Peripheral neuropathy associated with acquired immunodeficiency syndrome. Prevalence and clinical features from a population-based survey

Article Topic: Neuropathies Due to Infections and Antimicrobial Treatments

Purpose of eview

The aim of this review is to discuss the presentation, diagnosis, and management of polyneuropathy (PN) in selected infections. Overall, most infection related PNs are an indirect consequence of immune activation rather than a direct result of peripheral nerve infection,  Schwann cell infection, or toxin production, though note this review will describe infections that cause PN through all these mechanisms. Rather than dividing them by each infectious agent separately, we have grouped the infectious neuropathies according to their presenting phenotype, to serve as a guide to clinicians. Finally, toxic neuropathies related to antimicrobials are briefly summarized.

Recent findings

While PN from many infections is decreasing, increasing evidence links infections to variants of GBS. Incidence of neuropathies secondary to use of HIV therapy has decreased over the last few years.

Summary

In this manuscript, a general overview of the more common infectious causes of PN will be discussed, dividing them across clinical phenotypes: large- and small-fiber polyneuropathy, Guillain-Barré syndrome (GBS), mononeuritis multiplex, and autonomic neuropathy. Rare but important infectious causes are also discussed.

Investigation of nerve fibers in the skin by biopsy: technical aspects, indications, and contribution to diagnosis of small-fiber neuropathy

Skin biopsy with investigation of small-diameter nerve fibers in human epidermis and dermis has been proven to be a useful method for confirming small-fiber neuropathy. In medical practice, small-fiber neuropathy is increasingly recognized as a leading cause of neuropathic pain. It is a prevalent complaint in medical offices, brought by patients often as a “painful burning sensation”. The prevalence of neuropathic pain is high in small-fiber neuropathies of different etiologies, especially in the elderly; 7% of population in this age group present peripheral neuropathy. Pain and paresthesia are symptoms which might cause disability and impair quality of life of patients. The early detection of small-fiber neuropathy can contribute to reducing unhealthy lifestyles, associated to higher incidence of the disease.

Peripheral neuropathy in HIV-infected children attending care and treatment clinic, at Muhimbili National Hospital, Dar es Salaam: a cross sectional study

BACKGROUND

Peripheral neuropathy (PN) is a neurological complication of untreated Human Immunodeficiency Virus (HIV) infection or exposure to certain antiretroviral drugs. In Tanzania where HIV is a major public health problem, the burden of HIV associated peripheral neuropathy has not yet been well defined in children.Thisstudy investigated the prevalence and associated factors for peripheral neuropathy among children living with HIV, attending Care and Treatment Clinic (CTC) at Muhimbili National Hospital (MNH).

MATERIALS AND METHODS

A cross-sectional study was conducted among 383 HIV positive children aged 5 to 18 years at MNH, CTC in Dar es Salaam between October to December 2019. All participants provided written assent/consent. Structured questionnaires designed for this study was used to collect data and screening for peripheral neuropathy was done on each participant using the Pediatric modified Total Neuropathy Score (Ped m TNS) that includes subjective and objective assessment. A score of 5 or greater on the Ped m TNS was used to define peripheral neuropathy. Data analysis was done using SPSS Version 23.

RESULTS

The prevalence of peripheral neuropathy among HIV infected children was 14.1 % (95 % CI (10.8 - 18 %). Common neuropathic symptoms were numbness, tingling sensation, reduced ankle reflexes and reduced sensation to light touch and pain that was limited to the toes. Low CD4 cell count (OR = 12.21; 95 % CI3.75-39.66; p = 0.0001), high viral load (OR = 10.54; 95 % CI 3.19-34.77; p = 0.0001), ART regime containing NRTI plus PI (OR = 3.93; 95 % CI 1.43- 10.74; p = 0.01) and the last exposure to isoniazid more than 6 months ago (OR = 3.71; 95 % CI 1.57-8.77; p = 0.003) were independent predictors for peripheral neuropathy.

CONCLUSION

Peripheral neuropathy is common among HIV infected children attending CTC at MNH and its frequency increases with advanced disease. The choice of ART regimen and other drugs for treating comorbid conditions should carefully be evaluated.

The role of CAMKK2 polymorphisms in HIV-associated sensory neuropathy in South Africans

Human immunodeficiency virus-associated sensory neuropathy (HIV-SN) is a common neurological complication of HIV infection. It affected 57% of South African patients whose antiretroviral therapy (ART) included stavudine and was influenced by genotypes of the P2X-block (P2X7R, P2X4R and CAMKK2). We investigate associations between HIV-SN and P2X-block genotypes in patients who never received stavudine. An adjacent gene, ANAPC5, was included. 75 HIV+ individuals were assessed using the Brief Peripheral Neuropathy Screen before treatment and after 6-8 months on stavudine-free regimens. DNA was genotyped for 48 polymorphisms across the four genes using an OpenArray™ platform. Haplotypes were derived using fastPHASE. Associations with HIV-SN were assessed using bivariate and multivariate analyses. Nine individuals (12%) were diagnosed with HIV-SN prior to ART and a further 20 individuals (27%) developed HIV-SN within 6-8 months. Five polymorphisms, rs503720*G (OR = 133) in P2X7R, rs10849861*A (OR = 5.99), rs1653586*T (OR = 67.8) and rs11065504*C (OR = 0.02) in CAMKK2, and rs2089886*A (OR = 6.68) in ANAPC5, associated with HIV-SN after adjusting for body weight, nadir CD4 T-cell counts and prior tuberculosis (model p < 0.0001, n = 69, Pseudo R² = 0.54). Three CAMKK2 haplotypes were associated with HIV-SN (OR = 2.82, 3.42 and 6.85) after adjusting for body weight, nadir CD4 T-cell counts and prior tuberculosis (model p < 0.0005, n = 71, Pseudo R² = 0.26). The results support a role for CAMKK2 in HIV-SN, independent of mechanisms invoked by stavudine. SIGNIFICANCE STATEMENT: HIV-associated sensory neuropathy (HIV-SN) remains a clinically relevant complication of HIV infection and its treatment, affecting 38% of patients treated without neurotoxic stavudine. HIV-SN can impact an individual's ability to work and quality of life, with few effective therapeutic options, so an understanding of the underlying mechanisms would have clinical value. We confirm that CAMKK2 polymorphisms and haplotypes influence susceptibility to HIV-SN in South Africans treated without stavudine. This provides further evidence for a role for the protein encoded by CAMKK2 in the pathogenesis of HIV-SN, independent of mechanisms initiated by stavudine.

Finding a Role for Zalcitabine in the HAART era

Zalcitabine (ddC) is a nucleoside analogue reverse transcriptase inhibitor with demonstrated clinical benefit in combination use. More widespread use of zalcitabine has been limited by a number of factors including peripheral neuropathy and three times daily dosing. However, screening for the risk factors for peripheral neuropathy may enable a reduction in the incidence of neuropathy to below 10%. Additionally, new data on the use of zalcitabine twice daily suggest, based on the long intracellular half-life of the active triphosphate, that this is feasible. Additionally, while limited data exist for zalcitabine in true HAART combinations, data from small trials suggest a similar proportion of responders to standard HAART regimens.

