A rhythmic involuntary ankle plantar flexion movement following a stretch of muscles in and around the ankle
Normally, the body keeps clonus from sustaining but the presence of neurologic problems results in prolonged clonus. Thus, ankle clonus test is done in patients suspected of neurologic conditions.
To test, a passive dorsiflexion is done on foot, and then a slight tension on the foot in such position is held. Any subsequent ankle clonus is monitored, which when sustained to about more than five beats may mean pathologic.