Radial Extracorporeal Shock Wave Therapy for Spastic Plantar Flexor Muscles in Young Children With Cerebral Palsy

Cerebral palsy (CP) is a clinical syndrome characterized by a persistent disorder of posture or movement caused by a non-progressive disorder of the immature brain. The prevalence of CP has been reported to be between 1.86 cases per 1,000 population in the United Kingdom and 3.6 cases per 1,000 in 8-year-old children in the United States, with little variation among Western nations. In a very recent systematic review analyzing a total of 49 studies, the pooled overall prevalence of CP was 2.11 cases per 1,000 live births. Rates of CP in population-based settings in India and China gave figures of 2-2.8 cases per 1,000 births. A systematic literature review for a period spanning between 1965 and 2004 found CP more prevalent in more deprived socio-economic populations. The same study identified low birthweight, intrauterine infections and multiple gestation as the most important risk factors for CP.

Most children with CP suffer from spasticity as the main motor disorder. Spasticity is a major challenge for rehabilitation of children with CP. This is because spasticity can cause pain, prevent or hamper function and may disturb sleep. Spasticity of plantar flexor muscles is a particular problem in CP because it causes toe walking. This can result in major functional implications such as disturbances in balance and walking, and interfere with gross motor function.

The management of spasticity in CP is complex and is a major challenge to the treatment team. The ultimate goal of any therapy program must be to achieve the child's maximum potential in motor skills. Unfortunately, the scientific evidence for various physical therapy treatment options for children with CP is limited. Botulinum neurotoxin (BoNT) is a widely used and effective pharmacological treatment for focal muscle over-activity. An alternative to BoNT treatment is focal intramuscular treatment with phenol and alcohol, with the aim to improve activity limitations and other outcomes in children and adults with spasticity. However, focal intramuscular injection of BoNT, phenol and alcohol is not without problems: (i) BoNT is expensive and not available in many countries; (ii) a significant risk of focal intramuscular injection of alcohol and phenol is persisting pain; and (iii) all these procedures are invasive and, thus, not without risk when applied under difficult hygienic conditions. With regard to post-stroke spasticity, a recent Cochrane review concluded that, at best, there was 'low level' evidence for the effectiveness of outpatient multidisciplinary rehabilitation in improving active function and impairments following BoNT treatment for upper limb spasticity in adults with chronic stroke.

Orthopedic surgery is considered a last resort in managing spasticity in children with CP, but is not an option for managing spasticity per se. Instead, it is used to help correct the secondary problems that occur with growth alongside spastic muscles and poor motion control. Those problems include muscle shortening, joints contractures and bony deformities.

Recently, extracorporeal shock wave therapy (ESWT) has become an alternative in the treatment of spasticity. A byproduct of extracorporeal shock wave lithotripsy, ESWT has emerged as a noninvasive management option for tendon and other pathologies of the musculoskeletal system with minimal unwanted side effects such as temporary skin redness and pain during treatment. Prior studies on tendinopathy showed that ESWT can be as or more effective than other forms of treatment such as eccentric exercise, traditional physiotherapy, steroid injections and surgery. There are two different types of extracorporeal shock waves - focused (fESWT) and radial (rESWT) - and several modes of operation of focused and radial extracorporeal shock wave generators.

Among the studies on fESWT and rESWT for spasticity performed so far, six out of 18 (33%) were pilot studies without control group, seven (39%) were pseudo-controlled studies (i.e., each patient served as her/his own control, with one placebo treatment followed by one ESWT treatment one or two weeks later), and five (28%) were randomized controlled trials (RCTs).

It is of note that none of these studies on fESWT and rESWT for spasticity were performed on patients younger than an average of 4.8 years of age. However, it has been argued that the management of spasticity in children with CP should be started as early as possible, and there is evidence that early intervention (i.e., before the age of 36 months) can minimize secondary complications of CP.

Acknowledging (i) the particular problem of spastic plantar flexor muscles in CP, (ii) the limited scientific evidence for various physical therapy treatment options for children with CP, (iii) the risks and limitations associated with BoNT and focal intramuscular treatment with phenol and alcohol, and (iv) the proven effectiveness of rESWT in the treatment of spasticity in patients with CP aged between 10 and 46 years of age, the aim of the present study is to determine whether rESWT in combination with traditional conservative therapy is safe and effective for the management of spastic plantar flexor muscles in patients with CP younger than averaged three years of age.