Nitrosative damage during retrovirus infection-induced neuropathic pain

BACKGROUND

Peripheral neuropathy is currently the most common neurological complication in HIV-infected individuals, occurring in 35-50% of patients undergoing combination anti-retroviral therapy. Data have shown that distal symmetric polyneuropathy develops in mice by 6 weeks following infection with the LP-BM5 retrovirus mixture. Previous work from our laboratory has demonstrated that glial cells modulate antiviral T-cell effector responses through the programmed death (PD)-1: PD-L1 pathway, thereby limiting the deleterious consequences of unrestrained neuroinflammation.

METHODS

Using the MouseMet electronic von Frey system, we assessed hind-paw mechanical hypersensitivity in LP-BM5-infected wild-type (WT) and PD-1 KO animals. Using multi-color flow cytometry, we quantitatively assessed cellular infiltration and microglial activation. Using real-time RT-PCR, we assessed viral load, expression of IFN-γ, iNOS, and MHC class II. Using western blotting, we measured protein nitrosylation within the lumbar spinal cord (LSC) and dorsal root ganglion (DRG). Histochemical staining was performed to analyze the presence of CD3, ionized calcium binding adaptor molecule (Iba)-1, MHCII, nitrotyrosine, isolectin B4 (IB4) binding, and neurofilament 200 (NF200). Statistical analyses were carried out using graphpad prism.

RESULTS

Hind-paw mechanical hypersensitivity observed in LP-BM5-infected animals was associated with significantly increased lymphocyte infiltration into the spinal cord and DRG. We also observed elevated expression of IFN-γ (in LSC and DRG) and MHC II (on resident microglia in LSC). We detected elevated levels of 3-nitrotyrosine within the LSC and DRG of LP-BM5-infected animals, an indicator of nitric oxide (NO)-induced protein damage. Moreover, we observed 3-nitrotyrosine in both small (IB4+) and large (NF200+) DRG sensory neurons. Additionally, infected PD-1 KO animals displayed significantly greater mechanical hypersensitivity than WT or uninfected mice at 4 weeks post-infection (p.i.). Accelerated onset of hind-paw hypersensitivity in PD-1 KO animals was associated with significantly increased infiltration of CD4+ and CD8+ T lymphocytes, macrophages, and microglial activation at early time points. Importantly, we also observed elevated levels of 3-nitrotyrosine and iNOS in infected PD-1 KO animals when compared with WT animals.

CONCLUSIONS

Results reported here connect peripheral immune cell infiltration and reactive gliosis with nitrosative damage. These data may help elucidate how retroviral infection-induced neuroinflammatory networks contribute to nerve damage and neuropathic pain.

Update of HIV-Associated Sensory Neuropathies

PURPOSE OF REVIEW

HIV-sensory neuropathy (HIV-SN) remains a common complication of HIV infection and may be associated with significant morbidity due to neuropathic pain. The overall purpose of this review is to discuss trends in the changing epidemiology in HIV-SN, new data regarding the pathophysiology of the condition, and discuss approaches to management.

RECENT FINDINGS

While HIV-SN has been historically considered the most common neurological complication of HIV infection, improved accessibility to effective combination antiretroviral therapy (cART), use of less neurotoxic antiretroviral medication regimens, and trends towards earlier introduction of treatment have impacted the condition: overall incident HIV-SN is likely decreased compared to prior rates and patients afflicted by HIV-SN may more frequently have asymptomatic or subclinical disease. Traditional predictors of HIV-SN have also changed, as traditional indices of severe immune deficiency such as low CD4 count and high viral load no longer predict HIV-SN. Emerging evidence supports the contention that both peripheral and central mechanisms underlying the generation as well as persistence of neuropathic pain in HIV-SN exist. It is important to recognize that even mild neuropathic pain in this clinical population is associated with meaningful impairment in quality of life and function, which emphasizes the clinical importance of recognizing and treating the condition. The general approach to management of neuropathic pain in HIV-SN is the introduction of symptomatic analgesic therapy. There exist, however, few evidence-based analgesic options for HIV-SN based on available clinical data. Symptomatic treatment trials are increasingly recognized to have been potentially confounded by more robust placebo response than that observed in other neuropathic pain conditions. In the authors' experience, use of analgesic therapies with proven efficacy in other neuropathic pain conditions is appropriate, bearing in consideration potential pharmacokinetic interactions with the cART regimen. Combination analgesic regimens may also achieve meaningful analgesic responses, particularly when drugs with differing mechanisms of action are utilized. It is paramount that the patient is appropriately counseled regarding expectations and the anticipated benefit of analgesic therapy, as pain relief is often incomplete but clinically meaningful improvement in pain and function can be achieved.

Aging with HIV in the ART era

In the current era of therapy for human immunodeficiency virus (HIV), life expectancy for persons living with HIV (PLWH) approaches that of the general population. This newly prolonged survival among PLWH is associated with an increased prevalence of comorbidities due to the inflammation, immune activation and immune senescence associated with HIV infection. Higher prevalence of tobacco and alcohol use, co-infection with viral hepatitis and traditional cardiovascular risk factors such as hypertension and hyperlipidemia contribute as well. In this review, we hope to describe the current comorbidities occurring among PLWH and bring increased awareness for conditions that may otherwise not be considered given the younger age at time of presentation.

Didanosine

OBJECTIVE:

To review the chemistry, intracellular metabolism, pharmacokinetics, and clinical experience with didanosine (2',3'-dideoxyinosine [ddI]).

DATA SOURCES:

English-language articles and conference proceedings (indexing terms were didanosine, 2′,3′-dideoxyinosine, and ddI).

STUDY SELECTION:

Available Phase I studies and abstracts determined to have clinical significance were included.

DATA EXTRACTION:

Clinical experience with ddI is limited to uncontrolled Phase I studies and a large “expanded-access” program. The primary outcome parameters used to evaluate ddI were the HIV surrogate markers: CD4+ lymphocytes and p24 antigen. Thus, the clinical data reviewed here must be evaluated critically and be considered preliminary until the results of studies comparing ddI with zidovudine (ZDV) and combination studies are available.

DATA SYNTHESIS:

Didanosine has been approved for the treatment of HIV infection in patients who are unable to tolerate ZDV because of adverse effects (e.g., anemia and neutropenia) or who experience clinical or immunologic deterioration while receiving ZDV. Compared with ZDV, ddI has a long intracellular half-life and negligible bone-marrow toxicity. It also has in vitro activity against ZDV-resistant strains of HIV. Phase I studies indicate that ddI has a beneficial effect on the CD4+ cell counts and HIV p24 antigen concentrations. As a result of the acid-labile nature of ddI, oral formulations are buffered or must be mixed with antacid to neutralize gastric pH. Bioavailability then averages 20–40 percent, depending on the dose and formulation given. The plasma half-life, total body clearance, and volume of distribution of ddI are one to two hours, 0.7–1 L/kg/h, and 0.8–1 L/kg, respectively. Painful peripheral neuropathy and pancreatitis (dose-limiting toxicities of ddI) occurred in 34 and 9 percent of patients in Phase I studies, respectively.

CONCLUSIONS:

Didanosine has demonstrated preliminary efficacy in the treatment of late-stage HIV infection; however, its effect on patient survival, its efficacy relative to ZDV, and its utility in combination with other agents are still under evaluation.

