Traditional teaching seems to make heavy weather of ataxia.
From a personal perspective, I find it a much abused term in referrals from non-specialists.
Basically, ataxia can affect eye movements (nystagmus, hypermetria), speech (dysarthria or slurred speech), limb movements (intention tremor, hypermetria aka past pointing or overshoot) and gait (broad-based and unsteady).
Just because you wobble on your feet, does not mean you have ataxia; just because you have a tremor at the target, does not mean you have intention tremor.
Read one for a little more detail…
I recommend examining eye movements in the following sequence:
• voluntary saccades – “look left, look right etc”
• pursuit – “follow my pen”
• targeted saccades – “look at my nose, look at my finger”
If a cerebellar ataxia is present, you may be lucky enough to see obvious nystagmus. This is jerky, with a fast phase and a slow phase. Usually, the fast phase changes direction when gaze shifts from left to right – fast jerks to the right on right gaze, and fast phase to the left on left gaze.
Pursuit movements are often jerky and broken up, rather than being smooth and seamless.
Targeted saccades usually overshoot, and then flick back to the stimulus.
You will miss these signs if you simply ask people to follow your finger, which is how eye movement examination is usually taught.
I recommend looking for this in both the upper and lower limbs.
You can start, if you like, by observing the arms outstretched. In its own right, this tells you very little. You can then push the arms briskly down and see if they return to the position they started in. If they don’t, this might suggest cerebellar problems, but I rarely find it that illuminating.
Hold out your index finger as a target, and ask the patient to touch it with their own index finger. Then ask then to move the finger back to their nose (or chin – if they are at risk of poking their eye out!). Request that they repeat this as quickly and accurately as they can.
For crying out loud DO NOT MOVE YOUR FINGER ABOUT! Keep it still and watch for overshoot (hypermetria or past pointing) and tremor, as movements are corrected en route to the target.
You can then just get the patient to “chase” your finger from point to point, without them returning to their nose. I think this is a great way of demonstrating hypermetria.
Last of all, ask the patient to tap their hand on top of the other as fast as possible. In cerebellar ataxia, the movements are clumsy, and the sound of the slapping varies in rhythm and volume. If you get good at it, you can almost close your eyes and listen for this.
Some folk like you to tap and turn the hand. This is called dysdiadochokinesia, which is almost as hard to say as to type. You had best know how to do it, even though many neurologists think it is a bit rubbish as a sign. My view – if you have Parkinson’s, arthritis, ataxia, cognitive impairment, weakness – then this test will be difficult, and you can get caught out. I tend not to do it, for this reason alone.
In the lower limbs, ask the patient to place the heel on the knee, run it down the shin, lift it off at the ankle, and place it back on the knee. Repeat this a few times, looking for uncoordinated movements.
Okay, you have all seen ataxic gait. Some of you have had ataxic gait, and far be it from me to judge you!
If you have been drunk, or seen someone drunk, trying to walk down a road, then you know what an ataxic gait is. Broad-based and very unsteady.
Do not mistake this for the cautious, unsteady gait of people who are fearful of falling, or the narrow, shuffling gait of someone with PD.
You can also get an ataxic gait if you lose sensation in your feet. We call this a sensory ataxia.
When present, it is always worse in poor light, when folk get soap in their eyes in the shower, and with the eyes closed in clinic – this is the basis of Romberg’s test (no ‘H” in this please!). If a patient is pretty steady standing with their feet close together, but loses balance with the eyes shut, then they may have a sensory ataxia and you should be looking hard for signs of impaired sensation in the lower limbs.