Neuropsychological assessment in HTLV-1 infection: a comparative study among TSP/HAM, asymptomatic carriers, and healthy controls

Cognitive Assessment in HTLV-1 Patients Followed Up at a Reference Center in Salvador, Brazil

INTRODUCTION

Human T-cell lymphotropic virus type 1 (HTLV-1) is endemic to Brazil, and there is still no specific treatment for these patients. The literature shows that few studies have described the cognitive impairment associated with an HTLV-1 infection, with none of them examining the population of Salvador, where there are approximately forty thousand people infected with the virus.

OBJECTIVES

To determine the prevalence of cognitive impairment among individuals with HTLV-1. In addition, investigate whether sociodemographic aspects, time since the diagnosis of infection, and the diagnosis of HTLV-Associated Myelopatia/Tropical Spastic Paraparesis (HAM/TSP) or depression are associated with cognitive impairment in this population.

METHODS

This was an observational, cross-sectional study that consisted of consecutively approaching 100 HTLV-1 patients during outpatient care at a referral center followed by the administration of three questionnaires- the Mini Mental State Examination (MMSE), the Montreal Cognitive Assessment (MoCA), and Beck's Depression Inventory.

RESULTS

The prevalence of cognitive impairment found was 71% using the MMSE and 82% using the MoCA. There was a statistically significant association between the cognitive dysfunction and the variables of age and education according to the MoCA analysis but not the MMSE data. Diagnosis of HAM/TSP was correlated with cognitive impairment using the MMSE but not the MoCA. The prevalence of depression was 20%, and there was no association between cognitive impairment and depressive symptoms in these patients.

CONCLUSIONS

The findings of this study demonstrate a correlation between cognitive dysfunction and HTVL-1 infection, with a more evident involvement of executive functions and memory. Larger studies are needed to clarify the association between cognitive dysfunction, age, education, and the diagnosis of HAM/TSP.

Performance of the National Institute of Infectious Diseases disability scale in HTLV-1-associated myelopathy/tropical spastic paraparesis

HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) is a chronic disabling disease. However, there is a lack of an adequate and specific health measurement instrument validated and with good performance to assess their degree of physical disability. This led us to carry out this study and to evaluate the performance of Fiocruz's National Institute of Infectious Diseases (IDS) disability scale, a specific instrument for HAM/TSP. Ninety-two HAM/TSP patients participated in the study. One researcher applied the IDS, IPEC scale, Disability Status Scale (DSS), Expanded DSS (EDSS), Osame scale, Beck Depression Inventory, and the WHOQOL-BREF questionnaire. In parallel, blindly, and separately, other researchers applied the IDS. An inter-rater reliability analysis of the IDS, correlation analysis with the other scales, and depression and quality of life questionnaires were performed. The applicability of the IDS was also evaluated. The IDS showed high reliability in all scores. The inter-rater reliability test for the total IDS score was 0.94 (0.82-0.98) on its four dimensions. The scale adequately indicated the different degrees of disability, presenting a distribution similar to normal. There was a high correlation with the other scales (Spearman coefficients > 0.80, p < 0.001). The scale had good acceptance among users and a short application time. IDS for HAM/TSP was reliable, consistent, easy, and fast to use. It can be used for both prospective evaluations and clinical trials. The present study supports the IDS as a valid instrument to measure disability in patients with HAM/TSP compared to previously used scales.

Cognitive deficits in HTLV-1 patients

Human T-cell lymphotropic virus type 1 (HTLV-1) is a retrovirus known to be associated with adult T-cell lymphoma and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). Previous researches and brain imaging techniques have suggested cognitive abnormalities as well as brain damage in individuals infected with this virus. Given the insufficient amount of studies on how this virus can impact the affected person's cognition, we aimed to assess and compare the cognitive abnormalities of HAM/TSP patients, asymptomatic HTLV-1 carriers, and healthy controls. This cross-sectional study was conducted on 51 patients divided into 3 groups; a group of HAM/TSP patients, a group of asymptomatic HTLV-1 carriers, and an uninfected control group. Each group contained 17 members. The cognitive state of the studied population was assessed using the Mini-Mental State Exam (MMSE), Symbol Digit Modalities Test (SDMT), Rey-Osterrieth complex figure test (ROCF), the "Verbal Fluency Test" and the "Trail Making Test" (TMT) components of the Delis-Kaplan executive function system (D-KEFS) test, the Rey Auditory Verbal Learning Test (RAVLT), and digit span memory test. Patients diagnosed with HAM/TSP received significantly lower scores on the SDMT, ROCF, TMT, RAVLT, digit span memory test, and the orientation, calculation, and recall component of the MMSE assessment (p-value < 0.001). In addition, the asymptomatic HTLV-1 carriers obtained lower scores on the SDMT, ROCF, digit span memory test, and the orientation, calculation, and recall component of the MMSE assessment compared to the control group (p-value < 0.001). Overall, the findings suggest that HAM/TSP, or an asymptomatic infection with HTLV-1 could lead to cognitive deficits in the affected individuals. This can further emphasize the importance of assessing the cognitive function and psychiatric abnormalities of those infected with this virus.

Prevalence of sexual dysfunction in HTLV-1 patients without spastic paraparesis and the association with psychiatric symptoms

Introduction

The findings of previous studies are inconclusive in terms of psychological abnormalities and sexual function in asymptomatic human lymphotropic virus type 1 (HTLV-1) carriers.

