Tests that will elicit cerebellar signs are in Red
Tests that will elicit sensory ataxia are in Blue
The method of the test is in Green
If you are asked to test a person’s co-ordination, or asked to check for cerebellar signs, then in the OSCE, (and in a clinical situation), you don’t necessarily have to do a full examination. This article will show what to examine for in these situations
Have a system!
It makes it easier to remember what to do, and you are less likely to miss anything out. We will start at the top of the body, and work down
Eye movements – mainly cerebllar
In the case of cerebellar disorder, there may be Nystagmus.
Ask the patient to follow your finger, whilst you make an ‘H’ shape roughly about 40cm infront of their eyes.
- Don’t move your finger too quickly – if you do saccades may appear – giving the apparent indication that Nystagmus is present, when it is not.
- Also note that in normal individuals, you get nystagmoid movements at the extremities of gaze – and these are normal.
- Patients with nystagmus often have reduced visual acuity, as they are unable to fixate properly on objects.
- Phasic nystagmus – note the direction of the quick phase
- Pendular nystagmus – appears more like bobbing movements
- Lateral nystagmus – a defect within the cerebellum itself
- Vertical nystagmus – a defect in the brainstem. Sometimes called down beat nystagmus, this is associated with problems with the foramen magnum.
- Internuclearophthalmoplegia (INO) – a defect found specifically in MS.
The adducting eye is unable to move past he midline on binocular vision. Eye movements are normal when one eye is covered. See full article on MS
for more details.
Dysarthria – cerebellar defect
Ask the patient to say their name and address. If speech appears normal in tis response, ask them to say the phrases:
- British Constitution
- West Register Street
- This may help to elicit any dysarthria
At the same time, you should try to assess the scanning quality of the voice. Patients with cerebellar disorders may put equal emphasis on all words so that normal scanning quality is lost.
Note that any co-ordination activity may be repeated with the patient’s eyes open and eyes closed. If the activity is worse with the eyes closed, this is highly suggestive of a sensory ataxia and not a cerebellar disorder.
Hold your finger at roughly arms’ length away from the patient. Ask the patient to touch the tip of your finger with the tip of their finger, then ask them to touch their own nose. Repeat several times, and move your finger in-between each repeat. Repeat with the other hand
- Cerebellar dysfunction – the patient is likely to show past-pointing, and a tremor. The tremor is particularly apparent at nearly-full extension – this is why you should put your finger roughly arm’s length away from the patient.
- Sensory Ataxia – movement may appear slightly slow and un-coordinated. They may be some slight tremor at the extremities of reach
It is unlikely that you would repeat this test with eyes closed.
Stretched out arms
Ask the patient to hold their arms out straight infront of them, with palms facing downwards, and fingers pointed forwards (a bit like a zombie). Keep eyes closed. Ask the patient to stay like this for 30-60 seconds (or as long as they can manage). You may also press sharply downwards on one of the outstretched arms and view the response.
- Normal response – arms and fingers will not move. When pressed downwards, arm will return to normal position quickly, and in one smooth movement.
- Cerebellar dysfunction – the arms may pendulum up and down. The fingers may being to move around (piano fingers/Pseudoathetosis). When you press the arm downwards, it may swing past the original point several times before coming to rest (reduced damping of movement)
- Sensory Ataxia – the fingers may gradually move out of position, but are unlikely to move rapidly and freely like in cerebellar dysfunction. Arms and hands may begin to drop – this could be caused by distal weakness, which may or maynot be related to the underlying condition. Unlikely to be pendular movements. When you press the arm downwards there may be slight reduced damping of movement.
Ask the patient to out the back of one hand on top of the back of the other hand. Then to rapidly pronate and supinate the hand on top. Normal patients will be able to do this rapidly. In both cerebellar disorders and sensory ataxia the movements may be slowed and inaccurate.
Joint position Sense
In this test you should only move the distal inter-phalangeal joint. Hold the finger from both sides at this joint, so that when you move the distal phalanx, only this joint is involved in the movement. When moving the phalanx, hold the finger at the side, so as not to give away the type of movement by which side of the finger you are pressing on! With the patient’s eyes open, demonstrate which movement is up, and which is down. Get the patient to close their eyes, and then ask them which way the joint is moving.
In both cerebellar and sensory ataxia JPS may be reduced, although more likely to be true for sensory ataxia. Remember that patients can guess right 50% of the time anyway – so you have to do it several times! If JPS is intact at one joint, move up to the next largest joint.
Coordination – Heel/shin
Ask the patient to put the heel of one foot onto the knee of their opposite leg. Then to run the ankle down the shin to the ankle. Lift of the heel and repeat.
- Cerebellar disorder – patients are likely to find this difficult, but it is unlikely to be exaggerated by eyes closed
- Sensory Ataxia – patients are likely to find it difficult, but may be able to compensate with visual cues. When eyes are closed, movement disorder will be greatly exaggerated.
Ask the patient to sit on the side of the bed with their arms folded. See if they can maintain balance. Repeat the test with eyes closed.
This indicates a midline cerebellar problem.
This is THE TEST to distinguish cerebellar defects from sensory ataxia.
Ask the patient to stand up, with feet together. Be ready to catch them! Ask them if they feel unsteady if they are noticeably struggling at this point, it may not be suitable to perform the test.
If they seem reasonably steady, then ask the patient to close their eyes, and hold their arms out infront of themselves. Then watch and see if the patient is able to stay steady, or if they begin to wobble.
- Sensory ataxia – patient is likely to lose balance – this is a positive Rhomberg’s test
- Cerebellar Ataxia – the patient should be no more unsteady than with their eyes open
Will probably have similar characteristics in both sensory ataxia and in cerebellar disorders:
- Broad based
- May tend to veer to one side – usually the side ipsilateral to any lesion
To differentiate cerebellar from sensory ataxia – you could ask them to close their eyes whilst walking. Like Rhomberg’s test, this is likely to exaggerate the ataxia in sensory disorders, but have little effect in cerebellar disorders.
Also, in sensory ataxia, there may be extra features, such as:
- High stepping
- Patient looks at their feet as they walk
Heel – Toe Walking
This can exaggerate any ataxia. Ask the patient to put one foot infront of the other – heel-to-toe as they walk along