Bradykinesia (Pediatric) Overview

Bradykinesia means "slow movement." In the context of childhood movement disorders, bradykinesia essentially refers to a component of parkinsonism. The full spectrum of parkinsonism is derived from the features of Parkinson's disease, which include bradykinesia, tremor, and rigidity.

Parkinson's disease is only one cause of parkinsonism; others are listed below. A child with bradykinesia has slow and painstaking movements of the affected limbs. If the whole body is affected, there may be an unnatural stillness or frozen quality. In some cases, there are reduced movements of the face leading to an expressionless look referred to, in its extreme form, as a "mask face." Bradykinesia may affect one limb, one side of the body, or the entire body. The slowed movements are often most evident when the child is asked to make a rapid repetitive movement, such as tapping the fingers or repeatedly making a fist. Tremor may or may not be present. In some cases, the tremor may be felt but not seen. Tremor in parkinsonism is less common in children than in adults.

Rigidity refers to the difficulty experienced by the doctor or therapist when attempting to move the child's arm, leg, or neck. There is a resistance to passive movement that may make the limb feel like a "lead pipe." Rigidity also affects the response to gravity. The excessive stiffness may lead to the child maintaining his or her arm in a fixed posture while walking rather than swinging it loosely at the side. When rigidity and tremor are present at the same time, the examiner may be able to feel "cogwheeling," in which passive flexion or extension of the child's elbow results in a series of catches in rapid succession. "Rigidity" has been formally defined by the NIH taskforce on childhood motor disorders (Pediatrics 111(1):e89-e97, January 2003 [pdf]) as follows:

Rigidity is defined as hypertonia in which all of the following are true:

1. The resistance to externally imposed joint movement is present at very low speeds of movement, does not depend on imposed speed, and does not exhibit a speed or angle threshold;
2. simultaneous co-contraction of agonists and antagonists may occur, and this is reflected in an immediate resistance to a reversal of the direction of movement about a joint;
3. the limb does not tend to return toward a particular fixed posture or extreme joint angle; and
4. voluntary activity in distant muscle groups does not lead to involuntary movements about the rigid joints, although rigidity may worsen.

	Examination