Aim

This study aimed to evaluate the prevalence of sexual dysfunction and its relationship with psychological abnormalities in asymptomatic HTLV-1 carriers.

Materials and Methods

This cross-sectional study was conducted on asymptomatic HTLV-1 patients who were referred to the Neurology Clinic of a tertiary hospital in Mashhad, Iran. Patients with spastic paraparesis, leukemia, and uveitis, and those with an expanded disability status scale (EDSS) score higher than 2 were excluded. Sexual function in male and female subjects was evaluated using the brief male sexual function inventory (BMSFI) and female sexual dysfunction index (FSFI) questionnaires, respectively. The severity of psychological symptoms was evaluated in all patients using the symptom checklist-90-revised (SCL-90-R) questionnaire.

Results

A total of 117 patients (61 males and 56 females) with a mean age of 35.3 ± 6.3 years were evaluated. Overall, 50.9% of males had a high and 39.3% of females had a good sexual function. Both male and female patients with poor sexual function were older and had more children compared to those with good sexual function (P < 0.05). There was no significant difference in the distribution pattern of SCL-90 domains between patients with high and low to moderate sexual function among male patients (P > 0.05). Depression, hostility, interpersonal sensitivity, paranoid ideation, and psychological abnormality were significantly more prevalent in female patients with poor sexual function compared to those with good sexual function (P < 0.05).

Conclusion

The prevalence of psychological abnormalities was high in female with sexual dysfunction and these disorders might have a negative effect on various dimensions of sexual function.

STLV-1 Commonly Targets Neurons in the Brain of Asymptomatic Non-Human Primates

The human T-cell leukemia virus (HTLV)-1 is responsible for an aggressive neurodegenerative disease (HAM/TSP) and multiple neurological alterations. The capacity of HTLV-1 to infect central nervous system (CNS) resident cells, together with the neuroimmune-driven response, has not been well-established. Here, we combined the use of human induced pluripotent stem cells (hiPSC) and of naturally STLV-1-infected nonhuman primates (NHP) as models with which to investigate HTLV-1 neurotropism. Hence, neuronal cells obtained after hiPSC differentiation in neural polycultures were the main cell population infected by HTLV-1. Further, we report the infection of neurons with STLV-1 in spinal cord regions as well as in brain cortical and cerebellar sections of postmortem NHP. Additionally, reactive microglial cells were found in infected areas, suggesting an immune antiviral response. These results emphasize the need to develop new efficient models by which to understand HTLV-1 neuroinfection and suggest an alternative mechanism that leads to HAM/TSP.

Neuropsychological profile of patients with infectious disease: characterization and comparison of patients with HIV, HTLV, and HCV

Understanding the effect of the HIV, HTLV-1, and HCV viruses on cognitive aspects can help in the better characterization of dementia, as well as the best conducts to be suitable for rehabilitation. Thus, the present study aimed to characterize and compare the neuropsychological profile of 3 groups of patients with infectious diseases: HIV, HTLV, and HCV. The results of neuropsychological assessments and depression assessment of 325 people treated at a referral hospital for infectious diseases were analyzed, being 120 HIV carriers (74 (61.7%) men) with an average age of 47.5 years (SD = 10.3), 65 patients with HTLV-1 (16 (24.6%) men) with a mean age of 49.9 years (SD = 12.9), and 87 HCV patients (47 (54%) men) with a mean age of 55.5 years (SD = 11.2). In addition, 54 people (26 (48.1%) men) with negative serology who made up the control group were evaluated. The results of the statistical evaluation of the sociodemographic factors of the four groups (HIV, HTLV-1, HCV, and control) showed that in addition to age, schooling was a significant factor among them and may have a strong influence on the performance of cognitive tests. The HTLV-1 group had the lowest neurocognitive performance and also the highest rate of depressive symptoms.

Cognitive screening in HTLV-1-infected people using a self-perceived memory score and auditory P300

The HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) is the most common neurological manifestation associated with human T-cell lymphotropic virus type-1 (HTLV-1) infection. Although cognitive impairment has been highlighted in the spectrum of HTLV-1 neurological manifestations, it may go unnoticed in those who do not spontaneously report it. We aimed at evaluating the applicability of a self-perceived memory score (SMS) and the cognitive event-related potential (P300) for early detection of cognitive impairment in HTLV-1-infected people. The SMS was measured by a 0-10 point numeric scale combined with a sad-happy face rating scale. The higher the number, the better was the SMS. The P300 was obtained through an oddball paradigm with a mental counting task. The participants were 15 (21.4%) individuals with HAM/TSP, 20 (28.6%) HTLV-1 asymptomatic carriers, and 35 (50%) seronegative controls. We found that SMS (p < 0.001) and P300 latency (p < 0.001) got progressively worse from the seronegative controls to the asymptomatic carriers and then to the HAM/TSP. The results that indicated cognitive impairment were SMS < 7.2 points and P300 latency > 369.0 ms. The HAM/TSP group showed the highest prevalence of altered P300 (80%) and SMS (87%). Interestingly, the asymptomatic group also presented significantly higher prevalence of altered SMS (60%) and P300 (35%) when compared to controls (< 10%). The frequency of cognitive impairment was 16 times higher in the HTLV-1 asymptomatic group and 69 times higher in the HAM/TSP group when compared to controls. The use of SMS in the medical consultation was a useful and easy-to-apply method to screen HTLV-1-infected subjects for everyday memory complaints.

