Changes in Anticholinergic Burden in Parkinson's Disease After Deep Brain Stimulation.

OBJECTIVE: This study aimed to evaluate the effect of deep brain stimulation (DBS) on anticholinergic burden in Parkinson's disease (PD) and the association of anticholinergic burden with cognition. MATERIALS AND METHODS: A retrospective chart review in patients with PD who underwent bilateral subthalamic nucleus (STN) or globus pallidus internus (GPi) DBS from 2010 to 2020 reviewed medications with anticholinergic burden at baseline, six months, and one year (N = 216) after surgery. The cumulative anticholinergic burden at each visit was calculated using the Anticholinergic Risk Scale (ARS). RESULTS: ARS scores were significantly lower for patients six months and one year after surgery than at baseline (z = 6.58, p < 0.0001; z = 6.99, p < 0.0001). Change in ARS scores at both six months and one year were driven by down-titration of PD medications (z = 9.35, p < 0.0001; z = 8.61, p < 0.0001), rather than changes in pain, psychiatric, or urinary medications with anticholinergic effects. There was no significant difference in change in ARS scores at one year between targets (t = 0.41, p = 0.68). In addition, there was no significant association between anticholinergic burden and cognitive performance. CONCLUSION: GPi and STN DBS are associated with decreased anticholinergic burden due to PD medications in the first year after surgery.

Comorbid Pain Syndromes in HIV-Associated Peripheral Neuropathy.

Objective: Peripheral neuropathy (PN) is a common complication of HIV. There is increasing awareness that some forms of PN, particularly small-fiber neuropathies, can be associated with chronic widespread pain syndromes. Given the high prevalence of both PN and chronic pain in HIV, we sought to determine whether patients with a diagnosis of HIV-PN were more likely to experience other chronic pain syndromes. Methods: Data were obtained from the Clinical Data Warehouse maintained by our institution. All HIV-infected patients receiving standard of care antiretroviral therapy in our institution's primary care HIV clinic (N = 638) were included. Diagnoses of HIV-PN and other chronic pain disorders were established based on clinician-assigned ICD-9/10 codes. Results: Sixty-eight patients (11%) had a diagnosis of HIV-PN. Patients with HIV-PN were more than twice as likely to have other chronic pain disorders (66% vs 32%, χ2 = 30.3, P < 0.001). Patients with HIV-PN were also older and more likely to have substance use and psychiatric disorders; however, the association of HIV-PN with other chronic pain disorders persisted after adjusting for relevant confounders (χ2(5) = 81.38, P < 0.001). Conclusions: Patients with HIV-PN commonly experience other chronic pain disorders. Clinicians managing HIV-PN should seek a broad understanding of patients' pain experience as this may alter management strategies. Researchers studying HIV-PN should consider how the presence of other pain disorders might affect outcomes.

Incobotulinum Toxin-A in Professional Musicians with Focal Task-Specific Dystonia: A Double Blind, Placebo Controlled, Cross-Over Study.

Background: Musician's focal task-specific dystonia is a complex disorder of fine motor control, with incomplete understanding of its etiology. There have been relatively few trials of botulinum toxin in upper limb task-specific dystonia, and prior studies have yielded variable results, leading to skepticism regarding the utility of this approach in elite performers. Methods: We conducted a double-blind, placebo-controlled, randomized, cross-over study of incobotulinum toxin-A in 21 professional musicians with focal upper extremity task-specific dystonia affecting performance on their instrument, using a novel paradigm of initial injections followed by booster injections at two- and four-week intervals. The primary outcome measure was the change in blinded dystonia rating of the active arm by two expert raters using a Clinical Global Impression numeric scale at week 8 compared to enrollment. Findings: 19 men and 2 women with musicians' dystonia were enrolled over a six-year period. Nineteen patients completed the study. Analysis of the primary outcome measure in comparison to baseline revealed a change in dystonia severity of P = 0.04 and an improvement in overall musical performance of P = 0.027. No clinically significant weakness was observed, and neutralizing antibodies to toxin were not found. Interpretation: Despite its small sample size, our study demonstrated a statistically significant benefit of incobotulinum toxin-A injections as a treatment for musicians' task-specific dystonia. Tailoring the use of toxin with booster injections allowed refinement of dosing strategy and outcomes, with benefits that were meaningful to patients clearly visible on videotaped evaluations. In addition to its application to musicians' dystonia, this approach may have relevance to optimize application of botulinum toxin in other forms of focal dystonia such as blepharospasm, cervical dystonia, writer's cramp, and spasmodic dysphonia.

