Posts Tagged compensation

[WEB SITE] Neural works

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STROKE IS THE leading cause of disability in adults, and can affect many parts of the brain, causing multiple deficits including the ones in cognitive, behavioural, visual, speech, sensation, movement, muscle tone and sphincter functions. There are two types of recovery after stroke—spontaneous neurological recovery, which happens in the first three to six months owing to resolution of local injury and can be modified by newer interventions, and functional recovery, for which the time period is unlimited and that involves intensive training that triggers newer electrical circuits in the brain.

Similarly, there are two different approaches of neurological rehabilitation—compensation and remediation. In the compensatory approach, for example, if someone has difficulty in walking because of lack of movements in the leg, then we give him a stick to walk. In remediation, on the other hand, we try to minimise the impairment or improve power in the leg muscles and reduce the chances of using a stick. This ability of the brain to restore the function by minimising the impairment depends upon the formation of new or alternative circuits in the brain. This inherent but not widely known ability of the brain to change in response to a triggered stimulus is called neuroplasticity.

Neuroplasticity is the capacity of neurons and neural networks in the brain to change their connections and behaviour in response to new information, sensory stimulation, development, damage or dysfunction. In fact, for many years, it was believed that certain functions were hard-wired in specific, localised regions of the brain and that any incidents of brain change or recovery were mere exceptions to the rule—’brain cannot change’. However, since the 1970s and 1980s, neuroplasticity has gained wide acceptance in the scientific community as a complex, multifaceted, fundamental property of the brain. Remodelling of neural circuits through plasticity can occur spontaneously or can be triggered by intensive training (experience-dependent plasticity) and biological treatments (pharmacological agents and transcranial magnetic stimulation).

Dr Abhishek Srivastava

Dr Abhishek Srivastava

There are four different types of neuroplasticity: map expansion, homologous area adaptation, compensatory masquerade and cross-modal reassignment.

Map expansion entails flexibility of local brain regions that are dedicated to performing one type of function or storing a particular form of information. The arrangement of these local regions in the cerebral cortex is referred to as a ‘map’. When one function is carried out frequently enough through repeated behaviour or stimulus, the region of the cortical map dedicated to this function grows and shrinks as an individual exercises this function. This phenomenon usually takes place during the learning and practising of a skill such as playing a musical instrument or in task-specific trainings in stroke patients to improve specific functions like arm or leg movements, speech, language, cognitive or swallow function. This is the most commonly used approach in neurorehab.

Homologous area adaptation occurs during the early critical period of development. If a particular brain module becomes damaged in early life, its normal operations have the ability to shift to brain areas that do not include the affected module. The function is often shifted to a module in the matching or homologous area of the opposite brain hemisphere. This concept can help improve speech and language function after stroke with involvement of the dominant lobe.

Compensatory masquerade can simply be described as the brain figuring out an alternative strategy for carrying out a task when the initial strategy cannot be followed due to impairment. One example is when a person attempts to navigate from one location to another. Most people have an intuitive sense of direction and distance that they employ for navigation. However, a person who suffers some form of brain injury or stroke and impaired spatial sense will resort to another strategy for spatial navigation, such as memorising landmarks. The only change that occurs in the brain is a reorganisation of preexisting neuronal networks. This is a simple and novel way by which stroke survivors who were not able to do a complex everyday task can be trained to do it themselves.

Cross-modal reassignment entails the introduction of new inputs into a brain area deprived of its main inputs. A classic example of this is the ability of an adult who has been blind since birth to have touch or somatosensory input redirected to the visual cortex in the occipital lobe of the brain—specifically, in an area known as V1. Sighted people, however, do not display any V1 activity when presented with similar touch-oriented experiments. This occurs because neurons communicate with one another in the same abstract language of electrochemical impulses regardless of sensory modality. This strategy is useful to improve visual or auditory functions after stroke.

Most of the recent rehabilitation approaches to improve sensory-motor recovery, including rehab robotics, virtual reality, mirror training, constraint induced therapy, task-specific training and intensive locomotor training, work on the principles of neuroplasticity. These help in improving most of the functions after stroke including cognitive, visual, behavioural, speech, language, swallow, movements, tone or sphincter functions. I have seen many stroke patients, thought to be in a vegetative state for life, now living independently, thanks to neurological rehabilitation.

Srivastava is a neurorehab specialist and director, centre for rehabilitation, Kokilaben Dhirubhai Ambani Hospital, Mumbai.

 

via Neural works | health

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[ARTICLE] The impact of ankle–foot orthoses on toe clearance strategy in hemiparetic gait: a cross-sectional study – Full Text

Abstract

Background

Ankle–foot orthoses (AFOs) are frequently used to improve gait stability, toe clearance, and gait efficiency in individuals with hemiparesis. During the swing phase, AFOs enhance lower limb advancement by facilitating the improvement of toe clearance and the reduction of compensatory movements. Clinical monitoring via kinematic analysis would further clarify the changes in biomechanical factors that lead to the beneficial effects of AFOs. The purpose of this study was to investigate the actual impact of AFOs on toe clearance, and determine the best strategy to achieve toe clearance (including compensatory movements) during the swing phase.

