Lea Pollak, MD Colin Klein, MD Jose-Martin Rabey, MD
Arch Neurol 1997;54:935
Assaf Harofeh Medical CenterDept of Neurology
We noticed that in patients with pyramidal lesion, the distance between the finger and nose on repeated finger-nose testing shortens progressively in the paretic hand. The shortening of distance is also present in those patients in whom, on routine neurological examination, no obvious weakness, pronation drift, or changes in tone and reflexes can be found.
The patients set the starting point of the finger at a progressively shorter distance from the nose, despite the efforts of the examiner to correct the shortening. This shortening or lazy arm phenomenon can be explained by primary affection of the extensor muscles in upper limbs by a corticospinal lesion, resulting in the tendency to flexion and pronation of the elbow.[ 1-4]
The increased tone of the elbow flexors and pronators acts as an agonist during finger-nose touching, and as an antagonist on rendering of the finger to its primary position, thus causing a gradual shortening of the finger-nose-tip distance.
NeuroPhysiology teaches us that a pyramidal lesion is not only characterized by weakness and awkwardness of movements but also by decreased range of movements, as demonstrated by the finger abduction test where thumb and index finger are abducted more on the healthy side than on the affected one.
In summary, the routinely examined finger to nose testing can thus be helpful in revealing subtle pyramidal signs in addition to being a classic test for detection of a cerebellar lesion.
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