Understanding SMA Type ll - Indications why Hippotherapy by a qualified physiotherapist is appropriate | Association of Paediatric Chartered Physiotherapists

SMA Type II is a chromosomal condition which leads to wheelchair use and a curtailed life style within early childhood. However, children with the condition can still enjoy a life of interest and activity. One physical activity, which will allow the child to have ’fun in motion’ is Hippotherapy; a form of treatment overseen by a Physiotherapist trained by the Chartered Physiotherapists in Therapeutic Riding and Hippotherapy (CPTRH). The benefits of Hippotherapy have been very well documented in the case of Cerebral Palsy and other conditions, but there is little documentation of how people with SMA Type II could benefit.

From experience, and anecdotally (Quote) “it would appear that muscles affected by the condition and which are quiescent in a wheelchair are encouraged to perform on the horse”. Thus, the current level of postural control can be maintained over a longer period than would otherwise be expected. Each case is unique. Treatment is based on signs and symptoms so will change over time. The benefits will vary from child to child, as will the length of time Hippotherapy is effective. This can be judged by either validated or in-house outcome measures.

What is SMA Type II

SMA Type II is a genetic condition within a range of spinal muscular atrophies which affects the spinal, hip and shoulder muscles to varying degrees.

Distribution of muscles affected by SMA Type 11 (the neck and hands may also be affected)

It is caused by a mutationor deletion in the production of a particular protein by the

Survival Motor Neuron gene (SMN1) on Chromosome 5. SMN1 is involved in the conduction of information from the spine nerves to muscles. It is inherited in an autosomal recessive manner. The more copies of the SMN 2 gene present, the more severe the condition.

Although children with the condition are born normally and have a normal development initially, between 6 months and 18 months their physical development slows, and they are unable to sit unsupported, crawl or stand to varying degrees. The weakness is symmetrically proximal and sometimes there is accompanying fasciculation in the hands. Intellectually they are highly developed. Sensory and emotional development is entirely normal. Diagnosis is based on age of onset and of the above clinical facts. Depending on the severity of the condition, the child may have poor, or absent head control, respiratory difficulties and, as well as the poor or lack of use of their hips, shoulder range and strength may be limited. They may also have digestive difficulties. Over time, with decreasing nerve conductivity the muscles begin to waste, and as leverage increases with growth, muscle support reduces. Scoliosis becomes likely. Orthopaedic spinal support may be considered around the age of 10 to 12 years.

Life expectancy has improved as more is understood, but at present is likely to be limited; respiratory infections account for most deaths. The international incidence of the whole range of SMA diseases is 1 in 6,000 to 10,000; males more often being affected than females.

History of the Condition

In the early 1890’s Werdnig and Hoffman described a disorder of progressive weakness beginning in infancy and resulting in early death. Pathologically the disease was characterised by loss of anterior horn cells in the spinal column. Subsequently the disorder has been further understood to be a graded condition based on the age at which clinical features have appeared. Type II is the most common of the five grades.

Hippotherapy

Hippotherapy is a treatment which is dynamic. A team of horse and assistants, specially trained by the qualified therapist, help a patient to utilize, or gain, functional movement. A horse has a walking pattern similar to that of a human. When sitting astride a horse a rider’s pelvis is moved through flexion, extension, lateral flexion and rotation as the horse moves forward at walk. A rider unable to use their legs is therefore passively moved through walking motion and weak muscles are encouraged to function in response to the movement. This cannot be achieved by people who are wheelchair bound in any other way. Additionally, the shape of the horse encourages hip abduction which, with the warmth of the horse promoting muscle relaxation, reduces the potential for contracture.

Choosing the best horse for the individual is important. A wide barrelled horse gives the rider a good base from which to stack the spine. A smooth gait provides the best motion for weak postural support and a patient horse allows for pauses, or gait transitions and a flexibility of activity during the ride. The horse must also be kind and willing to have people close to it without complaint.

Hippotherapy Treatment

Although the aim of each sessional ride would be thought of as a treatment with planned goals and outcome measures, it is important that the rider also enjoys ‘their sport’. In the riding community, rosettes are a sign of success, and in this instance, a measure of achievement that can be shared with friends and family.

Assessing and Goal setting

Children can be referred for treatment once they can understand instruction. Around three or four years of age is a good time to start. An initial assessment will determine which muscle groups are affected and by how much and the possible ranges of affected joints. Although the child may appear to have function, it may be limited, and some joints may be hypermobile with active ranges limited by weakness.

