The Investigator recently conducted a study in patients who had suffered from a stroke where it investigated whether similar findings are observed following a single session of chiropractic care.36 The key findings from this study was that in a group of chronic stroke patients, with lower limb muscle weakness, plantar flexion muscle strength increased on average by 64.6% following a chiropractic care session and the change in muscle strength appears to be modulated by cortical factors as opposed to modulation at the spinal level.

Based on the promising results of this initial study now planning to perform a pragmatic pilot clinical trial that will investigate the effects of 4 weeks of chiropractic care on clinical measures associated with stroke rehabilitation and function

Stroke is one of the leading causes of death and disability in the world. It is estimated that 17 million people per year suffer from a significant stroke worldwide, with 5 million of those people experiencing long term physical disability following the stroke. The global burden of stroke continues to rise even though the rate of stroke-related mortality has decreased over recent years. Stroke often results in prolonged physical, emotional, social and financial consequences for stroke survivors, family, friends, and caregivers. One of the most commonly occurring deficits associated with strokes is hemiparesis, which affects upper limb function, or an individual's ability to stand, balance or walk. The long term impaired nervous system function that accompanies many strokes means millions of stroke survivors around the world are reliant on care-givers to assist them with rudimentary activities of daily living such as bathing, dressing, and toileting. The burden of care is immense and has a significant impact on modern society.

This burden is even higher in developing countries. Disability-adjusted life years (DALYs), which is a measure of both years of life lost and years lived with a disability, is seven times higher in developing countries compared to high-income countries. While part of this difference is possibly due to differences in age, incidence, and mortality in developing countries; the mortality of stroke has dropped by 20% while the age-standardized incidence of stroke increased by 12% between 1990 and 2010 in low and middle-income countries. This means more people have strokes, more survive, and as a result, the burden of stroke is even greater in developing countries.

Numerous rehabilitative approaches have been shown to promote motor recovery after a stroke, but advanced strategies are constantly being developed and tested in an attempt to improve long term outcomes for stroke survivors. One possible intervention that may improve post-stroke motor recovery, but has to date not been adequately tested, is chiropractic care.

Over the past two decades, numerous research studies have shown that chiropractic care can significantly influence central neural function. Studies have shown changes in somatosensory processing, sensorimotor integration and motor control following as little as a single session of chiropractic care. Sensorimotor integration is the ability of the central nervous system (CNS) to integrate sensory information from different body parts and formulate appropriate motor outputs to muscles. Effective sensorimotor integration is essential when learning new motor skills, or recovering from an injury. Another essential component for accurate movement, learning new motor skills, and/or recovering from an injury is the accuracy of internal representations of our body map, or body schema. It is essential for our brain to be accurately aware of the location of our limbs and core body in 3D space. The spine is linked biomechanically and neurologically to the limbs and yet, it know very little about how altered sensory feedback from the spine affects limb sensorimotor integration and motor performance. However, there is emerging evidence that altered spinal sensory input can alter central neural processing, possibly by impacting the brains inner body schema. There is also emerging evidence that improving spinal function with chiropractic care can rapidly alter central neural function in a variety of ways, and that these changes outlast the altered changes of input, i.e. that they are neural plastic changes.

It has been hypothesised that the central neural plastic changes that are observed following chiropractic care may be due to improvements in spinal function associated with the correction of vertebral subluxations. Vertebral subluxations have been defined as a diminished state of being, comprising of a state of reduced coherence, altered biomechanical function, altered neurological function and altered adaptability.

If chiropractic care results in improvements in spinal function that have a central neural plastic effect, this may be important for a variety of clinical populations. Recently, groups reported an increase in lower limb muscle strength of 16% in reasonably healthy subjects following a single session of chiropractic care.Study also assessed possible neural plastic changes associated with spinal manipulation by assessing the H-reflex and V-waves. By also assessing these reflexes it helped to establish whether changes in strength following chiropractic adjustments were due to spinal or supraspinal influences. The H-reflex and V-waves are neurophysiological measures that have previously been shown to change following chiropractic care and are also important indicators of changes in central nervous system function that are important for motor recovery following a stroke. The H-reflex is largely modulated by presynaptic inhibition, and motoneuron excitability (spinal input), and the V-wave is a measure of supraspinal input, or cortical drive, to the motor neuron pool. It found changes in both the H-reflex and V-waves associated with increases in strength in our study.

Other small studies have also shown an increase in strength following a single session of chiropractic care. It also recently found a significant 8% increase in lower limb muscle strength in elite taekwondo athletes after a single session of chiropractic care. One previous controlled pilot study reported a significant increase in quadriceps muscle strength following a single chiropractic adjustment session. However group allocation was not randomised, which resulted in baseline group differences, and post-intervention between-group differences were not significant (p=0.2).It also reported a decrease in quadriceps muscle inhibition and increased quadriceps muscle activation following a chiropractic adjustment session. If these changes are lasting, and also occur in people who have suffered from a stroke, they may be important for stroke recovery.

The improvements in muscle strength and fatigue following chiropractic care observed in these studies are likely attributed to increased descending drive and/or modulation in synaptic efficacy of primary afferents or their connections at spinal cord level. This may have clinical implications for a variety of patient populations and in particular, people who have suffered from a stroke, who are likely to benefit from gains in power and strength if they occur following chiropractic care.

Inclusion Criteria:

• patients must have suffered from a stroke at least 12 weeks prior to their involvement in the trial
• have ongoing neurological deficits
• upper and/or lower limb weakness
• with a Fugl-Meyer Assessment (FMA) motor score of less than 80 at the time of enrolment.

Exclusion Criteria:

• have absolute contraindications to chiropractic adjustments
• have experienced previous significant adverse reactions to chiropractic care or any type of manual therapy
• are unable to provide informed consent to participate in the trial due to cognitive impairment.

Participants and the outcome assessors ( Physiotherapists), and data analysts will remain blinded to group allocation throughout the study period.