Controlling Neuropathic Pain in HIV

Neurological Complications Caused by Human Immunodeficiency Virus (HIV) and Associated Opportunistic Co-infections: A Review on their Diagnosis and Therapeutic Insights

Neurocognitive disorders associated with human immunodeficiency virus (HIV) infected individuals increase the risk of mortality and morbidity that remain a prevalent clinical complication even in the antiretroviral therapy era. It is estimated that a considerable number of people in the HIV community are developing neurological complications at their early stages of infection. The daily lives of people with chronic HIV infections are greatly affected by cognitive declines such as loss of attention, learning, and executive functions, and other adverse conditions like neuronal injury and dementia. It has been found that the entry of HIV into the brain and subsequently crossing the blood-brain barrier (BBB) causes brain cell damage, which is the prerequisite for the development of neurocognitive disorders. Besides the HIV replication in the central nervous system and the adverse effects of antiretroviral therapy on the BBB, a range of opportunistic infections, including viral, bacterial, and parasitic agents, augment the neurological complications in people living with HIV (PLHIV). Given the immuno-compromised state of PLHIV, these co-infections can present a wide range of clinical syndromes with atypical manifestations that pose challenges in diagnosis and clinical management, representing a substantial burden for the public health system. Therefore, the present review narrates the neurological complications triggered by HIV and their diagnosis and treatment options. Moreover, coinfections that are known to cause neurological disorders in HIV infected individuals are highlighted.

Distal neuropathic pain in HIV is associated with functional connectivity patterns in default mode and salience networks

HIV-associated distal neuropathic pain (DNP) is one of the most prevalent, disabling, and treatment-resistant complications of HIV, but its biological underpinnings are incompletely understood. While data specific to mechanisms underlying HIV DNP are scarce, functional neuroimaging of chronic pain more broadly implicates the role of altered resting-state functional connectivity within and between salience network (SN) and default mode network (DMN) regions. However, it remains unclear the extent to which HIV DNP is associated with similar alterations in connectivity. The current study aimed to bridge this gap in the literature through examination of resting-state functional connectivity patterns within SN and DMN regions among people with HIV (PWH) with and without DNP. Resting state functional magnetic resonance imaging (rs-fMRI) scans were completed among 62 PWH with HIV-associated peripheral neuropathy, of whom 27 reported current DNP and 35 did not. Using subgrouping group iterative multiple estimation, we compared connectivity patterns in those with current DNP to those without. We observed weaker connectivity between the medial prefrontal cortex (MPFC) and posterior cingulate cortex (PCC) and stronger connectivity between the anterior cingulate cortex (ACC) and thalamus among those reporting DNP. Overall, these findings implicate altered within DMN (i.e., MPFC-PCC) and within SN (i.e., ACC-thalamus) connectivity as potential manifestations of adaptation to pain from neuropathy and/or mechanisms underlying the development/maintenance of DNP. Findings are discussed in the context of differential brain response to pain (i.e., mind wandering, pain aversion, pain facilitation/inhibition) and therapeutic implications.

Intravenous immunoglobulin therapy for HIV-associated Guillain-Barré syndrome

OBJECTIVE

To compare the efficacy of intravenous immunoglobulin (IVIG) added to antiretroviral therapy (ART) and ART alone in people living with human immunodeficiency virus-associated Guillain-Barré syndrome (HIV-associated GBS).

METHODS

The study was a retrospective analysis of clinical records of HIV-associated GBS patients from department of neurology at West China Hospital between January 2015 and October 2020. Patients treated with ART alone were compared with those treated with IVIG + ART. The primary outcome was the GBS disability score at 4 weeks, which was assessed with multivariable ordinal regression. Additional outcomes include the GBS disability scale at 1 week, improvement of ≥ 1 point on the GBS disability score at 1 and 4 weeks, median change in the MRC sum score at 1 and 4 weeks, number of patients who were able to walk independently at 4 weeks.

RESULTS

Two hundred and fifty-two (252) individuals living with HIV were recruited in the study. According to the inclusion and exclusion criteria, 21 HIV-associated GBS patients were finally included, of whom 8 were treated with IVIG + ART and 13 were treated with ART alone. At the fourth weeks after treatment, the GBS disability scale grade was significantly lower in patients treated with IVIG + ART than those with ART alone (1 vs. 2, P = 0.02). The adjusted OR for a lower GBS disability scale was 10.6 (95 % CI 1.15 to 98.05; P = 0.03) for the IVIG + ART group. Moreover, 6 of 8 (75 %) patients treated with IVIG + ART were able to walk independently at four weeks after treatment.