Cerebral and spinal cord changes observed through magnetic resonance imaging in patients with HTLV-1-associated myelopathy/tropical spastic paraparesis: a systematic review

To verify brain and spinal changes using magnetic resonance imaging in patients with HTLV-1-associated myelopathy/tropical spastic paraparesis. This was a systematic review. The descriptors used were tropical spastic paraparesis and magnetic resonance image. The keyword HTLV-1-associated myelopathy was also used. Twenty-three articles were included: 16 detected brain changes and 18 detected spinal changes. White matter lesions were the most frequent finding in the brain. Brain injuries were most frequently identified in the periventricular region, in the subcortical region, in the centrum semiovale, in the brain stem, and corpus callosum. Atrophy was the most frequent finding of the spinal cord, affecting the thoracic and cervical regions, and was associated with a longer evolution of myelopathy. White matter lesions in these regions were also observed. Cortical white matter lesions and thoracic spinal cord atrophy were the most frequently reported changes in patients with HTLV-1-associated myelopathy.

Cognitive impairment in the HTLV-1 infection: a comparative study associated with functional performance

Human T cell leukemia virus type-I (HTLV-1) infection courses with a myelopathy, the tropical spastic paraparesis (HAM/TSP). In a case-control study, we compared the neuropsychological profile and functional characteristics in two case HTLV-1-infected groups (asymptomatic and with HAM/TSP) with a control group negative for HTLV-1. Subjects were paired for age, sex, and educational features. The case group differed from control group in neuropsychological measures such as in episodic memory recall, executive functions, and fine motor dexterity measure. Individuals with HAM/TSP have more depressive symptoms and worst performance in activities of daily living (ADL) presenting a less functionality. In multivariate models, the fine motor performance, the executive functioning, the recognition memory, and the depressive symptoms explained part of the variance in functionality. Those findings may contribute to understand of everyday life impairments and limitations of HTLV-1-infected population and to organize the rehabilitation. Once more, based in neuropsychological and functional data, we can reaffirm that HTLV-1 is never a benign condition, but sometimes it is only in a stage coursing with less symptoms.

Association between high proviral load, cognitive impairment, and white matter brain lesions in HTLV-1-infected individuals

The association between high proviral load (PVL) in peripheral blood mononuclear cells (PBMC), cognitive disturbance and white matter brain lesions in HTLV-1-infected individuals is still undefined. A cross-sectional study included 62 participants: 22 asymptomatic carriers (mean age 43.4 ± 13.1 years old), 22 patients with HTLV-1-associated myelopathy (HAM/TSP) (mean age 51.5 ± 8.7 years old), and 18 uninfected controls (mean age 52.3 ± 11.1 years old). All individuals fulfilled the following criteria: between 18 and 65 years of age, more than 4 years of formal education, and completed neuropsychological evaluation and HTLV-1 serology. Infected individuals underwent brain conventional magnetic resonance imaging and PVL quantitative PCR (qPCR). Statistical analysis was adjusted in the models by age and education. Cognitive deficit was observed in all groups. Patients with HAM/TSP showed higher neurocognitive deviation in attention and motor skills, higher frequency (84%) of brain white matter lesions, and higher PVL median (range) 8.45 (0.5-71.4) copies/100 PBMC. Brain white matter lesion was associated with verbal memory deficit in HTLV-1-infected individuals (HAM/TSP and asymptomatic carriers) (p = 0.026). In addition, there was a correlation between higher PVL and neurocognitive dysfunction score (processing speed of visuomotor information and visuoconstructive praxis) in HTLV-1-infected patients. The study demonstrates an association between HTLV-1 infection, neurocognitive disorder, and white matter brain lesions on MRI as well as a correlation with higher HTLV-1 PVL, suggesting that the central nervous system involvement by HTLV-1 is not restricted to the spinal cord but involves the whole neuro-axis. HTLV-1-infected individuals should be tested for cognitive impairment.

Vestibular Evoked Myogenic Potential on Ocular, Cervical, and Soleus Muscles to Assess the Extent of Neurological Impairment in HTLV-1 Infection

Introduction: Vestibular Evoked Myogenic Potential (VEMP) can be used to test central vestibular pathways from the midbrain to the lumbar spine, according to the muscle tested.

Purpose: to compare the spinal cord alteration in individuals with HTLV-1-associated myelopathy (HAM) and with HTLV-1-asymptomatic infection using the VEMP recorded from different muscles.

Methods: VEMP was recorded in 90 individuals of whom 30 had HAM, 30 were HTLV-1 asymptomatic carriers, and 30 negative controls. VEMP was recorded in the oculomotor muscle (oVEMP), testing the vestibulo-ocular reflex, and in the cervical muscle (cVEMP) and soleus muscle (sVEMP), testing the vestibulospinal reflex, respectively, in the cervical and in the lumbar spinal level. The type of stimulation was auditory for oVEMP and cVEMP, and galvanic for sVEMP. The compared variables were the latencies of the electrophysiological waves.

