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.
[2] 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).
[3][4] Clonus is typically seen in people with cerebral palsy, stroke, multiple sclerosis, spinal cord damage and hepatic encephalopathy.
[1] This decreased synaptic current threshold would enhance motor neuron excitability as nerve impulses would be more readily conducted, and thus turn on this central oscillator.
[1] Clonus tends to co-exist with spasticity in many cases of stroke and spinal cord injury likely due to their common physiological origins.
[2] Clonus at the ankle is tested by rapidly flexing the foot into dorsiflexion (upward), inducing a stretch to the gastrocnemius muscle.
Gregory Bateson described the induction of clonus in healthy people:[6] Balance is a partly involuntary and unconscious business, dependent on "spinal reflexes."
When the weights and angles are correctly adjusted, an oscillation will start in the muscle of the calf with a frequency of about six to eight per second and an amplitude of about half an inch at the knee.