AIDS-associated vacuolar myelopathy

HIV-Associated Vacuolar Myelopathy and HIV-Associated Neurocognitive Disorder as an Initial Presentation in HIV Infection

Several neurological disorders have been described in HIV infection. Vacuolar myelopathy and neurocognitive disorders usually come at an advanced stage of the disease process. Here, we present a case where these features constitute the presenting complaints. Both of these conditions improved significantly following the start of HAART. We believe this clinical pathway can be a good learning point for the clinician.

HIV-associated dementia presenting predominantly with clinical motor deficits: A case report

HIV-associated dementia is commonly seen in older individuals and presents as a subcortical dementia associated with concentration, attention, and memory impairments. Motor signs, such as difficulty with gait, and mood changes are less prominent findings but are considered during diagnosis. We present a case of HIV-associated dementia in a young 29-year-old man who presented with progressive lower extremity weakness and difficulty ambulating.

Infections of the Spine and Spinal Cord

PURPOSE OF REVIEW

Infections of the spine and spinal cord are associated with a high risk of morbidity and mortality and, therefore, require prompt clinical recognition, efficient diagnostic evaluation, and interdisciplinary treatment. This article reviews the pathophysiology, epidemiology, clinical manifestations, diagnosis, and treatment of infections of the spine and spinal cord to help practicing clinicians recognize, evaluate, and manage patients with such infections.

RECENT FINDINGS

Aging of the population, increasing use of immunosuppressive medications, and other factors have contributed to increasing rates of spinal infections. Although the most common agents responsible for spinal infections remain bacteria and viruses, fungal infections occur in individuals who are immunocompromised, and parasitic infections are common in endemic regions, but patterns are in evolution with migration and climate change. Recent outbreaks of acute flaccid myelitis in children have been associated with enteroviruses A71 and D68.

SUMMARY

Infections of the spine and spinal cord can be challenging to diagnose, requiring a thorough history and neurologic examination, laboratory studies of serum and CSF, neuroimaging (particularly MRI), and, in some instances, biopsy, to establish a diagnosis and treatment regimen. Interdisciplinary management including collaboration with experts in internal medicine, infectious disease, and neurosurgery is important to improve clinical outcomes.

Neurologic Complications of Human Immunodeficiency Virus

PURPOSE OF REVIEW

This article reviews the neurologic complications associated with human immunodeficiency virus (HIV) infection.

RECENT FINDINGS

Neurologic complications of HIV may be caused by direct virally mediated pathology, immune-mediated phenomena in response to viral infection, or opportunistic infections secondary to depletion of lymphocytes. These neurologic disorders may be influenced by the degree of immunosuppression (ie, CD4+ T-cell lymphocyte count) and stage of infection (early versus late), as well as use of antiretroviral therapy, and may manifest as a variety of central and peripheral neurologic syndromes, including the more commonly encountered HIV-associated cognitive disorders and length-dependent sensorimotor polyneuropathy, respectively. Immune dysregulation underlies the majority of these neurologic phenomena, as well as other HIV-associated conditions including immune reconstitution inflammatory syndrome (IRIS), CD8 lymphocytosis, and potentially the development of compartmentalized infection within the CSF, also referred to as CSF escape.

SUMMARY

This article reviews a spectrum of clinical syndromes and related neuropathologic states associated with HIV infection.

Infectious Myelopathies

In the setting of both globalization and increasing use of immunosuppressive therapy, infectious myelopathies are an important cause of morbidity worldwide. Clinical spinal cord syndromes related to infection are varied, including transverse myelitis, acute flaccid paralysis related to anterior horn cell involvement, spinal cord compression, chronic spastic paraparesis, and myeloradiculitis. Causative pathogens include viruses, parasites, pyogenic and atypical bacteria, and fungi. The epidemiology, clinical characteristics, diagnosis, and treatment of selected organisms will be discussed in this article.

Paraparesis in a patient with advanced HIV infection: a diagnostic conundrum

In patients with HIV infection, lower limb weakness is a result of the pathological involvement of the brain, spinal cord or peripheral nervous system. The pathological process can be opportunistic infections, nutrient deficiencies, neoplastic infiltration or HIV itself. Here, we present the case of a 50-year-old manual labourer who presented with gradually progressive lower limb weakness, sensory disturbances, impotence and urinary urgency. He was diagnosed with HIV during evaluation. Based on the presentation and other supportive laboratory and radiological evidence, the following differentials were considered: vacuolar myelopathy, amyotrophic lateral sclerosis and myeloradiculopathy. The patient was initiated on antiretroviral therapy, and he showed significant improvement of symptoms on follow-up. We report this case to discuss the diagnostic puzzle.

