A central processing sensory deficit with Parkinson's disease.

Parkinson's disease (PD) is a progressive degenerative disease manifested by tremor, rigidity, bradykinesia, and postural instability. Deficits in proprioceptive integration are prevalent in individuals with PD, even at early stages of the disease. These deficits have been demonstrated primarily during investigations of reaching. Here, we investigated how PD affects sensory fusion of multiple modalities during upright standing. We simultaneously perturbed upright stance with visual, vestibular, and proprioceptive stimulation, to understand how these modalities are reweighted so that overall feedback remains suited to stabilizing upright stance in individuals with PD. Eight individuals with PD stood in a visual cave with a moving visual scene at 0.2 Hz while an 80-Hz vibratory stimulus was applied bilaterally to their Achilles tendons (stimulus turns on-off at 0.28 Hz) and a ±1 mA bilateral monopolar galvanic stimulus was applied at 0.36 Hz. The visual stimulus was presented at different amplitudes (0.2°, 0.8° rotation about ankle axis) to measure: the change in gain (weighting) to vision, an intramodal effect; and a simultaneous change in gain to vibration and galvanic stimulation, both intermodal effects. Trunk/leg gain relative to vision decreased when visual amplitude was increased, reflecting an intramodal visual effect. In contrast, when vibration was turned on/off, leg gain relative to vision was equivalent in individuals with PD, indicating no reweighting of visual information when proprioception was disrupted through vibration (i.e., no intermodal effect). Trunk and leg angle gain relative to GVS also showed no reweighting in individuals with PD. These results are in contrast to previous results with healthy adults, who showed clear intermodal effects in the same paradigm, suggesting that individuals with PD not only have a proprioceptive deficit during standing, but also have a cross-modal sensory fusion deficit that is crucial for upright stance control.

Does visual feedback during walking result in similar improvements in trunk control for young and older healthy adults?

BACKGROUND: Most current applications of visual feedback to improve postural control are limited to a fixed base of support and produce mixed results regarding improved postural control and transfer to functional tasks. Currently there are few options available to provide visual feedback regarding trunk motion while walking. We have developed a low cost platform to provide visual feedback of trunk motion during walking. Here we investigated whether augmented visual position feedback would reduce trunk movement variability in both young and older healthy adults. METHODS: The subjects who participated were 10 young and 10 older adults. Subjects walked on a treadmill under conditions of visual position feedback and no feedback. The visual feedback consisted of anterior-posterior (AP) and medial-lateral (ML) position of the subject's trunk during treadmill walking. Fourier transforms of the AP and ML trunk kinematics were used to calculate power spectral densities which were integrated as frequency bins "below the gait cycle" and "gait cycle and above" for analysis purposes. RESULTS: Visual feedback reduced movement power at very low frequencies for lumbar and neck translation but not trunk angle in both age groups. At very low frequencies of body movement, older adults had equivalent levels of movement variability with feedback as young adults without feedback. Lower variability was specific to translational (not angular) trunk movement. Visual feedback did not affect any of the measured lower extremity gait pattern characteristics of either group, suggesting that changes were not invoked by a different gait pattern. CONCLUSIONS: Reduced translational variability while walking on the treadmill reflects more precise control maintaining a central position on the treadmill. Such feedback may provide an important technique to augment rehabilitation to minimize body translation while walking. Individuals with poor balance during walking may benefit from this type of training to enhance path consistency during over-ground locomotion.

Antiretroviral therapy in community pharmacies - Implementation and outcomes of a differentiated drug delivery model in Nigeria.

INTRODUCTION: The World Health Organization recommended differentiated models of care portends opportunities to decongest hospitals providing antiretroviral therapy (ART) and improve retention, especially in developing countries. A community pharmacy-based ART refill model was implemented where stable clients were devolved to community pharmacies for routine refills at a service fee, to promote private sector participation and sustainability of ART services. The aim of this study was to assess the feasibility, acceptability and outcomes of this model in Nigeria. METHODS: A population-based retrospective analysis of the community pharmacy ART refill program of the United States Agency for International Development-funded 'Strengthening Integrated Delivery of HIV/AIDS Services' project in Lagos, Rivers, Cross River and Akwa Ibom States from October 2016 to February 2018 was conducted. Standard descriptive statistical methods were used for baseline demographic and clinical characteristics of study participants. Outcomes were assessed using the Chi-square test and a multivariate logistic regressions model. Statistical significance was defined at α-level of 0.05. Analyses were performed using SPSS for Windows version 23 (IBM Corp, Armonk, USA). RESULTS: A total of 10015 participants representing 14.4% of ART clients in 50 hospitals opted for this model and were devolved to 244 community pharmacies. All clients consented and paid a service fee of N1000 (about $3) per refill visit. Median follow-up duration was 6 months. Prescription refill rate was 95% (95% CI 94.2-95.3). Retention rate was 98% while viral suppression was 99.12%. Refill rates were significantly affected by ART duration, regimen, age and location (P < 0.001, 0.004, 0.034 and < 0.001 respectively). CONCLUSIONS: This community pharmacy ART refill model of differentiated care is feasible and acceptable by clients and providers and demonstrated excellent clinical outcomes of retention and viral suppression. The ability and willingness of some clients to contribute financially to their HIV care was also demonstrated.