Patterns of peripheral neuropathy in ART-naïve patients initiating modern ART regimen

The purpose of this study was to evaluate associations of pre-ART CD4 with peripheral neuropathy (PN) and estimate the prevalence of PN in HIV-positive patients starting modern combination antiretroviral therapy (cART) regimens. ART-naïve subjects initiating cART were followed longitudinally and screened for signs/symptoms of PN. Lower pre-ART CD4 count was associated with post-ART PN. After 7 years (n = 117), the prevalence (95% CI) of PN and SPN were 31% (23, 40%) and 5% (2, 11%) with pre-ART CD4 count >250 copies/μL. PN continues to be identified in HIV-infected individuals on modern cART by targeted assessment but is generally without symptoms.

Prevalence, incidence and predictors of peripheral neuropathy in African adults with HIV infection within the DART trial

OBJECTIVES

We investigated the prevalence, incidence and predictors of new peripheral neuropathy episodes in previously untreated, symptomatic HIV-infected Ugandan/Zimbabwean adults initiating zidovudine-based antiretroviral therapy (ART).

DESIGN

An open-label, multicentre, randomized trial.

METHODS

Peripheral neuropathy was self-reported at 12-weekly clinic visits. Cox regression models (excluding participants reporting preexisting peripheral neuropathy at ART initiation), considered sex; pre-ART WHO stage, age and CD4(+) cell count; CD4(+) cell count versus no CD4(+) cell count monitoring; and time-updated CD4(+) cell count, weight and use of stavudine, isoniazid and didanosine.

RESULTS

Four hundred and twenty-one out of 3316(13%) patients reported preexisting peripheral neuropathy at ART initiation. Median (interquartile range, IQR) follow-up in 2895 participants without preexisting peripheral neuropathy was 4.9 (4.7-5.4) years. Three hundred and fifty-four (12%) took stavudine as first-line substitution and 518 (18%) took isoniazid during follow-up. Two hundred and ninety (11%) participants developed a new peripheral neuropathy episode, an incidence of 2.12 per 100 person-years. Eighteen (0.1%) had a grade 3/4 episode. Independent predictors of peripheral neuropathy were current stavudine use [adjusted hazard ratio (a)HR 4.16 (95% confidence interval, 95% CI 3.06-5.66], current isoniazid use [aHR 1.59 (95% CI 1.02-2.47)] and current didanosine use [aHR 1.60 (95% CI 1.19-2.14)]. Higher risks were independently associated with higher pre-ART weight [aHR (per+5 kg) 1.07 (95% CI 1.01-1.13)] and older age aHR (per 10 years older) 1.29 (95% CI 1.12-1.49), but there was no significant effect of sex (P = 0.13), pre-ART CD4(+) cell count (P = 0.91) or CD4(+) cell count monitoring (P = 0.73).

CONCLUSION

Current stavudine, didanosine or isoniazid use continue to increase peripheral neuropathy risks, as does older age and weight at ART initiation; however, we found no evidence of increased risk in women in contrast to previous studies. The incidence of peripheral neuropathy may now be lower in ART programmes, as stavudine and didanosine are no longer recommended. All patients receiving isoniazid, either as part of antituberculosis (TB) chemotherapy or TB-preventive therapy, should receive pyridoxine as recommended in national guidelines.

The issues around opioid prescribing in HIV-related pain

SUMMARY Opioids are very useful analgesics but reports of abuse, addiction and occasionally death have led to an increase in scrutiny, particularly for chronic opioid therapy. The development of effective antiretroviral therapy has changed the focus of treatment of people living with HIV from palliative care to the management of a chronic disease. It is appropriate, therefore, to review the issues around opioid prescribing in HIV in light of this and recent research, and to review the guidance available. This review briefly examines the epidemiology of pain in people living with HIV and then the use and issues around strong opioid prescribing in this group.

Involvement of microglial CD40 in murine retrovirus-induced peripheral neuropathy

B6 mice infected with LP-BM5 develop severe immunodeficiency (termed murine acquired immunodeficiency syndrome (MAIDS)) and peripheral neuropathy. To determine whether microglial CD40 is involved in LP-BM5-induced peripheral neuropathy, B6-CD40 knockout (KO) mice and B6-CD40 KO mice adoptively transferred either total leukocytes or B cells were examined for behavioral sensitivity, tissue viral loads, cytokine responses, and the development of MAIDS. All three CD40 KO groups developed MAIDS, the severity of which was correlated with peripheral cytokine responses. CD40 KO mice displayed significantly reduced mechanical hypersensitivity post-infection compared to wild-type mice regardless of cell transfer. These findings support microglial CD40 involvement in LP-BM5-induced peripheral neuropathy.

Neurotoxicity of antiretroviral therapy

The neurological outcome of HIV infection has changed dramatically in the era of HAART. Despite effective suppression of plasma viral load and a substantial decrease in the incidence of HIV-associated dementia, neurocognitive impairment and peripheral neuropathy remain widespread. The neurotoxic side effects of antiretroviral (ARV) agents are among several contributing factors to this continued prevalence. Effective penetration of the CNS by ARV agents is paramount to treating neurological symptoms as well as systemic infection, but may also exacerbate the severity of drug-related neurotoxicity. The neurotoxic side effects of ARV agents vary widely between and within drug classes. The risks and benefits of combination regimens continue to evolve as more effective treatment protocols are developed.

The cutaneous nerve biopsy: technical aspects, indications, and contribution

Skin biopsy with a 3mm disposable circular punch is easy to perform and allows, after proper processing, the visualization of epidermal, dermal, and sweat gland nerve fibers. A technique of sampling the epidermis alone by applying a suction capsule, the "blister" technique, has also been developed. It is most common to stain immunohistochemically for the pan-axonal marker protein gene product 9.5 (PGP 9.5), an ubiquitin C-terminal hydroxylase. The sections are then observed and analyzed with bright-field microscopy or with indirect immunofluorescence with or without confocal microscopy. Most studies report quantification of intraepidermal nerve fiber density displayed in bright-field microscopy. Normative values have been established, particularly from the distal part of the leg, 10cm above the external malleolus. In diabetes mellitus early degeneration of intraepidermal nerve fibers is induced and there is slower regeneration even when there is no evidence of neuropathy. Skin biopsy is of particular value in the diagnosis of small fiber neuropathy when nerve conduction studies are normal. It may also be repeated in order to study the progressive nature of the disease and also has the potential of studying regeneration of nerve fibers and thus the effects of treatment. Inflammatory demyelinating neuropathies may also involve loss of small-diameter nerve fibers and IgM deposits in dermal myelinated nerve fibers in anti-MAG neuropathy. In some cases the presence of vasculitis in skin may indicate a nonsystemic vasculitic neuropathy and in HIV neuropathy intraepidermal nerve fiber density is reduced in a length-dependent manner. In several hereditary neuropathies intraepidermal nerve fiber density may be reduced but other abnormalities can also be demonstrated in dermal myelinated fibers. Some small swellings and varicosities may be present in the distal leg skin biopsy of healthy individuals but large axonal swellings are considered as evidence of a pathological process affecting the normal structure of nerves. The indirect immunofluorescence technique with confocal microscopy provides the opportunity to study the complex structure of sensory receptors and cutaneous myelinated fibers and the innervation of sweat glands, arrector pilorum muscles, and vessels.