HIV-associated vacuolar myelopathy: A rare initial presentation of HIV

HIV-associated vacuolar myelopathy, or AIDS-associated myelopathy, is a rare initial presentation of HIV. One of the common HIV-associated neurocognitive disorders, HIV-associated vacuolar myelopathy presents with advanced immunosuppression in patients and is frequently associated with dementia. However, most cases are subclinical with characteristic findings identified through physical examination and/or imaging modalities. HIV-associated vacuolar myelopathy is characterized by progressive spastic paraparesis, gait disturbance and lower extremity sensory abnormalities including vibratory sensation. Magnetic resonance imaging findings in the spinal cord are abnormal in some patients with HIV-associated myelopathy, characteristically showing spinal cord atrophy at the level of the thoracic spine, but they may also be normal. Unfamiliarity with this as initial presentation of HIV infection may lead to failure to diagnose and intervene appropriately. We present a case of newly diagnosed HIV with myelopathy and dementia with minimal spinal cord involvement on magnetic resonance imaging.

Successful Treatment of Human Immunodeficiency Virus-Associated Highly Active Antiretroviral Therapy-Resistant Vacuolar Myelopathy with Intravenous Immunoglobulin

For the first time, human immunodeficiency virus (HIV)-associated vacuolar myelopathy (VM) was detailed in an autopsy-based study of 89 cases in 1985. This condition is the most common cause for spinal cord lesions in HIV patients. VM's pathogenic mechanism remains unclear; however, it is assumed that the disease can be related to both, the direct neurotoxic impact of the HIV and HIV-induced activation of immunopathological processes in the central nervous system (CNS). Reviewed in this paper is a case where the VM presentation deteriorated drastically when treated with highly active antiretroviral therapy, and almost completely regressed after the patient received the intravenous immunoglobulin (IVIg) treatment. The considered case demonstrates the viability of IVIg treatment in patients with HIV-associated CNS pathology, particularly when autoimmune reactions are suspected. The results of placebo-controlled studies of IVIg in patients with HIV-associated myelopathy may give a reliable evaluation of IVIg use in this context.

HIV-associated synaptic degeneration

Human immunodeficiency virus (HIV) infection induces neuronal injuries, with almost 50% of infected individuals developing HIV-associated neurocognitive disorders (HAND). Although highly activate antiretroviral therapy (HAART) has significantly reduced the incidence of severe dementia, the overall prevalence of HAND remains high. Synaptic degeneration is emerging as one of the most relevant neuropathologies associate with HAND. Previous studies have reported critical roles of viral proteins and inflammatory responses in this pathogenesis. Infected cells, including macrophages, microglia and astrocytes, may release viral proteins and other neurotoxins to stimulate neurons and cause excessive calcium influx, overproduction of free radicals and disruption of neurotransmitter hemostasis. The dysregulation of neural circuits likely leads to synaptic damage and loss. Identification of the specific mechanism of the synaptic degeneration may facilitate the development of effective therapeutic approaches to treat HAND.

Metabolic responses to Orientia tsutsugamushi infection in a mouse model

Tsutsugamushi disease is an infectious disease transmitted to humans through the bite of the Orientia tsutsugamushi-infected chigger mite; however, host-pathogen interactions and the precise mechanisms of damage in O. tsutsugamushi infections have not been fully elucidated. Here, we analyzed the global metabolic effects of O. tsutsugamushi infection on the host using ¹H-NMR and UPLC-Q-TOF mass spectroscopy coupled with multivariate statistical analysis. In addition, the effect of O. tsutsugamushi infection on metabolite concentrations over time was analyzed by two-way ANOVAs. Orthogonal partial least squares-discriminant analysis (OPLS-DA) showed distinct metabolic patterns between control and O. tsutsugamushi-infected mice in liver, spleen, and serum samples. O. tsutsugamushi infection caused decreased energy production and deficiencies in both remethylation sources and glutathione. In addition, O. tsutsugamushi infection accelerated uncommon energy production pathways (i.e., excess fatty acid and protein oxidation) in host body. Infection resulted in an enlarged spleen with distinct phospholipid and amino acid characteristics. This study suggests that metabolite profiling of multiple organ tissues and serum could provide insight into global metabolic changes and mechanisms of pathology in O. tsutsugamushi-infected hosts.

