NursingCenter Blog

What is Pronator Drift?

Oct 10 2022 by Myrna Buiser Schnur, MSN, RN

A thorough neurologic assessment involves an evaluation of the motor system, including body position, involuntary movements, and coordination, as well as muscle bulk, tone, and strength. One basic component is the test for pronator drift which helps to assess motor function in a patient who is awake and able to follow directions (Rank, 2013).

How to Test for Pronator Drift

The test can be conducted with the patient sitting or standing. To perform the pronator drift test, ask the patient to close their eyes and then hold both arms straight out with palms facing up. Observe the arms for 20 to 30 seconds. The patient should be able to maintain the position of both arms equally if their motor pathway is intact.

Positive Pronator Drift

Pronator drift occurs when one arm and palm turn inward and downward. This is an indication of muscle weakness and an abnormal function of the corticospinal tract, the upper motor neurons in the brain and spinal cord that control voluntary muscle movement, in the hemisphere opposite to the affected limb. The palm may remain upward while the arm drifts downward with the fingers and elbow flexed. If the patient loses their position sense (proprioception), the arms may drift to the side or upward and the hands may writhe. The patient may not be aware of these movements and when asked to correct them, is unable to properly correct the position.

If the arms remain in the raised position equally without any drift, use your fingers to tap the arms briskly downward. The arms should return easily and smoothly to the horizonal position, indicating appropriate muscle strength, coordination, and normal proprioception. If the patient has cerebellar incoordination, the arm will bounce upward and miss its original starting position.

Pronator drift can occur with stroke or cervical spinal injury (Rank, 2013). Remember to document signs of pronator drift, which arm is affected, and the direction of the drift. Additional diagnostic tests, such as computed tomography or magnetic resonance imaging, may be needed, especially if this is a new finding (Rank, 2013).