what is clonus

Clonus is a neurological condition that causes involuntary and rhythmic muscle contractions. It is typically a sign of an upper motor neuron lesion and commonly occurs alongside hyperreflexia. Clonus usually happens as a result of an upper motor neuron lesion, which means there has been damage to certain nerve cells in the brain and spinal cord that help you move. Clonus can occur in any muscle with a frequency of 5-8 Hz and the average period of oscillations of the ankle clonus is approximately 160-200 ms. It can be evaluated in many joints but is most commonly seen in the ankle joint by briskly dorsiflexing the foot. Clonus can be a sign of an underlying medical condition, such as a brain injury or cerebral palsy, but you may not know you have clonus until a healthcare provider checks your reflexes. Clonus can also be a marker of hyperreflexia, which is part of an upper motor neuron syndrome. Clonus can be treated by using medications like sedatives and muscle relaxers, physical therapy, and botox injections.