Scrub typhus is an acute febrile illness caused by attacks of Orientia tsutsugamushi-carrying mites, and is the most prevalent febrile illness in the Asia-Pacific region. If not properly treated with antibiotics, patients often develop severe vasculitis that affects multiple organs, and the mortality rate can reach 30%. To explore the pathogenic mechanisms underlying the host-pathogen interaction, we characterized metabolic changes in various organs and the serum of O. tsutsugamushi-infected hosts. After O. tsutsugamushi infection, the host experienced decreased energy production, as well as a severe deficiency in re-methylation sources and glutathione, which impaired purine synthesis, DNA and protein methylation. In addition, abnormal pathways for phosphatidylcholine (PC) biosynthesis and phosphoethanolamine methylation were utilized in the enlarged spleen of O. tsutsugamushi-infected hosts. These results suggested that metabolic profiling could provide insight into global metabolic changes in O. tsutsugamushi-infected hosts, and increase our understanding of the pathogenic mechanisms of O. tsutsugamushi, as well as providing novel therapeutic targets for scrub typhus.

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.

Diffusion tensor MR imaging (DTI) metrics in the cervical spinal cord in asymptomatic HIV-positive patients

INTRODUCTION

This study was conducted to compare diffusion tensor MR imaging (DTI) metrics of the cervical spinal cord in asymptomatic human immunodeficiency virus (HIV)-positive patients with those measured in healthy volunteers, and to assess whether DTI is a valuable diagnostic tool in the early detection of HIV-associated myelopathy (HIVM).

METHODS

MR imaging of the cervical spinal cord was performed in 20 asymptomatic HIV-positive patients and in 20 healthy volunteers on a 3-T MR scanner. Average fractional anisotropy (FA), mean diffusivity (MD), and major (E1) and minor (E2, E3) eigenvalues were calculated within regions of interest (ROIs) at the C2/3 level (central and bilateral anterior, lateral and posterior white matter).

RESULTS

Statistical analysis showed significant differences with regard to mean E3 values between patients and controls (p = 0.045; mixed-model analysis of variance (ANOVA) test). Mean FA was lower, and mean MD, mean E1, and mean E2 were higher in each measured ROI in patients compared to controls, but these differences were not statistically significant.

CONCLUSION

Asymptomatic HIV-positive patients demonstrate only subtle changes in DTI metrics measured in the cervical spinal cord compared to healthy volunteers that currently do not support using DTI as a diagnostic tool for the early detection of HIVM.

[Imaging of demyelinating and neoplastic diseases of the spinal cord]

The clinical symptoms of myelopathy are variable and non-specific. Demyelinating as well as neoplastic spinal cord diseases can cause paresthesia, progressive sensomotoric deficits and bowel and bladder dysfunction. Imaging of the spine, especially with magnetic resonance imaging (MRI), is an essential component in the diagnostic assessment of myelopathy and makes a substantial contribution to achieving the correct diagnosis. Although intramedullary neoplasms are far less common than demyelinating spinal cord diseases, radiologists should be familiar with the three most common entities, astrocytoma, ependymoma and hemangioblastoma, which represent over 70% of all spinal cord neoplasms. An early diagnosis and therapy is essential with neoplastic and demyelinating spinal cord diseases to hold residual neurological deficits as low as possible.

Neurologic presentations of AIDS

The human immunodeficiency virus (HIV), the cause of AIDS, has infected an estimated 33 million individuals worldwide. HIV is associated with immunodeficiency, neoplasia, and neurologic disease. The continuing evolution of the HIV epidemic has spurred an intense interest in a hitherto neglected area of medicine, neuroinfectious diseases and their consequences. This work has broad applications for the study of central nervous system (CNS) tumors, dementias, neuropathies, and CNS disease in other immunosuppressed individuals. HIV is neuroinvasive (can enter the CNS), neurotrophic (can live in neural tissues), and neurovirulent (causes disease of the nervous system). This article reviews the HIV-associated neurologic syndromes, which can be classified as primary HIV neurologic disease (in which HIV is both necessary and sufficient to cause the illness), secondary or opportunistic neurologic disease (in which HIV interacts with other pathogens, resulting in opportunistic infections and tumors), and treatment-related neurologic disease (such as immune reconstitution inflammatory syndrome).

HIV and complement: hijacking an immune defense

The complement system is a central player of the innate immune system. Activation of the complement system protects the host against pathogens. However, uncontrolled synthesis can be detrimental to host. This concise review summarizes the current understanding of the mechanism(s) of complement activation, the mechanism of C3 regulation, and the role of complement in human immunodeficiency virus (HIV) pathogenesis with emphasis on the cross-talk between HIV and complement system in NeuroAIDS and HIV-associated nephropathy (HIVAN).