CONCLUSIONS

The introduction of IVIG combined with ART may be efficacious in the treatment of HIV-infected GBS and may provide better clinical outcomes.

Neuromuscular complications of HIV infection

With the introduction of combination antiretroviral therapy, human immunodeficiency virus (HIV)-infected individuals are living longer, and are commonly confronted with chronic neuromuscular complications. The spectrum of neuromuscular disorders in patients living with HIV infection is wide, and is caused by HIV per se and its products, particular antiretroviral drugs, or a combination of both. The purpose of this chapter is to review peripheral nervous system disorders in the setting of HIV infection, and to provide a general approach to diagnosis and management of these disorders. The early identification of these conditions may help with early intervention and management, allow prevention of morbidities associated with these disorders, and contribute to future research efforts in the field of HIV.

HIV Distal Neuropathic Pain Is Associated with Smaller Ventral Posterior Cingulate Cortex

Objective

. Despite modern antiretroviral therapy, HIV-associated neuropathy is one of the most prevalent, disabling and treatment-resistant complications of HIV disease. The presence and intensity of distal neuropathic pain is not fully explained by the degree of peripheral nerve damage. A better understanding of brain structure in HIV distal neuropathic pain may help explain why some patients with HIV neuropathy report pain while the majority does not. Previously, we reported that more intense distal neuropathic pain was associated with smaller total cerebral cortical gray matter volumes. The objective of this study was to determine which parts of the cortex are smaller.

Methods

. HIV positive individuals with and without distal neuropathic pain enrolled in the multisite (N = 233) CNS HIV Antiretroviral Treatment Effects (CHARTER) study underwent structural brain magnetic resonance imaging. Voxel-based morphometry was used to investigate regional brain volumes in these structural brain images.

Results

. Left ventral posterior cingulate cortex was smaller for HIV positive individuals with versus without distal neuropathic pain (peak P  = 0.017; peak t = 5.15; MNI coordinates x = -6, y = -54, z = 20). Regional brain volumes within cortical gray matter structures typically associated with pain processing were also smaller for HIV positive individuals having higher intensity ratings of distal neuropathic pain.

Conclusions

. The posterior cingulate is thought to be involved in inhibiting the perception of painful stimuli. Mechanistically a smaller posterior cingulate cortex structure may be related to reduced anti-nociception contributing to increased distal neuropathic pain.

Antihyperalgesic Activities of Endocannabinoids in a Mouse Model of Antiretroviral-Induced Neuropathic Pain

Background: Nucleoside reverse transcriptase inhibitors (NRTIs) are the cornerstone of the antiretroviral therapy for human immunodeficiency virus/acquired immune deficiency syndrome (HIV/AIDS). However, their use is sometimes limited by the development of a painful sensory neuropathy, which does not respond well to drugs. Smoked cannabis has been reported in clinical trials to have efficacy in relieving painful HIV-associated sensory neuropathy. Objectives: The aim of this study was to evaluate whether the expression of endocannabinoid system molecules is altered during NRTI-induced painful neuropathy, and also whether endocannabinoids can attenuate NRTI-induced painful neuropathy. Methods: BALB/c mice were treated with 25 mg/kg of 2',3'-dideoxycytidine (ddC, zalcitabine), a NRTI, to induce thermal hyperalgesia. The expression of endocannabinoid system molecules was evaluated by real time polymerase chain reaction in the brain, spinal cord and paw skin at 6 days post ddC administration, a time point when mice had developed thermal hyperalgesia. The effects of the endocannabinoids, N-arachidonoyl ethanolamine (AEA) and 2-arachidonoyl glycerol (2-AG), the cannabinoid type 1 (CB1) receptor antagonist AM 251, CB2 receptor antagonist AM 630, and G protein-coupled receptor 55 (GPR55) antagonists ML193 and CID 16020046 on ddC-induced thermal hyperalgesia were evaluated using the hot plate test. Results: ddC treatment resulted in thermal hyperalgesia and increased transcripts of the synthesizing enzyme Plcβ1 and decreased Daglβ in the paw skins, but not Napepld, and Daglα compared to vehicle treatment. Transcripts of the inactivating enzymes Faah and Mgll were downregulated in the brain and/or paw skin but not in the spinal cord of ddC-treated mice. Both AEA and 2-AG had antihyperalgesic effects in mice with ddC-induced thermal hyperalgesia, but had no effect in ddC-naïve mice. The antihyperalgesic activity of AEA was antagonized by AM251 and AM630, whereas the activity of 2-AG was antagonized by AM251, ML193 and CID 16020046, but not by AM630. Conclusion: These data show that ddC induces thermal hyperalgesia, which is associated with dysregulation of the mRNA expression of some endocannabinoid system molecules. The endocannabinoids AEA and 2-AG have antihyperalgesic activity, which is dependent on cannabinoid receptor and GPR55 activation. Thus, agonists of cannabinoid receptors and GPR55 could be useful therapeutic agents for the management of NRTI-induced painful sensory neuropathy.

