February 7, 2026

@michaelokun

When hands move and the mouth ‘joins in.’ An under-appreciated motor signal in Parkinson’s disease. Motor overflow refers to involuntary movements that appear in body parts not intentionally being used when another movement is being performed. Makhoul and Jankovic describe in a new paper in Movement Disorders Clinical Practice how repetitive hand or limb movements can trigger involuntary mouth and jaw movements in Parkinson’s disease. Key Points: - Mouth motor overflow movements were observed in about 1/3 of folks w/ Parkinson’s disease undergoing standardized motor testing. - These movements included repetitive jaw opening, closing, lip pursing or lateral jaw deviation that can be triggered by rapid sequential limb movements. - Mouth motor overflow appeared in both ON and OFF medication states and was more frequent during OFF periods. My take: This paper reminds us to look carefully during routine examinations. Subtle facial and jaw movements may carry important clues about motor control and inhibitory circuit dysfunction in Parkinson’s disease, and the features can be easy to miss if you are not watching for them. Notice it was commonly present in the OFF dopamine state. Here are 5 points that resonated w/ me: 1- Motor overflow in Parkinson’s disease is not limited to the arms and legs. 2- Mouth and jaw movements may reflect impaired inhibitory control across motor networks. 3- These findings may help health care providers better interpret exam findings during UPDRS testing. 4- Mouth motor overflow should not be confused w/ dyskinesia or tardive movements. 5- Careful observation during simple tasks can reveal meaningful biology that is hiding in plain sight. https://movementdisorders.onlinelibrary.wiley.com/doi/10.1002/mdc3.70548 #parkinson #michaelokun #fixelinstitute