RSI (CANS)
In recent years, the phenomenon of CANS (RSI) has become increasingly prominent in our society, simply because the condition is becoming more and more common. One of the biggest causes is the growing use of computers. In the Netherlands, around 2.6 million people now use a computer intensively in their daily lives — that's 40% of the working population. On top of that, another million people use a computer regularly. These numbers are expected to keep growing significantly in the years ahead.
RSI: "Performing short, cyclical work repeatedly places a one-sided load on the same muscles, ligaments and tendons; over time, this can lead to complaints in the neck, shoulder, arm and hand." (Pocket Dictionary of Medicine, Coëlho, Elzevier, 1997)
RSI or CANS?
RSI is an umbrella term for a number of specific tendon-, nerve- and muscle-related conditions of the neck and arm. More recently the term CANS has also come into use, since RSI doesn't clearly distinguish between the different conditions involved. However, the term is still so new that RSI remains the most widely used name, which is why we use "RSI/CANS" here. One of the best-known examples is "mouse arm". RSI is not as new a condition as is often assumed — an Italian physician wrote about "writer's disease" 300 years ago, having observed it in many notaries and office clerks. He described these people as having inflammation of the tendons in the arms, caused by extensive writing.
Symptoms
RSI/CANS develops gradually — it creeps in slowly. Its course can broadly be divided into three stages. The resulting symptoms occur in the neck, shoulder, arms and hands.
Stage 1
Pain during work, localised fatigue, cramp, tingling and a numb feeling. Symptoms disappear once work stops, after a period of rest. These complaints are often not taken seriously.
Stage 2
Pain also continues after work, irritation of tendons and muscles, tingling, sleeplessness, loss of strength. Symptoms resolve after an evening or a weekend of rest.
Stage 3
Swelling, tenderness to pressure, chronic pain, loss of function, changes in skin colour and temperature, numbness and tingling, persistent symptoms that no longer disappear, and pain both during work and in free time.
Causes
There are several theories about how RSI/CANS develops. The first is that continuous loading of a body part or muscle group impairs blood circulation in that area. When circulation is impaired, waste products are less effectively removed. As waste products build up in that part of the body, pain receptors in the muscle become irritated, causing muscle pain. Because of this pain, the muscle has to work harder to do its job properly. This increased tension further reduces blood flow, and the person ends up caught in a vicious cycle.
With RSI/CANS, the same small group of muscle fibres is loaded repeatedly over a long period. Over time, this group starts to fatigue — and become overloaded — at progressively lower loads. This repeated overloading can eventually cause tissue damage, resulting in scar tissue formation. A combination of psychological and physical causes is also thought to play a role: this model assumes that stress and other psychological complaints can raise muscle tension, which produces the same effect described above.
Why overload from something that takes so little effort?
It may sound strange that a tendon or muscle can become overloaded from operating something as light as, say, a computer mouse. This isn't actually related to the amount of force used to operate the mouse. The real cause lies in the precision of coordination needed to control it. To operate an object with great precision, the body uses many muscles, which need to generate a fair amount of force to coordinate the movement accurately. This creates considerable tension in the muscles of the arm. It's therefore important to sit relaxed at the computer — if this isn't the case, a person may develop extra tension in the muscles.
Environmental factors
The environment in which someone works also has a major influence on the development of RSI/CANS. The workstation must be suited to the work being done. A person should never have to adopt an unnatural posture in order to do their job properly. If this is the case, the workstation should be set up to relieve the strain on the person as much as possible. For example: it's important that the mouse is positioned at a good distance from the arm. Someone who uses the mouse a lot then doesn't have to reach for it, reducing the strain on the arm. The same applies to the monitor. If a screen is positioned to the side rather than directly in front of someone, they have to keep looking sideways throughout their work, which is unnatural for the neck. It's much more comfortable to have the screen directly in front of you — this takes the strain off the neck, since it no longer needs to be turned to look at the screen.
How can I avoid RSI/CANS?
Preventing RSI/CANS isn't always possible, but you can take measures to reduce the risk of developing it. Here are some ways to do that.
- Work organisation: make sure your work is structured to include as much variety as possible. For instance, it may be possible to alternate typing tasks with other activities. This prevents you from performing the same single activity for too long, with the added benefit that the work becomes less monotonous.
- Work and breaks: make sure you don't work for too long without a break. If this can't be avoided, do a few exercises regularly in between. It has also been shown that people perform much better when they take occasional breaks during work.
- Try to keep your workload from becoming too high, as this only causes more stress. This can be managed, for example, through good planning so you don't have to work within too tight a timeframe. There are also computer programs that prompt a set of exercises at set times and warn you when you've been at the computer for too long without a break.
- Workstation: the workstation needs to be properly set up. Poor posture leads to RSI/CANS and other complaints developing far more quickly than at a well-arranged workstation.
Treatment
Together with the physiotherapist, the search begins for the triggering factor, which should then be avoided going forward. If this isn't possible, other similar adjustments are explored. A McKenzie-based assessment is also carried out straight away, looking for movements that can reduce the symptoms; an exercise programme is then drawn up, to be repeated regularly throughout the day.
The therapist will also look for any muscle tension, which can be treated with dry needling, connective tissue massage and/or friction techniques.