Clonus is a neurological condition that occurs when nerve cells that control the muscles are damaged. This damage causes involuntary muscle contractions or spasms.
Clonus spasms often occur in a rhythmic pattern. Symptoms are common in a few different muscles, especially in the extremities. These include the:
Damaged nerves can cause muscles to misfire, leading to involuntary contractions, muscle tightness, and pain.
Clonus can make everyday activities strenuous and can even be debilitating. In this article, learn more about the causes and treatment.
While researchers do not understand the exact cause of clonus, it appears to be due to damaged nerve passageways in the brain.
A number of chronic conditions are associated with clonus. As these conditions require specialized treatment, the outcome may vary in each case.
Conditions associated with clonus include:
Multiple sclerosis (MS) is an autoimmune disorder that attacks the protective sheath around the nerves. The resulting damage disrupts the nerve signals in the brain.
A stroke starves a part of the brain of oxygen, usually due to a blood clot. A stroke may cause clonus if it damages the area in the brain that controls movement.
Major injuries, such as head trauma from a major accident, may also damage the nerves in the brain or spinal cord.
Serotonin syndrome is a potentially dangerous reaction that occurs if too much serotonin builds up in the body. This buildup could be due to drug abuse, but it may also be caused by taking high doses of medications or mixing certain medical drugs.
A brain tumor that pushes against the motor neurons in the brain or causes these areas to swell may lead to clonus.
Other causes of clonus include anything that has the potential to affect the nerves or brain cells, including:
To diagnose clonus, doctors may first physically examine the area that is most affected. If a muscle contracts while a person is in the doctor’s office, they may monitor the contraction to see how fast the muscle is pulsing and how many times it contracts before stopping.
Doctors will then order a specific series of tests to help them confirm the diagnosis. They may use magnetic resonance imaging (MRI) to check for damage to the cells or nerves.
Blood tests may also help identify markers for various conditions associated with clonus.
A physical test may also help doctors identify clonus. During this test, they will ask the person to quickly flex their foot, so their toes are pointing upward and then hold the muscle there.
This may cause a sustained pulsing in the ankle. A series of these pulses may indicate clonus. Doctors do not rely on this test to diagnose clonus, but it can help point them in the right direction during the diagnostic process.
Treatment for clonus varies depending on the underlying cause. Doctors may try many different treatment methods before finding the one that works best for each person.
Sedative medications and muscle relaxers help reduce clonus symptoms. Doctors often recommend these drugs in the first instance for people experiencing clonus.
Medications that may help with clonus contractions include:
- baclofen (Lioresal)
- dantrolene (Dantrium)
- tizanidine (Zanaflex)
- gabapentin (Neurotonin)
- diazepam (Valium)
- clonazepam (Klonopin)
Sedatives and anti-spasticity medications can cause drowsiness or sleepiness. People taking these medications should not drive a car or operate heavy machinery.
Other side effects may include mental confusion, lightheadedness, or even trouble walking. A person should discuss these side effects with a doctor, especially if they are likely to disrupt a person’s work or everyday activities.
Other than medication, treatments that may help reduce clonus include:
Working with a physical therapist to stretch or exercise the muscles may help increase the range of motion in the damaged area. Some therapists may recommend wrist or ankle splints for some people as they can provide structure and improve stability, reducing the risk of accidents.
Some people with clonus respond well to Botox injections. Botox therapy involves injecting specific toxins to paralyze muscles in the area. The effects of Botox injections wear off over time so a person will require repeat injections on a regular basis.
Surgery is often the last resort. During a procedure to treat clonus, surgeons will cut away parts of the nerve that are causing abnormal muscle movements, which should relieve symptoms.
While medical treatments for clonus are important, home remedies can be valuable in supporting these efforts.
Using heat packs or taking warm baths may relieve pain, while applying cold packs may help reduce muscle aches. Stretching and yoga may help promote an increased range of motion.
Some people may also find a magnesium supplement or magnesium salt bath helps relax the muscles. People should speak to a doctor before trying magnesium, as it may interact with other medications.
The outlook for clonus may vary according to the underlying cause. Where a sudden injury or illness causes clonus and muscle spasms, the symptoms will likely go away over time or respond well to physical therapy.
Chronic conditions such as multiple sclerosis, meningitis, or a stroke may require long-term treatments for symptom management.
Clonus may sometimes get worse if the underlying condition progresses. Many people find they can manage symptoms by working closely with a doctor and physical therapist.