HTLV-I-associated myelopathy/tropical spastic paraparesis in the United States

Screening for HIV-Associated Neurocognitive Disorder (HAND) in Adults Aged 50 and Over Attending a Government HIV Clinic in Kilimanjaro, Tanzania. Comparison of the International HIV Dementia Scale (IHDS) and IDEA Six Item Dementia Screen

Validated screening tools for HIV-associated neurocognitive disorders (HAND) are lacking for the newly emergent ageing population of people living with HIV (PLWH) in sub-Saharan Africa (SSA). We aimed to validate and compare diagnostic accuracy of two cognitive screening tools, the International HIV dementia scale (IHDS), and the Identification and Interventions for Dementia in Elderly Africans (IDEA) screen, for identification of HAND in older PLWH in Tanzania. A systematic sample of 253 PLWH aged ≥ 50 attending a Government clinic in Tanzania were screened with the IHDS and IDEA. HAND were diagnosed by consensus American Academy of Neurology (AAN) criteria based on detailed clinical neuropsychological assessment. Strict blinding was maintained between screening and clinical evaluation. Both tools had limited diagnostic accuracy for HAND (area under the receiver operating characteristic (AUROC) curve 0.639–0.667 IHDS, 0.647–0.713 IDEA), which was highly-prevalent (47.0%). Accurate HAND screening tools for older PLWH in SSA are needed.

Considerations on nosology for HIV-associated neurocognitive disorders: it is time to update?

AIMS

The prognosis and the clinical manifestations of HIV infection have changed with the introduction of the potent combination antiretroviral therapy (cART); however, up to 50% of patients meet research criteria for "HIV-associated neurocognitive disorders" (HAND) according with current nosology. The majority of patients affected by HAND, especially in cohorts with suppressed plasma viremia, showed an Asymptomatic Neurocognitive Impairment (ANI), without any functional impairment. After more than 10 years from the introduction of the current so-called "Frascati criteria", this mini-review aimed to address the emerging limitations in current diagnosis procedures.

METHODS

We discussed the most relevant literature on HAND prevalence, etiology, and diagnosis.

RESULTS

We addressed three main emerging issues: (1) the unclear clinical relevance of ANI entity; (2) the evidences that Frascati criteria could produce a significant overestimation of HAND; (3) the need to better identify patients with a higher risk to develop HAND requiring routine neuropsychological examinations.

CONCLUSIONS

Frascati criteria should be updated to better respond to the present characteristics of HIV + cohorts and to help clinicians in their cognitive and global management.

Macrophages but not Astrocytes Harbor HIV DNA in the Brains of HIV-1-Infected Aviremic Individuals on Suppressive Antiretroviral Therapy

The question of whether the human brain is an anatomical site of persistent HIV-1 infection during suppressive antiretroviral therapy (ART) is critical, but remains unanswered. The presence of virus in the brains of HIV patients whose viral load is effectively suppressed would demonstrate not only the potential for CNS to act as an anatomical HIV reservoir, but also the urgent need to understand the factors contributing to persistent HIV behind the blood-brain barrier. Here, we investigated for the first time the presence of cells harboring HIV DNA and RNA in the brains from subjects with undetectable plasma viral load and sustained viral suppression, as identified by the National NeuroAIDS Tissue Consortium. Using new, highly sensitive in situ hybridization techniques, RNAscope and DNAscope, in combination with immunohistochemistry, we were able to detect HIV-1 in the brains of all virally suppressed cases and found that brain macrophages and microglia, but not astrocytes, were the cells harboring HIV DNA in the brain. This study demonstrated that HIV reservoirs persist in brain macrophages/microglia during suppressive ART, which cure/treatment strategies will need to focus on targeting.

A comparison of the sensitivity, stability, and reliability of three diagnostic schemes for HIV-associated neurocognitive disorders

HIV-associated neurocognitive disorders (HAND) occur in approximately 50% of HIV-infected individuals, yet available diagnostic criteria yield varying prevalence rates. This study examined the frequency, reliability, and sensitivity to everyday functioning problems of three HAND diagnostic criteria (DSM-5, Frascati, Gisslén). Participants included 361 adults with HIV disease and 199 seronegative adults. Neurocognitive status as defined by each of the three diagnostic systems was determined via a comprehensive neuropsychological battery. Everyday functioning was evaluated through self-report and clinician ratings. Results of logistic regressions revealed an association of HIV serostatus with Frascati-defined neurocognitive impairment (p = .027, OR = 1.7[1.1, 2.7]), but not DSM-5 or Gisslén-defined criteria (ps > .05). Frascati and DSM-5 criteria demonstrated agreement on 71% of observations, Frascati and Gisslén showed agreement on 80%, and DSM-5 and Gisslén criteria showed agreement on 46%, though reliability across the three criteria was poor. Only Frascati-defined neurocognitive impairment significantly predicted everyday functioning problems (p = .002, OR = 2.3[1.4, 3.8]). However, when both neurocognitive and complaint criteria were considered, the DSM-5 guidelines demonstrated significant relationships to everyday functioning, serostatus, and also increased reliability overtime compared to neurocognitive criteria alone (all ps < .05). A subset (n = 118) of the HIV+ group was assessed again after 14.0 (2.2) months. DSM-5 criteria evidenced significantly higher rates of incident neurocognitive disorder compared to both Frascati (p = .003) and Gisslén (p = .021) guidelines, while there were fewer remitting neurocognitive disorder diagnoses when Gisslén criteria were applied to the study sample compared to Frascati (p = .04). Future studies should aim to identify gold standard biological markers (e.g., neuropathology) and clinical outcomes associated with specific diagnostic criteria.

No support for premature central nervous system aging in HIV-1 when measured by cerebrospinal fluid phosphorylated tau (p-tau)

BACKGROUND

The prevalence of neurocognitive deficits are reported to be high in HIV-1 positive patients, even with suppressive antiretroviral treatment, and it has been suggested that HIV can cause accelerated aging of the brain. In this study we measured phosphorylated tau (p-tau) in cerebrospinal fluid (CSF) as a potential marker for premature central nervous system (CNS) aging. P-tau increases with normal aging but is not affected by HIV-associated neurocognitive disorders.

METHODS

With a cross-sectional retrospective design, p-tau, total tau (t-tau), neopterin and HIV-RNA were measured in CSF together with plasma HIV-RNA and blood CD4⁺ T-cells of 225 HIV-infected patients <50 y of age, subdivided into 3 groups: untreated neuroasymptomatic (NA) (n = 145), on suppressive antiretroviral treatment (cART) (n = 49), and HIV-associated dementia (HAD) (n = 31). HIV-negative healthy subjects served as controls (n = 79).

