Background: HIV-associated distal sensory polyneuropathy (HIV-DSP) is a painful condition with limited effective treatment. Capsaicin desensitizes cutaneous nociceptors resulting in reduced pain. We report a placebo-controlled study of a high-concentration capsaicin dermal patch (NGX-4010) for the treatment of painful HIV-DSP.

Objective: To investigate the analgesic efficacy of lamotrigine in the treatment of painful HIV-associated distal sensory polyneuropathy (DSP). Background: The pathogenesis of HIV-associated DSP is unknown and there is no effective treatment. A novel anticonvulsant, lamotrigine, blocks voltage-sensitive sodium channels and inhibits the release of glutamate and aspartate. There have been anecdotal reports of efficacy of lamotrigine in the treatment of painful neuropathy and trigeminal neuralgia. Methods: In a multicenter, randomized, double-blind, placebo-controlled study, lamotrigine was initiated at 25 mg per day and slowly titrated over 7 weeks to 300 mg per day. Study duration was 14 weeks. The primary outcome measure was change in pain on the modified Gracely scale with secondary outcome measures including change in neurologic examination, use of concomitant analgesic medications, and global pain relief. Results: Of 42 enrolled subjects, 13 did not complete the 14-week study endpoint. In five of these, rash was the cause for dropout. In the remaining 29 evaluable subjects, 20 patients received placebo and 9 received lamotrigine. The pain scores at baseline were not significantly different. The reduction in average pain from baseline to week 14 was greater (p = 0.03) in the lamotrigine group (−0.55) than in the placebo group (−0.18), adjusting for baseline levels of pain. There was no difference between the groups on the change in peak worst pain. Conclusions: In this small trial, lamotrigine showed promise in the treatment of pain associated with HIV-related DSP. The frequency of rash was greater than in lamotrigine studies in epilepsy. A larger controlled study of lamotrigine is warranted.

Pregabalin is effective in several neuropathic pain syndromes. This trial evaluated its efficacy, safety, and tolerability for treatment of painful HIV-associated neuropathy. 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. 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. 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. This Class II trial showed that pregabalin is not more effective than placebo in treatment of painful HIV neuropathy.

Cerebral autoregulation (CA) refers to the control of cerebral tissue blood flow (CBF) in response to changes in perfusion pressure. Due to the challenges of measuring intracranial pressure, CA is often described as the relationship between mean arterial pressure (MAP) and CBF. Dynamic CA (dCA) can be assessed using multiple techniques, with transfer function analysis (TFA) being the most common. A 2016 white paper by members of an international Cerebrovascular Research Network (CARNet) that is focused on CA strove to improve TFA standardization by way of introducing data acquisition, analysis, and reporting guidelines. Since then, additional evidence has allowed for the improvement and refinement of the original recommendations, as well as for the inclusion of new guidelines to reflect recent advances in the field. This second edition of the white paper contains more robust, evidence-based recommendations, which have been expanded to address current streams of inquiry, including optimizing MAP variability, acquiring CBF estimates from alternative methods, estimating alternative dCA metrics, and incorporating dCA quantification into clinical trials. Implementation of these new and revised recommendations is important to improve the reliability and reproducibility of dCA studies, and to facilitate inter-institutional collaboration and the comparison of results between studies.

This 12-week study evaluated the efficacy and safety of capsaicin 8% patch versus placebo patch in painful diabetic peripheral neuropathy (PDPN). Patients aged 18 years or older with PDPN were randomized (1:1) to one 30-minute treatment (capsaicin 8% patch or placebo patch) to painful areas of the feet. Overall, 369 patients were randomized (capsaicin 8% patch, n = 186; placebo patch, n = 183). Percentage reduction in average daily pain score from baseline to between weeks 2 through 8 (the primary end point) was statistically significant for capsaicin 8% patch versus placebo (-27.4% vs -20.9%; P = .025); improvements in pain were observed from week 2 onward. Versus placebo, patients treated with capsaicin 8% patch had a shorter median time to treatment response (19 vs 72 days) and modest improvements in sleep interference scores from baseline to between weeks 2 through 8 (P = .030) and weeks 2 through 12 (P = .020). Apart from application site reactions, treatment-emergent adverse events were similar between groups. No indications of deterioration in sensory perception of sharp, cold, warm, or vibration stimuli were observed. In patients with PDPN, capsaicin 8% patch treatment provided modest pain relief and sleep quality improvements versus a placebo patch, similar in magnitude to other treatments with known efficacy, but without systemic side effects or sensory deterioration. To our knowledge, this is the first study of the capsaicin 8% patch versus placebo in patients with PDPN to show that one 30-minute capsaicin treatment provides modest improvements in pain and sleep quality. Results confirm the clinical utility of the capsaicin 8% patch in the diabetic population.

Distal sensory polyneuropathy (DSP) is the most common neurologic complication of human immunodeficiency virus (HIV) infection. Risk factors for DSP have not been adequately defined in the era of highly active antiretroviral therapy. The authors evaluated 101 subjects with advanced HIV infection over 48 weeks. Assessments included a brief peripheral neuropathy (PN) screen (BPNS), neurologic examination, nerve conduction studies, quantitative sensory testing (QST), and skin biopsies with quantitation of epidermal nerve fiber density. Data were summed into a Total Neuropathy Score (TNS). The presence, severity, and progression of DSP were related to clinical and laboratory results. The mean TNS (range 0 to 36) was 8.9, with 38% of subjects classified as PN-free, 10% classified as having asymptomatic DSP, and 52% classified as having symptomatic DSP. Progression in TNS from baseline to week 48 occurred only in the PN-free group at baseline (mean TNS change = 1.16 +/- 2.76, p = 0.03). Factors associated with progression in TNS were lower current TNS, distal epidermal denervation, and white race. As compared with the TNS diagnosis of PN at baseline, the BPNS had a sensitivity of 34.9% and a specificity of 89.5%. In this cohort of advanced human immunodeficiency virus (HIV)-infected subjects, distal sensory polyneuropathy was common and relatively stable over 48 weeks. Previously established risk factors, including CD4 cell count, plasma HIV RNA, and use of dideoxynucleoside antiretrovirals were not predictive of the progression of distal sensory polyneuropathy (DSP). Distal epidermal denervation was associated with worsening of DSP. As compared with the Total Neuropathy Score, the brief peripheral neuropathy screen had relatively low sensitivity and high specificity for the diagnosis of DSP.