Paul Van der Dolder, Senior Physiotherapist, Concord Hospital.
CMT affects the sensation and muscle control of the nerves of the lower legs and lower arms People with CMT commonly complain of difficulty walking, especially on uneven ground: catching toes and tripping (and occasionally falling); poor balance; going over on their ankles and weakness of the hands.
The difficulties with walking and running, the tripping and falling and ankle sprains are generally due to muscle imbalances in the lower leg. That means that some of the muscles of the leg become weaker due to the CMT whilst the muscles that are still working in the other direction tend to become shortened.
The muscles of the lower leg can be divided into two groups - the anterior (front) and the posterior (back) muscles. In CMT, the anterior muscles are primarily affected first. The main muscle in the front of the leg is the Tibialis Anterior muscle which pulls the foot up at the ankle. When this is affected the patient has trouble picking up their foot which thus leads to a 'high stepping' style of walking so that the foot clears the ground and may lead to increased tripping. Some other muscles are also innervated by the same muscle. These muscles, Peroneus Longus and Brevis run on the outside border of your lower leg and turn the foot up and out. They also prevent your foot from turning in ("going over on your ankles").
The posterior compartment (the calf muscles) is made up from the plantarflexors (those muscles that pull the foot down) and the invertors (those that turn the foot in). These muscles are affected at a later stage.
As a result of the weakness of the muscles on the front and outside of the leg you may have difficulty lifting your foot up to clear obstacles such as stairs or the edge of rugs. You may also tend to turn your foot in more as the muscles on the outside of your leg are not functioning properly.
The other problem with muscle imbalances is that you may develop a tightness of the opposing muscles. In patients with CMT this is usually the calf muscles and the muscles that turn the foot in (the invertors). As these muscles get tight then you may become aware that it is more difficult to stand with your heels on the ground. This also makes lifting the foot much more difficult. Tightening of some of the muscles within the foot and toes results in deformities of the feet e.g. claw toes and high arches. This can cause pain and difficulty when walking.
If some of the muscles are weak in the lower leg then you will usually have impaired balance. This is often due to the lack of the ability in the muscles around the ankle to support it. Balance sensation is felt by sensory receptors in the joints and these are affected as the nerves to the feet are affected. Your ability to feel what position your ankle is in is therefore affected which also affects your balance.
The goals of exercises with patients with CMT are therefore to:
There is no standard recipe for exercises with CMT. Some of the commonly prescribed exercises given to CMT patients here include:
These help to prevent tightening of muscles and to help lengthen already tight muscles. All stretches are specific for each muscle, so general stretching exercises are not sufficient. To be effective, muscles need to be stretched for at least 10-15 minutes with a sufficient amount of force applied. Here are some common stretches that we commonly prescribe:
If possible try and do something that you enjoy whilst doing these stretches e.g. read a book, watch TV, listen to some music. This will help the time pass. It is best if these stretches are done on most days of the week.
Stretches are probably the most important part of your exercise programme and will help to prevent foot deformities and calf tightness which will therefore help you maintain a pain-free, functional gait.
These are best done below your maximum capacity (i.e. don't exhaust your muscles). Strengthening exercises are usually most effective when commenced early in the disease when the muscle fibre degeneration and weakness is less. Some common strengthening exercise that we commonly prescribe are:
Any activities that challenge your balance are good for retraining. Some examples are throwing and catching a ball, standing on one leg, standing on a "wobble board".
Young children with CMT tend to display difficulty withsome basic gross motor skills, eg running, hopping and climbing. With practice, these skills can improve and should be encouraged.
These take on two forms - assistive and corrective. Assistive splints include AFO's (foot drop splints) which are worn inside shoes and act to hold the front of the foot up to prevent tripping. Corrective splints are night splints that hold the foot up at night to provide a mild stretch over a long period. These may be useful for some children with CMT.
All of these treatments although prescribed by a physiotherapist are your responsibilty. For them to be effective you must be doing them regularly - once every couple of days is not enough. Try to build your exercises into your daily life - do your stretches whilst watching the television, reading a book or listening to music.