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Background
Cerebral palsy (CP) also known as static encephalopathy, refers to a wide variety of non-progressive brain disorders resulting from insults to the central nervous system during the perinatal period. The management of the motor dysfunction of patients with CP includes the conventional orthopedic approach of range of motion, stretch, and strengthening, as well as neurodevelopmental treatment. A general objective of physiotherapy for children with CP is to reduce the influence of abnormal muscle tone and facilitate the emergence of normal postural and movement components. For many children with CP or other motor dysfunction, physical therapy is a long and arduous process. In order to sustain patients' interest and enthusiasm in their continuing treatment, therapists have developed adjunctive therapeutic activities such as dancing, swimming, and horseback riding.
Hippotherapy, also known as therapeutic horseback riding, equine-facilitated therapy, or horse therapy, is the passive use of the physical movements of the horse in the treatment of patients with neurological or other disabilities. This is often performed under the direct supervision of a physical therapist or occupational therapist who is horse-knowledgeable. By using the horse as a treatment modality, the therapist tries to facilitate normal muscle tone and inhibit abnormal posture. The therapist may place the patient in a variety of positions on the horse such as prone across horse, prone lengthwise with hips abducted and knees flexed, side sitting, or sitting. It is believed that the rhythmic, swinging movement of the horse enhances balance, co-ordination, and motor development. Patients who participate in therapeutic riding include not only children with CP, but also individuals with arthritis, multiple sclerosis, head injury, and stroke. The horse is usually led at a walking or trotting pace by a skilled equestrian to ensure safety and expert handling of the animal. Assistants are present, usually one on each side, to help repositioning or stabilizing the patient. For more severely disabled patients, the therapist may also serve as a back rider.
For children with CP, hippotherapy utilizes the basic principles of Rood, Bobaths (individuals who had put forth/developed neurodevelopment treatment concepts for neuromuscular dysfunction), and proprioceptive neuromuscular facilitation. It is believed that therapeutic horseback riding can reduce spasticity, maintain and increase range of motion in the upper extremities of these children. Haskin and colleagues (1982) described the benefits of a hippotherapy program (30 minutes per week) in a 5-year old patient who has participated in this type of therapy since she was 2 1/2. Improvements included strengthening of the back and neck, better balance, ability to sit up longer, less spasticity in the lower extremities, the legs are externally rotated and abducted, and the feet are dorseflexed. However, the patients also swam once a week and received physical therapy for her lower extremities 6 days a week. Thus, it is unclear whether the observed improvements were due to hippotherapy, adjunctive therapeutic swimming, intensive physical therapy, and/or the result of natural growth and development.
Using a repeated-measured design, Bertoti (1988) assessed postural changes in 11 children (4 girls and 7 boys, aged 28 to 114 months) with spastic CP after participation in a 10-week hippotherapy program (1-hour session, 2 times per week). Evaluation of posture was carried out 3 times by three pediatric physical therapists -- (i) pretest-1 followed by a 10-week period of no riding, (ii) pretest-2 followed by a 10-week therapeutic riding program, and (iii) post-test. A composite score for each test period was computed for each patient, and a median score was calculated for the entire group at each test period. A statistical difference was observed among the 3 test periods with significant improvement occurring during the period of hippotherapy. Subjective clinical improvements such as reduced hypertonicity, as well as improved weight-bearing and functional balance skills were reported by parents and referring physical therapists. These findings represented the first objective report that hippotherapy may have beneficial effect on the posture of children with spastic CP. However, the author concluded that further investigation is needed to isolate additional variables such as range of motion, balance, weight shift, and strength, and to evaluate the effects of hippotherapy on different disabilities.