Neuromuscular manifestations of HIV/AIDS

The human immunodeficiency virus (HIV) epidemic, now entering its fourth decade, affects approximately 33 million people living in both developed and resource-limited countries. Neurological complications of the peripheral nervous system are common in HIV-infected patients, and neuromuscular pathology is associated with significant morbidity. Peripheral neuropathy is the most common neuromuscular manifestation observed in HIV/AIDS, and in the antiretroviral era, its prevalence has increased. The purpose of this review was to describe the clinical spectrum of neuromuscular disorders in the setting of HIV infection and to provide an approach to diagnosis and management.

Painful HIV-associated sensory neuropathy

SUMMARY Painful HIV-associated sensory neuropathy (HIV-SN) is an early recognized neurological complication of HIV. The introduction of effective HIV treatments saw increased rates of HIV-SN, with some antiretrovirals (notably stavudine) being neurotoxic. Although neurotoxic antiretrovirals are being phased out, the available data suggest that incident HIV-SN will remain common, impairing quality of life, mobility and ability to work. Despite its major clinical importance, the pathogenesis and determinants of pain in HIV-SN are poorly understood, and effective prevention and analgesic strategies are lacking. Here, we review what is known about the rates and risk factors for painful HIV-SN, the laboratory models informing our understanding of neuropathic pain in HIV, and the future clinical and laboratory work needed to fully understand this debilitating condition and provide effective management strategies for those affected.

HIV neuropathy: an in vivo confocal microscopic study

Several approaches exist for quantitative assessment of human immunodeficiency virus (HIV)-associated distal sensory polyneuropathy (DSP). While useful, each has some limitations. This study evaluated non-invasive, in vivo reflectance confocal microscopy (RCM) of Meissner corpuscles (MCs) as a measure of HIV-DSP. Forty-eight adults (29 HIV-infected, 19 controls) underwent RCM of MC density (MCs/mm(2)) at the arch, fingertip, and thenar eminence (TE); ankle skin biopsy to measure epidermal nerve fiber density (ENFD); electrophysiologic studies; and tactile, vibration, and thermal threshold testing. HIV+ subjects were clinically categorized as having DSP signs or no signs. MC densities were lower in HIV+ subjects with DSP signs than in controls (arch, p = 0.0003; fingertip, p < 0.0001; TE, p = 0.0002). Tactile thresholds in the TE and foot were worse in HIV-DSP than in controls, but in this mild DSP cohort, sural amplitudes, ENFD, and vibration and thermal thresholds did not differ significantly from controls. Fingertip MC densities and tactile thresholds at the foot were also lower in HIV+ subjects without DSP signs than in controls. Other sensory measures were not significantly different in HIV+ subjects without DSP signs than in controls. MC density correlated inversely with tactile thresholds at each imaging location. The results suggest that RCM of MC density complements existing sensory DSP measures and discriminates mild HIV-DSP from controls at a stage when sural amplitudes do not. Further studies are required to determine whether RCM of MC density can establish quantitative changes in DSP, in response to treatment or disease progression.

HIV-associated sensory neuropathy: risk factors and genetics

HIV-associated sensory neuropathy (HIV-SN) remains a common neurological complication of HIV infection despite the introduction of effective antiretroviral therapies. Exposure to neurotoxic antiretroviral drugs and increasing age have consistently been identified as risk factors for HIV-SN, while comorbid conditions with underlying predisposition to cause peripheral neuropathy (eg, diabetes mellitus, malnutrition, isoniazid exposure), ethnicity, and increasing height also have been implicated. Genetic association studies have identified genes affecting mitochondrial function and genes involved in the inflammatory response that modify the risk for HIV-SN among patients exposed to neurotoxic antiretrovirals. However, there is a lack of data on clinical, demographic, and genetic risk factors for HIV-SN in the modern era, with the rate of HIV-SN remaining unacceptably high despite the introduction of safer medications. Thus, more work is required to identify the principal factors that increase an individual's risk for HIV-SN so that effective preventative or therapeutic strategies can be implemented.

Murine immunodeficiency virus-induced peripheral neuropathy and the associated cytokine responses

Distal symmetrical polyneuropathy is the most common form of HIV infection-associated peripheral neuropathy and is often associated with pain. C57BL/6 (B6) mice infected with LP-BM5, a murine retroviral isolate, develop a severe immunodeficiency syndrome similar to that in humans infected with HIV-1, hence the term murine AIDS. We investigated the induction of peripheral neuropathy after LP-BM5 infection in B6 mice. Infected B6 mice, like HIV-infected humans, exhibited behavioral (increased sensitivity to mechanical and heat stimuli) and pathological (transient loss of intraepidermal nerve fibers) signs of peripheral neuropathy. The levels of viral gag RNA were significantly increased in all tissues tested, including spleen, paw skin, lumbar dorsal root ganglia, and lumbar spinal cord, postinfection (p.i.). Correlated with the development of peripheral neuropathy, the tissue levels of several cytokines, including IFN-γ, IL-1β, IL-6, and IL-12, were significantly elevated p.i. These increases had cytokine-specific and tissue-specific profiles and kinetics. Further, treatment with the antiretroviral agent zidovudine either significantly reduced or completely reversed the aforementioned behavioral, pathologic, and cytokine changes p.i. These data suggest that LP-BM5 infection is a potential mouse model of HIV-associated distal symmetrical polyneuropathy that can be used for investigating the roles of various cytokines in infection-induced neuropathic pain. Further investigation of this model could give a better understanding of, and lead to more effective treatments for, HIV infection-associated painful peripheral neuropathy.

HIV-associated sensory neuropathy: still a problem in the post-stavudine era?

Sensory neuropathy (SN) is a common and difficult to manage cause of chronic pain in HIV. Recent recommendations for earlier HIV treatment and avoidance of neurotoxic antiretroviral drugs (such as stavudine) have led to optimism that HIV-SN rates may decline. We present several reasons as to why HIV-SN is likely to remain prevalent, despite improvements in HIV management, together with clinical evidence confirming high HIV-SN rates in cohorts never exposed to neurotoxic medications. A combination of epidemiologic studies, laboratory work and clinical trials are needed to understand the problem of HIV-SN in the post-stavudine era. Improved HIV-SN prevention and management strategies are needed if the morbidity associated with HIV infection is to improve along with life expectancy.

Determinants of epidermal nerve fibre density in antiretroviral-naïve HIV-infected individuals

OBJECTIVES

Distal leg epidermal nerve fibre density (ENFD) is a validated predictor of small unmyelinated nerve fibre damage and neuropathy risk in HIV infection. As pre-existing damage may increase the risk of neuropathy following antiretroviral (ARV) therapy, particularly when the regimen contains stavudine (d4T), we assessed the relationship between ENFD and various parameters including mitochondrial factors in HIV-infected Thai individuals naïve to ARV therapy.

METHODS

Distal leg and proximal thigh ENFDs were quantified in HIV-infected Thai individuals without neuropathy prior to randomization to a HIV clinical trial that focused on mitochondrial toxicity issues. We assessed their association with various clinical and immunovirological parameters as well as with peripheral blood mononuclear cell (PBMC) mitochondrial (mt) DNA copies/cell, oxidative phosphorylation (OXPHOS) complex I (CI) and complex IV (CIV) enzyme activities, and mt 8-oxo-deoxyguanine (8-oxo-dG) break frequencies.

