Freezing and Parkinson's disease

Freezing (sometimes called motor block) is a sudden, brief inability to start movement or to continue rhythmic, repeated movements, such as finger-tapping, writing, or walking. Freezing most often affects walking, but it also can affect speech, writing, and the person's ability to open and close his or her eyes. It tends to develop later in the course of the disease.

Freezing can be very disabling when it affects the way a person walks, causing the person to stop as though his or her feet suddenly have become glued to the floor. It can result in falls that cause significant injury, such as hip fracture. Freezing may occur at an open doorway (most common), at a line on the floor, or in crowds; it may be more likely to occur if the person is anxious or under stress.

Different strategies for breaking the motor block and getting the person moving again include having the person look at a target on the floor; step in a deliberate, precise way (like a marching step); or step over an object placed on the floor (such as a cane). Specially trained dogs, special canes, and, more recently, laser pointers also have been used with success.

Apomorphine (Apokyn) is a fast-acting dopamine agonist that seems to be helpful in treating freezing associated with Parkinson's disease. Apomorphine can be injected under the skin when muscles become "frozen." Apokyn can be taken with an antinausea drug to prevent side effects of severe nausea and vomiting.

Changing a person's levodopa dosage may improve freezing, but this does not work in all cases.