RESULTS

P-tau was not significantly higher in any HIV-infected group compared to HIV-negative controls. Significant increases in t-tau were found as expected in patients with HAD compared to NA, cART, and control groups (p < 0.001 ).

CONCLUSIONS

P-tau was not higher in HIV-infected patients compared to uninfected controls, thus failing to support a role for premature or accelerated brain aging in HIV infection.

The Chronicity of HIV Infection Should Drive the Research Strategy of NeuroHIV Treatment Studies: A Critical Review

HIV infection has become a chronic illness when successfully treated with combined antiretroviral therapy (cART). The long-term health prognosis of aging with controlled HIV infection and HIV-associated neurocognitive disorder (HAND) remains unclear. In this review, we propose that, almost 20 years after the introduction of cART, a change in research focus is needed, with a greater emphasis on chronicity effects driving our research strategy. We argue that pre-emptive documentation of episodes of mild neurocognitive dysfunction is needed to determine their long-term prognosis. This strategy would also seek to optimally represent the entire HAND spectrum in therapeutic trials to assess positive and/or negative treatment effects on brain functions. In the first part of the paper, to improve the standard implementation of the Frascati HAND diagnostic criteria, we provide a brief review of relevant quantitative neuropsychology concepts to clarify their appropriate application for a non-neuropsychological audience working in HIV research and wanting to conduct randomized clinical trials on brain functions. The second part comprises a review of various antiretroviral drug classes and individual agents with respect to their effects on HAND, while also addressing the question of when cART should be initiated to potentially reduce HAND incidence. In each section, we use recent observational studies and randomized controlled trials to illustrate our perspective while also providing relevant statistical comments. We conclude with a discussion of the neuroimaging methods that could be combined with neuropsychological approaches to enhance the validity of HIV neurology (neuroHIV) treatment effect studies.

Functional brain abnormalities during finger-tapping in HIV-infected older adults: a magnetoencephalography study

Despite the availability of combination antiretroviral therapy, at least mild cognitive dysfunction is commonly observed in HIV-infected patients, with an estimated prevalence of 35-70 %. Neuropsychological studies of these HIV-associated neurocognitive disorders (HAND) have documented aberrations across a broad range of functional domains, although the basic pathophysiology remains unresolved. Some of the most common findings have been deficits in fine motor control and reduced psychomotor speed, but to date no neuroimaging studies have evaluated basic motor control in HAND. In this study, we used magnetoencephalography (MEG) to evaluate the neurophysiological processes that underlie motor planning in older HIV-infected adults and a matched, uninfected control group. MEG is a noninvasive and direct measure of neural activity with good spatiotemporal precision. During the MEG recording, participants fixated on a central crosshair and performed a finger-tapping task with the dominant hand. All MEG data was corrected for head movements, preprocessed, and imaged in the time-frequency domain using beamforming methodology. All analyses focused on the pre-movement beta desynchronization, which is known to be an index of movement planning. Our results demonstrated that HIV-1-infected patients have deficient beta desynchronization relative to controls within the left/right precentral gyri, and the supplementary motor area. In contrast, HIV-infected persons showed abnormally strong beta responses compared to controls in the right dorsolateral prefrontal cortex and medial prefrontal areas. In addition, the amplitude of beta activity in the primary and supplementary motor areas correlated with scores on the Grooved Pegboard test in HIV-infected adults. These results demonstrate that primary motor and sensory regions may be particularly vulnerable to HIV-associated damage, and that prefrontal cortices may serve a compensatory role in maintaining motor performance levels in infected patients.

Epidemiological Aspects and World Distribution of HTLV-1 Infection

The human T-cell leukemia virus type 1 (HTLV-1), identified as the first human oncogenic retrovirus 30 years ago, is not an ubiquitous virus. HTLV-1 is present throughout the world, with clusters of high endemicity located often nearby areas where the virus is nearly absent. The main HTLV-1 highly endemic regions are the Southwestern part of Japan, sub-Saharan Africa and South America, the Caribbean area, and foci in Middle East and Australo-Melanesia. The origin of this puzzling geographical or rather ethnic repartition is probably linked to a founder effect in some groups with the persistence of a high viral transmission rate. Despite different socio-economic and cultural environments, the HTLV-1 prevalence increases gradually with age, especially among women in all highly endemic areas. The three modes of HTLV-1 transmission are mother to child, sexual transmission, and transmission with contaminated blood products. Twenty years ago, de Thé and Bomford estimated the total number of HTLV-1 carriers to be 10-20 millions people. At that time, large regions had not been investigated, few population-based studies were available and the assays used for HTLV-1 serology were not enough specific. Despite the fact that there is still a lot of data lacking in large areas of the world and that most of the HTLV-1 studies concern only blood donors, pregnant women, or different selected patients or high-risk groups, we shall try based on the most recent data, to revisit the world distribution and the estimates of the number of HTLV-1 infected persons. Our best estimates range from 5-10 millions HTLV-1 infected individuals. However, these results were based on only approximately 1.5 billion of individuals originating from known HTLV-1 endemic areas with reliable available epidemiological data. Correct estimates in other highly populated regions, such as China, India, the Maghreb, and East Africa, is currently not possible, thus, the current number of HTLV-1 carriers is very probably much higher.

Platelet decline as a predictor of brain injury in HIV infection

An association between platelet decline and increased risk of progression to dementia has been observed in an advanced HIV infection cohort study. This investigation evaluated the prognostic significance of platelet decline for dementia, for psychomotor slowing, and for brain injury, as quantified in vivo, in a much larger population of HIV+ men. Platelet counts and neurocognitive data were available from biannual visits of 2,125 HIV+ men participating in the prospective, Multicenter AIDS Cohort Study from 1984 to 2009. Brain volumetric data were also available from an imaging substudy of 83 seropositive participants aged 50 and older. The association of platelet counts with neurocognitive outcome was assessed using Cox proportional hazard models where change in platelet count from baseline was a time-updated variable. Marked platelet decline was associated with increased risk of dementia in univariate analysis (hazard ratio [HR] = 2.5, 95% confidence interval [CI] = 1.8-3.5), but not after adjustment for CD4 cell count, HIV viral load, age, study site, hemoglobin, race, education, smoking, and alcohol use (HR = 1.4, 95% CI = 0.78-2.5). Platelet decline did not predict psychomotor slowing in either univariate (HR = 0.79, 95% CI = 0.58-1.08) or multivariate (HR = 1.10, 95% CI = 0.73-1.67) analysis. Analysis of brain volumetric data, however, indicated a relationship between platelet decline and reduced gray matter volume fraction in univariate (p = 0.06) and multivariate (p < 0.05) analyses. Platelet decline was not an independent predictor of dementia or psychomotor slowing, after adjusting for stage of disease. Findings from a structural brain imaging substudy of older participants, however, support a possible relationship between platelet decline and reduced gray matter.

