What is clone?

clonus is a reflex that refers to involuntary, repetitive, and rhythmic muscle contractions. This abnormal reflex results from damage to descending motor neurons, which are responsible for motor function, muscle tone, reflex strength, and more. Clonus can be observed throughout the body, but is most commonly found in the biceps, triceps, patella, and ankle regions.

This article reviews the causes, diagnosis, and treatment of clonus.

Causes of clonus

Clonus is a stretch reflex, which means that when a muscle group is stretched or stimulated, neurons sense the stretch and cause the same muscle group to contract. This type of reflex is designed to prevent strains and muscle tears. However, with clonus, normal contractions do not occur once but several times before resolution.

Although the exact cause of clonus is unknown, clonus can be seen in many different disorders that affect the nervous system.

Common causes of clonus

  • multiple sclerosis
  • cerebral palsy
  • stroke
  • Spinal cord injury
  • traumatic brain injury
  • Orthopedic Trauma
  • serotonin syndrome

Clonic movements can also be observed in cases of seizures, side effects of certain medications, and chemical imbalances.

Cloning and MS

Multiple sclerosis (MS) is a chronic autoimmune inflammatory disease in which the immune system destroys the protective sheath that coats nerve cells, called myelinThis damage can lead to poor communication between the brain and the rest of the body, as well as a lower triggering threshold for the stretch reflex.

Due to the nature of the disease, people with MS often experience clonus, along with other symptoms such as involuntary muscle spasms, tremors, muscle weakness, and spasms. Other symptoms include loss of sensation, coordination problems, and cognitive impairment.

The link between MS and the immune system

clonus and spasms

Cramps are often seen in people with neurological disorders. It refers to abnormal muscle tightness or contraction.

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In addition to painful muscle spasms, spasticity can lead to clonus, pain, permanent muscle contractures, joint deformities, and even reduced ability to perform activities of daily living.

How to Diagnose Clonus

Clonus can be observed during the physical examination portion of a medical appointment. Depending on the affected area, a healthcare provider can apply pressure or “stretch” the muscle or tendon and watch for subsequent responses or reflexes. Using clonus, a healthcare provider can measure or count the number of involuntary contractions that occur.

Once clonus is observed, it becomes very important to try to determine the cause of the neurological problem. To find the underlying cause of clonus, a healthcare provider may order:

  • specific blood tests
  • MRI scan of the brain and/or spinal cord
  • nerve conduction studies
  • lumbar puncture (spinal tap)

Treatment of clonus

There are several oral medications and alternative therapies that may be beneficial in managing clonus.

While there is no “one-size-fits-all” therapy, a tailored treatment plan that manages both symptoms and underlying conditions can improve a person’s quality of life.

Treatment of clonus due to chemical imbalances, seizures, or drug side effects is intended to correct these acute medical problems.


The purpose of oral medications used to treat clonus caused by spasticity is to relax the affected muscles and reduce stiffness. Some of these drugs include:

  • muscle relaxants, such as baclofen and Tizanidine
  • BenzodiazepinesSuch as Diazepam and clonazepam

These drugs should be used with caution because of their side effects. These include, but are not limited to, drowsiness, dizziness, and fatigue.

other therapies

targeted injection botulinum toxin A/B or phenol Can relieve clonus.

Botulinum toxin is usually injected into the affected muscles to weaken or temporarily paralyze specific muscles so that they do not contract involuntarily. It may take up to 10 days to see results and an increase in range of motion and function may be observed. If successful, these injections can provide relief for several months.

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Unlike botulinum toxin injections, phenol injections are administered near the affected nerve root and immediately block nerve conduction, allowing the muscles to relax. If effective, phenol injections can also provide relief for several months.

Physical therapy for clonus

Physical therapy is a conservative but potentially transformative option for clonus management. A licensed physical therapist can help stretch and strengthen the affected muscles to improve mobility and functionality. They can also recommend whether and when a splint or brace might be a viable option to provide additional support, especially when clonus affects the lower extremities and may hinder normal activities.


If all other treatment options fail, a healthcare provider may recommend surgery to relieve clonus. Surgery may be performed to release tendons that have become inflamed and causing contractures of the underlying muscles, or surgery may be performed to sever the muscle pathways of affected neurons.

While these procedures can relieve clonus, they can also lead to permanent and disabling limitations of movement and muscle function.

Home Remedies for Cloning

In combination with other treatment modalities, vigilance using cold packs on the affected area and stretching at home can also help reduce the severity of clonus.


While there are several treatment options to help relieve clonus, severity and prognosis do depend on the underlying cause. Clonus can range from mild annoyance to disabled reflexes.

If possible, adequate management of the underlying disease or etiology can minimize clonus.


Clonus can refer to involuntary and repetitive muscle contractions that occur after a muscle is stimulated. Common causes of clonus include multiple sclerosis, cerebral palsy, spinal cord or traumatic brain injury, among others. It can also occur with certain seizures, medication side effects, or chemical imbalances.

With a thorough medical history and physical examination, healthcare providers will be able to diagnose clonus and provide treatment options such as physical therapy, medication, targeted injections, and surgery. The prognosis for clonus depends on the underlying cause and the effectiveness of treatment.

VigorTip words

Cloning ranges from inconvenient to disabled. If you have clonus, be sure to discuss your symptoms with your healthcare provider. The management of clonus requires multidisciplinary collaboration among neurologists, orthopedists, physical therapists, and others. Thankfully, there are several treatment options that can help manage clonus.

Frequently Asked Questions

  • What is a clonic reflex?

    Clones are involuntary and repetitive muscle contractions that occur in response to stimuli. Clonus is usually due to lesions of descending motor neurons. They can be observed throughout the body, but are most commonly found in the chin, biceps, triceps, patella, and ankle areas.

  • What is a positive clone test?

    A clonus test is performed when a healthcare provider applies force or stretch to an area, such as the ankle, and after the stretch is released, the ankle begins to swing up and down involuntarily and rhythmically. This is considered a positive clonus test. The resulting movement will vary depending on the area being tested, but this type of movement is indicative of clonus.

  • What triggers clonus?

    Clonus is a stretch reflex. When a muscle is stimulated or stretched, nerve impulses from the muscle are sent to the brain, which in turn sends messages to the muscle for defensive contractions. Clonic reflexes can be triggered by overstretching, injury, or some neurological dysfunction.

  • What is the difference between clonus and myoclonus?

    Clones are rhythmic, involuntary muscle contractions, while myoclonus refers to brief and sudden involuntary muscle twitches.