The Thumb Rolling Test: A Novel Variant of the Forearm Rolling Test

Abstract

Neurologists use a variety of tests to detect subtle upper motor neuron lesion causing a mild motor impairment of the upper limb. The forearm and index finger rolling tests are some of these. Their sensitivity varies, but in general these tests appear to be more likely to be abnormal in mild motor impairment of the arm and hand due to a cortico-spinal tract lesion than tests of power, muscle tone or reflexes. Thumb rolling involves more distal limb segments than forearm rolling and distal limb segments are typically more affected than proximal limb segments after cerebral lesions to the cortico-spinal tract. Thumb rolling was tested, in comparison to pronator drift, forearm rolling and index finger rolling, for its sensitivity to detect a cerebral lesion of the cortico-spinal tract in 17 consecutive patients with mild pure motor stroke affecting only one arm and hand. Thumb rolling is more sensitive (88%) than pronator drift (47%), forearm rolling (65%) and index finger rolling (65%) to detect a cerebral lesion of the cortico-spinal tract in mild pure motor stroke of the upper limb. The thumb rolling test may be a valuable adjunct clinical test to detect a subtle lesion of the cortico-spinal tract causing mild pure motor stroke of the arm and hand when the remainder of routine neurological examination is unremarkable.