What is tremor?
A tremor can be described as a rhythmic, trembling or shaking movement that you cannot control voluntarily.
Intention and postural tremor
For many people with MS, tremor comes on when they want to do something or reach for something. And, frustratingly, the closer they get to the object, the more their hand or arm shakes. This is called intention tremor or movement tremor and is the type of tremor people most often experience in MS.Tremor can also be postural, when you have a tremor as you sit or stand. It comes on while your muscles try to hold part of the body still against the force of gravity.
In MS, neither of these types of tremor is present when a person is lying down or asleep, that is, when the muscles are completely at rest. If tremor occurs when you are lying down or asleep, there may be a different reason for it, such as the effects of drugs or perhaps some other condition.
Other types of tremor
Intention tremor and postural tremor are the two forms of tremor commonly experienced by people with MS, but in practice it is very difficult to classify individual tremors like this. People often experience tremor together with other movement difficulties, such as muscle weakness and problems with coordination. The medical term for reduced coordination is ataxia and this word is often used instead of or as well as tremor.Tremor may be experienced as small, shaking movements (‘fine’ tremor) or as larger movements (‘gross’ tremor). While it is usually a rhythmic, back-and-forth shaking, tremor can also be irregular and unpredictable.
If tremor develops, it tends to be some years after people’s first symptom of MS, typically between five and 15 years, though it can also develop earlier or later than this. A tremor may become gradually noticeable or develop quite swiftly.
Other causes of tremor
Not every tremor is related to MS and there can be other reasons why you experience shaking or trembling. For example, everyone has a small level of tremor (physiological tremor), which caffeine, alcohol or stress can make more noticeable – you may be able to see this when you hold out your hand.Tremor can also be the result of muscle weakness and problems with posture, a side effect of some medications such as drugs for asthma, and result from other neurological conditions such as Parkinson’s.
Muscle spasms and stiffness
Tremor is different from spasm. When affected muscles stretch, spasticity may also cause them to jerk in an uncontrolled way. This is one kind of muscle ‘spasm’ that people with MS can experience. If muscles jerk repeatedly, this is known as ‘clonus’, for example when a foot taps repetitively on the floor.Some people with MS experience other spasms - sudden involuntary movements that can make the arms or legs move in different ways. These can occur even without the muscle being stretched.
