Spastic diplegia cerebral palsy (SDCP) is a form of cerebral palsy that causes muscle stiffness and spasms in a person’s legs and, sometimes, arms. This is due to damage to the motor cortex of the brain.

Around 35% of children with cerebral palsy have SDCP. This form of cerebral palsy is irreparable but does not worsen over time. Treatment can improve the symptoms.

SDCP is one of three forms of spastic cerebral palsy: spastic hemiplegia, which causes spasticity on one side of the body, usually the arm; spastic quadriplegia, which affects all four limbs, the trunk, and the face; and spastic diplegia, which causes spasticity mainly in the legs.Spastic cerebral palsy is the most common form.

This article explains SDCP, its symptoms, causes, treatments, outlook, and prevention.

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People with SDCP have an untypical increase in muscle tone in their legs, leading to stiff or abnormally tight muscles and extreme reflexes, or spasms. This is known as spasticity.

People with SDPC tend to experience symptoms predominantly in their legs, although some people have spasticity in their arms. SDPC tends to be symmetrical and affects both legs.

Who develops it?

Spastic diplegia can develop in some babies born prematurely or with low birth weight.

It is usually due to an injury to the white matter in the brain that transmits information between nerve cells, the spinal cord, and other areas of the brain. It is a common brain injury for very premature babies. Neonatal asphyxia or infant hypoxia refers to a lack of oxygen reaching the fetus via the umbilical cord and is one possible cause of CP.

Learn more about cerebral palsy here.

Symptoms of SDCP include late developmental movement and motor milestones in childhood. The delay in these milestones will vary for each child and depend on the severity of the SDCP.

Typical developmental milestones are as follows:

Developmental milestoneThe average age milestone is reached
supporting their head1–3 months
rolling over4–6 months
sitting6–9 months
crawling6–9 months
standing9–12 months
walking10–18 months

Children with more severe SDCP will generally take longer to reach these milestones. However, children who have mild SDCP may successfully reach these milestones around the same time as children without the condition.

Children with SDCP may also exhibit a scissoring gait whereby the knees and thighs hit or cross or may or crouch. This is due to severe adduction, hypertonia, and flexion in the legs, pelvis, and hips.

Many people with SDCP can walk unaided, but some may depend on an assistive mobility device, such as a wheelchair, leg braces, crutch, or walker.

Learn about Piaget’s stages of child development.

If there are concerns that a child is not meeting their developmental milestones, they should contact a doctor. Typically, developmental screening takes place at 9, 18, and 30 months.

If someone suspects that their child is showing signs of SDCP, they can contact a doctor earlier than this. However, a doctor may not be able to diagnose spastic diplegia until the child is 1–2 years old or older if the symptoms are mild.

Many pediatricians, neurologists, developmental behavior specialists, geneticists, and therapists specialize in cerebral palsy.

An injury to or problem with the brain’s motor cortex typically causes SDCP. This is the part of the brain that affects movement. This brain damage can occur during the fetal stage.

SDCP tends to cause motor difficulties only in the legs, so medical professionals associate it with milder brain damage than other forms of cerebral palsy.

While it is usually difficult to determine the exact cause of spastic diplegia in an individual, common risks factors associated with a child developing spastic diplegia include:

  • Premature birth: Babies born earlier than 37 weeks have a higher chance of developing SDCP.
  • Low birth weight: Babies with a low birth weight are more susceptible to developing cerebral palsy, even babies delivered at term.
  • Multiple births: The more fetuses a person carries, the higher the risk of one or more babies developing SDCP or another form of cerebral palsy. This is due to an increased risk of premature birth, low birth weight delivery, or both.
  • Infection: Studies link SDCP and other forms of cerebral palsy to an infection during pregnancy. These can include viral infections, such as meningitis, cytomegalovirus (CMV), chickenpox, or rubella; bacterial infections of the placenta or fetal membrane; or sexually transmitted infections, such as herpes.
  • Blood type incompatibility and jaundice: If a pregnant person has Rh-negative blood and their fetus has Rh-positive blood, it can lead to jaundice and oxygen deprivation to the brain.

An effective treatment for people with SDCP is rewiring the neural pathways in damaged parts of the brain to unaffected areas to improve motor function. The brain’s ability to do this is called neuroplasticity.

The best way to do this is through the repetition of specific tasks.

Physical therapy

The main form of treatment for people with SDCP is physical therapy. Physical therapy focuses on rewiring the brain to improve brain-to-muscle connection. It includes:

  • stretching stiff or spastic muscles
  • improving walking form or gait
  • strengthening underused muscles
  • building stamina and strength
  • helping balance and posture issues


Medication can help people with SDCP by minimizing their symptoms. The doses of these drugs, or whether they are necessary, will depend on the individual and the severity of their disability.

Medications include:

  • Botox: Botulinum toxin reduces localized muscle spasticity by blocking chemical signals from nerves that cause muscles to contract.
  • Muscle relaxers: Medicinal drugs such as Baclofen, Dantrolene, Tizanidine, Flexeril, and Diazepam relax the muscles and reduce spasms.
  • Anticholinergic drugs: These medications work by blocking the area of the brain that causes muscle movement.
  • Antidepressants: Some people with cerebral palsy experience various mental health problems and may benefit from medication to help them with their emotional well-being.

Learn more about treatment options for spasticity.

It is not possible to completely prevent SDCP. However, by reducing their risk of exposure to infection, receiving an Rh factor test, and maintaining as healthy a lifestyle as possible during pregnancy, people can reduce their risk of their child developing the condition.

SDCP is a condition that mainly affects the legs and sometimes arms and rarely causes cognitive problems. Most people with SDCP can live independent lives.

With early diagnosis and treatment, the prognosis for individuals with SDCP is favorable.