Characterization of HIV-Associated Neurocognitive Disorders among individuals starting antiretroviral therapy in South Africa

HIV-Associated Neurocognitive Disorders (HAND) exert an impact on everyday functions, including adherence. The prevalence of and risk factors for HAND in patients commencing anti-retroviral therapy in Southern Africa are unknown. Participants from primary care clinics in Cape Town, South Africa underwent detailed neuropsychological, neuropsychiatric, and neuromedical evaluation. Using the updated American Academy of Neurology (AAN) criteria, participants were classified into categories of HAND, and demographic and clinical risk factors for HIV-dementia (HIV-D) were assessed. The prevalence of mild neurocognitive disorder (MND) and HIV-D were 42.4 and 25.4%, respectively. There were significant associations between lower levels of education and older age with HIV-D, and a trend to association with HIV-D and lower CD4 count. In a regression model, a lower level of education and male gender were predictive of HIV-D. These findings suggest that HAND are highly prevalent in primary care settings in South Africa where clade C HIV is predominant.

Comparison of scales to evaluate the progression of HIV-associated neurocognitive disorder

AIM: First, to compare the characterization of neurocognitive deficits in milder stages of HIV-associated neurocognitive disorder (HAND) derived from existing dementia rating scales of the American Academy of Neurology (AAN) and Memorial Sloan Kettering (MSK) with the 2007 consensus ('Frascati') classification. Second, to identify potential sociodemographic and clinical predictors of HAND progression during 1-year follow-up. METHODS: 104 HIV-infected subjects in an existing cohort system were evaluated with a medical history, exam, neuropsychological test battery and functional assessments. The degree of HAND was rated using the AAN, MSK and Frascati scales. The degree of concordance among these scales was determined. In addition, 45 subjects were reassessed for changes in their neurocognitive status at 1-year follow-up. Associations between age, education, sex, depression ratings, substance abuse, race, hepatitis C serostatus, CD4 count and progression of HAND were examined. RESULTS: There was excellent concordance (gamma > 0.8) among the Frascati, MSK and AAN ratings. Subjects rated as having minor cognitive motor disorder on the AAN scale (n = 45) were evenly split between Frascati rating of asymptomatic neurocognitive impairment (n = 24) and mild neurocognitive disorder (n = 21). At 1-year follow-up of 45 subjects, 31% had worsened, 13% had improved and 56% were stable. Predictors of progression included age older than 50 years (odds ratio: 5.57; p = 0.013) and female gender (odds ratio: 3.13; p = 0.036). CONCLUSION: The Frascati HAND rating scale has excellent concordance with previous neurocognitive rating scales and can be used to better characterize milder stages of cognitive impairment. Older individuals and women appeared to be more likely to show neurocognitive progression.

Neurological disease: the effects of HIV and antiretroviral therapy and the implications for early antiretroviral therapy initiation

PURPOSE OF REVIEW

The purpose of this review is to examine the literature regarding HIV-associated neurocognitive disorders, early HIV infection of the central nervous system (CNS), the role of the peripheral immune system in controlling HIV infection and disease within the brain and the potential role that early antiretroviral treatment may play in the preservation of neurocognitive health in patients with more than 500 CD4+ cells/microl.

RECENT FINDINGS

In the post highly active antiretroviral therapy (HAART) era, HIV-associated neurocognitive disorders remain prevalent and even mild-moderate immunosuppression carries a risk for the development of HIV-associated dementia. HIV infection of the CNS occurs early in the illness, and data suggest that a robust peripheral immune system is key to the long-term control of CNS HIV infection. HAART results in clinical, neuropsychological and neuroradiological improvement in patients with HIV-associated neurocognitive disorders, and the prescription of HAART regimens with good cerebrospinal fluid penetration appears to be preferable in this setting. There is little evidence that HAART causes CNS toxicity. The benefits and risks of HAART in the preservation or enhancement of neurocognitive function in well, HIV-infected patients with more than 500 CD4+ cells/microl are unknown.

SUMMARY

The prescription of HAART in well, HIV-infected patients with high CD4+ cell counts may afford enhanced control of CNS HIV infection as a result of the benefits of HAART upon peripheral immune function. In turn, this may result in superior or preserved neurocognitive performance in comparison to the current practice of commencing HAART when CD4+ cells reach 350 cells/microl or lower. This hypothesis will be tested in an upcoming randomized clinical trial.

Correlations between computerized battery testing and a memory questionnaire for identification of neurocognitive impairment in HIV type 1-infected subjects on stable antiretroviral therapy

Neurocognitive impairment (NCI) remains prevalent in the highly active antiretroviral therapy (HAART) era. Memory function is commonly affected. There is a need for a rapid, but sensitive screening tool. This study compares the Prospective and Retrospective Memory Questionnaire (PRMQ) and a computerised battery cognitive assessment to establish if the questionnaire has potential as a rapid screening tool for HIV-associated NCI. Neurologically asymptomatic patients with an undetectable HIV viral load on stable HAART were eligible to participate. Asymptomatic NCI (aNCI) was defined as a performance score more than 1SD below the normative mean in at least two domains of the computerised test. Memory impairment (MI) was defined as a t-score more than 1 SD below the normative mean using the PRMQ. Forty-five subjects participated. The mean age was 48 years (SD 11), the mean CD4 count was 546 cells/mul (SD 271), and 84% were male. Of subjects, 14/45 (24%) had NCI and 15/45 (33%) had MI. Two subjects had both types of impairment. No significant association was found between the presence of aNCI and MI (p = 0.229, r = 0.18, 95% CI -1.2, 0.23). aNCI was statistically significantly associated with younger age (p = 0.38, r = 0.31, 95% CI -0.02, 0.001). MI was statistically significantly associated with the set-shifting cognitive domain of the computerized battery (p = 0.04, r = 0.326) and time elapsed since HIV diagnosis (p = 0.035, r = 0.316). High rates of asymptomatic NCI were observed in this cohort, especially in younger individuals. The memory questionnaire did not reliably identify HIV-associated NCI other than executive function deficits and based on our data should therefore not be used as a rapid screening tool for this purpose.

