There are brisk stretch reflexes and clonus occurs in patients. Although closely linked, clonus is not seen in all patients with spasticity. Clonus is a series of involuntary, rhythmic, muscular contractions and relaxations. Some consider clonus as simply an extended outcome of spasticity. However, dyskinesia, hypertonia, and clonus may occur in some cases. Grade 4 ankle hyper reflexia is called ankle clonus. Clonus is another symptom that is characterized by alternating, rapid muscle contraction and relaxation. In the third stage, neurological examination may reveal clonus and positive Babinski sign. A horror movie, "The Clonus Horror" (1979), was partially filmed at CLU.