Wren, T. A. L. , Lee, D. C. , Hara, R. , Rethlefsen, S. A. , Kay, R. M. , Dorey, F. J. , & Gilsanz, V. (2010) performed a randomized study to examine the effects of vibration therapy in children with cerebral palsy (CP). The investigators pursued effects on bone and muscle in this population. The criteria for inclusion were children with cerebral palsy 6-12 years old (most likely to show response for bone mass accrual due to their young age), children with Gross Motor Function Classification System (GMFCS) levels 1 -4, and able to stand for 10 minutes.
Exclusion criteria included high vertebral cancellous bone density (>295mg/cm3, approximately 1 standard deviation (SD) above the average for typical development), surgery, casting, botulinum – toxin injection in the last 12 months, metal rods or plates in the tibia or lumbar spine, scoliosis > 20 degrees, bowing of the tibia, concomitant medical conditions affecting bone or muscle, and use of corticosteroids or seizure medications. Children who met the criteria (n=36) were recruited by calling current and former patients from the orthopaedic clinics from a tertiary pediatric medical center.
Participants were requested to stand on a vibrating platform at home for 10 minutes per day for six months (30Hz with a peak acceleration of 0. 3g) and without the vibrating platform for an additional six months (control period). One group (18 participants) did vibration first and the second group (other 18 participants) started with standing without platform first to randomize the order of the interventions. The participants were assessed at baseline, 6 months, and 12 months after the interventions and they were able to use orthotic devices if needed.
The vibrating platform used was the Juvent Medical. This device had an internal computer that recorded the time and the usage duration. Participants were followed up via phone calls. Assessment of dietary intake was done by using written records with tracking of Vitamin D consumption. All participants were assessed using the General Electric Light Speed QX/i and a computerized tomography (CT) -T Bone densitometry package. Studies were conducted by the same clinician who was blinded to the participants group assignments.
For the axial skeleton (head and trunk) bone scanning a single 10mm slice was obtained at the mid-portion of the L3 vertebral body (lateral scout view). Cancellous bone and cross-sectional area were determined at that level. For the appendicular skeleton site location was done by physical examination: R side was aligned for children with bilateral involvement and for children with one side involvement the affected side was aligned. Continuous 1. 25mm slices were taken from the proximal tibial metaphysis and one 10mm slice was taken at the midshaft of the tibia.
Mean cancellous bone density (CBD) below the growth plate were obtained from the metaphysis. For the midshaft the following measurements were obtained: cortical bone area or CBA (bone’s compressive properties), Imax, Imin, JAP and IML (bone’s bending properties) and J (bone’s torsional properties). For muscle measurement, the calf muscle area was determined from the CT cross sectional images; the plantar flexors muscle strength was assessed using a Kin-Com 125 AP dynamometer. All image analysis was done using the Matlab Version R2006b.
Statistical data was collected by using mixed model linear regression and the Pearson’s correlation. Linear regression was utilized to whether baseline vertebral density was lower than typical and to investigate the influence of sex and GMFCS level on the vertebral Z-scores. Pearson’ correlation was used to examine the relationship between the participants’ compliance and the outcomes. Changes in participants’ height were included in a regression model to estimate the relationship among the variables. Values were mean and standard deviation.
When comparing typical development vertebral density with the children in the study, the participants showed a significantly lower density with Z scores between-1 and -2 and 0 and -1. No influence of gender (p=0. 98) or GMFCS level (p=0. 64) was seen in this study. No baseline measure differences among participants regarding bone and muscle strength were identified, therefore, they were not included for outcome purposes. Differences were established based on treatment (vibration and standing) and periods (first or second) and the interaction between treatment and period.
Statistical significance was obtained between vibration and standing in favor of vibration therapy (p value = 0. 02) in the cortical bone properties in the appendicular skeleton. In tibial diaphysis cortical bone area and all moments of inertia, increased in both periods (standing and vibration) were observed while larger changes in bone growth, from 139 (38) in baseline to 159 (40) after 12 months, were seen with vibration first in the mid-shaft of the tibia.
The cross sectional area of L3 increased in both periods (vibration first group from 6. 8 in baseline to 7. 7 after 12 months, and standing first group from 7. in baseline to 7. 8 after 12 months). Cancellous bone density did not change during either period. Muscle area did not change significantly in any period, however, eccentric torque increased in both periods and concentric torque increased during vibration showing values from 840 (758) in baseline to 1463 (1379) at the end of the 12 months. No correlation was reported related to the participants’ nutritional status and treatment compliance. The authors concluded that the primary benefit of vibration intervention in children with CP was to cortical bone in the appendicular skeleton.
Increased cortical bone area and structural properties could translate into a decrease risk of long bone fractures for some patients. Positive aspects of this trial included a cohort study design (0,6, 12 months), performance of power analysis to determine the amount of participants needed to get statistical difference, non-investigator tester; also blinded to the group allocation, randomization of the groups, nonconvenience sample: use of community participants, and 88. 5% of the participants completed the full year of participation.