Osteopontin is increased in HIV-associated dementia

Since the introduction of highly active antiretroviral therapy, survival rates for human immunodeficiency virus (HIV) infection have markedly improved, but less of an effect has been found for HIV-associated neurocognitive disorders. On the basis of our previous findings, we hypothesized that increased production of osteopontin might contribute to the persistence of central nervous system (CNS) dysfunctions. We found increased levels of osteopontin in the brains of humans with HIV encephalitis and monkeys with simian immunodeficiency virus (SIV) encephalitis. In cerebrospinal fluid, osteopontin levels were found to be elevated in HIV-infected individuals, regardless of their neuropsychological status. However, plasma osteopontin levels were significantly increased in individuals with HIV-associated dementia. In addition, a longitudinal study of monkeys revealed that plasma levels of osteopontin increased before the development of SIV-induced neurological and clinical abnormalities. Thus, plasma levels of osteopontin are significantly correlated with HIV-induced CNS dysfunction in the current era of efficacious antiviral treatment, and this finding suggests that the development of interventions to modulate osteopontin production or signaling might be beneficial in the prevention or treatment of HIV-induced CNS disorders.

Evolution of HIV dementia with HIV infection

Dementia remains one of the most fearsome complications of HIV infection. It also poses a significant challenge for the clinician both in terms of diagnosis and treatment. The use of antiretroviral agents has led to a decrease in the incidence of HIV dementia but the prevalence of milder forms of neurocognitive impairment has increased. Occasionally, the immune reconstitution caused by these agents may target the brain leading to a syndrome characterized by a severe, progressive and often fatal dementia. The progression of HIV dementia may also be determined by host and viral genetic factors, and the existence of co-morbid factors such as drug abuse, hepatitis C infection and aging. Oxidative stress markers appear to be predictive of active dementia. However, currently there is no specific treatment available for HIV dementia.

Phenotypic and genotypic comparisons of human T-cell leukemia virus type 1 reverse transcriptases from infected T-cell lines and patient samples

It is well established that cell-free infection with human T-cell leukemia virus type 1 (HTLV-1) is less efficient than that with other retroviruses, though the specific infectivities of only a limited number of HTLV-1 isolates have been quantified. Earlier work indicated that a post-entry step in the infectious cycle accounted for the poor cell-free infectivity of HTLV-1. To determine whether variations in the pol gene sequence correlated with virus infectivity, we sequenced and phenotypically tested pol genes from a variety of HTLV-1 isolates derived from primary sources, transformed cell lines, and molecular clones. The pol genes and deduced amino acid sequences from 23 proviruses were sequenced and compared with 14 previously published sequences, revealing a limited number of amino acid variations among isolates. The variations appeared to be randomly dispersed among primary isolates and proviruses from cell lines and molecular clones. In addition, there was no correlation between reverse transcriptase sequence and the disease phenotype of the original source of the virus isolate. HTLV-1 pol gene fragments encoding reverse transcriptase were amplified from a variety of isolates and were subcloned into HTLV-1 vectors for both single-cycle infection and spreading-infection assays. Vectors carrying pol genes that matched the consensus sequence had the highest titers, and those with the largest number of variations from the consensus had the lowest titers. The molecular clone from CS-1 cells had four amino acid differences from the consensus sequence and yielded infectious titers that were approximately eight times lower than those of vectors encoding a consensus reverse transcriptase.

The neuropsychological profile of symptomatic AIDS and ADC patients in the pre-HAART era: a meta-analysis

It remains essential to document the neuropsychological profile of acquired immunodeficiency syndrome (AIDS) dementia complex (ADC) and minor forms human immunodeficiency virus (HIV)-associated neurocognitive impairment by quantifying the magnitude of impairment across eras of treatment. Indeed, with the introduction of the highly active antiretroviral therapy (HAART), there is evidence of changes in aspects of ADC. To allow quantitative and qualitative comparisons with the HAART era studies, we developed a summary of neuropsychological performance acquired in pre-HAART era studies in advanced HIV infection and ADC. Using a meta-analytical procedure and a test nomenclature that accounts for task complexity, we found that individuals with symptomatic infection (but no AIDS) demonstrated a global mild level of cognitive impairment, except for the domains complex attention/psychomotor speed, motor coordination, and learning, which showed moderate impairment. Individuals with AIDS demonstrated a global moderate level of cognitive impairment with a predominance of deficits in attention, complex attention/psychomotor speed, learning, motor coordination, with additional deficits in verbal memory and reasoning. Individuals with ADC demonstrated the most severe cognitive disturbances in domains of learning, motor coordination, with additional deficits in veibal fluency and verbal memory. Moderate impairment was evidenced in domains of complex attention/psychomotor speed, whereas naming and visuospatial functions were relatively preserved. The profile of deficits in ADC suggests that it may not be only interpreted as a worsening form of the impairment that is seen in the AIDS and symptomatic stages of HIV disease but that there are also additional deficits suggestive of an alternate pathogenetic process(es).

Aquaporin 4 is increased in association with human immunodeficiency virus dementia: implications for disease pathogenesis

Changes in astrocyte shape and function are known to occur in association with human immunodeficiency virus (HIV) dementia (HIVD). However, the causes and consequences of such changes are not completely understood. In vitro data suggest that changes in the expression of aquaporin 4 (AQP4), the aquaporin subtype expressed by astrocytes, can significantly influence cell shape and physiology. In the present study, the authors therefore investigated the possibility that AQP4 levels may be altered in HIVD. Using Western blot, the authors show that immunoreactivity for AQP4 is elevated in brain homogenates from the mid frontal gyrus of patients who died with HIVD (P < .005 HIV seronegative versus HIVD). Of interest, a significant increase was also observed in homogenates from HIV-infected individuals without dementia (P < .05 HIV seronegative versus neurologically normal HIV seropositive). In the present study the authors also examined the stimulated expression of AQP4 in cultured cells. Previous in vitro studies have shown that AQP4 expression may be increased by stimuli that induce cytoskeletal changes and/or the activation of p38 mitogen-activated protein (MAP) kinase. The authors therefore focused on tumor necrosis factor (TNF)-alpha, which has been linked to p38 MAP kinase activation, and thrombin, which may also induce changes in the actin cytoskeleton. Both may be elevated with HIVD. Again using Western blot, the authors show an increase in both AQP4 and phosphorylated p38 MAP kinase in homogenates from TNF-alpha- and thrombin-stimulated organotypic cerebellar and spinal cord cultures. Together, these studies suggest that AQP4 expression may be altered in HIVD and/or in response to exogenous proteinases. Additional studies may be warranted to determine whether altered AQP4 expression represents a protective and/or maladaptive response to central nervous system (CNS) inflammation.

