clonus
Sign in to savethumb|Ankle clonus Clonus is a set of involuntary and rhythmic muscular contractions and relaxations. Clonus is a sign of certain neurological conditions, particularly associated with upper motor neuron lesions involving descending motor pathways and, in many cases, is accompanied by spasticity (another form of hyperexcitability). Unlike small spontaneous twitches known as fasciculations (usually caused by lower motor neuron pathology), clonus causes large motions that are usually initiated by a reflex. Studies have shown clonus beat frequency to range from three to eight Hz on average and may
Key facts
- Medical condition (new).name
- Clonus
- Medical condition (new).field
- Neurology
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Article
11 sectionsContents
- Signs
- Cause
- Mechanism
- Hyperactive stretch reflexes
- Central oscillator
- Clonus and spasticity
- Diagnosis
- Voluntary induction in healthy people
- See also
- References
- External links
thumb|Ankle clonus Clonus is a set of involuntary and rhythmic muscular contractions and relaxations. Clonus is a sign of certain neurological conditions, particularly associated with upper motor neuron lesions involving descending motor pathways and, in many cases, is accompanied by spasticity (another form of hyperexcitability). Unlike small spontaneous twitches known as fasciculations (usually caused by lower motor neuron pathology), clonus causes large motions that are usually initiated by a reflex. Studies have shown clonus beat frequency to range from three to eight Hz on average and may last a few seconds to several minutes depending on the patient's condition.
==Signs== Clonus is most commonly found at the ankle, specifically with a dorsiflexion/plantarflexion movement (up and down). Some case studies have also reported clonus in the finger, toe, and laterally in the ankle (as opposed to the typical up and down motion). Ankle (medial gastrocnemius) Patella (knee cap) Triceps surae Biceps brachii