Description of the condition
Stroke is a leading source of acquired disability and has potentially enormous emotional and socioeconomic consequences for patients, their families and health services (Feigin 2003). There are two main causes of stroke: haemorrhagic stroke resulting from a ruptured blood vessel inside brain, and ischaemic stroke caused by vascular insufficiency (such as cerebrovascular thromboembolism). With the worldwide population ageing, the burden of stroke will increase in the next 20 years (Donnan 2008). Despite the rapid progress in medical science, there are limited effective interventions for people with acute stroke (Langhorne 2009). Consequently, the management strategy for most people with stroke remains secondary prevention and rehabilitation (Quinn 2009). Of those who survive the acute stroke, about 50% will still experience some level of disability after six months (Wade 1987). Therefore, stroke has become a severe public health problem worldwide.
A number of therapies in development aim to improve patient outcomes and any intervention that enables people to recover more rapidly or gain functional independence would have major benefits for them and their families. In addition, brain recovery and rehabilitation will also be a prioritised field in future stroke research (Hachinski 2010). There is a lot of evidence that some therapies, such as functional electrical stimulation (FES) (Glanz 1996; Price 2000) and constraint-induced movement therapy (CIMT) (Sirtori 2009; Wolf 2006; Wolf 2008), can improve motor function and quality of life when used in rehabilitation after stroke.
Description of the intervention
The effect of vibration stimuli on the nervous and muscular system has been studied in different fields (Cardinale 2003; Goetz 2009) and has evolved into full body training known as whole-body vibration (WBV). WBV therapy involves placing the individual (using static position or dynamic exercises, or both) on an oscillating platform that generates a specific frequency and amplitude of mechanical vibrations. It generates an oscillatory vertical motion (vertical platform) or a movement around a horizontal axis (oscillating platform) (Marín 2010). The contact surface of the platform transmits a vibration (in feet or hands) throughout the body. There is another Cochrane Review of WBV therapy that describes its effectiveness and the methodological weakness of randomised controlled trials (RCTs) in neurodegenerative disease (Sitjà Rabert 2012).
How the intervention might work
The seesaw-like displacement of the WBV platform is reported to mimic human gait (Schyns 2009). WBV can activate the Ia and II afferents of (large) muscle groups (Nardone 2001; Roll 1989) and induce sensory stimulation of foot-sole afferents (Kavounoudias 1999; these afferents are well known to play an important role in postural control (Meyer 2004)). The vibration signals of the WBV platform activate the muscle spindles in the leg musculature, which in turn induces reflexive activation of the motor units (Pang 2006) and increases their synchronisation (Cardinale 2003; Kossev 2001). Muscular vibration has contralateral effects on motor cortex excitability, suggesting transcallosal motor-evoked potential modulation (Kossev 2001), which could be especially important in people with stroke (Chollet 1991).
Why it is important to do this review
The effects of WBV therapy on posture and motor symptoms have also been examined in other clinical conditions including people with Parkinson's disease (Haas 2006; Turbanski 2005), cerebral palsy (Ahlborg 2006; Semler 2007) and multiple sclerosis (Schuhfried 2005). Although there are published studies of the clinical efficacy of WBV therapy on function recovery in stroke patients, its potential therapeutic effect has been inconclusive (Brogardh 2012; Chan 2012; Lau 2012; Merkert 2011; Tihanyi 2007; Tihanyi 2010; van Nes 2006). The reason for doing this review is that, in principle at least, WBV therapy might also do harm: if it is ineffective, it is wasting resources, if it is effective, it is a relatively simple way to assist stroke patients in their recovery. The aim of this review is to assess systematically all RCTs of WBV therapy on functional recovery in people with stroke to provide the best evidence and further research planning for stroke treatment. At the same time, we also expect to have a statement regarding when and how often WBV therapy should be used in practice.