Results: HTLV-1-asymptomatic group was similar to the controls regarding oVEMP (p = 0.461), but different regarding cVEMP (p < 0.001) and sVEMP (p < 0.001). HAM group has presented the worst latencies and was different from the HTLV-1-asymptomatic group in the VEMP of all the tested muscles (p < 0.001). The concomitant occurrence of VEMP alterations in the three recorded muscles of the same individual was found in 2 (6.7%) asymptomatic carriers and in 20 (66.7%) patients with HAM (p = 0.001). The analysis of VEMP alteration per group and per muscle has showed that, in HTLV-1-asymptomatic group, oVEMP was altered in 3 (10.0%) individuals, cVEMP in 10 (33.3%) and sVEMP in 13 (43.3%). In HAM group, oVEMP was altered in 23 (76.6%) individuals, cVEMP in 27 (90%), and sVEMP in 30 (100%).

Conclusion: HTLV-1-neurological damage has followed an ascendant progression beginning at the lumbar spine in the stage of a clinically asymptomatic infection, whereas HAM has affected not only the spine, but also the midbrain.

Case Report: Cognitive Impairment without Clinical Spinal Disease May Be the First Sign of HTLV-1 Neurological Alteration

Human t-cell lymphotropic virus type 1 (HTLV-1)-associated myelopathy (HAM) is a progressive neurological disease whose diagnosis is defined by clinical manifestations and seropositivity for HTLV-1 infection. Cognitive impairment (CI) is considered to occur after spinal impairment. A 51-year-old HTLV-1-infected man classified as an asymptomatic carrier presented difficulties in listening comprehension and executive memory. He was assessed for central auditory processing (CAP), cognition (event-related auditory evoked potential [P300]), and otoneurological functions (galvanic vestibular-evoked myogenic potential [gVEMP]). Altered responses were found in CAP, P300, and gVEMP, but the neurological examination and cognitive screening were normal. After a 2-year follow-up, we disclosed a positive Babinski sign, a mild CI, worsened P300, and gVEMP latencies, and the patient reported progressive lumbar pain and difficulty running. He was, then, reclassified as HAM. The first examination, in 2016, had already shown abnormal results in P300 and gVEMP despite the HTLV-1-asymptomatic carrier status. Therefore, tests that provide subclinical measures of neurological disease progression can be useful tools for an early diagnosis and intervention in HTLV-1 patients. Electrophysiological results had worsened as well as the clinical status and the cognitive function and the progression from asymptomatic status to an HTLV-1-associated neurological disease occurred within 2 years. Thus, HTLV-1-infected individuals with complaints of CI, hearing, or otoneurological manifestations should be submitted to neuropsychological and electrophysiological tests, allowing them to be properly cared in case of HAM progression.

Memory impairment: an intermediate clinical syndrome symptom in HTLV-1-infected patients?

BACKGROUND

Although classical human T-cell lymphocyte virus type 1 (HTLV-1)-associated myelopathy/tropical spastic paraparesis syndrome is the most frequent HTLV-1-associated neurological disorder, some "minor" neurological disorders can be seen in "asymptomatic" carriers. These disorders, including cognitive alterations already described in clinical cases and studies, may constitute an intermediate syndrome (IMS) between the asymptomatic state and myelopathy. The aim of this study was to investigate the presence of cognitive deficits in patients with HTLV-1 virus, who usually are diagnosed as asymptomatic.

METHODS

A total of 54 HTLV-1-infected patients were evaluated, 35 asymptomatic and 19 with minor neurological alterations (evaluated by a neurologist); 25 HTLV-1-seronegative individuals served as controls. The instruments used were: Beck's Depression Inventory, Lawton's Daily Life Activity Scale, and a complete neuropsychological battery. The application of these evaluation instruments was performed blindly, with the evaluator neuropsychologist not knowing the clinical condition of the patient.

RESULTS

Most of the participants in this cohort, including seronegative controls, were female (n = 57, 72.21%), their mean age was 52.34 years (SD = 14.29) and their average schooling was 9.70 years (SD = 4.11).

DISCUSSION

Participants classified with IMS had lower gross scores when compared with both the patients classified as asymptomatic and with the control group, and when tested for auditory episodic memory of immediate (p < 0.01), and late (p = 0.01), recall.

CONCLUSION

Patients with IMS presented with memory impairment when compared with asymptomatic patients and seronegative individuals; this is one of the symptoms that aids in the classification of the syndrome.

Phenotypic and functional changes in gamma delta T lymphocytes from HTLV-1 carriers

Human T-cell lymphotropic virus type-1 (HTLV-1) is the etiologic agent of HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP), which is a chronic inflammatory disease that leads to gradual loss of motor movement as a result of the death of spinal cord cells through immune mediated mechanisms. The risk to develop HAM/TSP disease positively correlates with the magnitude of HTLV-1 proviral load. Gamma-delta T lymphocytes have been recognized as important players in a variety of infectious diseases. Therefore, we have investigated interactions between HTLV-1 infection and γδ T lymphocytes during HAM/TSP. Similar frequencies of total γδ T lymphocytes and their Vγ9δ2⁺ and Vγ9δ2^neg subpopulations were observed in HAM/TSP patients. However, T lymphocytes obtained from HTLV-1 carriers displayed significantly higher rates of spontaneous proliferation and NKp30 expression when compared to cells from uninfected donors. In addition, an important decrease in the frequency of granzyme B⁺ γδ T lymphocytes (approximately 50%) was observed in HAM/TSP patients. Higher proportion of IFN-γ⁺ γδ T lymphocytes was found in HTLV-1-infected patients, which positively correlated with the HTLV-1 proviral load in peripheral blood mononuclear cells. Collectively, our data indicates that HTLV-1 infection leads to phenotypic and functional changes in the population of γδ T lymphocyte population, suggesting that HTLV-1 infection modulates functions associated to these cells, which might be involved in controlling the infection or in the development of HTLV-1-associated diseases.

