Clonus After Spinal Cord Injury: How to Minimize Involuntary Shaking Leave a comment

After a spinal cord injury, you may experience involuntary, rhythmic shaking called clonus.

To help you better understand clonus after spinal cord injury, this article will go over its causes, symptoms, and management.

What Causes Clonus After Spinal Cord Injury

Clonus is a reflex typically caused by sudden, passive stretch of a muscle. For example, when you lift your leg and place your foot back on the ground, the slight upwards stretch of the ankle can trigger clonus.

Clonus is most common in the ankles and feet. However, depending on your level of injury, it can also occur in the knees, calves, wrists, triceps, and biceps.

After a spinal cord injury, you might have spinal shock, which causes temporary loss of all reflexes below your level of injury.

Once spinal cord inflammation starts to stabilize and swelling dies down, some reflexes may slowly start to return.

The spinal cord can act independently from the brain. When messages from the brain can’t reach the muscles due to spinal cord damage, your spinal cord may become hypersensitive and send nerve impulses to the muscles on its own.

As a result, you experience two different extremes. Previously limp muscles can become hyperreactive to stimulation, which can cause clonus.

What’s the Difference Between Spasticity and Clonus?

Spasticity and clonus are both outcomes of upper motor neuron damage that cause involuntary muscle contractions. However, they describe two very different reactions.

Spasticity is velocity-dependent increases in muscle tone that create resistance to movement. The more rapidly a muscle is stretched, the more severely it contracts.

While spasticity results in prolonged muscle contractions, clonus results in fluctuating contractions and relaxations in the form of jerks or rhythmic shaking.

Clonus can also be mistaken for tremors. The difference is that clonus is caused by passive muscle stretching, while tremors are typically caused by stress, exhaustion, medication side effects, an overactive thyroid, or alcohol abuse.

How to Manage Clonus in Spinal Cord Injury Patients

Every spinal cord injury is different, so the severity of clonus can vary quite a bit from person-to-person.

Some people will experience occasional mild shaking while others may be unable to stand or walk.

Severe clonus can disrupt sleep, cause extreme fatigue, and make it difficult to perform self-care tasks.

Effective ways to manage clonus after spinal cord injury include:

1. Physical Therapy

Physical therapy for clonus management will primarily consist of stretching, range of motion, and strengthening exercises.

Stretching helps lengthen tight muscles and repetitive exposure to movement will help reduce reflex excitability.

The spinal cord is capable of rewiring itself through neuroplasticity. The more you practice movements, the more your spinal cord recognizes a demand for that function, which helps promote neurological adaptions.

2. Cold Application

Another way to reduce the frequency and severity of clonus is through cold applications.

In this study, researchers wrapped crushed ice in wet towels around susceptible muscles for 10 minutes and then had the patient exercise those muscle groups.

It resulted in immediate clonus reduction that lasted 12 hours.

Additionally, this study had patients use a combination of cryotherapy and physical therapy for 10 sessions. It resulted in a significant decrease in clonus frequency compared to the control group.

Notice that both studies involved some form of physical activity. As stated in the previous section, repetitive movement is essential for promoting neurological adaptations in the spinal cord.

3. Orthotics

Orthotic devices like braces, casts, and splints can help spinal cord injury patients better manage their clonus.

They provide additional structure and stability to mildly resist involuntary movements.

Orthotics will also subtly lengthen tight muscles, which will help reduce hypersensitivity to movement and touch.

4. Medications

A doctor may prescribe medications to help temporarily relieve clonus after spinal cord injury.

Typically, muscle relaxants and anticonvulsants are taken to reduce the excitability of muscles below the level of injury. However, oral medications can affect the entire body and cause unwanted side effects like drowsiness and disorientation.

Instead, Botox injections might be a better option. By injecting the nerve block directly into the overactive muscle, you get localized clonus relief.

Keep in mind that medications and Botox only work temporarily and will not treat clonus long-term. It’s ideal for SCI patients to take advantage of the temporarily reduce clonus and work on physical therapy to promote lasting changes.

5. Surgery

Due to its invasive and costly nature, surgery is often used as a last resort when all other management interventions prove ineffective.

Surgery for clonus involves incisions at the spinal nerves. This will cut off some innervation at those muscles, which will reduce their excitability.

Clonus and Spinal Cord Injury: Key Points

Clonus commonly occurs after spinal cord injuries due to upper motor neuron damage.

The rhythmic shaking or jerking characteristic of clonus can interfere with your day-to-day life, so it’s essential to properly manage it to minimize its effects.

Hopefully, this article helped you better understand what clonus is, how it differs from spasticity, and how to effectively manage it. Good luck!

-Flint Rehab

** This post was originally published on

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