THE EDITORIAL DEBATE
|Year : 2015 | Volume
| Issue : 3 | Page : 307--309
Stepping to reorganize the damaged brain: Does the journey lead to a destination?
Kamal Narayan Arya1, Ravindra K Garg2,
1 Department of Occupational Therapy, Pt. Deen Dayal Upadhayaya Institute for the Physically Handicapped, 4 VD Marg, New Delhi, India
2 Department of Neurology, King George Medical University, Lucknow, India
Kamal Narayan Arya
Department of Occupational Therapy, Pt. Deen Dayal Upadhayaya Institute for the Physically Handicapped, 4 VD Marg, New Delhi
|How to cite this article:|
Arya KN, Garg RK. Stepping to reorganize the damaged brain: Does the journey lead to a destination?.Neurol India 2015;63:307-309
|How to cite this URL:|
Arya KN, Garg RK. Stepping to reorganize the damaged brain: Does the journey lead to a destination?. Neurol India [serial online] 2015 [cited 2020 Feb 24 ];63:307-309
Available from: http://www.neurologyindia.com/text.asp?2015/63/3/307/158162
Post-stroke rehabilitation is increasingly developing as an essential component of the stroke management program. Limb weakness requires specific rehabilitation therapy in addition to the usual medical care. Rehabilitation follows two pathways: Compensatory (perform functions with available movement) and remediation (induce normal motor control). The second type of rehabilitation methods are more acceptable because they are neuroplasticity-based interventions. Currently, numerous motor-rehabilitation methods, that may help to reorganize functions of the cerebral cortex, are under investigation.  The techniques range from simple task-specific training programs to complex non-invasive brain stimulation paradigms. The underlying mechanisms may differ among the interventions; however, their common goal is to accelerate motor recovery.
More than two-thirds of post-stroke patients experience some form of locomotor disability. Due to an incomplete motor recovery, majority of them do not regain independent and safe ambulation in the community. Motor recovery in patients with post-stroke hemiparesis is a hierarchical and sequential phenomenon. The recovery passes through phases of flaccid-to- spastic paresis. The course encompasses reflexive-to-stereotypical synergistic motor behaviour that may progress to near-normal movements. The typical synergistic pattern emerges as an involuntary flexor or extensor association between the hip, knee and ankle. As locomotion is dependent on the functional activity of both the lower limbs, even with minimal motor control, one starts walking in an awkward manner. Due to poor ankle dorsiflexion and knee flexion control, the gait is usually characterized by excessive hip hiking to clear the ground. However, for daily functional needs, the patient keeps walking with asymmetry and gradually the pattern gets stronger with time. Conventionally, an ankle-foot support with or without a walker or a cane is indicated to restore the functional ambulation in post-stroke hemiparesis.  However, only a small proportion of patients would achieve safe ambulation in the community, especially in the difficult natural and man-made environment.
In addition to the functional ambulation, the goal of any gait-rehabilitation program should also be to overcome the existing dissociation between the joints of lower limbs; to augment the walking speed and endurance, and the balance and coordination between the upper and lower limbs; and, to reduce excessive muscular effort. These goals may be attained by interventions such as task-specific training that is based on the principle "Practice the task to learn it." The challenge is to rehearse the type of walking that would have been possible if all impairments were non-existent, in the presence of a difficult weight-bearing dynamic position. This type of training is not feasible over the normal ground utilizing any means. Thus, the concept of treadmill training, with or without a bodyweight support system, has been borrowed from spinal cord injury rehabilitation. The body-weight support system, by gradually releasing the desired load on the treadmill, allows negligible gait deviation during training. The treadmill facilitates an alternate, coordinated, repetitive stepping of the lower limbs along with synchronized swinging of the arms.  The practice also utilizes the principle of motor learning that leads to synaptogenesis, dendritic sprouting, and formation of new motor engrams.