Characteristics and early clinical outcomes of key populations attending comprehensive community-based HIV care: Experiences from Nasarawa State, Nigeria.

BACKGROUND: Despite a call for differentiated care, there are limited data from sub-Saharan Africa on comprehensive community-based HIV care for key populations (KP), including commercial sex workers (CSW), men who have sex with men (MSM), and people who inject drugs (PWID). In Nigeria, a programme was implemented that liaised with community-based organizations and offered HIV testing, same-day ART initiation, and ART follow-up to KP. Here we characterize KP and their partners enrolled on ART. Our objective is to assess the early treatment outcomes and to estimate predictors of attrition among KP. METHOD: This is a retrospective cohort study of routinely collected data in a community-based HIV program for KP in Nasarawa state, Nigeria from August 2016 to November 2017. Variables of interest were socio-demographic, KP types, treatment outcomes, ART adherence, WHO stage, TB status and viral load. Summary statistics, logistic and Cox proportional hazard regression were used to describe the characteristics of KP and estimate predictors of attrition (patients either lost to follow-up (LTFU) or dead). RESULT: Seven hundred and ten (710) KP and their partners were enrolled into this study, 77.3% (549) of study participants were female and the median age was 30 years (IQR: 24-35). Respectively, 74.2%, 4.5%, 1.1% and 20% were FSW, MSM, PWID and their partners. Of 710 KP who started ART, 13.9% (99/710) discontinued after the first visit. After a median follow-up time of 7 months on ART 73.2% of patients were retained, 23.4% were LTFU, and 3.4% were dead. Lack of formal education (aHR 1.8; 95% CI 1.3-2.6) and unemployment (aHR 1.8; 95% CI 1.2-2.6) were significantly associated with attrition. CONCLUSION: Comprehensive community-based HIV care, including HIV testing and same-day ART is feasible. However, ART initiation on the same day of confirmatory HIV testing resulted in a high uptake of ART, but possibly inflated early attrition on ART. To mitigate early attrition among KP after same-day ART initiation, the psychosocial readiness of clients should be assessed better. We strongly recommend further studies to understand factors contributing to high attrition among the KP.

Spatiotemporal gait changes with use of an arm swing cueing device in people with Parkinson's disease.

Impaired arm swing is a common motor symptom of Parkinson's disease (PD), and correlates with other gait impairments and increased risk of falls. Studies suggest that arm swing is not merely a passive consequence of trunk rotation during walking, but an active component of gait. Thus, techniques to enhance arm swing may improve gait characteristics. There is currently no portable device to measure arm swing and deliver immediate cues for larger movement. Here we test report pilot testing of such a device, ArmSense (patented), using a crossover repeated-measures design. Twelve people with PD walked in a video-recorded gym space at self-selected comfortable and fast speeds. After baseline, cues were given either visually using taped targets on the floor to increase step length or through vibrations at the wrist using ArmSense to increase arm swing amplitude. Uncued walking then followed, to assess retention. Subjects successfully reached cueing targets on >95% of steps. At a comfortable pace, step length increased during both visual cueing and ArmSense cueing. However, we observed increased medial-lateral trunk sway with visual cueing, possibly suggesting decreased gait stability. In contrast, no statistically significant changes in trunk sway were observed with ArmSense cues compared to baseline walking. At a fast pace, changes in gait parameters were less systematic. Even though ArmSense cues only specified changes in arm swing amplitude, we observed changes in multiple gait parameters, reflecting the active role arm swing plays in gait and suggesting a new therapeutic path to improve mobility in people with PD.

Complementary mechanisms for upright balance during walking.

Lateral balance is a critical factor in keeping the human body upright during walking. Two important mechanisms for balance control are the stepping strategy, in which the foot placement is changed in the direction of a sensed fall to modulate how the gravitational force acts on the body, and the lateral ankle strategy, in which the body mass is actively accelerated by an ankle torque. Currently, there is minimal evidence about how these two strategies complement one another to achieve upright balance during locomotion. We use Galvanic vestibular stimulation (GVS) to induce the sensation of a fall at heel-off during gait initiation. We found that young healthy adults respond to the illusory fall using both the lateral ankle strategy and the stepping strategy. The stance foot center of pressure (CoP) is shifted in the direction of the perceived fall by ≈2.5 mm, starting ≈247 ms after stimulus onset. The foot placement of the following step is shifted by ≈15 mm in the same direction. The temporal delay between these two mechanisms suggests that they independently contribute to upright balance during locomotion, potentially in a serially coordinated manner. Modeling results indicate that without the lateral ankle strategy, a much larger step width is required to maintain upright balance, suggesting that the small but early CoP shift induced by the lateral ankle strategy is critical for upright stability during locomotion. The relative importance of each mechanism and how neurological disorders may affect their implementation remain an open question.

