Rigidity

Rigidity in parkinson disease is called as cogwheel rigidity. Doctors can discover the prescence of rigidity on physical examination. Rigidity basically refers to the tone of muscles. Sometimes rigidity is experinced as a sense of stiffness or even tightness in muscles. Sometimes rigidity also results in isolated shoulder pain or liw back pain . Rigidity also 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 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
although rigidity may worsen.

For more details contact Dr.Alok Gupta at
guptaa@ndf.vsnl.net.in , guptaa@parkinsonindia.org

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