Among the limitations of this study were trials done at home (with phone contact), participants compliance ranged from 24 -99%, all subjects were ambulatory, use of non-parametric statistical analysis, and the pursue of cancellous density outcomes on a young population, when literature states it does not change until approx. the age of 12 y/o (Gilzanz & Nelson, 2003). The outcomes in this study suggested increased of bone accretion on mid-shaft of the tibia, and changes in concentric torque as a result of high frequency, low magnitude vibration therapy. No other statistically significant changes were obtained.
The researchers stated the results may obey to the difficulties measuring / verifying participants’ compliance and skeletal immaturity among other factors, recommending larger and more inclusive studies to determine the most appropriate treatment parameters. Discussion Cerebral palsy (CP) is characterized by motor performance and postural challenges appearing early in life. Impaired muscle strength and tonicity are major predictors of poor motor control affecting the ability for children with CP to develop age appropriate milestones including ambulation and other functional skills.
Muscle weakness is associated with abnormal bone development (Stevenson, Conaway, Barrington, Cuthill, Worley & Henderson, 2006). The prevention and treatment of muscle weakness and bone fragility are critical areas of research in children with cerebral palsy. The main purpose of this paper was to review and appraise literature related to whole body vibration in children with cerebral palsy and its efficacy in their bones and muscles and potential positive results in walking and other functional outcomes.
Please note, as a primary provider of therapy services for children with cerebral palsy in the Central Florida community, this educational activity was also driven by a great sense of responsibility to always research additional tools for this population. Several previous studies have reported benefits of WBV in strength and power in elite athletes (Rittweger, J. 2010), by increasing muscle strength and bone mineral density (de Zepetnek, 2009).
It is important to mention that balance control resides in a combination of musculoskeletal actions; for children with cerebral palsy, disturbances in those areas make the recovering from the effects of slips or trips very challenging due to their instability many times resulting in despicable falls and fractures. A meta – analysis previously conducted, showed that gait and balance challenges are the most accurate predictors of future falls (Henderson, 2002). Scientific research on the benefits of WBV on fitness and health has been limited and mostly devoted to the adult population. All four studies appraised, shared some commonalities.
They all presented with similar methodology and attainable interventions to access the effect of WBV in cerebral palsy in the pre-teen years. No injuries were reported in any of the studies, and when some of the children (very minimal amount) reported fatigue or pain, the studies were stopped until the participants were ready to continue. Whole body vibration on children with cerebral palsy under the same parameters used in these four studies seems to be a safe program for this population. Statistical significance data were derived from three of the four studies in favor of WBV in some specific areas.
Two of the tests used parametric statistics while the other two produced analyses from non-parametric methods. The study by Ibrahim, Eid, & Moawd (2012) reported improvement in knee extensors muscle strength combine with the decrease spasticity in the same muscle group, increase in walking speed, and improvement in motor function in walking, running and jumping when using WBV. Similar results in walking speed after WBV were obtained from the study conducted by Ruck, Chabot & Rauch (2010) reporting a 38% improvement comparing with no changes in the control group.
In the research done by Wren, Lee, Rethlensen, Kay, Drey & Gilsanz (2020) data collected showed increased of cortical bone area in the tibial diaphysis and bone accretion on the tibial midshaft after WBV. Interesting enough, in the only other study addressing bone density directly (Ruck, Chabot & Rauch, 2010) decreased values were obtained when using whole body vibration therapy. In the study by Olama & Thabit (2010) evaluating balance control, improvements in postural stability, balance and coordination where obtained comparing suspension and WBV therapy with post-treatment values in favor of suspension therapy.
Two of the studies exhibited negative NNT where the control groups performed better than the experimental groups: one it its totality and the other in one of the variables tested. With this research review it was suggested that WVB promotes some structural influences in children with cerebral palsy along with benefits in walking speed, gross motor performance related to standing, walking and jumping. The efficacy of balance control was not proved in this review. WBV protocols to treat children with cerebral palsy appears to be safe and able to improve mobility functions.
This non-invasive, non-pharmacological intervention based on mechanical stimulus requires additional research to establish meaningful applications and to determine the most effective treatment parameters for children with CP. There is a need for additional WBV studies with larger samples addressing one outcome at a time, using WBV without any concurrent PT program, and tracking long term outcomes after treatment exposure in natural environments, for the potential of deriving and supporting WBV clinical significances resulting in customized treatment configurations based on each child’s needs.
Conclusion Children with cerebral palsy present with decreased muscle strength, abnormal bone development, susceptibility to fractures, tonicity challenges, balance, coordination and gait deficits. As health care providers it is critical to get embedded in professional literature and continue evaluating different physical therapy programs such as whole body vibration to help ddress all above mentioned problems, improving the lives of those individuals and identifying those approaches that are more effective and fiscally sounded, in an already convoluted health care system. Functional mobility and motor skills allowed people with cerebral palsy to integrate themselves to the community from an early age in the environment where they belong. An inclusive community starts from the day somebody is born looking at each other as equals from the get go and by facilitating to all individuals to “keep up” with their healthy peers.