Stroke Recovery: Unlocking Natural Plasticity For Rehabilitation

how natural plasticity can help someone survive a stroke

Stroke disturbs the structural and functional integrity of the brain, and it is the leading cause of long-term disability. The brain has the ability to reorganise its function and structure in response to stimuli and injuries, and this process is known as neuroplasticity. Neuroplasticity can be further augmented by rehabilitative therapy.

Neuroplasticity can be stimulated by repetitive motion, which will retrain the brain and force it to create new neural connections and pathways. The frequency of structured exercise increases the speed and effectiveness of neuroplasticity.

Therapies such as physical, occupational, and speech therapy are designed to spark neuroplasticity, encouraging the brain to correct mental and physical deficits. The brain also temporarily increases its natural neuroplasticity in response to traumatic damage, which is why it's so important to begin the rehabilitation process shortly after a stroke occurs.

Characteristics Values
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Brain plasticity The brain's ability to reorganise its function and structure in response to stimuli and injuries
Stroke A reduction in blood flow to the brain that leads to damage to neuronal networks and the impairment of sensation, movement or cognition
Recovery The restoration of performance through the use of modified or alternative response strategies
Compensation The use of modified or alternative response strategies to perform motor tasks
Remapping The formation of new structural and functional circuits through remapping between related cortical regions
Interventions Multiple novel therapies have been developed to improve clinical outcomes by improving brain plasticity
Conventional therapies Physical, occupational and speech therapy
Novel approaches Modern rehabilitation, brain stimulation, cell therapy, brain-computer interfaces and peripheral nervous transfer
Brain stimulation Techniques including transcranial magnetic stimulation, transcranial direct current stimulation, cortical microelectrode stimulation and deep brain stimulation
Cell therapy The use of donor cells to replace dead cells in the infarct area
Brain-computer interfaces A novel idea for functional recovery after stroke that avoids the injured area, builds a neural bypass and promotes dominance in some brain regions
Peripheral nerve transfer An alternative way to bypass a lesion by transferring the seventh cervical nerve from the non-paralysed side to the paralysed side

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Brain stimulation

Non-invasive stimulations have been more widely used, and the stimulation parameters determine whether the stimulation increases or decreases brain activity. Generally, anodal tDCS (A-tDCS) has been shown to enhance cortical activity, whereas cathodal tDCS (C-tDCS) usually has the opposite effect. Depending on the frequency, repetitive TMS (rTMS) can reduce [low frequency (LF): ~1 Hz] or increase [high frequency (HF): 5~20 Hz] corticospinal excitability.

Both tDCS and rTMS have been used to treat various post-stroke deficits, particularly motor impairment and aphasia. Meta-analyses may imply the effectiveness of non-invasive stimulations, and recent trials with randomized, blind and controlled designs have encouraged further investigation in this field. For example, activating the left hemisphere by A-tDCS in chronic stroke patients with aphasia led to a relative 70% increase in correct naming compared to that in the sham tDCS group; this effect lasted for 24 weeks after treatment. For acute stroke patients with motor impairment, enhancing cortical activity via HF-TMS and A-tDCS resulted in improved motor function, and stimulation-induced increased neural activity correlated with recovery.

The advantage of TMS and tDCS is the non-invasive, precise regulation of excitability within specific brain regions. However, some concerns remain regarding clinical applications that need to be further explored, including the stimulation target, therapeutic time point, and stimulation frequency and parameters. Regarding safety, both interventions have been suggested to be safe and well-tolerated. Common adverse effects include dizziness, headache, transient aching and burning sensations. Skin reactions at the electrode contact site are also reported. Serious adverse events, such as epileptic seizures, have rarely been reported in related trials.

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Robot-assisted training

Several studies have shown that robot-assisted therapy can be effective in improving gait function and upper limb and hand motor function in stroke patients. For example, a 2012 Cochrane review found that robot-assisted arm training improved upper limb function and activities of daily living. However, there is still some debate about the effectiveness of robot-assisted therapy compared to conventional therapy, with some studies suggesting that it can be used as a complement to conventional therapy, while others finding no significant difference between the two approaches. Overall, robot-assisted therapy appears to be a promising novel technology for stroke rehabilitation, but more research is needed to establish its efficacy and determine the best ways to integrate it into rehabilitation programs.

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Virtual reality technology

VR can be used in combination with conventional therapy approaches to improve upper limb function and activities of daily living. It can also be used to improve post-stroke balance, gait and neglect. VR provides a more interesting and engaging environment for goal-oriented tasks to be performed. It also creates a safe environment that can be easily manipulated to advance tasks as stroke patient’s functional abilities progress. Moreover, VR can be performed without supervision, meaning that VR therapy can be performed more often than standard supervised physiotherapy sessions.

VR can be implemented in two ways: immersive and non-immersive. The former is typically delivered through a head-mounted device and creates a realistic environment for the user. However, it may cause motion sickness. The latter usually comes in the form of a video game device and is more cost-effective but does not create the same high level of engagement within the environment as immersive systems.

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Cell therapy

Exogenous cell therapy is the more common approach and has been shown to be safe and effective in clinical trials. The transplanted cells can promote the formation of new neurons and enhance axonal myelination, synaptic transmission, neurogenesis, angiogenesis, and immunomodulation. They can also secrete neurotrophic and growth factors, which can improve the microenvironment of the brain and promote functional modulation.

The sources of donor cells for exogenous therapy are typically bone marrow-derived or neural progenitor/stem cells. Bone marrow-derived cells are more commonly used due to their ease of collection and reduced risk of immune rejection. These cells can be administered through various routes, such as intravenous, intra-arterial, or intracerebral infusion.

The timing of cell therapy is critical, as the optimal window for treatment is usually within the first few days after a stroke. However, the results of clinical trials have been mixed, with some studies showing improvements in neurological outcomes, while others have found no significant effects.

Overall, cell therapy for stroke is a promising approach that has the potential to improve recovery and repair the brain. However, further research and larger clinical trials are needed to fully understand its efficacy and optimize the treatment protocol.

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Peripheral nerve transfer

The procedure has been used to treat injury to the brachial plexus since the 1980s, and has been found to improve upper arm function. It has also been found to induce brain plasticity, which has led to its use in treating spastic arm paralysis.

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Frequently asked questions

Neuroplasticity is the brain's ability to reorganise its function and structure in response to stimuli and injuries. After a stroke, the brain initiates the plasticity process to compensate for the lesion and its remote effects.

The brain uses 100 trillion neural connections or pathways to retrieve and store information. When a stroke occurs, any combination of those 100 trillion connections could be impacted. The brain can identify environmental, behavioural, and neural damage, but it needs assistance and stimulation to change or adapt. That's where therapists and stroke survivors play a vital role. A variety of exercises and movements can be used to provide cues to the brain. Those cues direct the brain on how to rewire and adapt, creating new neural pathways that can work around any brain damage and alleviate or compensate for physical and mental deficits.

The best way to stimulate the brain and activate the neuroplastic response is through repetitive motion. Heavy repetition of certain movements or activities will retrain the brain and force it to create new neural connections and pathways. The frequency of structured exercise increases the speed and effectiveness of neuroplasticity.

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