Identifying the therapeutic zone in globus pallidus deep brain stimulation for Parkinson's disease.

OBJECTIVE: The globus pallidus internus (GPI) has been demonstrated to be an effective surgical target for deep brain stimulation (DBS) treatment in patients with medication-refractory Parkinson's disease (PD). The ability of neurosurgeons to define the area of greatest therapeutic benefit within the globus pallidus (GP) may improve clinical outcomes in these patients. The objective of this study was to determine the best DBS therapeutic implantation site within the GP for effective treatment in PD patients. METHODS: The authors performed a retrospective review of 56 patients who underwent bilateral GP DBS implantation at their institution during the period from January 2015 to January 2020. Each implanted contact was anatomically localized. Patients were followed for stimulation programming for at least 6 months. The authors reviewed preoperative and 6-month postsurgery clinical outcomes based on data from the Unified Parkinson's Disease Rating Scale Part III (UPDRS III), dyskinesia scores, and levodopa equivalent daily dose (LEDD). RESULTS: Of the 112 leads implanted, the therapeutic cathode was most frequently located in the lamina between the GPI external segment (GPIe) and the GP externus (GPE) (n = 40). Other common locations included the GPE (n = 24), the GPIe (n = 15), and the lamina between the GPI internal segment (GPIi) and the GPIe (n = 14). In the majority of patients (73%) a monopolar programming configuration was used. At 6 months postsurgery, UPDRS III off medications (OFF) and on stimulation (ON) scores significantly improved (z = -4.02, p < 0.001), as did postsurgery dyskinesia ON scores (z = -4.08, p < 0.001) and postsurgery LEDD (z = -4.7, p < 0.001). CONCLUSIONS: Though the ventral GP (pallidotomy target) has been a commonly used target for GP DBS, a more dorsolateral target may be more effective for neuromodulation strategies. The assessment of therapeutic contact locations performed in this study showed that the lamina between GPI and GPE used in most patients is the optimal central stimulation target. This information should improve preoperative GP targeting.

Chronic pain disorders in HIV primary care: clinical characteristics and association with healthcare utilization.

Chronic pain is common in HIV, but incompletely characterized, including its underlying etiologies, its effect on healthcare utilization, and the characteristics of affected patients in the HIV primary care setting. These data are needed to design and justify appropriate clinic-based pain management services. Using a clinical data warehouse, we analyzed one year of data from 638 patients receiving standard-of-care antiretroviral therapy in a large primary care HIV clinic, located in the Harlem neighborhood of New York City. We found that 40% of patients carried one or more chronic pain diagnoses. The most common diagnoses were degenerative musculoskeletal disorders (eg, degenerative spinal disease and osteoarthritis), followed by neuropathic pain and headache disorders. Many patients (16%) had multiple chronic pain diagnoses. Women, older patients, and patients with greater burdens of medical illness, and psychiatric and substance use comorbidities were disproportionately represented among those with chronic pain diagnoses. Controlling for overall health status, HIV patients with chronic pain had greater healthcare utilization including emergency department visits and radiology procedures. In summary, our study demonstrates the high prevalence of chronic pain disorders in the primary care HIV clinic. Colocated interventions for chronic pain in this setting should not only focus on musculoskeletal pain but also account for complex multifaceted pain syndromes, and address the unique biopsychosocial features of this population. Furthermore, because chronic pain is prevalent in HIV and associated with increased healthcare utilization, developing clinic-based pain management programs could be cost-effective.