Identification of the Unstable Human Postural Control System.

Maintaining upright bipedal posture requires a control system that continually adapts to changing environmental conditions, such as different support surfaces. Behavioral changes associated with different support surfaces, such as the predominance of an ankle or hip strategy, is considered to reflect a change in the control strategy. However, tracing such behavioral changes to a specific component in a closed loop control system is challenging. Here we used the joint input-output (JIO) method of closed-loop system identification to identify the musculoskeletal and neural feedback components of the human postural control loop. The goal was to establish changes in the control loop corresponding to behavioral changes observed on different support surfaces. Subjects were simultaneously perturbed by two independent mechanical and two independent sensory perturbations while standing on a normal or short support surface. The results show a dramatic phase reversal between visual input and body kinematics due to the change in surface condition from trunk leads legs to legs lead trunk with increasing frequency of the visual perturbation. Through decomposition of the control loop, we found that behavioral change is not necessarily due to a change in control strategy, but in the case of different support surfaces, is linked to changes in properties of the plant. The JIO method is an important tool to identify the contribution of specific components within a closed loop control system to overall postural behavior and may be useful to devise better treatment of balance disorders.

Dynamic reweighting of three modalities for sensor fusion.

We simultaneously perturbed visual, vestibular and proprioceptive modalities to understand how sensory feedback is re-weighted so that overall feedback remains suited to stabilizing upright stance. Ten healthy young subjects received an 80 Hz vibratory stimulus to their bilateral Achilles tendons (stimulus turns on-off at 0.28 Hz), a ± 1 mA binaural monopolar galvanic vestibular stimulus at 0.36 Hz, and a visual stimulus at 0.2 Hz during standing. The visual stimulus was presented at different amplitudes (0.2, 0.8 deg rotation about ankle axis) to measure: the change in gain (weighting) to vision, an intramodal effect; and a change in gain to vibration and galvanic vestibular stimulation, both intermodal effects. The results showed a clear intramodal visual effect, indicating a de-emphasis on vision when the amplitude of visual stimulus increased. At the same time, an intermodal visual-proprioceptive reweighting effect was observed with the addition of vibration, which is thought to change proprioceptive inputs at the ankles, forcing the nervous system to rely more on vision and vestibular modalities. Similar intermodal effects for visual-vestibular reweighting were observed, suggesting that vestibular information is not a "fixed" reference, but is dynamically adjusted in the sensor fusion process. This is the first time, to our knowledge, that the interplay between the three primary modalities for postural control has been clearly delineated, illustrating a central process that fuses these modalities for accurate estimates of self-motion.

Assessment of satisfaction with pharmaceutical services in patients receiving antiretroviral therapy in outpatient HIV treatment setting.

BACKGROUND: The patient's perception and satisfaction are increasingly considered as a useful factor in the assessment of competency of health care providers and quality of care. However, these patient focused assessments are largely ignored when assessing health care outcomes. OBJECTIVE: The study assessed the perception and satisfaction of patients receiving antiretroviral therapy (ART) with pharmaceutical services received in outpatient HIV treatment settings. SETTING: Seventeen HIV treatment centres in Nigeria. METHODS: This cross-sectional survey included 2,700 patients randomly selected from 26,319 HIV patients on ART, who received pharmaceutical services in the study setting. A study-specific Likert-type instrument was administered to the participants at point of exit from the pharmacy. Midpoint of the 5-point scale was computed and scores above it were regarded as positive while below as negative. Chi-square was used for inferential statistics. All reported p values were 2-sided at 95 % confidence interval (CI). MAIN OUTCOME MEASURE: Patient satisfaction with pharmaceutical services. RESULTS: Of 2,700 patients sampled, data from 1,617 (59.9 %) were valid for analysis; 62.3 % were aged 26-40 years and 65.4 % were females. The participants had received pharmaceutical services for a mean duration of 25.2 (95 % CI 24.3-26.1) months. Perception of participants regarding the appearance of pharmacy was positive while that regarding the pharmacists' efforts to solve patients' medication related problems was negative. The participants' rating of satisfaction with the waiting time to access pharmaceutical services was negative; the satisfaction decreases with increasing waiting time. However, the satisfaction with the overall quality of pharmaceutical services received was rated as positive; 90.0 % reported that they got the kind of pharmaceutical services they wanted; 98.2 % would come back to the pharmacy if they were to seek help again and would recommend services to others. The level of satisfaction was found to be associated with educational status of the participants (p = 0.006) unlike age, sex, marital and employment status. CONCLUSION: The satisfaction with overall quality of pharmaceutical services received by participants was positive. Longer waiting times resulted in lower patient satisfaction. High patient load may be the cause of the long waiting time and the inadequate duration of interaction between pharmacist and the patient.