RESULTS

In 132 subjects, the median (interquartile range) ENFD (fibres/mm) values were 21.0 (16.2-26.6) for the distal leg and 31.7 (26.2-40.0) for the proximal thigh. By linear regression, lower CD4 count (P < 0.01), older age (P < 0.01), increased body mass index (BMI) (P = 0.04), increased height (P = 0.02), and higher PBMC OXPHOS activity as measured by CIV activity (P = 0.02) were associated with lower distal leg ENFD.

CONCLUSIONS

Older age, increased height, higher BMI, poorer immunological status and higher PBMC OXPHOS activity are associated with lower distal leg ENFD in HIV-infected subjects free of neuropathy prior to initiation of first-time ARV therapy.

A Prospective Study Assessing Tumour Response, Survival, and Palliative Care Outcomes in Patients with HIV-Related Kaposi's Sarcoma at Queen Elizabeth Central Hospital, Blantyre, Malawi

Background. Human-Immunodeficiency-Virus- (HIV-) related Kaposi's sarcoma (KS) has a high prevalence in Africa; however, there is minimal published data on treatment and outcomes in this population. Objective and Design. This was a prospective study of 50 patients, aiming to assess the impact of vincristine therapy on tumour response and survival and to assess palliative care outcomes in patients with HIV-related KS. Methods. 50 consecutive patients were recruited during 2008. Vincristine therapy and highly active antiretroviral therapy (HAART) were given. Tumour response, survival, and chemotherapy-related toxicities were documented. Palliative care outcomes were assessed using the African Palliative Care Association (APCA) Palliative Outcome Scale (POS). Results. The majority of patients were male, and the median age was 33 years. At baseline assessment, the median CD4 T-cell count was 263, and 50% patients had evidence of peripheral neuropathy. The overall response rate was 64% at 6 weeks, and median progression-free survival was 30 weeks. Treatment was generally well tolerated, with peripheral neuropathy the main dose-limiting toxicity. Conclusion. The combination of vincristine and HAART is feasible and effective in a low resource setting, although peripheral neuropathy is a dose-limiting factor. This patient group carries a high mortality and as such adequate access to palliative care is crucial.

Epidemiology of HIV-related neuropathy: a systematic literature review

We sought to identify and summarize the incidence and prevalence of neuropathy among HIV patients and subgroups. A systematic search of the literature was performed using MEDLINE and EMBASE. The relevant literature was identified based on predefined criteria. Prevalence data were collected from cross-sectional and cohort studies. Incidence data were collected from cohort and case-control studies. Thirty-seven studies were included of which there were 23 cohort studies, 13 cross-sectional studies, and one case-control study. The prevalence of neuropathy among HIV patients derived from 25 studies varied from 1.2% to 69.4%. Regarding the development of neuropathy among HIV-positive patients, standardized by study duration, the rates per 100 person-years ranged from 0.7 to 39.7. Among older patients there is a greater risk of neuropathy. The same seems to be the case for patients with more severe disease. Currently available studies providing information on the incidence and prevalence of neuropathy among HIV patients suggest a significant burden, but there is a great variation in results across studies. There is no definitive explanation for the variation. However, it underscores the fact that complexity of the disease, along with absence of standardized diagnostic criteria, has considerably influenced the methodologies and outcomes of the studies.

HIV neuropathy risk factors and symptom characterization in stavudine-exposed South Africans

CONTEXT

HIV-associated sensory neuropathy (HIV-SN) is a frequent complication of both HIV and neurotoxic antiretroviral medications such as stavudine.

OBJECTIVES

To determine the prevalence, risk factors, and clinical characteristics of symptomatic HIV-SN in a Black South African cohort of patients exposed to stavudine.

METHODS

HIV-positive Black South Africans (n=395) who had received stavudine for at least six months were recruited at the Virology Clinic of the Charlotte Maxeke Academic Johannesburg Hospital, South Africa, and screened for neuropathy using the AIDS Clinical Trials Group neuropathy screening tool. HIV-SN was defined as present if the patient had both symptoms and signs of peripheral neuropathy. If present, the distribution and intensity of symptoms were recorded. In addition, anthropomorphic, demographic, and clinical information were recorded and analyzed as risk factors.

RESULTS

The prevalence of symptomatic HIV-SN was 57% (226 of 395). Increasing age and height were independently associated with the development of SN among patients who had used stavudine. Pain was the primary symptom reported by participants with HIV-SN (76%, 172 of 226), followed by numbness (48%, 108 of 226), and pins and needles (46%, 105 of 226). About three-quarters of participants rated their symptoms as being of moderate to severe intensity. Symptoms were always present in the feet and only 23% experienced symptoms proximal to the feet.

CONCLUSION

HIV-SN was common in this population and frequently associated with moderate to severe pain in the feet. HIV-SN was significantly associated with increasing age and height, factors that could be measured at no added cost prior to stavudine prescription, allowing higher risk patients to be offered priority access to nonneurotoxic drugs.

Neurologic manifestations of human immunodeficiency virus-2: dementia, myelopathy, and neuropathy in West Africa

While well documented in human immunodeficiency virus (HIV)-1, neurologic sequelae have not been systematically evaluated in HIV-2. After excluding for confounding comorbidities, 67 individuals from a rural cohort in Guinea-Bissau (22 HIV-2 participants, 45 seronegative controls) were evaluated. HIV + individuals were divided into CD4 < 350 and CD4 ≥ 350 for analysis. HIV-associated neurocognitive disorders (HAND), assessed by the International HIV Dementia Scale (IHDS), distal sensory polyneuropathy (DSPN), and myelopathy were the main outcome variables. In univariate analysis, there was no difference in IHDS scores among groups. When analyzed by primary education attainment, IHDS scores were nonsignificantly higher (p = 0.06) with more education. There was no significant difference in DSPN prevalence among groups; overall, 45% of participants had DSPN. There were no cases of myelopathy. In multivariate linear regression, higher IHDS scores were significantly correlated with older age (coefficient = -0.11, p < 0.001). Logistic regression analysis showed that older age (odds ratio (OR) 95% CI 1.04-1.20), lower CD4 count (OR 95% CI 0.996-0.999), and higher BMI (OR 95% CI 1.02-1.43) significantly predicted the presence of DSPN. While a significant increase in cognitive impairment was not observed in HIV-2-infected individuals, the study suggests the IHDS may be a less effective screening tool for HAND in settings of lower educational attainment as encountered in rural Guinea-Bissau. Similar to HIV-1, DSPN seems to occur with lower CD4 counts in HIV-2. Further study of the viral-host interactions in HIV-2 and its consequent neurological diseases may provide an avenue for understanding the epidemic problems of HIV-1.