Cognitive impairment in HTLV-1-associated myelopathy, proviral load and inflammatory markers

OBJECTIVES

Myelopathy is a well-established long-term clinical manifestation of HTLV-1 infection. Besides motor dysfunction, cognitive impairment may be another consequence of HTLV-1 infection. Moreover, inflammatory markers may be associated with cognitive impairment in these patients. The present study compared the cognitive performance of HAM/TSP patients with healthy controls and investigated the associations between cognitive performance, proviral load and blood inflammatory markers.

METHODS

Eighty-three patients fulfilling diagnostic criteria for HAM/TSP were submitted to a comprehensive clinical, cognitive and functional evaluation, brain magnetic resonance imaging and determination of levels of IL-1β, IL-6, TNF-α, immunoglobulins and HTLV-1 proviral load in blood and cerebrospinal fluid. The control group was composed of 88 cognitively healthy subjects, matched for age, sex and educational level.

RESULTS

Compared to healthy subjects, HAM/TSP patients displayed significant global cognitive impairment and executive function deficits. HAM/TSP cognitive impairment was significantly associated with altered levels of IgM, IgG, IL-6 and TNF-α in blood. There was no association between HAM/TSP cognitive impairment and HTLV-1 proviral load.

CONCLUSIONS

This study suggests cognitive impairment may be a long-term clinical manifestation of HTLV-1 infection, which seems to be linked to the persistent inflammatory activity that is found in the disease.

HTLV-1 infection-induced motor dysfunction, memory impairment, depression, and brain tissues oxidative damage in female BALB/c mice

AIMS

The HTLV-1 infection is associated with a neuro-inflammatory disease. In the present study, the behavioral consequences and brain oxidative damages were evaluated in HTLV-1-infected BALB/c mice.

MATERIAL AND METHODS

20 female BALB/c mice were divided into two groups comprising control and HTLV-1-infected. The HTLV-1-infected group was inoculated with a 10⁶ MT-2 HTLV-1-infected cell line. Two months later, the behavioral tests were conducted. Finally, oxidative stress was assessed in the cortex and hippocampus tissues.

KEY FINDINGS

In the HTLV-1-infected group, running time and latency to fall, travel distance and time spent in the peripheral zone, total crossing number and total traveled distance in open field test, the latency of entrance into the dark compartment in the passive avoidance test, the new object exploration percentage, and discrimination ratio were significantly lower than in the control group. The immobility time, time spent in the dark compartment in passive avoidance test, and total exploration time significantly increased in the HTLV-1-infected group compared to the control group. In the cortical tissue of the HTLV-1 group, the malondialdehyde levels were elevated while the total thiol levels decreased in comparison to the control group. The activity of superoxide dismutase in the cortical and hippocampal tissues, and catalase activity in cortical tissue significantly decreased in the HTLV-1 group in comparison to the control group.

SIGNIFICANCE

The HTLV-1 infection seems to induce depression-like behavior, motor dysfunction, disruption in working and fear memory and also oxidative stress in the cortex and hippocampus.

Cognitive impairment is frequent among symptomatic carriers of human T-cell lymphotropic virus type 1 (HTLV-1), regardless of their clinical status

The main goal of this study was to investigate the presence of cognitive impairment in patients infected with HTLV-1 presenting or not TSP/HAM.

METHODS

Cross-sectional study including 104 participants: 37 asymptomatic HTLV-1 carriers, 37 patients diagnosed with TSP/HAM and 30 HTLV-1 negative control patients. Within the HTLV-1 positive group, 53 were female and 21 were male, the average age was 46 (SD=13.5) and the average schooling time was 7.7years (SD=3.3).The sociodemographic variables (genre, age and education) were compared between the three groups. The assessment tools used were: Beck Depression Inventory, Lawton's Activities of Daily Life Scale and a complete neuropsychological battery. The application of these assessment tools was carried out in blind. Both HTLV-1 asymptomatic subjects and HAM/TSP patients showed a lower performance on neuropsychological tests and higher depression scores when compared to the control group. HTLV-1 patients performed poorly in several cognitive domains, but only fluid intelligence, estimated intellectual functioning, immediate and delayed recall of visual memory and information processing speed (in the specific case of patients with TSP/HAM) reached statistical significance when compared with controls. Depression was not associated with cognitive impairment. HTLV-1 carriers presented a higher frequency of cognitive impairment than normal controls.