Methods

This study included 24 patients with hemiparesis due to stroke. The gait performance of these patients with and without AFOs was compared using three-dimensional treadmill gait analysis. A kinematic analysis of the paretic limb was performed to quantify the contribution of the extent of lower limb shortening and compensatory movements (such as hip elevation and circumduction) to toe clearance. The impact of each movement related to toe clearance was assessed by analyzing the change in the vertical direction.

Results

Using AFOs significantly increased toe clearance (p = 0.038). The quantified limb shortening and pelvic obliquity significantly differed between gaits performed with versus without AFOs. Among the movement indices related to toe clearance, limb shortening was increased by the use of AFOs (p < 0.0001), while hip elevation due to pelvic obliquity (representing compensatory strategies) was diminished by the use of AFOs (p = 0.003). The toe clearance strategy was not significantly affected by the stage of the hemiparetic condition (acute versus chronic) or the type of AFO (thermoplastic AFOs versus adjustable posterior strut AFOs).

Conclusions

Simplified three-dimensional gait analysis was successfully used to quantify and visualize the impact of AFOs on the toe clearance strategy of hemiparetic patients. AFO use increased the extent of toe clearance and limb shortening during the swing phase, while reducing compensatory movements. This approach to visualization of the gait strategy possibly contributes to clinical decision-making in the real clinical settings.

Background

Impaired paretic limb advancement is a clearly observable manifestation of gait pathology in individuals with hemiparesis due to stroke [123]. Previous studies have reported specific gait changes following hemiparesis, such as decreased knee flexion, hip flexion, and ankle dorsiflexion during the swing phase, which can negatively influence the achievement of toe clearance [123456]. Reduction in toe clearance of the affected limb leads to tripping while walking, which is a major cause of falls [78]. In healthy individuals, toe clearance is mainly achieved by limb shortening, which is affected by hip flexion, knee flexion, and ankle dorsiflexion. On the other hand, to obtain sufficient toe clearance during the swing phase, individuals with hemiparesis often require compensatory strategies that modify the kinematic pattern, including hip hiking and circumduction, which are common gait deviations [39]. These changes during the swing phase have a reciprocal relationship. When the limb shortening is reduced due to paresis, the compensatory movements will be increased to contribute to toe clearance; hence, they are in a trade-off relationship [10].

Ankle–foot orthoses (AFOs) are frequently prescribed to improve walking ability in hemiparetic patients, as they provide passive or dynamic support of ankle movement. AFOs provide support not only during the stance phase of gait by encouraging lateral stability or improving early stance knee moments, but also in the swing phase to maintain ankle dorsiflexion and facilitate toe clearance [11121314151617]. The effect of AFOs on the swing phase is additionally reflected in the compensatory movements. Cruz et al. [18] demonstrated that the compensatory pelvic obliquity observed in response to impaired ankle dorsiflexion in hemiplegic patients was minimized when the patients wore an AFO. Improved joint motions and decreased compensatory movement when using AFOs could potentially contribute to an efficient gait and promote walking activity in hemiparetic patients.

Clarification of the mechanical effect of AFOs on these gait parameters, and quantifications of compensatory movements would be helpful for clinical decision-making in rehabilitation clinics. For example, understanding the influence of rehabilitative training and the use of AFOs on gait indices (i.e., ankle angle, knee angle, hip elevation, or toe clearance) would help to determine the best rehabilitative strategy and to identify the need for AFO use in individual patients.

The aim of this study was to clarify the mechanical effect of AFOs and to quantify the impact of AFO use on hemiparetic gait pattern during the swing phase, as this information would be helpful for clinical decision-making in rehabilitation clinics. For example, understanding the influence of rehabilitative training and the AFO and its types on gait indices (i.e., ankle angle, knee angle, hip elevation, or toe clearance) would help to determine the best rehabilitative strategy and to investigate the need for AFO use in individual patients. Based on a prior study showing the relationship between limb shortening and compensatory movements [10], we hypothesized that the AFOs would positively affect functional limb shortening in a way that would consequently impact on toe clearance and compensatory maneuvers, particularly represented by hip elevation. Previous studies have shown the effects of AFOs and a relationship between limb shortening and compensatory movements. In the normal gait pattern, functional limb shortening (representing lower limb joint movement) is a main strategy for toe clearance. However, patients with hemiparesis have impaired lower limb function, and thus require compensatory strategies (e.g., hip hiking, circumduction of the paretic limb) to promote swing phase propulsion [1920]. Additionally, the extent of toe clearance is mainly determined by the extent of functional limb shortening and hip elevation as compensatory movements, which are in a trade-off relationship [10]. AFO usage reduces the gait pattern deviation and increases the walking ability, thereby reducing energy costs [2122]. In this study, we hypothesized that the AFOs would positively affect functional limb shortening in a way that would consequently impact on toe clearance and compensatory maneuvers, particularly represented by hip elevation. To determine the actual impact of limb shortening and compensatory movements on toe clearance, the vertical component of the movements that comprised toe clearance was calculated using three-dimensional kinematic motion analysis. The changes in joint angles were also investigated.[…]

