CHAPTER 3 Impact of SCI on the Musculoskeletal System Voluntary movement of the body is dependent on a number of systems. These include: The brain initiates the movement and receives feedback to assess if the movement was correct. The spinal cord carries the messages from the brain to the nerves that supply the trunk, limbs and internal organs (peripheral nerve). The peripheral nerve carries the messages from the spinal cord to the muscle. The muscle receives the message, and performs the movement. When impulses from the brain do not reach the target, the system is no longer under full control. Following a spinal cord injury the messages from the brain to the muscles are interrupted, therefore voluntary movements are affected. When only some of the messages get through the movement occurs but is weak. This usually occurs when a SCI is incomplete. When all of the messages are interrupted then the muscle gets no stimulation to move, and no voluntary movement can occur. This usually occurs when a SCI is complete. Functioning or independence in performing activities relies on the ability to move body parts voluntarily. Following a spinal cord injury your ability to do this will depend on the level of injury and on the extent to which the cord is damaged. The degree of independence that can be achieved may be estimated, based on the degree of impairment 14 th Edition Dec 2012 3-1
caused by the SCI. However, it is important to remember that many factors can impact on the level of independence achieved, including: age exercise tolerance presence of other injuries or medical conditions completeness of injury body build degree of spasticity former lifestyle motivation As a general principle, the lower the level of the spinal cord lesion, the greater the independent function of the individual. Sensations and Pain Most people with SCI will experience numbness or altered sensations after their injury. Although they might be uncomfortable, for most people these sensations are tolerable with time. In a few people these sensations are mildly to significantly painful. Because this pain is due to injury to the nerves of the spinal cord, this pain is called neurogenic pain. MediSpeak Dysaesthesia = Uncomfortable sensation Hyperaesthesia = Excessive sensation Hypoaesthesia = Less than normal sensation Anaesthesia = Lack of sensation 14 th Edition Dec 2012 3-2
Over the months to years after SCI, these sensations will change dramatically. They are influenced strongly by general health, physical conditioning, activity and posture. Other psychological factors such as stress or lack of sleep have a strong influence. Excessive alcohol, nicotine or drug use also will strongly worsen neurogenic pain. Pain medications used for normal pain, such as sprains, fractures, or after surgery, might not work for neurogenic pain. Because managing unusual sensation after SCI requires some expertise, it is a good idea to discuss your sensations with your doctor. Spasticity Muscle activity depends on control from nerves in the spinal cord which carry messages to and from the brain. Some nerve signals cause muscles to become active, or contract. Others cause muscles to relax, and can dampen the effect of naturally-occurring reflexes. Without these dampening signals, natural reflexes can become overactive. This state of extra excitability occurs below the level of the lesion and is known as spasticity. Typically this might be seen with injury above T12. This loss of inhibition from above can produce multiple and sometimes constant, involuntary contractions in the muscles of the limbs or trunk. These involuntary movements are called spasms. Spasticity can have a negative impact on function; it may make moving/positioning difficult, increase discomfort and interfere with transfers. On the other hand there are some advantages; spasticity helps maintain muscle bulk, assists circulation and some 14 th Edition Dec 2012 3-3
individuals can selectively use their spasm to assist with functional tasks, eg rolling. The amount of spasticity varies over time and between individuals, however it is usually made worse by any condition that would normally cause pain or discomfort, e.g. full bladder, infections, wounds or haemorrhoids. Spasticity may be managed with physiotherapy including prolonged stretches to the involved muscle groups, exercise and weight bearing. Also avoiding aggravating factors and taking prescribed medications will help to control spasms. If you are given any medication to control spasticity, you will be given information regarding the medication. The need for anti-spasmodic medication will be determined by the rehabilitation team and yourself. Contractures When a joint is allowed to sit in one position for prolonged periods of time, it becomes less flexible. This is called a contracture and results from tightening of the muscles and the tissues around the joint. Contractures can potentially have a significant limiting impact on functional activities and general care. There may also be negative aesthetic appearance due to contractures. Spasticity can accelerate the formation of contractures if it is not well controlled. Preventing contracture is one of the main aims of effective spasticity management. If allowed to progress, they can become permanent or require surgery to correct. 14 th Edition Dec 2012 3-4
