Introduction
Tremor is an involuntary shaking movement of a body part. In MS tremor can be mild, but if severe it an cause significant disability. Ataxia is a Greek term which means lack of order. In medicine, it is used to describe incoordination of purposeful movements. In MS, ataxia can affect eye movements, speech, limb movement, standing and walking.
 Why assess tremor?
Evaluating the impact of tremor on a person’s life is crucial for its management. Certain types of tremor respond better to medical or to surgical treatments.
Therefore, knowing the type of tremor and its severity can prevent inappropriate therapies and unnecessary side effects.
Assessing tremor features
Evaluating tremor affecting the arms
When tremor is assessed, the examiner wants to know the following:
● Is tremor present at rest with the limb muscles in a relaxed position (rest tremor)?
● Is it activated while maintaining a posture against gravity (postural tremor)?
● Is it worse on moving the affected limb towards a target (intentional or goal directed tremor)?
● Is one or both arms affected?
● Is it distal (affecting the hands and wrists mainly) or proximal (affecting the shoulder)?
● How significant is the associated ataxia?
In most individuals with MS-related tremor, the involuntary movement is present when attempting to maintain posture or/and with movement. Rest tremor is highly unusual in MS, unlike Parkinson’s disease.
 Examination of MS arm tremor
The postural part of the tremor is best assessed with the arms outstretched in front of the individual first, then with the elbows bent. The intentional component of the tremor is assessed by asking the individual to move the hand between two targets (for example, the finger-to-nose test). If the shaking worsens as the finger approaches the target, the tremor is considered intentional.
Evaluating tremor affecting the head, trunk and leg Head tremor in MS is mostly of the “yes-yes” type. It is usually not associated with abnormal head and neck position (dystonia), although a mild head tilt can sometimes be seen. The tremor disappears when the head is rested, for example when lying down.
Trunk tremor can accompany head tremor and is assessed with the patient standing or taking steps.
Leg tremor is best assessed with the individual lying down and the leg lifted rather than on walking, because it is a postural tremor.
Voice tremor is a feature of essential tremor rather than MS but it has been reported to occur rarely in MS (this is different to dysarthria, which is described below). It is usually assessed by asking the person to sing a note. Face tremor is rarely present in MS and jaw, chin and tongue tremors are not seen.
Assessment of tremor severity in MS Tremor severity can be scored from the examination described above on simple scales such as 0-10, where zero means no tremor and a score of 10 is the most severe.
The tremor can also be rated by assessing its effect on a person’s hand function such as handwriting, drawing a spiral (see below) or holding a cup of water. These functions can also be scored on a scale.
Drawing spirals is a useful aid in determining arm tremor severity, especially if it is mild to moderate in severity, but it is less useful in severe tremor.
The effect of tremor on everyday life can be evaluated by activities of daily living (ADL) scores (see page 18).
Ataxia
Eye movements
In order to assess whether ataxia involves the eye movements, the individual is asked to look straight ahead, then in various directions. The presence of nystagmus (involuntary rhythmical movements of the eye balls) indicates the presence of ataxia.
Speech
If speech is affected by ataxia, it can sound slurred and is called dysarthria. The severity of dysarthria can be scored on a simple scale 0-4, (zero being normal speech, four being unintelligible).
Arm movements
Incoordination of arm movements can be assessed by asking the individual to perform alternate hand movements. Slowing or impairment of these movements is an indication of the presence of ataxia and is called dysdiadochokinesia. The severity can be scored on a simple scale as mentioned above. Scales designed to look at arm function can also provide helpful indications to the degree of the incoordination.
Stance and gait
Assessing an individual’s ability to stand with or without aid is useful in determining the degree of ataxia affecting the trunk.
Similarly, measuring the distance and the speed of walking with or without aids is helpful, but not specific to ataxia as it can also be affected by leg weakness or numbness. Nevertheless, tests like the “100-metre timed walk” are useful tools in evaluating the effect of ataxia on a person’s mobility and day-to-day functional ability.
Summary
Assessment of ataxia and tremor and its severity, as well as evaluating the impact these symptoms have on a person’s life, are crucial for their management and should be a priority.
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