HIV neuropathy

PURPOSE OF REVIEW

To present an overview of HIV-associated distal symmetric polyneuropathy (HIV-DSP) and other HIV-related peripheral neuropathies in the post-highly active retroviral therapy era.

RECENT FINDINGS

HIV-DSP has become the most common neurologic complication of HIV largely due to the prolonged survival of HIV-positive patients with the advent of highly active retroviral therapy. HIV-DSP can be attributed to the disease itself or to secondary effects of certain HAART agents, and often the two disease entities cannot be distinguished. HIV-DSP can lead to significant morbidity and interfere with daily activities. Diagnosis can be obtained from a detailed history and neurologic exam revealing absent ankle jerks and abnormal, vibratory perception or decreased pinprick or temperature. Supporting studies include nerve conduction studies and skin biopsy. Although there are no United States Food and Drug Administration-approved treatments for HIV-DSP, clinicians often use off-label medications, including antidepressants, anticonvulsants, topical agents and other analgesics.

SUMMARY

The prevalence of those affected by HIV-DSP will continue to grow with the aging population of HIV-infected individuals. Compared to the diabetic neuropathy drug trials, trials in both symptomatic and disease-modifying agents for HIV-DSP have had little success. Other forms of HIV-related peripheral neuropathies are discussed briefly, and include acute and chronic inflammatory demyelinating polyneuropathy, autonomic neuropathy, polyradiculopathy, mononeuropathies, mononeuritis multiplex, cranial neuropathies, and amyotrophic lateral sclerosis-like motor neuropathy.

HIV-associated distal neuropathic pain is associated with smaller total cerebral cortical gray matter

Despite modern antiretroviral therapy, HIV-associated sensory neuropathy affects over 50 % of HIV patients. The clinical expression of HIV neuropathy is highly variable: many individuals report few symptoms, but about half report distal neuropathic pain (DNP), making it one of the most prevalent, disabling, and treatment-resistant complications of HIV disease. The presence and intensity of pain is not fully explained by the degree of peripheral nerve damage, making it unclear why some patients do, and others do not, report pain. To better understand central nervous system contributions to HIV DNP, we performed a cross-sectional analysis of structural magnetic resonance imaging volumes in 241 HIV-infected participants from an observational multi-site cohort study at five US sites (CNS HIV Anti-Retroviral Treatment Effects Research Study, CHARTER). The association between DNP and the structural imaging outcomes was investigated using both linear and nonlinear (Gaussian Kernel support vector) multivariable regression, controlling for key demographic and clinical variables. Severity of DNP symptoms was correlated with smaller total cerebral cortical gray matter volume (r = -0.24; p = 0.004). Understanding the mechanisms for this association between smaller total cortical volumes and DNP may provide insight into HIV DNP chronicity and treatment-resistance.

Health-related quality of life 'well-being' in HIV distal neuropathic pain is more strongly associated with depression severity than with pain intensity

BACKGROUND

Despite modern antiretroviral treatment, HIV-associated distal neuropathic pain (DNP) remains one of the most prevalent and debilitating complications of HIV disease. Neuropathic pain is often accompanied by depressed mood, and both pain and depression have been associated with decreased health-related quality of life (HRQOL) well-being. The relative contribution of depression and pain to worse life quality has not been addressed, however, even though a better understanding might sharpen intervention strategies.

METHODS

We used the Medical Outcomes Study HIV (MOS-HIV) Health Survey and the Beck depression inventory-II and linear regression models to investigate HRQOL well-being in HIV-infected patients with DNP (n = 397) participating in an observational cohort study at six U.S. sites (CNS HIV Antiretroviral Treatment Effects Research Study, CHARTER).