Hepatitis C virus and human T-cell lymphotropic virus type 1 co-infection: impact on liver disease, virological markers, and neurological outcomes

OBJECTIVES

Human T-cell lymphotropic virus type 1 (HTLV-1) infection is associated with neurological abnormalities, such as HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) and peripheral neuropathy (PN). Hepatitis C virus (HCV) infection is the leading cause of chronic liver disease worldwide, and causes PN in approximately 9% of patients. Because the interplay between these potentially neuropathogenic viruses in the same individual is still poorly understood, the clinical and laboratory outcomes of co-infected patients were evaluated and compared with those of controls.

METHODS

The prevalence rates of neurological and laboratory abnormalities were evaluated in HCV/HTLV-1 co-infected patients (n=50), and in subjects with single HCV (n=46) or HTLV-1 (n=150) infection.

RESULTS

A higher frequency of isolated PN was present in HCV-infected patients; this was not associated with cryoglobulinemia. No difference was found in the frequency of PN or HAM/TSP when co-infected subjects were compared to singly infected subjects. Hepatic involvement was present in HCV-infected subjects, as shown by increased levels of serum alanine aminotransferase, aspartate aminotransferase, gamma-glutamyl transferase, and bilirubin, in addition to thrombocytopenia. On the other hand, HCV/HTLV-1 co-infected individuals presented a better prognosis for hepatic involvement when compared with singly HCV-infected subjects.

CONCLUSIONS

These data suggest that HCV/HTLV-1 co-infection does not mutualistically alter the outcome with regard to neurological manifestations. Nonetheless, changes in the immunological environment induced by HTLV-1 infection could lead to a reduction in hepatic damage, even without significant HCV clearance.

Evidence of Brain Inflammation in Patients with Human T-Lymphotropic Virus Type 1-Associated Myelopathy (HAM): A Pilot, Multimodal Imaging Study Using 11C-PBR28 PET, MR T1-Weighted, and Diffusion-Weighted Imaging

HTLV-1-associated myelopathy (HAM; HTLV-1 is human T-lymphotropic virus type 1) is a chronic debilitating neuroinflammatory disease with a predilection for the thoracic cord. Tissue damage is attributed to the cellular immune response to HTLV-1-infected lymphocytes. The brains of HTLV-1-infected patients, with and without HAM but no clinical evidence of brain involvement, were examined using a specific 18-kDa translocator protein ligand, ¹¹C-PBR28, and T1-weighted and diffusion-weighted MRI.

METHODS

Five subjects with HAM and 2 HTLV-1 asymptomatic carriers were studied. All underwent clinical neurologic assessment including cognitive function and objective measures of gait, quantification of HTLV-1 proviral load in peripheral blood mononuclear cells, and human leukocyte antigen-antigen D related expression on circulating CD8+ lymphocytes. ¹¹C-PBR28 PET and MRI were performed on the same day. ¹¹C-PBR28 PET total volume of distribution and distribution volume ratio (DVR) were estimated using 2-tissue-compartment modeling. MRI data were processed using tools from the FMRIB Software Library to estimate mean diffusivity (MD) and gray matter (GM) fraction changes. The results were compared with data from age-matched healthy volunteers.

RESULTS

Across the whole brain, the total volume of distribution for the subjects with HAM (5.44 ± 0.84) was significantly greater than that of asymptomatic carriers (3.44 ± 0.80). The DVR of the thalamus in patients with severe and moderate HAM was higher than that in the healthy volunteers, suggesting increased translocator protein binding (z > 4.72). Subjects with more severe myelopathy and with high DR expression on CD8+ lymphocytes had increased DVR and MD (near-significant correlation found for the right thalamus MD: P = 0.06). On the T1-weighted MRI scans, the GM fraction of the brain stem was reduced in all HTLV-1-infected patients compared with controls (P < 0.001), whereas the thalamus GM fraction was decreased in patients with HAM and correlated with the disease severity. There was no correlation between neurocognitive function and these markers of central nervous system inflammation.

CONCLUSION

This pilot study suggests that some patients with HAM have asymptomatic inflammation in the brain, which can be detected and monitored by ¹¹C-PBR28 PET together with structural and diffusion-weighted MRI.

HTLV-1-associated myelopathy/tropical spastic paraparesis

Human T-lymphotropic virus 1 (HTLV-1)-associated myelopathy/tropical spastic paraparesis (HAM/TSP) is a progressive disease of the CNS that causes weakness or paralysis of the legs, lower back pain and urinary symptoms. HAM/TSP was first described in Jamaica in the nineteenth century, but the aetiology of the condition, infection with the retrovirus HTLV-1, was only identified in the 1980s. HAM/TSP causes chronic disability and, accordingly, imposes a substantial health burden in areas where HTLV-1 infection is endemic. Since the discovery of the cause of HAM/TSP, considerable advances have been made in the understanding of the virology, immunology, cell biology and pathology of HTLV-1 infection and its associated diseases. However, progress has been limited by the lack of accurate animal models of the disease. Moreover, the treatment of HAM/TSP remains highly unsatisfactory: antiretroviral drugs have little impact on the infection and, although potential disease-modifying therapies are widely used, their value is unproved. At present, clinical management is focused on symptomatic treatment and counselling. Here, we summarize current knowledge on the epidemiology, pathogenesis and treatment of HAM/TSP and identify areas in which further research is needed. For an illustrated summary of this Primer, visit: http://go.nature.com/tjZCFM.

