Question about neuro exam

[Sunshyne]

When I have my neuro appointments he always does one test that I can never 'pass'.

The doc holds the index finger at the first joint of one of my hands and holds it in front of me. He then asks me to close my eyes and touch the finger he is holding with the index finger of the opposite hand. I always miss.

Sort of like the finger to nose test, which I can do fine; but this test I cannot do.

Does any one know what this means????

[Bob698]

We're messed up.

My neuro always has me try to heel-toe walk and I always crash into something. I think she films it for conventions or a bloopers reel..

[22cyclist]

When I have my neuro appointments he always does one test that I can never 'pass'.

The doc holds the index finger at the first joint of one of my hands and holds it in front of me. He then asks me to close my eyes and touch the finger he is holding with the index finger of the opposite hand. I always miss.

Sort of like the finger to nose test, which I can do fine; but this test I cannot do.

Does any one know what this means????

This is called dysmetria, like another poster asked about today. You can do the finger nose test with your eyes open, but not closed, this indicates a CNS problem. It means undershoot or overshoot of your extremity (finger), to your other finger. Common finding.

They test this many different ways, not just finger, nose, finger. That is why the modification. Just checkin'.

[Redwings]

The doc holds the index finger at the first joint of one of my hands and holds it in front of me. He then asks me to close my eyes and touch the finger he is holding with the index finger of the opposite hand. I always miss. ... Sort of like the finger to nose test, which I can do fine; but this test I cannot do.

Hi Sunshyne:
Those tests are, in part, tests of your proprioception. Proprioception is the awareness of the position of one's body parts without having to look at them.

The finger-to-nose test is the easier of the two because the nose is always in the same position relative to the face. So if you're aware of where your face is (the normal state), you're also aware of where your nose is because it's always in the same place. And, in the normal state, you know where your arm is and where it's going. So it's relatively easy to touch your fingertip to your nose (if all systems are working properly). Only one part is moving in space, and your brain has to keep track of (by proprioception) only one moving part.

The finger-to-finger test is harder to do because the finger the doctor is holding isn't always in the same place relative to your body. So your brain has to start by localizing that arm/finger.

Proprioception helps your brain to know the position of your target arm/finger relative to your body, but it can't tell you the position of your arm relative to open space. Likewise, your body knows the position of your aiming arm/finger relative to your body and relative to the target arm/finger, but it can't tell the position of the aiming finger relative to open space. And to the aiming finger, the target finger is in open space and the aiming finger can't find the target finger by itself. The aiming finger only knows where the target finger is by your brain's awareness of where they are relative to each other. And that's a more complex mechanism because your brain has to keep track of two moving parts.

Of course there are other functions involved, but the complexity of adding a movable (though not moving) target explains why the finger-to-finger test is harder to do than the finger-to nose test. Proprioceptively, it's harder to find a target that isn't always in the same place than it is to find one that is.

[22cyclist]

I have to respectfully disagree with Redwings here. Testing for proprioception is done with eyes closed, but is done with more positioning of fingers and toes. Example is this up, down, straight.

You have to feel it without your eyes.

For dysmetria, the operative word here is that you missed with your finger. You should be able to hit the target even with your eyes closed. You saw where your body part was, and you should be able to hit that target even with your eyes closed. This is a modified point to point exam.
You can always ask you neurologist. Mine has me just touch my nose and outstretch my arms on both hands with eyes closed. "It is a hot mess." Sometimes I just touch mine like you do. Same story.

This is a bit different from proprioception.

My references are:

http://meded.ucsd.edu/clinicalmed/neuro2.htm
http://cloud.med.nyu.edu/modules/pub...rdination.html

[Sunshyne]

Interesting.....and just so I'm clear about this test.

I can do the 'touch my nose' with my eyes closed, could do it all day.

If I hold my index finger in the air in front of me, I can touch it with the other index finger with my eye closed...no problem.

It's when the doc physically holds my finger in front of me, that I am unable to touch it with the opposite hand with my eyes closed. It's him holding my finger that throws me off the deep end...I will miss every time.

...now as soon as he grabs a hold of that finger, I just start laughing..."like what's the use guy, did you think I was actually going to get it this time?"

[Redwings]

The tests described by the OP involve more than one function, which is why I pointed that out earlier and said that the tests are in part tests of proprioception.

If the "touch with the finger" tests were tests for only dysmetria, an aiming finger that misses the target finger would likely also miss the nose in that test because of the dysmetria exhibited by the same arm. If a person can reach out and accurately touch one object (like their nose or a water glass), they should also be able to reach out and touch another object (like another finger or a coffee cup) without dysmetria, and vice versa. If they can't, there must be another function involved besides the ability to judge or scale distance.

For example, being able to see the location of the target finger first, before the eyes are closed, also involves the use of visual spatial perception and visual memory to locate the finger in space. Visual input is necessary to the test because, other than by proprioception, the aiming finger has no way to locate the target finger after the eyes are closed. Visual skills are other functions being indirectly tested.

If these tests were merely tests of scaling ability, the tests could be done with any object in space (and some tests are done this way, including one of the point-to-point tests described in the NYU link). But the fact that these two tests (nose and finger touching) are done by having a person touch their own body parts indicates that the person's awareness of where those body parts are (proprioception) is an intentional factor in the tests.

The finger-to-finger test as described by the OP is a modified point-to-point test. Because of the modification, it isn't quite the same test as the one described in the point-to-point movement evaluation in the NYU link. That test involves the establishment and practicing of motor scale as well as visual scale before the eyes are closed. It also removes target proprioception by using the examiner's finger (or it could be any other object) as the target.

The test described by the OP involves only visual distance scaling without the establishment of motor scaling before the eyes are closed. It's also a test in which target proprioception can't be removed as a factor. Because proprioception is a built-in factor, it can't be said that the test is one of only motor scaling/dysmetria.

In coming back the the OP's question, the question as written wasn't what the tests are for, but rather what it means that she can touch her nose accurately but can't touch her target finger accurately with her eyes closed. In other words, what's the difference?

The answer isn't, "You have dysmetria." Because by touching her nose accurately, the OP has already established that she doesn't have dysmetria doing that task.

The answer is that the results of the two tests are different -- the OP is dysmetric doing one task and not the other -- because there's a fault somewhere in one or more of the factors/functions that make the tests different. Those differences include (there are more):

1) The finger-to-finger test includes a visual estimate of the position of and distance to the target finger, whereas the finger-to-nose test doesn't include a visual estimate. The visual estimate involves the complexities of visual input and visual spatial perception.

2) The finger-to-finger test involves visual memory of the location of the target finger after the eyes are closed, but the finger-to-nose test doesn't.

3) Motor scaling (judging/knowing the distance) to the nonmovable nose is already well established and is part of motor memory, whereas there is no preset motor scale for the movable target finger. Every situation for a movable target is unique, so some other function has to be used to locate the target finger in space and establish the distance.

4) Proprioception of a moveable body part (the target finger) is more complex than proprioception of a stationary body part (the nose).

Proprioception is built into the tests and can't be ruled out as a factor. Sensorimotor integration -- which is the basis of scaling/dysmetria -- includes proprioception. Which is why I said in my earlier post that these tests are, in part, tests of proprioception, but include other functions.

Bottom line, Sunshyne, ask your neuro.