The signaling and apoptotic effects of TNF-related apoptosis-inducing ligand in HIV-1 associated dementia

HIV-1 Associated Dementia (HAD) develops during progressive HIV-1 infection and is characterized by cognitive impairments, behavioral disorders and potential progressive motor abnormality. Abnormal inflammation within the central nervous system (CNS), activation of macrophage/microglia and involvement of proinflammatory cytokines have been suggested as primary factors in the pathogenesis of HAD. Impairment of neuronal function and neuronal cell death are believed to be the end pathophysiological result of HAD. TNF-related apoptosis-inducing ligand (TRAIL), a member of the TNF family of cytokines, was suggested to participate in apoptotic cell death during HAD. As a death ligand, TRAIL was originally thought to target only tumor cells. TRAIL is not typically present in CNS; however, emerging data show that TRAIL can be induced by immune stimuli on macrophage and microglia, major disease effector cells during HAD. Upregulated TRAIL may then cause neuronal apoptosis through direct interaction with TRAIL receptors on neurons or through macrophage death-mediated release of neurotoxins. In this review, we summarize the pivotal role of TRAIL in HAD and TRAIL-initiated intracellular death cascades that culminate in neuronal apoptosis as observed in HAD.

Tropical Spastic Paraparesis/Human T Leukemia Virus Type 1--Associated Myelopathy in HIV Type 1--Coinfected Patients

BACKGROUND

Tropical spastic paraparesis/human T leukemia virus type 1 (HTLV-1)-associated myelopathy (TSP/HAM) is rarely reported in the United States. The causative agents of TSP/HAM are HTLV-1 and, possibly, its cosmopolitan variant, human T leukemia virus type 2 (HTLV-2). Among HTLV-1- or HTLV-2-monoinfected individuals, the estimated lifetime risk for development of TSP/HAM is <2%. However, it has been suggested that HIV/HTLV coinfection may increase the risk for development of TSP/HAM.

METHODS

A total of 2239 human immunodeficiency virus (HIV)-infected patients were tested for HTLV-1 and HTLV-2 infection at the New Orleans Outpatient Clinic (Louisiana) during the period 1991-1998. HTLV-1-infected patients with suspected myelopathy were referred for additional evaluation.

RESULTS

Four cases of TSP/HAM (9.7%) were identified among 41 individuals with Western blot-confirmed HTLV-1 infection. The diagnosis was confirmed with use of molecular diagnostic assays and viral isolation. No TSP/HAM cases were identified among 65 patients with HIV-HTLV-2 coinfection. An additional patient with HIV-HTLV-1 coinfection also received a diagnosis of TSP/HAM at the New Orleans Veteran's Affairs HIV Outpatient Clinic (Louisiana). All patients had normal CD4+ T cell counts at the time of diagnosis.

CONCLUSIONS

Given the high rates of HIV-HTLV coinfection in the United States, a heightened suspicion for TSP/HAM should be considered in HIV-infected patients who present with normal CD4+ T cell counts and myelopathy in the absence of other acquired immunodeficiency syndrome-defining conditions.

Cerebrospinal fluid HIV viral load in different phases of HIV-associated brain disease

We compared CSF HIV viral load in 33 asymptomatic HIV seropositive patients, 11 patients with incipient minor motor deficits (MMD), 11 patients with sustained MMD, and 16 patients with HIV-associated dementia. Patients with incipient MMD showed significantly higher CSF viral load than asymptomatic patients. Demented patients also had higher CSF viral loads than asymptomatic patients. This phenomenon is independent of antiretroviral therapy. Thus, correlation of viral load with time suggests a multiphasic course of HIV-associated CNS disease.

Psychomotor slowing in hepatitis C and HIV infection

BACKGROUND

Both HIV and hepatitis C virus (HCV) may enter the central nervous system and cause cognitive and/or motor dysfunction. There are limited data on cognition and no data on motor performance in HIV/HCV-coinfected patients.

OBJECTIVE

To provide data on cognition and motor performance in HIV/HCV infected patients.

METHODS

We compared 43 HIV-seropositive but HCV-seronegative patients, 43 HIV/HCV-coinfected patients, and 44 HIV-negative but HCV-positive patients, all of whom went through neuropsychologic testing and electrophysiologic assessment of basal ganglia-mediated motor function.

RESULTS

No significant differences could be found among the groups with regard to premorbid verbal and actual nonverbal intelligence, attention, and memory; the HIV dementia scale; and all somatic and most psychiatric complaints. Affective disorders were less frequent in HIV-negative but HCV-positive patients. This group also scored lower for depression. For all 3 groups, significant pathologic slowing of most rapid alternating movements (right hand) compared with those of HIV/HCV-negative controls as well as significantly prolonged contraction times (both hands) could be diagnosed. Simple reaction times were significantly prolonged only in HIV/HCV-coinfected patients.

CONCLUSIONS

Although clinically asymptomatic, both HIV-positive and HCV-positive patients may show affective disturbances and significant psychomotor slowing. A potential predictive value for the further course of infection, which is well established in HIV-positive patients, remains to be investigated in HCV-positive or HIV/HCV-coinfected patients.

HIV dementia patients exhibit reduced viral neutralization and increased envelope sequence diversity in blood and brain

OBJECTIVES

To examine the relationship between the humoral immune response and viral envelope diversity among HIV/AIDS patients with or without HIV-associated dementia (HAD).

METHODS

Whole blood and sera were collected from age- and disease-progression matched AIDS-defined patients with and without neuro-cognitive impairment at two centers. Peripheral blood mononuclear cells were isolated from whole blood and separated into monocyte/macrophage and peripheral blood lymphocyte (PBL) preparations. Genomic DNA, isolated from the PBL population, was used as template to amplify HIV-1 C2V3 envelope sequences in a nested PCR protocol. The resulting fragments were sequenced and subjected to a phylogenetic analysis.

RESULTS

Sera from non-demented (ND; n = 21) patients neutralized infection of CCR5-dependent, but not CXCR4-dependent viruses, more efficiently than sera from HAD patients (n = 15) (P < 0.05). A recombinant virus containing a brain derived C2V3 sequence was also neutralized less efficiently by sera from HAD patients ( < 0.05). C2V3 envelope sequences amplified from PBL revealed significantly greater diversity within the V3 region from HAD compared with ND patients (P < 0.001). The number of non-synonymous substitutions was positively correlated with the severity of neuro-cognitive impairment of patients (P < 0.005). Similarly, brain derived V3 sequences exhibited significantly increased diversity among HAD patients (P < 0.001).

CONCLUSION

Our findings imply that HAD patients exhibited impaired serological responses that may lead to the emergence of viral mutants that potentially could infect the brain and mediate neurodegeneration.

Therapeutic effects of nucleoside analogues on psychomotor slowing in HIV infection

OBJECTIVE

Since psychomotor slowing predicts the development of HIV-1-associated dementia, AIDS and death independently of the immune status, there is urgent need for a neurological therapeutic rationale.