RESULTS

For this sample of patients with HIV DNP, severity of depressed mood was more highly correlated with HRQOL well-being than was pain intensity.

CONCLUSIONS

These results suggest that interventions to improve HRQOL well-being in individuals with HIV-associated DNP may need to address not only pain intensity but mood state as well.

Associations between factors affecting access to care and health-related quality of life: results of a statewide HIV/AIDS cross-sectional study

The objective of this cross-sectional study was to describe the relationship between access to care and health-related quality of life (HRQOL) for persons living with HIV/AIDS (PLWHA) in Mississippi by administering a statewide survey. A random probability sample of PLWHA was derived from the Mississippi State Department of Health's communicable disease tracking system. Interviews were conducted with 220 PLWHA to collect data on access to care, demographic and social characteristics, and HRQOL. Overall, most participants had access to care and reasonable HRQOL. Multivariate and univariate analyses were performed to measure associations between access to care and HRQOL. Univariate analyses showed that age, income, social networks, severity of disease, having been prescribed medications, and having experienced problems accessing care to be significantly associated with HRQOL scales. Multivariate analysis of variance models further demonstrated low-income level, having experienced problems accessing care, and having been prescribed antiretroviral medications to be significantly associated with HRQOL. Reducing barriers is a major factor in improving quality of life. This study provides needed insight into the relationship between access to care and HRQOL among PLWHA in Mississippi, which could be valuable to public health planners to help them better understand how to make the greatest impact on HRQOL.

Continued high prevalence and adverse clinical impact of human immunodeficiency virus-associated sensory neuropathy in the era of combination antiretroviral therapy: the CHARTER Study

OBJECTIVE

To provide updated estimates of the prevalence and clinical impact of human immunodeficiency virus-associated sensory neuropathy (HIV-SN) and neuropathic pain due to HIV-SN in the combination antiretroviral therapy (CART) era.

DESIGN

Prospective, cross-sectional analysis. Clinical correlates for HIV-SN and neuropathic pain, including age, exposure to CART, CD4 levels, plasma viral load, hepatitis C virus infection, and alcohol use disorders, were evaluated in univariate and multivariate models.

SETTING

Six US academic medical centers.

PATIENTS

One thousand five hundred thirty-nine HIV-infected individuals enrolled in the CNS (Central Nervous System) HIV Anti-Retroviral Therapy Effects Research study.

MAIN OUTCOME MEASURES

The presence of HIV-SN, defined by 1 or more clinical signs (diminished vibration or sharp sensation in the legs and feet; reduced ankle reflexes) in a distal, symmetrical pattern. Neuropathic pain was defined as aching, stabbing, or burning in a similar distribution. The effect on quality of life was assessed with the Medical Outcomes Study HIV Health Survey.

RESULTS

We found HIV-SN in 881 participants. Of these, 38.0% reported neuropathic pain. Neuropathic pain was significantly associated with disability in daily activities, unemployment, and reduced quality of life. Risk factors for HIV-SN after adjustment were advancing age (odds ratio, 2.1 [95% confidence interval, 1.8-2.5] per 10 years), lower CD4 nadir (1.2 [1.1-1.2] per 100-cell decrease), current CART use (1.6 [1.3-2.8]), and past "D-drug" use (specific dideoxynucleoside analogue antiretrovirals) (2.0 [1.3-2.6]). Risk factors for neuropathic pain were past D-drug use and higher CD4 nadir.

CONCLUSIONS

Neuropathic pain and HIV-SN remain prevalent, causing substantial disability and reduced quality of life even with successful CART. The clinical correlates of HIV-SN have changed with the evolution of treatment. These findings argue for redoubled efforts to determine HIV-SN pathogenesis and the development of symptomatic and neuroregenerative therapies.

Pregabalin for painful HIV neuropathy: a randomized, double-blind, placebo-controlled trial

OBJECTIVE

Pregabalin is effective in several neuropathic pain syndromes. This trial evaluated its efficacy, safety, and tolerability for treatment of painful HIV-associated neuropathy.

METHODS

This randomized, double-blind, placebo-controlled, parallel-group trial included a 2-week double-blind dose-adjustment (150-600 mg/day BID) phase, a 12-week double-blind maintenance phase, and an optional 3-month open label extension phase. The primary efficacy measure was the mean Numeric Pain Rating Scale (NPRS) score, an 11-point numeric rating scale. Secondary measures included Patient Global Impression of Change (PGIC) and sleep measurements.

