II. Definitions
- Clonus
- Involuntary Muscle movement rapidly alternating Muscle Contraction and relaxation (typically 5-7/sec)
- Sustained Clonus
- Following persistent stimulus (e.g. ankle dorsiflexion), Clonus persists (10 beats or more)
- Unsustained Clonus
- Following persistent stimulus (e.g. ankle dorsiflexion), Clonus may occur briefly and rapidly extinguish
III. Technique: Ankle Clonus
- Patient lies supine, relaxed with knee in slight flexion
- Examiner grasps the foot and suddenly forces the ankle into dorsiflexion and holds the foot in that position
IV. Findings: Abnormal Ankle Clonus
- Rhythmic ankle flexion and extension for at least 3 beats of Clonus before it extinguishes
V. Causes: Sustained Ankle Clonus
-
Upper Motor Neuron Lesion
- Cerebrovascular Accident
- Multiple Sclerosis
- Cerebral Palsy
- Encephalopathy
- Other systemic conditions
VI. References
- Degowin and Degowin (1987) Bedside Diagnostic Exam, Macmillan Publishing, New York, p. 818
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Related Studies
| Definition (NCI) | A form of involuntary muscular movement characterized by alternating contractions and relaxation in rapid succession. In the context of reflex testing, the ability to elicit clonus indicates injury to the nerve tracts above the point at which the reflex was initiated. |
| Concepts | Sign or Symptom (T184) |
| SnomedCT | 36649002 |
| Italian | Clono |
| Japanese | 間代, ｶﾝﾀﾞｲ, ｶﾝﾀｲ |
| Czech | Klonus |
| English | clonus, Clonus, Clonus (finding) |
| Hungarian | Clonus |
| Portuguese | Clonus |
| Spanish | Clonus, clonospasmo, clonus (hallazgo), clonus, clono (hallazgo), clono |
| Dutch | clonus |
| French | Clonus |
| German | Klonus |
Ontology: Ankle clonus (C0238651)
| Concepts | Finding (T033) |
| SnomedCT | 39055007 |
| English | ankle clonus, Ankle clonus, Foot clonus, Ankle clonus (finding) |
| Spanish | clonus del pie, clonus del tobillo (hallazgo), clonus del tobillo, clono del tobillo (hallazgo), clono del tobillo |