METHODS

The therapeutic efficacy of nucleoside analogues with different abilities to penetrate into the cerebrospinal fluid was assessed in 410 HIV-1-seropositive patients using the results of detailed fine motor tests, which detect minor motor deficits. Patients were selected who showed pathological psychomotor slowing as signs of central nervous system (CNS) dysfunction before therapy onset and who were then treated only with nucleoside analogues for at least 6 months.

RESULTS

Both zidovudine and didanosine improve CNS function to an equal degree when given as monotherapy. Adding a second nucleoside analogue (didanosine, lamivudine, zalcitabine) to zidovudine does not further improve psychomotor performance. However, adding a second nucleoside after a period of zidovudine monotherapy does result in a second but less remarkable therapeutic effect. Combinations containing stavudine are as effective as those including zidovudine when given as first antiretroviral treatment. Furthermore, stavudine effectively improves motor performance even after pretreatment with zidovudine.

Outcome of patients with HIV-1-related cognitive impairment on highly active antiretroviral therapy

OBJECTIVE

To examine the impact of highly active antiretroviral therapy (HAART) on the outcome of HIV-1-related cognitive impairments using a neuropsychological (NP) battery to assess separately the psychomotor, executive function and memory fields.

DESIGN

A longitudinal study of HIV-1-infected patients based on serial NP tests in a Paris University Hospital.

METHODS

A group of 91 HIV-1-infected patients, of whom 47 were already taking HAART at their first NP examination, were initially categorized as cognitively impaired (n = 53) or non-impaired (n = 38) and underwent one to six serial NP batteries (mean follow-up 12.3+/-8.3 months). Generalized estimating equations (GEE) were used to evaluate performance in a given NP test according to the number of days on HAART.

RESULTS

Despite a 25% mortality rate among patients who had cognitive impairment at their first NP examination, GEE showed a positive relationship between the duration of HAART and cognitive performance. Performance in psychomotor tests (e.g. Purdue Pegboard dominant hand) improved continuously during the study period, while memory test performance (e.g. Grober and Buschke free recall) tended to reach a plateau.

CONCLUSIONS

HAART improves subcortical cognitive functions during the first year of treatment. Distinct neuropathological mechanisms appear to underlie psychomotor and memory dysfunctions in AIDS.

HAART is neuroprophylactic in HIV-1 infection

BACKGROUND

To find out about the prophylactic value of antiretroviral therapy on HIV-1-associated subclinical and clinical psychomotor slowing as one marker of HIV-1-associated CNS disease.

METHODS

Prospective study with regular clinical and neurophysiologic examination every three months of 1482 consecutive HIV-1-seropositive and AIDS patients seen at our department till June 30, 1999.

RESULTS

Antiretroviral therapy has a significant prophylactic value over an individual observation period of ten years with regard to the first, potentially transient manifestation of HIV-1-associated subclinical psychomotor slowing and with regard to the clinical manifestation of motor signs. However, a subgroup of patients is characterized through a second, more sustained manifestation of subclinical psychomotor slowing which cannot be prevented by any type of currently available antiretroviral therapy.

CONCLUSIONS

These findings suggest the existence of different pathomechanisms underlying HIV-1-associated brain disease which may in part be effectively prevented, but which in part also escape all antiretroviral treatment strategies in use today.

On the etiology of tropical spastic paraparesis and human T-cell lymphotropic virus-I-associated myelopathy

The purpose of this review is to present some concepts on the etiology of tropical spastic paraparesis or human T-cell lymphotropic virus-I (HTLV-I)-associated myelopathy (TSP/HAM). The large number of syndromes that have been associated with HTLV-I (60 to date), the existence of TSP/HAM cases associated with other retroviruses (human immunodeficiency virus-2 [HIV-2], HTLV-II), the existence of many TSPs without HTLV-I, and the evidence of clear epidemiologic contradictions in TSP/HAM indicate that the etiopathogenesis of TSP/HAM is not yet clear. Tropical spastic paraparesis/HAM affects patients of all human ethnic groups, but usually in well localized and relatively isolated geographic regions where HTLV-I has been endemic for a long time. Environmental factors and geographic locations appear to be critical factors. Because the neuropathology of TSP/HAM suggests a toxometabolic, rather than a viral cause, it is proposed that an intoxication similar to neurolathyrism could account for some of TSP/HAM cases, mainly in tropical and subtropical countries. If this were the case, HTLV-I could be a cofactor or act as a bystander. it is possible that co-infection with another agent is necessary to produce TSP/HAM and most of the syndromes associated with HTLV-I.

Simple and choice reaction time performance in SIV-infected rhesus macaques

It is well established that HIV infection can lead to motor/cognitive disorders in humans. A number of studies have shown that simian immunodeficiency virus (SIV) infection in rhesus macaques parallels many aspects of HIV disease in humans. The purpose of this study was to define further the SIV-infected rhesus macaque as a model of neuro-AIDS. Our objective was to detect movement-related impairments in behaviorally trained, SIV-infected macaques using both simple and choice reaction time tasks. Reaction times (RTs), movement times (MTs), and error types were examined. Nine monkeys were infected with neurovirulent strains of SIVmac, four of which served initially as controls before their inoculation. Seven of the nine monkeys developed simian AIDS within 4 months of inoculation (rapid progressors), while two monkeys survived for more than 1 year postinoculation (slow progressors). Of the rapid progressors, four exhibited slowed reaction times and six showed movement time slowing. One rapid progressor showed evidence of a strategy shift to overcome impaired motor abilities. Monkeys with rapidly progressing SIV-related disease consistently show behavioral abnormalities reflecting underlying neuronal injury. Although the slow progressors also showed RT and/or MT slowing, a role for nonspecific factors related to late-stage simian AIDS could not be ruled out in these cases. The results demonstrate that motor impairments associated with SIV infection in rhesus macaques can be detected using RT and MT measures, further establishing the SIVmac-infected macaque monkey as a viable model of neuro-AIDS.

