When limited by the number of motor tests that can be performed on a patient suspected of having a stroke, the pronator drift may be your best bet! The sensitivity of this test has varied from 22% to as high as 94% for patients within a week of having a stroke; it is highly specific, however (1,2).
An advantage of this maneuver is that it can point to subtle lesions in the corticospinal tract (CST) often missed by formal strength testing.
To perform the test, ask the patient to hold his or her arms straight out in front with palms facing upwards and eyes closed for 20-30 seconds. Slight pronation of one hand and flexion of the elbow suggests mild drift. Additional downward drift of the entire arm may also be present with more severe deficits (3). Interestingly, if one arm drifts upward this suggests a lesions outside the CST, possibly a cerebellar or parietal lesion, which may be equally concerning.
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- Louis ED, King D, Sacco R, et al. Upper motor neuron signs in acute stroke: prevalence, interobserver reliability, and timing of initial examination. J Stroke Cerebrovasc Dis 1995;5:49-55. https://www.ncbi.nlm.nih.gov/pubmed/26486559
- Anderson NE, Mason DF, Fink JN. Detection of focal cerebral hemisphere lesions using the neurological examination. J Neurol Neurosurg Psychiatry 2005;76:545-49. https://jnnp.bmj.com/content/jnnp/76/4/545.full.pdf
- Campbell, WW. In DeJong’s The Neurologic Examination-6th Ed, p389-392, 2005. Lippincott Williams&Wilkins, Philadelphia.
Contributed in part by Alexis Roy, Harvard Medical Student, Boston, MA.
Disclosures: The listed questions and answers are solely the responsibility of the author and do not necessarily represent the official views of Mercy Hospital-St. Louis or its affiliate healthcare centers. Although every effort has been made to provide accurate information, the author is far from being perfect. The reader is urged to verify the content of the material with other sources as deemed appropriate and exercise clinical judgment in the interpretation and application of the information provided herein. No responsibility for an adverse outcome or guarantees for a favorable clinical result is assumed by the author. Thank you!