Distinct patterns of metabolic motor cortex activity for phantom and residual limb pain in people with amputations: A functional near-infrared spectroscopy study

BACKGROUND

Phantom pain limb (PLP) has gained more attention due to the large number of people with amputations around the world and growing knowledge of the pain process, although its mechanisms are not completely understood.

OBJECTIVES

The aim of this study was to understand, in patients with amputations, the association between PLP and residual limb pain (RLP), and the brain metabolic response in cortical motor circuits, using functional near-infrared spectroscopy (fNIRS).

METHODS

Sixty participants were recruited from the rehabilitation program in São Paulo, Brazil. Included patients were aged over 18 years, with traumatic unilateral lower-limb amputation, with PLP for at least 3 months after full recovery from amputation surgery. PLP and RLP levels were measured using visual analogue scales. fNIRS was performed during motor execution and motor mirror tasks for 20 s. In order to highlight possible variables related to variation in pain measures, univariate linear regression analyses were performed for both experimental conditions, resulting in four fNIRS variables (two hemispheres x two experimental conditions). Later, in order to test the topographic specificity of the models, eight multivariate regression analyses were performed (two pain scales x two experimental conditions x two hemispheres), including the primary motor cortex (PMC) related channel as an independent variable as well as five other channels related to the premotor area, supplementary area, and somatosensory cortex. All models were controlled for age, sex, ethnicity, and education.

RESULTS

We found that: i) there is an asymmetric metabolic activation during motor execution and mirror task between hemispheres (with a predominance that is ipsilateral to the amputated limb), ii) increased metabolic response in the PMC ipsilateral to the amputation is associated with increased PLP (during both experimental tasks), while increased metabolic response in the contralateral PMC is associated with increased RLP (during the mirror motor task only); ii) increased metabolic activity of the ipsilateral premotor region is associated with increased PLP during the motor mirror task; iii) RLP was only associated with higher metabolic activity in the contralateral PMC and lower metabolic activity in the ipsilateral inferior frontal region during motor mirror task, but PLP was associated with higher metabolic activity during both tasks.

CONCLUSION

These results suggest there is both task and region specificity for the association between the brain metabolic response and the two different types of post-amputation pain. The metabolic predominance that is ipsilateral to the amputated limb during both tasks was associated with higher levels of PLP, suggesting a cortical motor network activity imbalance due to potential interhemispheric compensatory mechanisms. The present work contributes to the understanding of the underlying topographical patterns in the motor-related circuits associated with pain after amputations.

Predictive factors of response in radial Extracorporeal Shock-waves Therapy for Myofascial and Articular Pain: A retrospective cohort study

BACKGROUND

Myofascial Pain Syndrome causes disability in daily life activities and despite all efforts, it continues to be a challenge, perpetuating suffering, overloading services and costs. New treatment options need to be tested.

OBJECTIVE

We aimed to quantify the rESWT short-term analgesic effect and identify the predictors of success through comparing results achieved in MPS and Articular Pain (AP).

METHOD

Retrospective cohort study of 1,580 patients with Myofascial Pain Syndrome or Articular Pain underwent two weekly radial Extracorporeal Shock-wave Therapy sessions. The pain intensity was measured by Visual Analog Scale before and one week after the end of the treatment (3 weeks).

RESULTS

The therapy decreases pain by 62.50% (p< 0.0001), with a high success rate (91.59%) and a low worsening of baseline conditions rate (2.1%). The best recommendation is for patients with intense myofascial pain (Visual Analog Scale ⩾ 70 mm), using high shock-wave frequency (⩾ 15 Hz).

CONCLUSIONS

Two rESWT sessions promote pain relief, with a high success rate and low rates of treatment abandonment and worsening. The best results are obtained in myofascial pain patients with high pain intensity, treated with high-frequency dosage.

Developing a rigid frame wheelchair in Brazil

PURPOSE

Describing the development process of a rigid frame wheelchair using user-centered and open innovation approaches, as envisaged by the WHO Wheelchair Guidelines.

METHODS

Unstructured interviews and group discussions with conveniently sampled active wheelchair users oriented the initial brief, product design and selection. The initially approved prototype was subject to ISO 7176 tests, leading to further product adjustments. The long-term follow-up was inclusive of a new group of purposively selected active wheelchair users and measured user satisfaction and safety, as well as user mobility and wheelchair fitting. Data on user satisfaction, safety and effectiveness was produced using QUEST 2.0 and WHO Wheelchair Service Training Package's forms and checklists in Portuguese.

RESULTS

Iterative design and selection led to a prototype that was found appropriate by multiple stakeholders. ISO testing ensured its safety and durability. Follow-up trials included 40 active wheelchair users, who used the studied wheelchair for at least two months. They were 80% male, on average 36.3 years old, and had received their rigid frame wheelchair approximately 4.7 years after disability onset. 92.5% of them had SCI, 7.5% had bilateral transfemoral amputations. Users' assessments showed satisfaction with products (4.4) and services (4.1). Users spent an average of 4.2 h/day sat in their wheelchairs. 7.5% and 20% of users reported pressure sores and falls, respectively.

CONCLUSION

A user-centered, open innovation approach led to the development of a good quality, affordable, and acceptable rigid frame wheelchair model that increased the range of manual wheelchairs available through the Brazilian public healthcare system.Implications for rehabilitationThe feedback of rehabilitation professionals with respect to new products' features is fundamental in order to understand how these devices will be adequately serviced and delivered to users.Engaging users of assistive products and rehabilitation professionals in developing new and innovative products facilitates the iteration and selection of the best project alternatives and saves considerable time and resources.Rehabilitation professionals are in the best position to work with user of assistive products and other stakeholders, such as the industry and research and development centres, to identify the impact of new assistive products in users' functionality, acknowledging their conditions and environments and exploring their potential.Working with users and other stakeholders from different backgrounds and areas of expertise makes the moto "Nothing about us, without us" real. Working towards improving functionality often requires developers to challenge the usual top-down development process in order to adopt a user-centered perspective.