A risk assessment will indicate whether a hoist is necessary for mounting, but hoisting can present additional difficulties in achieving the optimum pelvic position. Sitting on the horse unsupported is different to sitting on a stool, so must be tested. A saddle and stirrups give better support than a pad, as the feet are supported at an optimum height to enable the rider to sit on their ischial tuberosities, and stack the spine in an upright posture, at halt.

The ability to maintain the optimum posture as motion commences needs to be assessed. It can be an enormous challenge and is difficult to assess adequately off the horse. The therapist, leader and side walkers work with the rider to prepare well, walk off smoothly with the side walkers ready to support if necessary. It may be helpful for the rider to gain support by using their arms to prop on their knees (See Pic I). Coming to halt is as challenging as starting forward motion, so preparation and awareness is essential. Even the weight of a riding hat may be more than the spinal muscles can cope with during the ride. Overall, the safety of the child at every stage must be assessed and ensured.

Having assessed, a treatment plan can be made. The activity on the horse may be as basic as the activity carried out at the assessment. Progress may be small, and goals limited. The Revised Hammersmith Scale (RHS) is a validated test for SMA Type II. As an inhouse test, by modifying the timed sitting test found within the RHS, the ability of the rider to sit at halt, can be recorded as change in postural ability. The aim of treatment is to maintain what strength, stamina and range the rider has; to improve them a little for as long as possible, and to have fun. The sessions will probably not last long, as the rider will tire quickly, and more so as weakness increases; they grow, and leverage is increased. Frequent re-assessment of ability is important and treatment plan adapted accordingly.

As explained above, from experience, starting and stopping are the most challenging aspect of a ride. So, introducing Halt/ Walk transitions and change of pace as a treatment plan encourages abdominal activity as well as activating other postural muscles. Weaving around cones; circles and slopes are all progressions, but need to be considered with great care. Singing, and playing with light toys at halt encourages lung function and arm movement.

Self-esteem is important for the rider and family and achievements will provide this. Achievements can be arranged by setting realistic goals. Although initially they may seem small, over time they may have to reduce rather than progress as the child grows. Managing the promotion of maximum function as deterioration occurs is a crucial physiotherapy skill.

Managing a progressive disease requires great sensitivity, so a planned exit from riding should be thought through so that the child and parents are prepared for what can be another time of grief if not managed well. There are options. Rosettes are a wonderful way of providing an outward sign of success to school, friends, and family. Horse Care Theory can accompany the period of riding, then carried on after the riding stops, maintaining the child’s interest for as long as suits them. If a small, reliable pony is available, the rider can

continue to have a relationship with a pony by helping to mix feed or perhaps lead from the wheelchair (after a risk assessment and with a side walker accompanying them). These alternative options enable the child to exit more happily than having the rides terminated abruptly.

Some children may be offered spinal rod support. If so, they will be unable to ride for at least 6 months after the operation. If they wish to resume riding, written confirmation that the surgeon is confident that riding will not be adverse should be obtained before a completely new assessment of ability is made. It is quite possible that the time lapse leads to further weakness and riding is no longer safe.

Conclusion

SMA Type II is a rare, complex condition which affects physical ability enormously. The psychological effect on a person with such gross disability, while having normal emotions and heightened intellect, affects not only the rider, but the whole family. A CPTRH trained physiotherapist is the ideal person to help a child with SMA Type II learn to optimize the use of their postural muscles at the same time as enjoying a sporting activity for as long as is safe. The sensitivity to change in a deteriorating condition is a physiotherapeutic skill. Physiotherapists understand body mechanics and the subtleties of changing stamina and strength. They also have the skills of setting realistic goal and of encouraging weak muscles to perform optimally.

For a child with SMA Type II to be able to take part in a sport which many normally able people enjoy is a tremendous lift for the whole family. It is important that the riding succeeds. So, it is vital that the person dealing with the rider understands not only the psychological element of the condition, but the full structural implications. Hippotherapy is therefore the only way these children should ride.

Acknowledgements

I would like to thank the parents and children with whom I have worked for the experience I have gained. They have taught me so much about myself as well as them and this overwhelming disease. I hope they have had as much fun as I have had at times!

QUOTE:-

“Have there been any benefits for your child…………and family?

HUGE BENEFITS –– physical, mental, and social……… his core and his neck strength control have improved significantly. ……......... It’s given us encouragement about how to be with his condition. It’s wonderful to see improvement at a point when everything seemed unlikely and a struggle ….

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