ankle clonus


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clonus

 [klo´nus]
1. alternate involuntary muscular contraction and relaxation in rapid succession.
2. a continuous rhythmic reflex tremor initiated by the spinal cord below an area of spinal cord injury, set in motion by reflex testing.
ankle clonus (foot clonus) a series of abnormal reflex movements of the foot, induced by sudden dorsiflexion, causing alternate contraction and relaxation of the triceps surae muscle.
toe clonus abnormal rhythmic contraction of the great toe, induced by sudden passive extension of its first phalanx.
wrist clonus spasmodic contraction of the hand muscles, induced by forcibly extending the hand at the wrist.

an·kle clo·nus

a rhythmic contraction of the calf muscles following a sudden passive dorsiflexion of the foot, the leg being semiflexed.

ankle clonus

an involuntary tendon reflex that causes repeated flexion and extension of the foot. It may be caused by pressure on the foot or corticospinal disease. More than four beats of clonus is pathological.
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Ankle clonus

ankle clonus

A rhythmical, sustained series of flexion movements at the ankle. This is produced in people with damage to the nerve pathways in the spinal cord or brain (an upper motor neurone lesion), by a deliberate rapid, stretching of the ACHILLES TENDON, by forcibly flexing the foot. The spinal reflex arc is intact but the normal control on it, from above, is defective.
References in periodicals archive ?
Clinicians that only use Babinski sign and ankle clonus in the lower extremities to evaluate for the possibility of upper motor neuron disease should consider expanding the scope of their neurologic evaluation.
Possibly affected' members are asymptomatic at- risk subjects who have a normal gait but who show possible corticospinal tract deficits on examination (mild hyper-reflexia a few beats of unsustained ankle clonus but with flexor plantar responses).
On neurological examination, Glasgow coma scale was 6/15, pupils were equally reactive, deep tendon reflexes were brisk, plantar responses were extensor and bilateral ankle clonus was noted.
Abnormal deep tendon reflexes, crossed adductors, and ankle clonus are other signs of upper motor neuron lesions.