Clonus

Rapid oscillatory movements in which muscular rigidity and relaxation rapidly follow each other. Occurs following the tonic phase in a grand mal epileptic seizure.

The rhythmic contraction and relaxation of a muscle, usually a sign of upper motor neurone lesions.

Abnormal condition in which a skeletal muscle alternately contracts and relaxes; a rhythmical spasm often indicative of central nervous system disease.

Rhythmical contraction of a muscle in response to a suddenly applied and then sustained stretch stimulus. It is most readily obtained at the ankle when the examiner bends the foot sharply upward and then maintains an upward pressure on the sole. It is caused by an exaggeration of the stretch reflexes and is usually a sign of disease in the brain or spinal cord.

A succession of intermittent muscular relaxations and contractions usually resulting from a sustained stretching stimulus. An example is the clonus stimulated in the calf muscle by maintaining sustained upward pressure on the sole of the foot. The condition is often a sign of disease in the brain or spinal cord.

The occurrence of rapid and irregular muscle contractions defines clonus, an abnormality indicative of compromised nerve fibers responsible for transmitting signals from the motor cortex in the cerebrum to specific muscles. These peculiar muscle spasms can manifest in various regions of the body, such as the wrist, knee, ankle, or toe, triggered by the stretching of muscles in those particular areas. Clonus, serving as a potential red flag, signifies damage to the nerve pathways crucial for coordinated muscle movements. Moreover, clonus may also manifest as a characteristic feature during seizures, further highlighting its significance in understanding and diagnosing neurological conditions. By delving into the intricacies of clonus, medical professionals gain valuable insights into the complex interplay between nerve fibers and muscle activity, ultimately leading to more accurate assessments and targeted interventions.