Continue —> The impact of ankle–foot orthoses on toe clearance strategy in hemiparetic gait: a cross-sectional study | Journal of NeuroEngineering and Rehabilitation | Full Text

Figure 1

Fig. 1 Marker placement. The positions of 12 measurement markers (bilateral acromion, iliac crest, hip, knee, ankle and toe)

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[WEB SITE] What is an Occupational Therapist?

Occupational therapy is an allied health profession that plays a key role in the rehabilitation process of many conditions, injuries or illnesses. Occupational therapists possess knowledge about how individuals, the environment and human occupation (activity) stimulate health and well-being.

The Occupational Therapists professional philosophy is to maximise occupational (often referred to as functional) independence.  They use activities that are meaningful to the client to develop treatment plans, taking an holistic and client centred approach.

For occupational therapists, occupation refers to the activities of everyday living that people need to, want to and are expected to do. Therefore an occupational therapist can help a person regain and/or maintain personal purpose and independence in everyday living.

Consider the activities you participate in every day. Getting washed and dressed, cooking, making a drink, getting to work and socialising; or the roles you have, father/mother, son/daughter, colleague, friend and carer.  How would you complete these tasks or perform the expected roles if you were affected by trauma, chronically deteriorating health or relapse of some kind?

The Occupational Therapist provides practical support to enable people to facilitate recovery and overcome any barriers that prevent them from doing the activities that matter to them, covering all developmental & life stages.

Continue —> What is an Occupational Therapist?

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[ARTICLE] Visual rehabilitation: visual scanning, multisensory stimulation and vision restoration trainings

Neuropsychological training methods of visual rehabilitation for homonymous vision loss caused by postchiasmatic damage fall into two fundamental paradigms: “compensation” and “restoration”. Existing methods can be classified into three groups: Visual Scanning Training (VST), Audio-Visual Scanning Training (AViST) and Vision Restoration Training (VRT). VST and AViST aim at compensating vision loss by training eye scanning movements, whereas VRT aims at improving lost vision by activating residual visual functions by training light detection and discrimination of visual stimuli.

This review discusses the rationale underlying these paradigms and summarizes the available evidence with respect to treatment efficacy. The issues raised in our review should help guide clinical care and stimulate new ideas for future research uncovering the underlying neural correlates of the different treatment paradigms. We propose that both local “within-system” interactions (i.e., relying on plasticity within peri-lesional spared tissue) and changes in more global “between-system” networks (i.e., recruiting alternative visual pathways) contribute to both vision restoration and compensatory rehabilitation that ultimately have implications for the rehabilitation of cognitive functions.

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via Frontiers | Visual rehabilitation: visual scanning, multisensory stimulation and vision restoration trainings | Frontiers in Behavioral Neuroscience.

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[ARTICLE] Visualisation of two-dimensional kinematic data from bimanual control of a commercial gaming system used in post-stroke rehabilitation – Full Text PDF

Abstract

Kinematic data from two stroke participants and a healthy control were collected using a novel bimanual rehabilitation system. The system employs two customized PlayStation Move Controllers and an Eye camera to track the participants’ hand movements.

In this study, the participants played a Facebook game by symmetrically moving both hands to control the computer’s mouse cursor. The collected data were recorded during one game session, and movement distribution analysis was performed to create density plots of each participant’s hand motion in the XY plane.

This type of kinematic information that can be gathered by rehabilitation systems with motion tracking capabilities has the potential to be used by therapists to monitor and guide home-based rehabilitation programs.

Full Text PDF

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[ARTICLE] Translational Vision Science and Technology – Homonymous Visual Field Loss and Its Impact on Visual Exploration: A Supermarket Study – Full Text

Conclusion

…Homonymous VFDs may critically interfere with quality of life. In a special-offer supermarket search task, we investigated the performance of 10 patients with homonymous VFDs and 10 control subjects. A considerable number of patients completed the task successfully despite the visual impairment and performed indistinguishably from the control subjects. On average, homonymous visual-field loss was associated with longer search time. Analysis of eye-tracking data revealed that efficient visual search strategy may help some patients to compensate for their visual impairment. For the present supermarket search task, effective visual exploration included longer glancing toward the peripheral visual field…

via Translational Vision Science and Technology – Homonymous Visual Field Loss and Its Impact on Visual Exploration: A Supermarket Study.

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