What is Clonus

We all have felt them at least once in our lives. I am talking about a series of involuntarily muscle twitches. The sudden muscle twitching that occurs in form of waves or shock-like motions. In a more severe condition, it is known as clonus. It is a medical condition that may be a sign of underlying neurological conditions.

Definition
It is defined as a repetitive, rhythmic contraction of muscles. The most common form of clonus is ankle clonus. These are deep tendon reflexes that occur due to abnormal neuromuscular activity. When the muscles are stretched, it leads to the deep tendon reflex that leads to the condiiton. Many people confuse clonus with myoclonus, but the two are quite different. The irregular and uncontrollable jerks of a muscle or group of muscles is called myoclonus. In the next few sections, we try and understand the condition that is known as clonus.

Causes
The causes generally involve neurological problems and disorders. These neurological conditions arise due to upper motor neuron lesions. The motor neurons originate from the motor region in the cerebral cortex. They help carry the electrical impulses send out by the brain and the spinal cord. When these nerves are injured or damaged, it leads to the condition of clonus.

Spinal cord injury is one of the most common causes. It can also be due to presence of neurological disorders like stroke, hepatic encephalopathy, multiple sclerosis, etc. When the myelin sheath around the nerve fibers is lost, it causes disruption of impulses send by the brain and spinal cord. Thus, leading to the condition due to multiple sclerosis.

Epilepsy is also one of the causes. Other disorders like spastic paraparesis, Huntington's disease, meningitis, Creutzfeldt-Jakob Disease, Brown-Sequard syndrome all lead to the condition. Other non-neurological conditions that lead to clonus include adverse reaction to drugs like serotonergic. This leads to serotonin syndrome. Other drugs like oxycodone, cocaine, LSD drugs, etc. can also lead to the disorder.

Test
The most common way to detect the condition is the ankle clonus test. In this test, the doctor gently pushes the foot backwards into a dorsiflexion position. When he releases the foot, it should quickly come back to its normal position. However, when this does not happen and the foot tends to repeat the contraction and relaxation motion repeatedly, it indicates clonus. Another test involves pushing the patella down towards the toes. If the foot shows more than 5 beats, it may indicate an underlying neurological problem.

Treatment
It is observed in many healthy people and they show no signs of any neurological conditions. If it occurs under 5 beats, it is termed as normal. However, 5 or more than 5 beats requires treatment. The doctor may take your medical history and try to find out the underlying cause. The treatment generally involves curing the underlying ailment. However, medications like immunosuppressants, anticonvulsants, tranquilizers, etc. are prescribed to keep the condition under control. Physical therapy helps in reducing the severity of symptoms. Many times a Botox injection proves to be helpful in controlling involuntary muscle contractions. If spinal injury is the cause, then surgery is advised to treat the damaged or injured nerve that leads to muscle twitching.

As you can see, experiencing less than 5 beats is considered to be normal. However, more than 5 beats requires medical diagnosis to uncover a possible neurological condition. If you have any further queries, speak to your doctor for more advise.