HIV neuropathogenesis and therapeutic strategies

Human immunodeficiency virus (HIV)-1 neuropathogenesis can be divided into three important components: (i) virus entry into the nervous system; (ii) the role of viral proteins and/or cellular products in neural tissue damage; (iii) the mechanisms of neuronal injury/death. Both blood derived macrophages or trafficking HIV-1 infected T-lymphocytes have been implicated in viral entry to the central nervous system (CNS). The major cell type harboring productive HIV-1 infection in the nervous system is the perivascular macrophage/microglia. The HIV-1 infection of brain astrocytes, restricted to the expression of regulatory gene products, may cause astrocyte dysfunction and contribute to neuronal injury or to disruption of the blood-brain barrier (BBB). Studies of cerebrospinal fluid and postmortem tissues reveal chronic inflammation/immune activation in the nervous system during the later stages of HIV-1 infection associated with disruption of BBB integrity. Blood-brain barrier damage may underlie the white matter pallor described in HIV-1 infection and could result in further entry into the CNS of toxic viral or cellular products, or additional HIV-1 infected cells. The HIV infected and activated macrophages/microglia produce excessive amounts of pro-inflammatory cytokines, including tumor necrosis factor alpha, and platelet activating factor. These products are directly toxic to human neurons in vitro. The HIV-1 envelope glycoprotein, gp 120 may stimulate the release of toxic factors from brain macrophages. Blocking N-methyl-D-aspartate (NMDA; or AMPA) glutamate receptors can antagonize candidate toxins of both viral and cellular origin. It has been postulated that (weak) excitotoxicity leads to oxidative stress in neurons and ultimately to apoptosis. Neuronal apoptosis occurs in the brains of both children and adults with HIV-1 infection. This understanding of HIV neuropathogenesis implies that therapeutic strategies should include: (i) anti-retroviral medications to decrease systemic and CNS virus load, and possibly to prevent perinatal transmission of HIV; (ii) anti-inflammatory compounds to decrease the chronic immune activation in microglia and allow the restoration of BBB integrity; and (iii) neuroprotective compounds to reduce neuronal injury and apoptotic death.

Axonal sprouting in hippocampus of cats infected with feline immunodeficiency virus (FIV)

Neurologic dysfunction and neuropathology are common findings in patients infected with HIV and in cats infected with feline immunodeficiency virus (FIV). The pathogenesis of lentivirus-associated alterations in the central nervous system (CNS) is multifactorial. Because seizures, alterations in memory, and behavioral changes are clinical manifestations in adults and children infected with HIV, we explored the possibility that changes in neuronal structure may occur in the hippocampus. To do this, we examined the dentate gyrus of FIV-infected cats, an animal model of HIV infection. Neuropathologic findings included gliosis within the hilus of the dentate gyrus and granule cell axonal sprouting. Using the Timm's method, which labels axons of dentate gyrus granule cells, abnormally high amounts of staining were observed in the inner one third of the molecular layer in 45% of FIV-infected cats (n = 11) and in none of the controls (n = 19). Prominent axonal sprouting was seen in three FIV-infected cats that were infected as kittens, suggesting that younger cats may be more susceptible. Axon reorganization of the dentate granule cells has been hypothesized to underlie complex partial seizure activity in human temporal lobe epilepsy. These results suggest that FIV infection causes granule cell axon reorganization in the hippocampus of cats. A similar neuropathogenetic mechanism may contribute to neurologic dysfunction in HIV-infected patients.

Cortical cell loss in asymptomatic cats experimentally infected with feline immunodeficiency virus

Specific pathogen-free cats experimentally infected with feline immunodeficiency virus (FIV) were used to evaluate the development of central nervous system changes during the asymptomatic stages of viral infection. The brains of asyptomatic cats were examined at postinoculation times ranging from 8 weeks to 3 years for changes in neuron density, glutamate receptor density, and synaptophysin immunoreactivity. At 2-3 years postinoculation a small decrease in neuronal density was found in layers 2-3 and layer 5 of the frontal cortex (-14.4%), parietal cortex (-18.1%), and striatum (-29.5%). The only other indications of pathology within these regions were a mild diffuse astrogliosis, occasional microglial nodules, and the accumulation of satellite cells around selected neurons. An average loss of large neurons of 56-68% was seen in the cortex of four random source cats euthanized with AIDS. These values contrasted with the absence of any significant cell loss in FIV-infected cats 18 weeks after inoculation or FIV-negative controls. The loss of neurons in the asymptomatic cats showed a significant positive correlation with a decrease in the blood CD4:CD8 ratios. Morphometric evaluation of synaptic terminal densities immunocytochemically stained with synaptophysin revealed a significant increase in the asymptomatic cats at 2-3 years postinoculation that correlated negatively with the CD4:CD8 ratios. Random source AIDS cats showed a 34% decrease in synaptophysin-immunoreactive profiles. Glutamate binding in the cortex did not change significantly in the asymptomatic cats (4-7% decline). Thus, experimentally infected specific pathogen-free cats show a loss of cortical neurons similar to what has been observed in postmortem studies of humans infected with HIV. The detection of neuronal loss during the asymptomatic stage of disease and the correlation with the peripheral CD4:CD8 cell ratios indicate that neurodegeneration may progress in parallel with peripheral disease.

Immunologic NO synthase: elevation in severe AIDS dementia and induction by HIV-1 gp41

Indirect mechanisms are implicated in the pathogenesis of the dementia associated with human immunodeficiency virus-type 1 (HIV-1) infection. Proinflammatory molecules such as tumor necrosis factor alpha and eicosanoids are elevated in the central nervous system of patients with HIV-1-related dementia. Nitric oxide (NO) is a potential mediator of neuronal injury, because cytokines may activate the immunologic (type II) isoform of NO synthase (iNOS). The levels of iNOS in severe HIV-1-associated dementia coincided with increased expression of the HIV-1 coat protein gp41. Furthermore, gp41 induced iNOS in primary cultures of mixed rat neuronal and glial cells and killed neurons through a NO-dependent mechanism. Thus, gp41-induced NO formation may contribute to the severe cognitive dysfunction associated with HIV-1 infection.

AIDS Dementia and HIV-1-Induced Neurotoxicity: Possible Pathogenic Associations and Mechanisms

AIDS Dementia Complex (ADC) is a syndrome of cognitive, behavioral, and motor deficits resulting from HIV-1 infection within the brain. ADC is characterized by variable degrees of neuronal cell death and gliosis that likely result, at least, in part from release of metabolic products, cytokines, and viral proteins from infected macrophages, although a unifying explanation for the neurological dysfunction has yet to be established. Major unanswered questions include: (i) do neurologic symptoms result from neuronal cell death and/or dysfunction in surviving neurons?; (ii) are viral genomic sequences determinants of neurotoxicity?; (iii) is HIV infection of neurons and astrocytes relevant to pathogenesis?, and (iv) what circulating factors within the brain affect neuronal cell survival and function? This review addresses the association between HIV-1 replication within the brain, production of potential neurotoxins and possible mechanisms of induction of neurotoxicity and neuronal dysfunction contributing to the pathogenesis of ADC. Copyright 1996 S. Karger AG, Basel

Prevalence of HTLV type I infection in Iran: a serological and genetic study

Several publications describe the presence of the human T cell lymphotropic virus type I (HTLV-I) in Jewish individuals born in Mash-had, Iran. We report here the results of HTLV-I serological and genetic studies in the non-Jewish population of Mash-had as well as a neighboring area: Gonbad-Kavous. Seven hundred and seven serum samples from Mash-had (694 healthy individuals and 13 patients with lymphoma) and 90 from Gonbad-Kavous were tested for HTLV antibodies by gelatin particle agglutination assay (PA) and confirmatory Western blots (WBs). Seropositive rates of 3.0% (21 of 694) in Mash-had, 0% (0 of 90) in Gonbad-Kavous, and 100% (13 of 13) in lymphoma cases were observed. HTLV-I DNA sequence were amplified by polymerase chain reaction directly from the fresh PBMCs of seropositive individuals. Phylogenetic analysis of the viral DNA sequence indicated that the HTLV-I present in Mash-had belong to the HTLV-I cosmopolitan clade. Altogether, these data indicate that Mash-had, located in northeastern Iran, is a newly recognized endemic center for HTLV-I.