In an article on hippotherapy, Tuttle (1987) stated that research on the effect and application of the various forms of therapeutic horseback riding is needed to refine program planning, and to support funding and third party reimbursement. Furthermore, a workshop on “The Health Benefits of Pets” sponsored by the National Institutes of Health concluded that “solid data on the success of therapeutic riding is limited. ... Future research is indicated to compare the efficacy of therapeutic riding with other clinical treatment procedures that do not involve the horse and to validate dramatic clinical observations” (NIH, 1983). Additionally, in an article published in the Journal of American Veterinarian Medicine Association, Potter and colleagues (1994) stated that “Lack of scientific documentation of the benefits of therapeutic riding is a major obstacle that must be overcome. ... Research is critically needed in all aspects of therapeutic riding”.
In a single-subject experimental design study (n = 11), Hammer and associates (2005) examined whether therapeutic riding (TR, Sweden), also known as hippotherapy (HT, United States) may affect balance, gait, spasticity, functional strength, coordination, pain, self-rated level of muscle tension (SRLMT), activities of daily living (ADL), and health-related quality of life in patients with multiple sclerosis (MS). The intervention comprised 10 weekly TR/HT sessions of 30 minutes each. The subjects were measured a maximum of 13 times. Physical tests were: the Berg balance scale, talking a figure of eight, the timed up and go test, 10-m walking, the modified Ashworth scale, the Index of Muscle Function, the Birgitta Lindmark motor assessment, part B, and individual measurements. Self-rated measures were: the visual analog scale for pain, a scale for SRLMT, the Patient-Specific Functional Scale for ADL, and the SF-36. Data were analyzed visually, semi-statistically and considering clinical significance. Results showed improvement for 10 subjects in one or more of the variables, particularly balance, and some improvements were also seen in pain, muscle tension, and ADL. Changes in SF-36 were mostly positive, with an improvement in Role-Emotional seen in 8 patients. These investigators concluded that balance and Role-Emotional were the variables most often improved, but TR/HT appeared to benefit the subjects differently.
Debuse et al (2005) noted that despite a substantial body of anecdotal and clinical evidence for its benefits, research evidence for hippotherapy is sparse. In a questionnaire survey, these researchers explored the views of physiotherapists and people with CP who use hippotherapy. This study was aimed to: (i) establish the pattern of hippotherapy practice in Germany and the U.K.; (ii) examine the perceived main effects of hippotherapy on people with CP in Germany and the U.K.; and (iii) investigate how these effects are being measured in both countries. The results highlighted considerable differences in how hippotherapy is practiced in the U.K. compared with in Germany. In spite of this, the study revealed agreement among respondents on the overall perceived effects of hippotherapy on individuals with CP, namely, the regulation of muscle tone, improvement of postural control and psychological benefits. The results also indicated scant use of outcome measures to evaluate these effects.
Casady and Nichols-Larsen (2004) examined if hippotherapy has an effect on the general functional development of children with CP. The study employed a repeated-measures design with two pre-tests and two post-tests conducted 10 weeks apart using the Pediatric Evaluation of Disability Inventory (PEDI) and the Gross Motor Function Measure (GMFM) as outcome measures. A convenience sample of 10 children with CP participated whose ages were 2.3 to 6.8 years at baseline (mean +/- SD 4.1 +/- 1.7). Subjects received hippotherapy once weekly for 10 weeks between pre-test 2 and post-test 1. Test scores on the GMFM and PEDI were compared before and after hippotherapy. The authors concluded that results of this study suggest that hippotherapy has a positive effect on the functional motor performance of children with CP. Hippotherapy appears to be a viable treatment strategy for therapists with experience and training in this form of treatment and a means of improving functional outcomes in children with CP, although specific functional skills were not investigated.
There are two main drawbacks with this study: (i) the GMFM scorers were not blinded to the order of test date and they were allowed to keep the scores sheets, which may have biased the scorers, and (ii) with the individualized approach to treatment, there is no protocol that would allow replication of this study. The authors stated that hippotherapy has the potential to be a valuable treatment strategy in treating children with CP. Future studies should use more homogeneous patient populations in terms of age and type of CP to ascertain precise areas of function affected most by hippotherapy.
In a review on the use of complementary and alternative therapies for the treatment of children with CP, Liptak (2005) noted that although studies of hippotherapy have shown beneficial effects on body structures and functioning, unanswered questions remain. For example, it is unclear which subgroups of children with CP would benefit the most, what "dose" or frequency of intervention is optimal.