Tumour necrosis factor haplotypes associated with sensory neuropathy in Asian and Caucasian human immunodeficiency virus patients

In human immunodeficiency virus (HIV) patients, neuropathy is a common adverse side effect to some antiretroviral treatments, particularly stavudine. As stavudine is cheap, it is widely used in Asia and Africa. We showed that increasing age and height moderately predict the development of neuropathy. This was improved by the inclusion of tumour necrosis factor (TNF)-1031 (rs1799964). To investigate this association, Malay (n = 64), Chinese (n = 74) and Caucasian patients (n = 37) exposed to stavudine were screened for neuropathy. DNA samples were genotyped for polymorphisms in the central major histocompatibility complex (MHC) near TNF, and haplotypes were derived. The haplotype group FVa6,7,8 (incorporating TNF-1031) was found to be associated with neuropathy in Chinese patients in bivariate analyses (P = 0.03), and in Malays and Chinese in a multivariate analysis correcting for age and height (P = 0.02, P = 0.03, respectively). This trend was also confirmed in Caucasians.

Incident neuropathy in HIV-infected patients on HAART

We determined the incidence of and risk factors for distal sensory polyneuropathy (DSP) in individuals on HAART. Sixty-one HIV-positive subjects on HAART for at least 6 months and neuropathy free were retrospectively selected. The study included subjects who had previously tolerated d-drugs without developing DSP. Neuropathy incidence over 4 years was calculated. Cox proportional hazards models were used to determine risk factors associated with incident DSP. Nineteen subjects developed DSP over a mean follow-up of 2.4 years. Subjects never treated with a d-drug developed DSP at a rate of 21 cases per 100 person-years (95% CI, 8.9-33.7). Subjects with a history of d-drug treatment but not on a d-drug at enrollment developed DSP at a rate of 17 cases per 100 person-years (95% CI, 2.1-31.8). Those on d-drug treatment developed DSP at a rate of 25 cases per 100 person-years (95% CI, 8.7-41.6). Multivariable analysis identified age [hazard ratio (HR) = 1.09; p < 0.01] and low CD4(+) nadir [hazard ratio (HR) = 0.79; p = 0.03] as significant risk factors. Current or prior history of treatment with d-drug was not a significant risk factor for incident DSP in subjects who had previously tolerated d-drug treatment without developing a toxic DSP. Age and low CD4(+) are risk factors for incident DSP. However, current or prior history of d-drug treatment is not a significant risk factor for incident DSP in subjects who had previously tolerated d-drug treatment without developing a toxic DSP.

Oral uridine supplementation antagonizes the peripheral neuropathy and encephalopathy induced by antiretroviral nucleoside analogues

OBJECTIVE

Peripheral neuropathy and central nervous system neurodegeneration may result from the mitochondrial toxicity of some antiretroviral nucleoside analogues. We investigated whether this neuropathology may be antagonized by uridine supplementation in vivo.

DESIGN

Because of the obvious difficulties in obtaining human neural tissues, the mitochondrial neurotoxicity of the nucleoside analogues was studied in mice.

METHODS

BALB/C mice (7 weeks of age) were fed for 9 weeks with zalcitabine (13 mg/kg per day) or zidovudine (100 mg/kg per day) with or without mitocnol (340 mg/kg per day), a dietary supplement with high uridine bioavailability. Hippocampal and sciatic nerve mitochondria were analyzed.

RESULTS

Zalcitabine and to a lesser extent zidovudine induced a significant peripheral neuropathy and encephalopathy with disrupted mitochondrial ultrastructure, depleted mitochondrial DNA, reduced levels of cytochrome c oxidase activity and diminished expression of mitochondrial DNA-encoded cytochrome c oxidase subunit I. Mitocnol had no intrinsic effects but attenuated or fully normalized all measured disorder of the peripheral and central nervous system.

CONCLUSION

Zidovudine and zalcitabine induce a mitochondrial disorder in the peripheral and central nervous system, both of which are antagonized by uridine supplementation.

Acetyl-l-carnitine and nucleoside reverse transcriptase inhibitor-associated neuropathy in HIV infection

OBJECTIVES

Antiretroviral toxic neuropathy (ATN) is associated with dideoxynucleoside reverse transcriptase inhibitor use in patients infected with HIV, possibly as a result of mitochondrial toxicity. Acetyl-l-carnitine (ALC) has been linked to symptomatic improvement in ATN. We present an open-label single-arm pilot study to evaluate changes in intra-epidermal nerve fibre (IENF) density and mitochondrial DNA (mtDNA) copies/cell among subjects treated with 3000 mg ALC daily.

METHODS

Punch skin biopsies were examined at baseline and after 24 weeks of therapy. Participants reported neuropathic symptoms using the Gracely Pain Intensity Score. Neurological examinations were completed.

RESULTS

Twenty-one subjects completed the study. ALC was generally well tolerated. The IENF density did not change in cases completing 24 weeks of ALC therapy, with median (90% confidence interval) IENF changes of -1.70 (-3.50, infinity) (P=0.98) and 2.15 (-0.10, infinity) (P=0.11) for the distal leg and proximal thigh, respectively. Fat mtDNA copies/cell did not change with therapy. Improvements in neuropathic pain (P<0.01), paresthesias (P=0.01), and symptoms of numbness (P<0.01) were noted. Similarly, improvement was noted on the Gracely Pain Intensity Score.

CONCLUSIONS

ALC therapy coincided with improvements in subjective measures of pain in this open-label single-arm study. However, changes were not observed in objective measures of IENF density or mtDNA levels, providing little objective support for use of ALC in this setting.

Genome-wide screen identifies drug-induced regulation of the gene giant axonal neuropathy (Gan) in a mouse model of antiretroviral-induced painful peripheral neuropathy

Painful peripheral neuropathy is a debilitating complication of the treatment of HIV with nucleoside reverse transcriptase inhibitors (NRTIs). Patients are living longer with these drugs; however many develop excruciating, unremitting, and often treatment-limiting neuropathy that is resistant to conventional pain management therapies. Improving patient comfort and quality of life is paramount and depends on a clearer understanding of this devastating side effect. The mechanisms underlying the development of NRTI-induced neuropathy, however, remain unclear. Using a mouse model of NRTI-induced neuropathy, the authors conducted an unbiased whole-genome microarray screen to identify molecular targets in the spinal dorsal horn, which is the location where integration of ascending sensory transmission and descending modulatory effects occur. Analysis of the microarray data identified a change in the gene giant axonal neuropathy 1 (Gan1). Mutation of this gene has been linked to the development of giant axonal neuropathy (GAN), a rare autosomal recessive condition characterized by a progressive sensorimotor neuropathy. Gan1 has not been previously linked to nerve pathologies in other populations. In this study, downregulation of the Gan1 gene and the gene protein product, gigaxonin, was validated via quantitative polymerase chain reaction ([qPCR] gene expression) and Western blot analyses (protein level). Our report is the first to suggest that Gan1 might be a novel molecular target in the development of NRTI-induced peripheral neuropathy with implications for new therapeutic approaches to preventing or reducing a significant side effect of HIV treatment.

