially, the CSF. Effective treatments are available for toxoplasmosis and cryptococcosis, although adverse effects are common and some patients may not respond to therapy. In contrast, there is no specific treatment for PML, and the efficacy of anticytomegalovirus therapy is poor and the toxicity significant. HAART has improved the outcome of patients with AIDS who have infections of the CNS, and the initiation of this therapy is mandatory for all patients with such infections, particularly in those conditions for which effective therapy is not available. Lifelong secondary prophylaxis with agents for the opportunistic infections was necessary before the HAART era because the risk of recurrence was very high if only induction therapy was administered. However, today, the discontinuation of secondary prophylaxis in patients treated with HAART who have stably reached a certain immune reconstitution is possible.

Occurrence and Management of Opportunistic Infections Associated with HIV/AIDS in Asia

Illnesses, diseases and malignancies occur among HIV-infected individuals along a continuum. These are directly correlated with the degree of immune suppression and are caused by common patho gens and opportunistic infections. In decreasing order offrequency, frequent opportunistic infections and malignancies that occur in Asia are: Mycobacterium tuberculosis, Cryptococcus neoformans, Candida spp., Herpes simplex, Cryptosporidium parvum, Pneumocystis carinii, Toxoplasma gondii, non-Hodgkin's lymphoma and Kaposi's sarcoma. The association of morbidityand mortality due to co-infection with HIV and M.tuberculosis has become more evident in the region. Natural history studies conducted in Mumbai and Bangkok have reported incubation periods from infection to AIDS of eight and nine years respectively. Despite the advent of antiretroviral therapy (ART) and improved affordability of the generic drugs, only 30,000 (2 to 3 per cent) of the estimated 1.3 million eligible persons with AIDS in South Asia are presently on AR T. Apparently, the focus of the low-cost care in the region still continues to be of care and management of prevalent opportunistic infections. As care practices start to include ART over the next few years, there will be consequent change in the occurrence of opportunistic infections and need for their prophylaxis.