Pronation test: eyes closed or open?

The pronation test reveals slight paresis in the upper limbs. Patients hold their arms outstretched in front of them with the hands supinated while they keep their eyes closed. Position changes such as pronation, abduction, or drift indicate a positive pronation test. However, proprioceptive disorders also result in position changes when the eyes are closed.

To evaluate the effects of vision on the pronation test and the relation of test results to electrophysiological findings.

Sixteen patients with slight unilateral paresis due to recent stroke were included in the study. Two pronation tests, one while the patients' eyes were open and the other while the eyes were closed (in randomized order), were performed in all patients and recorded with a video camera. Two neurologists double-blinded to the position of the patients' eyes then assessed the position changes in each recording. Electrophysiological examination included median sensory and motor evoked potentials in both upper limbs. Sensory and motor central conduction times (CCTs) were determined for all patients.

Assessments of position changes by two physicians were concordant. Ten patients had position changes more evident in the pronation test with the eyes closed (group 1), while 6 patients had similar position changes in both tests (group 2). Motor CCT difference between two sides was similar in the two groups. However, sensory CCT difference longer than 1.0 ms was significantly more frequent in group 1 (p < 0.01).

All patients who developed more obvious position changes during the pronation test with eyes closed had sensory CCT abnormalities. Therefore, we suggest that patients should keep their eyes open and then close them during the pronation test in order to distinguish motor or proprioceptive involvement.