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Selective Dorsal Rhizotomy

  • Selective dorsal rhizotomy is a neurosurgical treatment for leg spasticity—increased muscle tone and tightness that limits leg movement. This operation is sometimes recommended for children with spasticity from cerebral palsy when other treatments, like physical therapy and Botox injections, are no longer helping.

    The goal of the operation is to increase mobility and encourage independent walking. Many children can transition from walkers to crutches or canes and avoid the need for other surgical procedures.

    Selective dorsal rhizotomy (SDR) surgery works by calming down an over-active feedback loop between the motor nerves and sensory nerves that run between the spinal cord and the leg muscles. Our surgeons make a small incision in the lower back and cut some of the sensory nerves close to where they enter the lower spinal cord.

    We use the term "selective" because only the nerves that are most abnormal are cut. We closely monitor muscle responses during the operation to ensure that the correct nerves are targeted. This allows us to reduce the excess muscle tone without affecting sensation in the child’s legs.

    Contact Us

    Selective Dorsal Rhizotomy
    Department of Neurosurgery
    Boston Children's Hospital
    300 Longwood Avenue
    Boston MA 02115

    Phone: 617-355-6008 

  • In order to work properly, muscles need to both contract and relax. But in children with spasticity, the signal to relax a muscle doesn’t get through. Instead, the sensory nerves keep telling the muscles they need to be tighter, so they contract even when they don’t need to.

    Selective dorsal rhizotomy (SDR) is designed to disrupt this harmful feedback loop by cutting some of the sensory nerves, allowing muscles to relax when they need to.

    selective dorsal rhizotomySelective Dorsal Rhizotomy


    SDR is performed under general anesthesia and normally takes about 4 hours. The surgery requires a stay in the hospital of 4 to 5 days.

    What happens during SDR surgery?

    SDR surgery is done on an inpatient basis, and normally takes about four hours. General anesthesia is required, and after the child is asleep:

    • The neurosurgeon makes a small cut in the upper lumbar region of the spine, and removes a small section of bone to expose the nerve roots as they leave the spinal cord.

    • The surgeon then looks through a microscope to see the nerve roots and separates them into groups, finding those that bring sensation back from the legs and leaving the motor nerves aside.

    • Next, the surgeon tests each sensory nerve root in turn by stimulating it electrically, while an electrophysiologist monitors the response in the leg muscles. If the nerve responses are abnormal, these nerve roots may be selectively cut. 

    • After about half of the abnormal nerve roots have been cut, the surgical team carefully closes the wound.

    Selective dorsal rhizotomy usually requires a child to stay in the hospital for four to five days.

    Who will be helped most by SDR surgery?

    Each child is evaluated by our cerebral palsy team to determine whether he or she qualifies for selective dorsal rhizotomy. The procedure is most effective in children whose cerebral palsy is the result of being born prematurely, and whose spasticity mainly affects their legs. (Children with spasticity in all their limbs, or who are affected more on one side of the body, may get more benefit from an intrathecal baclofen pump).

    Children are good candidates for the operation if they:

    • Have spasticity mainly in their legs

    • Can walk on their own or with the help of a walker or braces, or have the potential to do so

    • Are motivated and able to follow instructions

    • Are physically and mentally able to participate in intensive physical therapy after the operation, to maintain its benefits.

    Children with a great deal of spasticity in their arms, or who require support to sit up, may benefit less from SDR surgery.

    SDR surgery is best done as soon as it becomes clear that a child will have trouble walking (typically between ages 3 and 6) and is no longer improving with other treatments like Botox injections or physical therapy alone. The earlier children are treated, the more normally their muscles and limbs will develop, the less stigma they will experience in school and the more independence they can enjoy. However, older children and young adults can also have very good results.

    What is the recovery like after SDR surgery?

    During the hospital stay:

    • The evening after surgery, children are closely watched in the intensive care unit and given a strong IV medication to minimize pain and discomfort. Pain is closely monitored. It’s important to lie flat in bed immediately after surgery to allow the wound to start healing and prevent spinal fluid from leaking out.

    • On the second day, children can usually move to a regular room. On the third day, they can discontinue the IV medications, switching to oral pain medications.  Most children are also allowed to sit up in bed.

    • Over the next week, patients may experience numbness, tingling and a feeling of heaviness in their legs. This is normal, though rare.

    • Intensive physical therapy begins before the child leaves the hospital. This therapy will continue outside the hospital, at clinics close to home.


    • Most children return to their baseline level of mobility within 1 to 2 weeks after surgery. Because the operation releases tone in the muscles, they will have noticeably less spasticity right away. 

    • Once spasticity is reduced, however, the underlying muscle weakness becomes more obvious. This means that the child will feel weaker at first and will need to gradually regain muscle strength through intensive physical therapy.

    • We recommend at least five physical therapy sessions a week for at least six weeks. If children and families can stick to it faithfully, most children will have greatly improved strength and gait within six months. Our team works with physical therapists in the community.

    What results could we expect?

    Selective dorsal rhizotomy can permanently reduce spasticity in children with cerebral palsy. Many children are able to transition from walkers to crutches or a cane, and they are less likely to need orthopedic surgery, particularly if they have SDR surgery at a young age.

    Results depend on the child’s medical status before the operation and adherence to physical therapy afterward. But overall:

    • Studies that have followed children for 10 to 15 years after SDR surgery have shown long-term improvement in muscle tone.

    • Studies also show better gait and greater mobility 5 to 10 years after the operation and greater improvements when compared with intensive physical therapy alone.

    Although the reasons for this aren’t clear, many parents report that children speak better, do better on mental tasks and interact better socially after SDR surgery.


  • Why Boston Children’s Hospital?

    Our nationally ranked neurosurgical team uses a less invasive form of rhizotomy than surgeons typically do elsewhere, removing a smaller amount of bone from the spinal cord and working through a smaller window. We are among a handful of centers offering this “single-level” SDR surgery, which helps children recover faster.

    Our neurosurgeons work closely with a multidisciplinary team of specialists including:

    • Neurologists
    • Physical therapists
    • Occupational therapists
    • Physiatrists
    • Orthopedic surgeons
    • Anesthesia and pain management specialists
    Boston Children’s Hospital has a highly rated pain service, dedicated to keeping surgical discomfort to a minimum. We also have a team of specialized pediatricians skilled in complex care for children who have other medical complications related to their cerebral palsy.

The future of pediatrics will be forged by thinking differently, breaking paradigms and joining together in a shared vision of tackling the toughest challenges before us.”
- Sandra L. Fenwick, President and CEO