An early symptom of Parkinson’s disease in which the muscles of a limb stiffen and resist passive movement (attempt by another person to manipulate the arm or leg when the person relaxes the limb). It gets its name from both the fact that it gives smooth constant resistance no matter how fast or slow the limb is moved and the perception that the limb is heavy and nonresponsive, “like a lead pipe.” Lead pipe resistance is typically what a neurologist looks for as a sign of rigidity. Another form of passive resistance in people with Parkinson’s is common cogwheeling, in which the muscles move in a ratcheting motion and that neurologists recognize as being tied to tremor. Both cogwheel and lead pipe resistance result from the same damage to the extrapyramidal system, the network of nerves that conveys signals between the basal ganglia and the muscles. The person with Parkinson’s often does not notice this resistance but may perceive aching and stiffness in the arm or leg. It is apparent to the doctor examining the person, however.
As can cogwheeling, lead pipe resistance can affect any muscle group on either side of a joint and is most commonly detected at the ankle, knee, wrist, and elbow. It is most often an asymmetrical, or one-sided, symptom. As Parkinson’s progresses, the delays and confusion in the nerve communication between the brain and the muscles expand beyond symptoms such as lead pipe resistance and cogwheeling to become gait disturbances such as start hesitation and freezing of gait. The kind of rigidity that marks lead pipe resistance can be a symptom of other neurological conditions such as tumors of the basal ganglia;