Update on Neurological Manifestations of HTLV-1 Infection

The human T cell lymphotropic virus type 1 (HTLV-1) is a retrovirus that infects 10-20 million persons around the world. Initially associated with the hematological malignancy adult T cell leukemia/lymphoma (ATLL), HTLV-1 is also the cause of a chronic progressive myelopathy named "HTLV-1-associated myelopathy/tropical spastic paraparesis" (HAM/TSP). HAM/TSP arises as the tip of the iceberg of an assortment of neurological syndromes triggered by the virus such as inflammatory myopathies, polyneuropathies, amyotrophic lateral sclerosis (ALS)-like syndromes, dysautonomia, and cognitive impairment. HAM/TSP typifies a chronic progressive spastic paraparesis with neurogenic bladder and minimal sensory signs. The neuropathology of HAM/TSP is concentrated in the thoracic spinal cord and is typically biphasic. Initially, there is a perivascular lymphocytic cuffing and mild parenchymal mononuclear infiltrates. Subsequently, this is replaced by gliosis and scarring. The neuropathogenesis of HTLV-1 is still partially understood. At present, the therapy of HAM/TSP remains basically symptomatic.

[Recurrent facial palsy revealing Human T-lymphotropic virus type 1 (HTLV-1) infection]

INTRODUCTION

Neurological involvement of Human T-lymphotropic virus type 1 (HTLV-1) mainly results in myelopathy (tropical spastic paraparesis). However, cranial nerve impairment, including facial nerve damage, is rare in patients with HTLV-1 infection.

OBSERVATION

We report the case of a patient, originally from Caribbean islands, who developed recurrent bilateral facial palsy (six recurrences during the 7-year follow-up). Both blood and cerebrospinal fluid serologies were positive for HTLV-1. The diagnosis of recurring bilateral facial palsy revealing HTLV-1 infection was made.

CONCLUSION

Our case report underscores that HTLV-1 infection should be considered in patients, coming from endemic areas (Caribbean islands, South America, Japan and Africa), who exhibit recurrent bilateral facial palsy. Our data therefore indicate that HTLV-1 serology should be routinely performed in these patients.

Encephalomyelopathy associated with HTLV-I a primary disease or coexisting with multiple sclerosis?

HTLV-I-associated myelopathy (HAM/TSP) is the most common neurological manifestation of HTLV-I, causing progressive weakness, sensory disturbance, and sphincter dysfunction. Although motor disorders have been well described, few studies have associated cognitive disorders and HTLV-I infection. In areas endemic for HTLV-I infection, the differential diagnosis between HAM/TSP and other myelopathy etiologies can be difficult, particularly if the patient has signs and symptoms of brain involvement, since seropositive HTLV-I patients can present other neurological diseases. Here, we report one case initially diagnosed as Multiple Sclerosis (MS) which, upon further investigation, was found to be HTLV-I seropositive.

Immunopathogenesis and neurological manifestations associated to HTLV-1 infection

The human T lymphotropic virus type-1 (HTLV-1) was the first human retrovirus identified. The virus is transmitted through sexual intercourse, blood transfusion, sharing of contaminated needles or syringes and from mother to child, mainly through breastfeeding. In addition to the well-known association between HTLV-1 and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP), several diseases and neurologic manifestations have been associated with the virus. This review was conducted through a PubMed search of the terms HTLV-1, immune response and neurological diseases. Emphasis was given to the most recent data regarding pathogenesis and clinical manifestations of HTLV-1 infection. The aim of the review is to analyze the immune response and the variety of neurological manifestations associated to HTLV-1 infection. A total of 102 articles were reviewed. The literature shows that a large percentage of HTLV-1 infected individuals have others neurological symptoms than HAM/TSP. Increased understanding of these numerous others clinical manifestations associated to the virus than adult T cell leukemia/lymphoma (ATLL) and HAM/TSP has challenged the view that HTLV-1 is a low morbidity infection.

Neurolathyrism: two Ethiopian case reports and review of the literature

Neurolathyrism is a toxic myelopathy caused by ingestion of the Lathyrus sativus grasspea. An irreversible acute to subacute spastic paraparesis or quadriparesis ensues. Despite public education, new cases of this preventable disease still occur. Two Ethiopian cases of neurolathyrism are reported to illustrate the disease, followed by a literature review. Two teenage male farmers from the same village developed irreversible spastic myelopathy following L. sativus ingestion. There was no sensory, sphincter or bulbar dysfunction. Likely causative factors identified were increased consumption of L. sativus prior to and following disease onset, heavy physical exertion and male gender, similar to those reported in the literature. Neurolathyrism is an entirely preventable neurotoxic myelopathy with permanent disability accrued. Treatment is symptomatic. Because of personal disability and subsequent socioeconomic effects, this disease warrants further public health measures to prevent occurrence. Education, avoidance of the grasspea and measures to reduce toxin burden are possible methods.