RESULTS

Baseline mean NPRS score was 6.93 for patients randomized to pregabalin (n = 151) and 6.72 for those to placebo (n = 151). Pregabalin average daily dosage (SD) was 385.7 (160.3) mg/d. At endpoint, pregabalin and placebo showed substantial reductions in mean NPRS score from baseline: -2.88 vs -2.63, p = 0.3941. Pregabalin had greater improvements in NPRS score relative to placebo at weeks 1 (-1.14 vs -0.69, p = 0.0131) and 2 (-1.92 vs -1.43, p = 0.0393), and at weeks 7 (-3.22 vs -2.53 p = 0.0307) and 8 (-3.33 vs -2.53, p = 0.0156). At all other time points, differences between groups were not significant. Sleep measurements and 7-item PGIC did not differ among treatment groups; however, collapsed PGIC scores showed 82.8% of pregabalin and 66.7% of placebo patients rated themselves in 1 of the 3 "improved" categories (p = 0.0077). Somnolence and dizziness were the most common adverse events with pregabalin.

CONCLUSIONS

Pregabalin was well-tolerated, but not superior to placebo in the treatment of painful HIV neuropathy. Factors predicting analgesic response in HIV neuropathy warrant additional research.

CLASSIFICATION OF EVIDENCE

This Class II trial showed that pregabalin is not more effective than placebo in treatment of painful HIV neuropathy.

[Treatment of neuropathic pain in HIV-infected patients]

Neuropathic pain of various etiologies is a frequent symptom in HIV-infected patients that is underdiagnosed and inadequately treated. It requires a multidisciplinary pain approach based on psychosocial factors, diet and exercise, etiologic treatment whenever possible, symptomatic medical treatment, and sometimes, interventional techniques. Medical treatment should be individualized and introduced gradually, with a mind to potential drug interactions. Neuropathic pain responds poorly to conventional analgesics, such as nonsteroidal antiinflammatory drugs and opiates; tricyclic antidepressants and anticonvulsants are the drugs of choice. Before establishing an analgesic treatment, possible drug interactions should be ruled out, mainly those occurring with antiretroviral agents.

Human immunodeficiency virus-associated peripheral neuropathies

Peripheral neuropathy has emerged as the most common neurologic complication of human immunodeficiency virus (HIV) infection. It will continue to play an Important role in HIV Infection given the fact that HIV-infected Individuals are living longer, are at risk of long-term metabolic complications, and face an Increasing exposure to potentially neurotoxic antiretroviral drugs. We review the various types of peripheral neuropathy that have been associated with HIV infection, including distal symmetrical polyneuropathy, toxic neuropathy from antiretroviral drugs, diffuse infiltrative lymphocytosis syndrome, inflammatory demyelinating polyneuropathies, multifocal mononeuropathies, and progressive polyradiculopathy.

HIV-associated neuropathic pain: epidemiology, pathophysiology and management

Peripheral neuropathy is associated with numerous systemic illnesses including HIV infection. Neuropathic pain constitutes approximately 25-50% of all pain clinic visits. Distal symmetrical polyneuropathy (DSP) is the most common form of peripheral neuropathy in individuals with HIV infection. DSP is distinguished from other forms of neuropathy on the basis of history and neurological examination. The pain associated with DSP can be debilitating. Therefore, it is important to diagnose HIV-associated DSP properly and treat the neuropathic pain in order to improve quality of life. We review the clinical manifestations, epidemiology, pathophysiology and management strategies for HIV-associated DSP.

Treatment of painful polyneuropathies

The treatment of painful polyneuropathies has begun to improve over the past several years. This is based on an evolving understanding of the pathogenesis related to the development of diabetic neuropathy and other diseases that may lead to peripheral nerve injury. Consensus on evaluation strategies for patients presenting with pain has furthered our ability to define neuropathic pain and accompanying signs and symptoms that may respond to particular therapeutic approaches. Recent therapeutic advances in medical management have demonstrated improved outcomes in pain relief. This, along with lower side effect-related issues, has led to improved compliance and patient satisfaction. The assessment and treatment of comorbid conditions, which include sleep, anxiety, and depression, have further advanced the management of painful polyneuropathies in patients. New antiepileptics, antidepressants, and topical therapies have contributed to improved patient outcomes.