Spasticity: Definition, Prevalence, Causes, Symptoms, Treatments and Therapies

It is a disorder in which some muscles contract continuously.

This contraction causes muscle stiffness and can interfere with normal movement, speech, and walking. Spasticity is usually caused by damage to the portion of the brain or spinal cord that controls voluntary movement.

The damage causes a change in the balance of signals between the nervous system and the muscles. This imbalance leads to increased activity in the muscles.

Spasticity adversely affects the muscles and joints of the extremities and is particularly harmful to grow children.

Prevalence, incidence, and causes

Spasticity affects more than an estimated 12 million people worldwide.

About 80 percent of people with cerebral palsy (CP) have different degrees of spasticity. With an estimated 500,000 people in the United States with some CP, this equates to about 400,000 people with CP-related spasticity.

About 80 percent of people with multiple sclerosis (MS) have different degrees of spasticity. With an estimated 400,000 people in the United States with MS, about 320,000 people with some degree of MS-related spasticity.


Other conditions that can cause spasticity to include:

  • Traumatic brain injury (TBI).
  • Spinal cord injury (SCI).
  • Brain damage due to lack of oxygen.
  • Stroke.
  • Encephalitis.
  • Meningitis.
  • Adrenoleucodistrofia.
  • Amyotrophic lateral sclerosis (Lou Gehrig’s disease).
  • Phenylketonuria.

Spasticity in cerebral palsy (CP)

In a person with CP, brain damage has occurred. For unknown reasons, the damage tends to be in the brain area that controls muscle tone and movement of the arms and legs.

Therefore, the brains of people with CP cannot influence the amount of flexibility the muscles should have.

The command of the muscle itself dominates the spinal cord and produces forces that are too tight or spastic. People born with CP do not have limb deformities at birth but develop them over time.

Spasticity of the muscles, along with limitations in stretching and using the powers in daily activities, is a significant cause of these deformities.

Spasticity in Multiple Sclerosis (MS)

Spasticity is a prevalent symptom of MS. There are two types of spasms related to MS: flexor and extensor.

Flexor spasticity is an involuntary bending of the hips or knees (mainly involving the hamstring muscles in the back of the leg).

The hips and knees bent toward the chest. Extensor spasticity is an involuntary stretching of the legs. Extensor spasticity involves the quadriceps (muscles in the front of the upper portion) and the adductors (inner thigh muscles).

The hips and knees remain straight with the legs close together or crossed at the ankles. Spasticity can also occur in the arms, but it is less common in people with MS.

Spasticity can be made worse by sudden movements or changes in position, muscle tension, extreme temperatures, humidity, or infections. It can even be triggered by tight clothing.

Spasticity in traumatic brain injury (TBI)

Spastic hypertonia often occurs after TBI due to damage to the brainstem, cerebellum, or half of the brain. This damage affects the reflex centers in the brain, interrupting the flow of messages along different nerve pathways.

This disruption can cause muscle tone, movement, sensation, and reflex changes.

The location of the TBI can determine which areas of the body are affected and which motor deficits occur. Reflex centers in the brain are more complex than those in the spinal cord.

This can make the treatment of spastic hypertonia in people with TBI more challenging to treat than in people with spinal cord injuries or neurological disorders.

Shortly after a brain injury, many people experience a period of increased muscle tone in which their body posture becomes very stiff. A common position is to keep your elbows rigid at your sides, your wrists and fingers bent, and your fists clenched.

The legs are generally extended at the hips and knees, with the ankles and toes flexed. The nerve signals that control motor functions can change as a TBI patient recovers.

Some signals may not reach the brain’s reflex centers and may send too many alerts, causing the muscles not to respond correctly.

Symptoms of spasticity

Spasticity can be as mild as a sensation of tightness in the muscles, or it can be severe enough to cause painful and uncontrollable spasms of the extremities, most commonly the legs and arms.

Spasticity can also create a sensation of pain or tension in and around the joints and cause low back pain.