Unraveling the neuroimmune mechanisms for the HIV-1-associated cognitive/motor complex

Infection of the brain with human immunodeficiency virus 1 (HIV-1) often leads to the devastating loss of mental faculties. Surprisingly, HIV-1 elicits such brain dysfunction without significantly infecting neurons, astrocytes and oligodendroglia. The target for HIV-1 in the brain is the macrophage, which usually functions as a phagocytic, antigen-presenting and immune-regulatory cell. How can these cells produce such serious cognitive and motor brain impairments? Here, Hans Nottet and Howard Gendelman propose that HIV-1 penetrates the blood-brain barrier inside differentiating macrophages, which become immune activated once inside the brain, and secrete high levels of neurotoxins. Chronic, subclinical disease results by astrocyte regulation of macrophage effector functions. Ultimately, endogenous control mechanisms break down, leading to motor and mental impairments in some affected subjects.

HTLV-I associated tropical spastic paraparesis. Cerebral spinal fluid evolutive aspects in 128 cases

In order to evaluate if there is variation on the intensity of cerebral spinal fluid (CSF) response during HTLV-I associated tropical spastic paraparesis (TSP) evolution we retrospectively reviewed 128 cases. The results indicate that although CSF inflammatory alterations can persist over a 10-year period, they tend to become slight or even absent after the second year of TSP evolution.

Feline immunodeficiency virus as a model for study of lentivirus infection of the central nervous system

Feline immunodeficiency virus infects the CNS and results in predictable pathophysiology strikingly similar to that seen with HIV-1 infection of humans. The observed pathophysiology is mimicked in several physiologically assessed modalities, further supporting the validity of the feline model. Peripheral and control evoked potential findings and the occurrence of the sleep architecture changes in both cat and human disease provide an intriguing focus for further investigation. Although structurally diverse in an absolute sense, FIV and HIV-1 share basic structural features and commonalities of their life cycle. It is likely that by understanding the common mechanisms by which these lentiviruses influence CNS function, a more complete understanding of the neurological deficits seen in HIV-1 infected patients will be obtained. The cat model is particularly valuable for study of CNS disease, since it allows detailed analyses of events during the acute phase of infection, under circumstances in which the nature and timing of the infection are carefully controlled. The availability of molecular clones for mutational analysis will facilitate mapping of genomic regions critical to the perturbation of CNS function. It is suggested that development of intervention strategies in the cat model will yield treatment modalities directly applicable to HIV-1 infection of humans.

Human T-cell lymphotrophic virus type-I (HTLV-I) retrovirus and human disease

Human T-cell lymphotrophic virus type-I (HTLV-I) was the first pathogenic retrovirus identified in humans. HTLV-I is now linked to a number of clinical diseases, most notably adult T-cell leukemia/lymphoma and the syndrome known as HTLV-associated myelopathy or tropical spastic paraparesis (HAM/TSP). For the emergency physician practicing among patients from high-risk groups, HTLV-I infection and its associated diseases are presenting an increasing challenge. This report describes its transmission, seroprevalence, associated diseases, and methods to control the spread of this retrovirus.

[HTLV-1 associated myelopathies in the city of Salvador, Bahia]

Chronic myelopathy associated with human T-lymphotropic virus type I (HTLV-I) has been described in several endemic areas in Brazil. In Salvador, 102 patients with myelopathy were screened for HTLV-I/II by ELISA and Western blot assays. We found 36 patients with HTLV-I/II associated myelopathy confirming the high prevalence of HAM in Salvador. The initial complaint of our patients were urinary urgency, back pain and progressive unsteadiness on walking. On examination all of them had a spastic paraparesis, variable degrees of lower motor neuron syndrome, deep and superficial sensitive syndrome. MRI analysis revealed lesions in the periventricular white matter in addition to atrophy of the thoracic spinal cord. Clinical and magnetic resonance findings reveal that the inflammatory lesions of HAM involve not only the spinal cord but also the brain and peripheral nervous system.

Prospective utility of cerebral proton magnetic resonance spectroscopy in monitoring HIV infection and its associated neurological impairment

Neurological manifestations of HIV disease occur in most adults and children with AIDS. Many of those affected will inevitably suffer clinical neurological deficits involving mental function, movement, and sensation. Surprisingly, there are not as yet adequate monitoring systems to predict the onset and/or progression of HIV infection of the CNS. Neurological, neuropsychological, CSF, and magnetic resonance imaging (MRI) analyses cannot accurately detect mental deterioration during advancing HIV disease. Reports suggest that in vivo proton MR spectroscopy (1H MRS) of the brain could be a predictor of virus-induced neurological deterioration. H MRS can measure N-acetylaspartate (NAA), a metabolite present only in neurons. Decreased NAA reflects neuronal loss seen during HIV infection of brain. To uncover possible associations between NAA levels and HIV-induced neurological disease we performed serial 1H MRS brain tests in HIV-infected patients with or at risk for encephalopathy. Serial testing, for 1 year, of 10 patients showed that brain NAA levels decreased in all HIV-infected subjects. The most severe NAA reductions were associated with progressive neurological impairment. These findings suggest that NAA can be used as a noninvasive measure of neuronal loss in patients with HIV disease. Most important, the results suggest that 1H MRS could be used to monitor therapeutics directed against HIV infection within the CNS.

Neurologic syndromes

It is now well recognized that HIV-1 associated CNS disease may complicate the course of HIV-1 infection and AIDS in infants and children. It is also well recognized that the neurologic dysfunction in these young patients adds significantly to the morbidity of the disease and is often a devastating complication. It is apparent that HIV-1 CNS infection in infants and young children is complicated by numerous developmental issues. The effects, direct and indirect, of HIV-1 on the developing nervous system must be considered. The effects of HIV-1 on the immature immune system must also be considered. Moreover, the possible effects of HIV-1 on the many complex interactions between these two systems during development will clearly also require investigation. In order to care for these children and to design rational approaches for treatment and prevention, it is now critical to develop a better understanding of how HIV-1 affects the developing nervous system.