In this issue of Neurology India, Srivastava and co-workers  have reported the role of task-specific motor-rehabilitation in enhancing ambulation in the chronic stroke patients. The favourable locomotor recovery may be attributed to the associated neural reorganization induced by the rehabilitation technique. Although this study is a single group design (Level III evidence), the authors have taken possible precautions such as the recruitment of independent assessors in order to avoid bias. Only one-third of the screened subjects were found to be eligible for recruitment. In view of the heterogeneity in post-stroke manifestations, this is always a concern for all the stakeholders.
The treadmill training unquestionably provided task-specific training to enhance walking. The task-demands generate specific gait patterns of human locomotion. The treadmill training using body-weight support would be a safer option for subjects on a lower level of the disability scale (Functional Ambulation Classification 2 and lower). Although the present study observed an improvement in the walking speed and independency, a Cochrane review  of 44 trials has indicated a positive change only for the "speed" paradigm. The latter review comprised trials that utilized treadmill and body support either independently or in combination. The assessment of improvement in the disability at a follow-up at 3 months has only been possible due to an admirable effort put forth by the investigators. The endeavour confirmed that the sustained recovery that occurs at a follow up of three months is a result of neural reorganization rather than just being a learned behaviour. The change in walking speed is one of the best indicators for gait improvement in stroke. This study exhibited a change of 0.12 m/s post-intervention that was retained to 0.10 m/s at follow-up; similar changes has also been reported (0.14 m/s to 0.12 m/s) in a systematic review.  The functional independence in response to the intervention improved at the post-training assessment (mean Barthel index improved to 89/100 from the existing figure of 77/100) and was retained as well as increased by an average score of 3/100 at a follow-up of three months.
The treadmill activity may induce cortical activation (primary motor cortex of the undamaged brain, and the premotor and supplementary motor areas of the damaged brain) and exploit the central pattern generators (CPGs). , These functional-neural networks in the spinal cord produce spontaneous, rhythmic and repetitive movement patterns that are usually needed for walking. The treadmill activity may activate the CPGs, which in turn improve walking. However, in the absence of a supraspinal control, CPGs alone cannot plan and execute motor programs during a complex walking situation.
In this prospective study,  measures were used to assess walking speed, ambulation level, balance, functional independence, and stroke-related impairment. To investigate the effects of motor therapies, an array of outcome measures are in practice. Considering the International Classification of Functioning (ICF) model, the measures may assess neuro-motor recovery (Body structure and function), functional performance (Activity) or the impact of the disease (Participation).  The outcome of any rehabilitation method also relies on the preference of the investigator to use a particular tool. A therapeutic technique may induce a change at the neural level but not at the functional level and vice versa. The study has primarily evaluated body functions (Scandinavian Stroke Scale) and activity [10-meter walk test, Functional ambulation classification and Berg balance scale]. Evaluation of cortical changes using fMRI studies, and assessment of gait deviation by a gait-analyser may be utilized in future studies to understand the underlying neural mechanisms that become activated in response to the intervention. In addition to this, the improvement obtained in cardiopulmonary endurance in response to the rehabilitative intervention, especially while working on the treadmill, also needs to be considered.
Age and the duration of onset may be some of the key factors influencing the development of neuroplasticity, Srivastava et al.  have recruited subjects ranging in age from 24 to 65 years and having a post-stroke duration ranging from 6 months to 5 years. The spasticity reducing exercises, resistive exercises, balance, and functional and gait training illustrate that a multi-therapy protocol must be implemented for a lasting relief. The assessment of effectiveness of these interventions, however, requires an independent scrutiny.
In conclusion, walking is one of the basic activities of life required to explore the surrounding environment. This activity of daily living gets hampered after the brain-insult. The recent developments in rehabilitative intervention that are succinctly summarised in the study in focus considerably help in alleviating the resultant gait dysfunction. The technique utilizes established neuro-scientific principles to reorganize the relevant neural systems. However, there is further scope of developing new regimens or redesigning the existing protocols to achieve a favourable recovery at all levels of the locomotor outcome.
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