The adverse effects of spasticity include:

  • Muscle stiffness makes movements less precise and challenging to perform specific tasks.
  • Muscle spasms cause uncontrollable and often painful muscle contractions.
  • Involuntary crossing of the legs.
  • Muscle and joint deformities.
  • Muscular fatigue.
  • Inhibition of longitudinal muscle growth.
  • Inhibition of protein synthesis in muscle cells.

Additional complications

  • Urinary tract infections
  • Chronic constipation
  • Fever or other systemic illnesses.
  • Pressure sores.

Treatment options

Several types of treatments available must be evaluated on a case-by-case basis, depending on the underlying cause, the age of the patient, and the severity of the spasticity.

Different treatments share the common goals of:

  • Relieve the signs and symptoms of spasticity.
  • Reduce pain and the frequency of muscle contractions.
  • Improved gait, hygiene, activities of daily living, and ease of care.
  • Reduce challenges for caregivers, such as dressing, feeding, transporting, and bathing.
  • Improved voluntary motor functions involving objects such as reaching, grasping, moving, and releasing.
  • Allows more normal muscle growth in children.

Physical and occupational therapy

Physical and occupational therapy for spasticity reduces muscle tone, maintains or improves range of motion and mobility, increases strength and coordination, and enhances comfort.

Therapy may include stretching and strengthening exercises, temporary braces, limb positioning, application of cold packs, electrical stimulation, and biofeedback.

Oral medications

Using oral medications to treat spasticity may be indicated when symptoms interfere with daily functioning or sleep.

Effective medication management may require two or more medications or a combination of oral medications with another type of treatment.

It is essential to work closely with a doctor to design an individualized treatment plan. Side effects vary greatly depending on the class of medication and the patient.

Medications include :

  • Baclofeno.
  • Benzodiazepines.
  • Dantrolene sodium.
  • Imidazolinas.
  • Gabapentina.

Botulinum toxin injections (BTA)

BTA, also known as Botox injections, when used in small amounts, is effective in paralyzing spastic muscles. Injection sites are carefully determined based on the spasticity pattern.

When Botox is injected into the muscle (s), the release of acetylcholine is blocked, resulting in the relaxation of the overactive muscles.

The injection (s) usually take effect within a few days and last between 12 and 16 weeks until the new nerve endings grow back and the affected muscles recover.

Functional benefits may last longer than this. There are limitations on the number of injections that can be administered.


The primary neurosurgical procedures to treat spasticity are intrathecal baclofen pumps (ITB) and selective dorsal rhizotomy (SDR).

Baclofeno Intratecal (ITB)

In severe cases of spasticity, baclofen can be administered through a pump that has been surgically implanted in the patient’s abdomen.

By administering baclofen directly to the spinal fluid, a much more powerful reduction in spasticity and pain can be achieved with fewer side effects.

ITB is highly effective in treating spasticity in the lower and upper extremities.

Selective dorsal rhizotomy (SDR)

In SDR, the neurosurgeon cuts the selective nerve roots (rhizotomy), the nerve fibers located just outside the posterior bone (spine) that send sensory messages from the muscles to the spinal cord.

SDR is used to treat severe leg spasticity that interferes with movement or position. By cutting only the sensory nerve roots that cause spasticity, muscle stiffness decreases while other functions remain intact.

Decreasing spasticity can improve mobility and function and help prevent muscle scarring (contractures) and joint and bone deformities. It is used most effectively in CP patients who meet specific criteria.

Individuals with the following criteria are not candidates for SDR:
  • Patients with meningitis, congenital brain infection, congenital hydrocephalus not related to preterm birth, head trauma, or family disease.
  • Patients with mixed CP have predominant stiffness or dystonia, significant athetosis, or ataxia.
  • Patients with severe scoliosis.
  • Patients who will not achieve functional gains after surgery.

The benefits of surgery should always be carefully weighed against its risks.

Randomized controlled clinical trials have shown that many CP patients report a significant reduction in spasticity and an improvement in function after surgery. However, surgery is not an option for all cases of spasticity.