Altered cutaneous nerve regeneration in a simian immunodeficiency virus / macaque intracutaneous axotomy model

To characterize the regenerative pattern of cutaneous nerves in simian immunodeficiency virus (SIV)-infected and uninfected macaques, excisional axotomies were performed in nonglabrous skin at 14-day intervals. Samples were examined after immunostaining for the pan-axonal marker PGP 9.5 and the Schwann cell marker p75 nerve growth factor receptor. Collateral sprouting of axons from adjacent uninjured superficial dermal nerve bundles was the initial response to axotomy. Both horizontal collateral sprouts and dense vertical regeneration of axons from the deeper dermis led to complete, rapid reinnervation of the epidermis at the axotomy site. In contrast to the slower, incomplete reinnervation previously noted in humans after this technique, in both SIV-infected and uninfected macaques epidermal reinnervation was rapid and completed by 56 days postaxotomy. p75 was densely expressed on the Schwann cells of uninjured nerve bundles along the excision line and on epidermal Schwann cell processes. In both SIV-infected and uninfected macaques, Schwann cell process density was highest at the earliest timepoints postaxotomy and then declined at a similar rate. However, SIV-infection delayed epidermal nerve fiber regeneration and remodeling of new sprouts at every timepoint postaxotomy, and SIV-infected animals consistently had lower mean epidermal Schwann cell densities, suggesting that Schwann cell guidance and support of epidermal nerve fiber regeneration may account for altered nerve regeneration. The relatively rapid regeneration time and the completeness of epidermal reinnervation in this macaque model provides a useful platform for assessing the efficacy of neurotrophic or regenerative drugs for sensory neuropathies including those caused by HIV, diabetes mellitus, medications, and toxins.

Benefits and risks of stavudine therapy for HIV-associated neurologic complications in Uganda

BACKGROUND

The frequency of HIV dementia in a recent study of HIV+ individuals at the Infectious Disease Institute in Kampala, Uganda, was 31%. Coformulated generic drugs, which include stavudine, are the most common regimens to treat HIV infection in Uganda and many other parts of Africa.

OBJECTIVE

To evaluate the benefits and risks of stavudine-based highly active antiretroviral therapy (HAART) for HIV-associated cognitive impairment and distal sensory neuropathy. The study compared neuropsychological performance changes in HIV+ individuals initiating HAART for 6 months and HIV- individuals receiving no treatment for 6 months. The risk of antiretroviral toxic neuropathy as a result of the initiation of stavudine-based HAART was also examined.

METHODS

At baseline, 102 HIV+ individuals in Uganda received neurologic, neuropsychological, and functional assessments; began HAART; and were followed up for 6 months. Twenty-five HIV- individuals received identical clinical assessments and were followed up for 6 months.

RESULTS

In HIV+ individuals, there was improvement in verbal memory, motor and psychomotor speed, executive thinking, and verbal fluency. After adjusting for differences in sex, HIV+ individuals demonstrated significant improvement in the Color Trails 2 test (p = 0.025) compared with HIV- individuals. Symptoms of neuropathy developed in 38% of previously asymptomatic HIV+ patients after initiation of the stavudine-based HAART.

CONCLUSIONS

After the initiation of highly active antiretroviral therapy (HAART) including stavudine, HIV+ individuals with cognitive impairment improve significantly as demonstrated by improved performance on a test of executive function. However, peripheral neurotoxicity occurred in 30 patients, presumably because of stavudine-based HAART, suggesting the need for less toxic therapy.

A report on the effect of commencing enfuvirtide on peripheral neuropathy

Enfuvirtide is the first fusion inhibitor approved for use in HIV treatment and is a useful therapeutic option for highly treatment experienced individuals. Passive reporting has associated increased neuropathy rates with enfuvirtide use in some early studies but not others. The aim of this study was to describe any functional or clinical changes consistent with neuropathy among enfuvirtide users. A prospective cohort study of patients commencing or continuing enfuvirtide at a state HIV referral service, including clinical and sensory threshold monitoring, was conducted. A total of 14 patients were studied. All had advanced HIV disease and 13 (93%) had symptoms and/or signs consistent with neuropathy at baseline. Patients who entered the study on enfuvirtide-based therapy remained neurologically stable throughout follow-up. Eleven patients were assessed preand postenfuvirtide. No evidence was found for any clear effect of enfuvirtide on neuropathic symptoms, neuropathic signs, or sensory thresholds at a cohort level (p > 0.3 for all, Wilcoxon signed rank test). However, three (21%) patients experienced worsening of existing neuropathy symptoms (transient in two cases) and two (14%) patients' symptoms improved with enfuvirtide commencement. Breakthrough HIV viremia was associated with worsening symptoms in two patients at 5 and 18 months of enfuvirtide use. This study found no clear effect on peripheral nerves from enfuvirtide. Although limited by a small sample size, this study involved patients who would have been particularly vulnerable to a neurotoxin, with advanced HIV disease and a high rate of baseline neurological abnormalities. We observed no clear evidence of neurotoxicity from enfuvirtide in this population.

Antiretroviral therapy-associated toxicities in the resource-poor world: the challenge of a limited formulary

Toxicities related to antiretroviral therapy make long-term adherence to therapy difficult for patients and present challenges to providers, especially those in the resource-poor world who work with a limited formulary. In resource-poor settings, where limited drug options are the rule, when and how to change therapy are especially difficult problems. Drugs such as stavudine and didanosine are associated with serious metabolic complications, such as lactic acidosis, pancreatitis, and peripheral neuropathy. Antiretroviral agents associated with fewer metabolic effects, such as tenofovir and abacavir, remain widely unavailable. Because the current formulary restrictions appear to be unlikely to change quickly, providers in resource-poor countries must be familiar with the common adverse events-including metabolic complications, hypersensitivity reactions, anemia, and liver enzyme abnormalities-and must understand how to manage them with what is locally available. Most importantly, to avoid drug toxicities, a larger formulary is needed in resource-poor settings, and this must be a high priority for policy makers and health care professionals involved in treating human immunodeficiency virus infection globally.

A review of the epidemiology of painful diabetic peripheral neuropathy, postherpetic neuralgia, and less commonly studied neuropathic pain conditions

Although the burden of neuropathic pain is well-recognized, the descriptive epidemiology of specific neuropathic pain conditions has not been well-described. While painful diabetic peripheral neuropathy and postherpetic neuralgia have been widely evaluated, many other peripheral and central neuropathic pain syndromes have been less frequently studied. This review summarizes incidence and/or prevalence information about two relatively frequent neuropathic pain conditions-painful diabetic peripheral neuropathy and postherpetic neuralgia-and similarly summarizes the more limited epidemiologic information available for other peripheral and central neuropathic pain conditions. The data suggest that while our knowledge is still incomplete, the high frequency of several of these conditions in specific populations should be considered an important impetus for further studies designed to evaluate their contribution to the overall burden of neuropathic pain.

Prevalence of and risk factors for HIV-associated neuropathy in Melbourne, Australia 1993-2006

OBJECTIVES

The aim of the study was to describe the prevalence of and risk factors for HIV-associated sensory neuropathy (HIV-SN) in 2006 [the era of stavudine, didanosine and zalcitabine (dNRTI)-sparing highly active antiretroviral therapy (HAART)] and to compare our findings with data obtained in the same clinic in 1993 (pre-HAART) and 2001 (frequent use of dNRTI-containing HAART).

METHODS

This was a cross-sectional comparative study using convenience sampling. HIV-positive adults attending a tertiary referral clinic over a 2-week period were screened for HIV-SN using the AIDS Clinical Trials Group screening tool. HIV-SN was defined as present if the patient had both neuropathic symptoms and abnormal signs. Demographic, clinical, laboratory and treatment data were considered as possible risk factors for HIV-SN, and results were compared with data obtained in the same clinic in 1993 and 2001.

