A Patient With Kaleidoscope Vision. The Pronator Drift and Mingazinni Sign

The pronator drift sign can detect subtle upper motor neuron lesions.

The patient sits with their arms extended in front of them, elbows straight and palms facing upwards. They need to hold this position for 30 seconds.

The normal response is no change, a slight deviation bilaterally, or a slight pronation of the dominant hand.

An abnormal response includes the following:

1. Downward Pronator drift with eyes open. The affected side, which is contralateral to the lesion, will drift downwards with pronation, as the pronators are more powerful than the supinators. This indicates a motor deficit and a contralateral middle cerebral artery territory stroke. Please note that a downward drift of the arm without pronation is considered to be potentially functional in origin.
2. Downward pronator drift with eyes closed. This demonstrates that position sense is affected and indicates a posterior column lesion. It may also indicate neglect.
3. Upward arm drift with eyes closed. This indicates a loss of position sense and is usually caused by a contralateral parietal lesion.
4. Upward and Outward drift with eyes closed. This indicates a cerebellar drift.

The Mingazzini Sign

Mingazzini was an Italian Neurologist, who in 1913 introduced this sign to detect subtle weakness. The patient holds their arms straight in front of them, with their fingers spread, for as long as possible. The test is considered positive when one wrist or arm starts to drop, or the fingers cannot be maintained in abduction. In an upper motor neuron lesion, the hand should be affected before the arm is affected.

A similar test was also proposed for the  lower limb.  The patient lies on their back, with legs raised at right angles to the trunk and the knee bent at 90 degrees.  The lower limb must be kept horizontal. Weakness will result in the lower leg not being able to maintain that horizontal position.