An assessment of the evidence for hippotherapy by the Institute for Clinical Effectiveness and Health Policy (Pichon Riviere, et al., 2006) concluded: "The efficacy of this therapy does not seem to have been sufficiently proven for any specific indication. Its recreational role and impact on the quality of life of these patients have not been sufficiently analyzed."
Snider et al (2007) performed a systematic review of the literature on hippotherapy as an intervention for children with CP. Retrieved articles were rated for methodological quality using Physiotherapy Evidence Database (PEDro) scoring to assess the internal validity of randomized trials and the Newcastle Ottawa Quality Assessment Scale to assess cohort studies. Population, Intervention, Comparison, and Outcomes (PICO) questioning was used to identify questions of interest to clinicians for outcomes within the context of the International Classification of Functioning, Disability and Health. Levels of evidence were then accorded each PICO question. There is Level 2a evidence that hippotherapy has short-term positive effects on muscle symmetry in the trunk and hip and that hippotherapy is effective for improving muscle tone in children with CP when compared with regular therapy or time on a waiting list. However, no studies addressed participation outcomes. (Note: Level 2a evidence refers to one or more "fair" quality randomized controlled trials [PEDro = 4 to 5]; 6 to 8 is considered "good"; and 9 to 10 is considered "excellent").
Hamill et al (2007) examined the effects of a once-weekly, 10-week hippotherapy program for 3 children, aged 27 to 54 months, with CP. Participants were rated as Level V on the Gross Motor Function Classification System. The Sitting Dimension of the Gross Motor Function Measure was used to establish a baseline of sitting abilities, and was administered every 2 weeks during intervention. The Sitting Assessment Scale and the Gross Motor Function Measure were administered before, after, and 4 weeks post-intervention. Parental perceptions of the hippotherapy intervention were assessed using questionnaires. None of the children made gains on any of the standardized outcome measures. However, parental perceptions were very positive, with reported improvements in range of motion and head control.
Lechner et al (2007) examined the effect of hippotherapy on spasticity and on mental well-being of persons with spinal cord injury (SCI), and compared it with the effects of other interventions. A volunteer sample of 12 people with spastic SCI (American Spinal Injury Association grade A or B) were included in this study; interventions consisted of hippotherapy, sitting astride a Bobath roll, and sitting on a stool with rocking seat. Each session lasted 25 minutes and was conducted twice-weekly for 4 weeks; the control condition was spasticity measurement without intervention. Main outcome measures were clinical rating by a blinded examiner of movement-provoked muscle resistance, using the Ashworth Scale; self-rating of spasticity by subjects on a visual analog scale (VAS); and mental well-being evaluated with the self-rated well-being scale Befindlichkeits-Skala of von Zerssen. Assessments were performed immediately after intervention sessions (short-term effect); data from the assessments were analyzed 3 to 4 days after the sessions to calculate the long-term effect. By analyzing the clinically rated spasticity, only the effect of hippotherapy reached significance compared with the control condition (without intervention); median differences in the Ashworth scores' sum before and after hippotherapy sessions ranged between -8.0 and +0.5. There was a significant difference between the spasticity-reducing effect of hippotherapy and the other two interventions in self-rated spasticity by VAS; median differences of the VAS before and after hippotherapy sessions ranged between -4.6 and +0.05cm. There were no long-term effects on spasticity. Immediate improvements in the subjects' mental well-being were detected only after hippotherapy (p = 0.048). The authors concluded that hippotherapy is more efficient than sitting astride a Bobath roll or on a rocking seat in reducing spasticity temporarily. Hippotherapy had a positive short-term effect on subjects' mental well-being. The major drawbacks of this study was its small sample size and that hippotherapy had no long-term effects on spasticity.
More scientific evidence, especially controlled studies with outcome measures, is needed to ascertain the effectiveness of hippotherapy for the treatment of CP, MS, and other motor dysfunction.
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