The motor evoked potential in aids and HAM/TSP State of the evidence

OBJECTIVE: We aimed to better understand the involvement of the corticospinal tract, assessed by non-invasive transcranial stimulation, in order to determine the actual involvement of the motor system in patients with HAM/TSP and AIDS. METHOD: An exhaustive MEDLINE search for the period of 1985 to 2008 for all articles cross-referenced for "HTLV-I, HTLV-II, HTLV-III and HIV, HIV1, HIV2, evoked potential, motor evoked potential, high voltage electrical stimulation, transcranial magnetic stimulation, magnetic stimulation, corticomotor physiology, motor pathways, acquired immunodeficiency syndrome, AIDS, SIDA, tropical spastic paraparesis, HTLV-I-associated myelopathy, HAM, TSP, and HAM/TSP" were selected and analysed. RESULTS: Eighteen papers published in English, Spanish, Portuguese, French and Japanese were identified. Only the central motor conduction time has been analyzed in seropositive patients to human retroviruses. The investigations done on HAM/TSP support the involvement of the pyramidal tract mainly at lower levels, following a centripetal pattern; in AIDS, such an involvement seems to be more prominent at brain levels following a centrifugal pattern. CONCLUSION: The central motor conduction time abnormalities and involvement differences of the corticospinal tract of patients with AIDS and HAM/TSP dissected here would allow to re-orient early neurorehabilitation measures in these retroviruses-associated neurodegenerative disorders. Besides this, more sophisticated and sensitive non-invasive corticospinal stimulation measures that detect early changes in thalamocortical-basal ganglia circuitry will be needed in both clinically established as well as asymptomatic patients at times when the fastest corticospinal fibers remain uninvolved.

Neurologic abnormalities in HTLV-I- and HTLV-II-infected individuals without overt myelopathy

BACKGROUND

Human T-lymphotropic virus (HTLV) type I is the causative agent of HTLV-associated myelopathy (HAM)/tropical spastic paraparesis, and a number of HAM cases with HTLV-II infection have also been reported. However, despite some reports, it is unclear whether HTLV-I or -II infection is associated with other neurologic manifestations.

METHODS

An analysis of medical histories and screening neurologic examinations from a prospective cohort of 153 HTLV-I, 388 HTLV-II, and 810 HTLV-seronegative individuals followed up for means of 11.5, 12.0, and 12.2 years was performed. Participants diagnosed with HAM were excluded. We calculated odds ratios (ORs) and 95% confidence intervals (CIs), adjusting for age, sex, race or ethnicity, income, educational attainment, body mass index, alcohol and cigarette consumption, injection drug use, diabetes, and hepatitis C virus status, using generalized estimating equations for repeated measures.

RESULTS

HTLV-I and -II participants were more likely than seronegative participants to have leg weakness (ORs 1.67 [95% CI 1.28-2.18] and 1.44 [1.16-1.78]), impaired tandem gait (ORs 1.25 [95% CI 1.07-1.47] and 1.45 [1.27-1.64]), Babinski sign (ORs 1.54 [95% CI 1.13-2.08] and 1.51 [1.18-1.93]), impaired vibration sense (ORs 1.16 [95% CI 1.01-1.33] and 1.27 [1.14-1.42]), and urinary incontinence (ORs 1.45 [95% CI 1.23-1.72] and 1.70 [1.50-1.93]). For both HTLV-I and -II participants, higher odds of sensory neuropathy by monofilament examination were no longer significant after adjustment for confounding.

CONCLUSIONS

These results provide strong evidence that human T-lymphotropic virus (HTLV)-I and -II are associated with a spectrum of predominantly motor abnormalities in patients without overt HTLV-associated myelopathy. Further investigation of the clinical course and etiology of these abnormalities is warranted.

HTLV-1 and neurological conditions: when to suspect and when to order a diagnostic test for HTLV-1 infection?

HTLV-1 is a retrovirus associated with a myriad of clinical conditions, especially hematological and neurological ones. Regarding nervous system diseases, it is of utmost importance to select those cases in which HTLV-1 infection could really be associated. This is particularly true for patients from endemic areas and for HIV-infected patients and drug users, since that these groups are at a higher risk for HTLV infection. This caution in selecting neurological patients for HTLV diagnostic tests is justified by the fact that in some circumstances the seropositivity may merely represent an epiphenomenon. In this paper we enroll some neurological conditions that have been associated with HTLV-1/2 infection in the literature and discuss the real need for HTLV-1/2 diagnostic tests in each one. Because HIV/HTLV-co-infected patients seem to be at an increased risk for neurological diseases development, a special consideration about this matter is also made.

Human T Lymphotropic Virus Type 1 (HTLV-1) Proviral Load in Asymptomatic Carriers, HTLV-1-Associated Myelopathy/Tropical Spastic Paraparesis, and Other Neurological Abnormalities Associated with HTLV-1 Infection

Recent reports have demonstrated that human T lymphotropic virus type 1 (HTLV-1) is associated with other neurological abnormalities in addition to HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). It has been well established that high HTLV-1 proviral loads are associated with the development of HAM/TSP. We now demonstrate, for the first time, to our knowledge, that HTLV-1 proviral loads in patients with other neurological abnormalities are also significantly higher than in asymptomatic HTLV-1 carriers.

The HTLV-1 neurological complex

Human T-cell lymphotropic virus type 1 (HTLV-1) is a retrovirus that infects about 20 million people worldwide and causes immune-mediated diseases of the nervous system. The classic neurological presentation of HTLV-1 infection is a myelopathy called HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). However, HAM/TSP is not the only neurological outcome that can result from HTLV-1 infection. In this Personal View, we show that HTLV-1 has a broader neurological spectrum than the names HAM/TSP suggest and that people infected with this virus can present with various isolated or assorted syndromes.