Passive Movements Maintenance of joint range (flexibility) is a goal throughout and after your hospital admission. Staff will perform these initially but it is important that you or your family/carers take over this responsibility once you have been given sufficient training. Passive movements are important because they: Maintain full muscle range of movement - preventing muscles from becoming tight and joints from becoming stiff (contractures). Muscle function and position/posture can have a significant influence on contracture development. When a normal muscle has no working muscle to oppose it or when one muscle surrounding a joint is more powerful than another deformity at the joints may occur. In these circumstances the joint will become bent in the direction of the more active muscle group. Consistent positioning in one spot will also result in contractures, e.g. consistent sitting will result in tight bent hips and knees. Reduce spasticity if present the effects of regular passive movement on spasticity are two fold. 1. Passive movements have a direct role in decreasing spasticity. The trunk (or body) helps to set the degree of tone (or muscle tension at rest) of the limbs, and it is therefore important to include passive movements of the trunk. 2. The presence of a contracture will act to increase spasticity. Therefore, passive movements can protect against this by preventing contractures from developing. 14 th Edition Dec 2012 3-5
Looking After Your Shoulders Pain in the shoulder is a common occurrence in wheelchair users. While you may experience pain in the wrist, elbow or shoulder during your rehabilitation at Hampstead, it is also quite common to experience pain later on after going home. Studies have shown that between a third to a half of people with a spinal cord injury experience shoulder pain, and those with tetraplegia more so than people with paraplegia. If you develop shoulder pain, it may affect you in several ways: Initially, it may reduce your speed of movement, lower your endurance and change your posture. If the pain increases, it may then restrict your function and independence. If you are using a manual wheelchair, shoulder pain may reduce your ability to push your wheelchair. You may then need someone to help you, which will reduce your level of independence. Shoulder pain is often experienced when pushing up an incline, so it may limit your ability to be able to do this. It may also limit your independence with transfers by limiting your ability to weight bear through your arms. Thus you may need to use a slideboard, get people to assist with your transfers, or have to use a lifter. Shoulder pain may limit your ability to lift your arms above your head, which might in turn restrict your ability to access your environment. A change in your level of function and independence may lead to more 14 th Edition Dec 2012 3-6
complications associated with decreased activity, including obesity, contractures and skin breakdown. These complications may result in you being admitted to hospital, often for a prolonged period. Why Does Shoulder Pain Develop? You are now probably placing greater demands on your shoulders compared to before your injury. You rely on your shoulders during transfers, for pushing your wheelchair and to reach overhead for objects within your environment. You may also rely on your shoulders to support you to walk with a frame or crutches. The shoulder joint is a very mobile joint designed for mobility not stability. Weight bearing through your shoulder requires stability. Unlike the hip joint, which is a very stable joint, the shoulder relies on the surrounding muscle, ligaments and capsule to provide stability. Using your shoulders during transfers and pushing your wheelchair places strain on these structures. Muscle imbalance and overuse are often the cause of shoulder pain. There are four muscles called the rotator cuff, which provide stability to the shoulder joint. In people with tetraplegia, only some of these muscles may be working. The shoulder is therefore less stable and more likely to become painful. In people with paraplegia, the muscles at the front of the shoulder may become strong and shortened, and the muscles behind the shoulder may become long and weakened. This leads to an imbalance around the shoulder, which changes the mechanics of the joint and may result in shoulder pain. Overuse of the shoulder muscles can occur if there is a sudden increase in the amount 14 th Edition Dec 2012 3-7
of activity required of them. Preventing Shoulder Pain During your rehabilitation, your physiotherapist and your physical educator will teach you appropriate strengthening and flexibility exercises to maintain muscle balance around your shoulders. If you experience any shoulder pain during your rehabilitation, inform your physiotherapist immediately. It is important that you continue an exercise program when you return home both for general strengthening and to target specific muscles to minimise the risk of shoulder pain in the future. Your physiotherapist and your physical educator will advise you what exercises are appropriate for strengthening different muscle groups and maintaining flexibility. Avoid overuse. Don t do too much, too early. Do not increase loads suddenly. Take frequent rests. Train for extra activities. For example, do not go for long pushes without training first. Allow time for your shoulders to accommodate to new activities. Warm up your shoulders before transferring or pushing in the morning. If playing sport, you will need to be more careful not to overuse your shoulders. Build up your training slowly. Use a variety of training activities to alter the demands 14 th Edition Dec 2012 3-8
placed on your shoulders. Change your environment to avoid reaching overhead repeatedly. Place objects either equal to or below shoulder height. Seek treatment early if you experience any shoulder or arm pain. Rest from the activity that is causing pain if possible. You may need to allow someone to assist you with transfers or pushing your wheelchair. Remember shoulder pain is a common long term problem affecting wheelchair users and prevention is better than cure! 14 th Edition Dec 2012 3-9