Hyperactive stretch reflexes[edit]
The self re-excitation of hyperactive stretch reflexes theory involves a repetitive contract-relax cycle in the affected muscle, which creates oscillatory movements in the affected limb.[1] In order for self re-excitation to exist, both an increase in motor neuron excitability and nerve signal delay are required.[1] Increased motor neuron excitability is likely accomplished by alterations to the net inhibition of neurons occurring as a result of injury to the CNS (stroke/ spinal cord injury).[1] This lack of inhibition biases neurons to a net excitatory state, therefore increasing total signal conduction.[1] Signaling delay is present due to an increased nerve conduction time.[1] Long delays are primarily due to long reflex pathways, which are common in distal joints and muscles.[1] This may therefore explain why clonus is typically found in distal structures like the ankle.[1] Frequency of clonus beats have been found to be directly proportional to the length of the reflex pathway it is found in.[1]