RESULTS

One hundred patients were screened. The prevalence of HIV-SN was 42%, which was unchanged since 2001 (44%) despite a significant reduction in the use of dNRTIs. HIV-SN remained much more common than in 1993 (42% vs 13%; P<0.0001). The only independent associations with HIV-SN in 2006 were increasing patient age and a history of exposure to either stavudine or indinavir. This compares with 1993 when neuropathy was increased in those with Mycobacterium avium complex infection, and 2001 when patient age and use of stavudine and didanosine were the independent associations with HIV-SN in this clinic.

CONCLUSIONS

HIV-SN remained common among ambulatory patients in 2006 (42% prevalence) despite a significant reduction in the use of dNRTIs. In addition to patient age and stavudine exposure, indinavir use may be a risk factor for HIV-SN.

Managing HIV peripheral neuropathy

Peripheral nerve disorders are frequent complications of HIV disease. Distal symmetrical polyneuropathy (DSP) is the most common peripheral nerve disorder associated with HIV and occurs in over one third of infected patients but may occur in up to 67% if asymptomatic patients are included. Risk factors for DSP include increased age, advanced HIV disease, and history of "d-drugs" or other neurotoxic drugs. The primary manifestations of polyneuropathy are slowly progressive numbness and paresthesias, with burning sensations in the feet usually in a symmetrical pattern. The etiology of HIV-associated DSP is unknown, although neurotoxic effects of cytokines, toxicity of HIV proteins, and mitochondrial damage have been implicated. The current treatment for HIV-associated DSP is symptomatic, with pain modifying medications, including anti-inflammatory agents, opioids, antidepressants, antiepileptics, topical anesthetics, and capsaicin. Sustained virologic control may improve DSP. Novel therapies such as -acetyl-l-carnitine or neurotrophic factors are being studied for treatment of DSP.

Clinical Toxicity of Highly Active Antiretroviral Therapy in a Home-Based AIDS Care Program in Rural Uganda

BACKGROUND

We evaluated clinical toxicity in HIV-infected persons receiving antiretroviral therapy (ART) in Uganda.

METHODS

From May 2003 through December 2004, adults with a CD4 cell count < or =250 cells/microL or World Health Organization stage 3/4 HIV disease were prescribed ART. We calculated probabilities for time to toxicity and single-drug substitution as well as multivariate-adjusted hazard ratios for development of toxicity.

RESULTS

ART (stavudine plus lamivudine with nevirapine [96%] or efavirenz [4%]) was prescribed for 1029 adults, contributing 11,268 person-months of observation. Toxicities developed in 543 instances in 411 (40%) patients (incidence rate = 4.47/100 person-months): 36% peripheral neuropathy (9% severe); 6% rash (2% severe); 2% hypersensitivity reaction; < or =0.5% acute hepatitis, anemia, acute pancreatitis, or lactic acidosis; and 13% other. Probabilities of remaining free from any toxicity at 6, 12, and 18 months were 0.76, 0.59, and 0.47 and from any severe toxicity at 6, 12, and 18 months were 0.92, 0.86, and 0.85, respectively. For 217 patients (21%), 222 single-drug substitutions were made, mostly because of peripheral neuropathy or rash.

CONCLUSIONS

Clinical toxicities were common, but no patients discontinued ART because of toxicity. The most common toxicities, peripheral neuropathy and rash, were managed with single-drug substitutions. In resource-limited settings, toxicity from ART regimens containing stavudine or nevirapine is manageable but more tolerable regimens are needed.

The frequency and profile of neurology in black South African HIV infected (clade C) patients — A hospital-based prospective audit

AIM

To determine the frequency and spectrum of neurological illnesses in Black South African hospital-based HIV infected (clade C) patients.

METHOD

A prospective audit of 506 consecutive HIV infected medical inpatients at the Helen Joseph Hospital, Johannesburg, South Africa.

RESULTS

The patients had a mean age of 37 years; a male:female ratio of 1.2:1; a mean CD4 count of 107 cells/ml. Eighty four percent of patients had AIDS defining CD4 counts (less than 200 cells/ml). Seventy five percent of patients had a neurological illness. In 64% the neurological illness occurred in association with a non-neurological (systemic) illness. Eleven percent of patients had an isolated neurological illness. The predominant systemic illness was tuberculosis (TB), occurring with a frequency of 46%. The neurological spectrum in our patients was similar to that described in the literature, (clade B virus data) other than for a greater frequency of infectious illnesses.

CONCLUSION

The neurological profile of HIV infection is a function of the environment and the immunological state of the patient (CD4 count) rather than an influence of the clade.

Infectious Neuropathies

Peripheral neuropathies can result from several infective agents, ranging from viruses, especially retroviruses, to parasites and bacilli. Leprosy, which often is considered a disorder of the past, still is common in dome geographic areas, especially in Africa, South America, and Asia. An increasing number of cases of neuropathies occurs in patients who have HIV or Lyme disease. The important point is that all these neuropathies are treatable and often preventable.

Specific neurologic complications of human immunodeficiency virus type 1 (HIV-1) infection in children

Pediatric human immunodeficiency virus type 1 (HIV-1) infection is endemic throughout southern Africa. Neurologic complications are described in 20% to 60% of published series, mostly related to HIV-1 encephalopathy. With increasing HIV prevalence, more atypical cases are presenting. We present, as illustrative cases, seven children (three girls) with unusual neurologic sequelae as a consequence of HIV-1 infection. The median age at presentation was 33 months (range 7 months-6 years). Five of the seven children were developmentally normal before presentation. They presented with progressive multifocal leukoencephalopathy, myelopathy, intractable seizures, acute vasculitis and blindness, hemiplegia, peripheral neuropathy, and paraspinal lymphoma. Neuroimaging of the brain was performed in five patients, of whom one had basal ganglia calcification. All children had poor outcome with incomplete recovery or continued deterioration. In conclusion, children with HIV-1 infection who survive beyond the first year of life can present with a wide variety of neurologic complications. A similar spectrum of neurologic manifestations is likely to occur in other sub-Saharan African countries, characterized by high HIV prevalence. The case histories demonstrate that the neurologic features of pediatric HIV infection do not easily fit into a simplified classification system.

Endothelial adhesion molecule expression is unaltered in the peripheral nerve from patients with AIDS and distal sensory polyneuropathy

Some evidence suggests that endothelial dysfunction, including altered expression of cell adhesion molecules contributes to pathophysiology of nervous system disorders in the course of HIV infection. In this immunohistochemical study we investigated and compared the expression of E-selectin, intercellular adhesion molecule-1 (ICAM-1), platelet endothelial cell adhesion molecule-1 (PECAM-1) in peripheral nerve blood vessels from patients with distal sensory polyneuropathy (DSP) and control patients with other axonal neuropathies. Similar quantitative pattern of immunoreactivity was found in patients with DSP and controls. E-selectin and PECAM-1 immunostained vessels tended to increase in number only in patients with major CD4 cell depletion. The vascular endothelium of the peripheral nerve in HIV-infected subjects with DSP shows no changes facilitating the migration of infected or activated monocytes/macrophages into the nerve. These phenomena probably do not play a critical role in the development of axonal damage in DSP.