Selective Dorsal Rhizotomy: An Overview
By Casey Daniel
Selective dorsal rhizotomy (SDR) is an irreversible neurosurgery performed on the lower spinal cord to treat spasticity, especially in the lower limbs. A neurosurgeon identifies nerve rootlets in the spinal cord that are sending abnormal messages and cuts them. SDR is presently the only surgical procedure that can provide permanent reduction of muscle spasticity caused by spastic CP.
How Does SDR Work?
Sensory nerves collect information from a muscle and bring it to the spinal cord, which sends motor nerves back to the muscle, telling it to contract. Normally, the brain “oversees” muscle activity by communicating with the spinal cord. In people with CP, the brain has less control, and the spinal cord instructs some muscles to contract continuously.
During SDR surgery, doctors cut only the sensory nerve rootlets that cause spasticity. Motor nerves are untouched. This means that muscle tightness is reduced, but other functions, like leg movement, remain intact.
The Surgical Process
First, an incision – usually less than six inches long – is made on the child’s back. The spinal canal is opened so the surgeon can locate nerve roots. Using a surgical microscope, he or she then separates roots into smaller “rootlets.”
Several dozen rootlets are stimulated via electric impulse; this allows the surgeon to see which rootlets create spastic reactions. The sensory rootlets that cause spasticity are then cut.
What are the Benefits of SDR?
Reduction of spasticity offers muscle groups the opportunity to move normally. This leads to a broadened range of functional mobility, which makes self-care activities – like dressing and grooming – easier. SDR also lessens contractures, prevents bone and joint deformities, improves gait patterns, and optimizes the body’s use of energy and oxygen.
What are the Risks of SDR?
The most serious complications include paralysis of the legs and bladder, impotence, and sensory loss. Wound infections and meningitis are possible but generally controllable with antibiotics. Spinal fluid sometimes leaks from the wound and requires surgical correction.
Sensitivity of the skin on the feet and legs is common following SDR surgery, but usually goes away within two months. Temporary changes in bladder control are also relatively common, but usually cease within a few weeks.
Who are candidates for SDR surgery?
SDR is generally performed on children with spastic CP between the ages of 3 and 10, though older children are sometimes candidates. Because SDR involves considerable post-op rehabilitation, candidates for this surgery are cognitively able to follow directions.
Spastic diplegics. Children with spastic diplegic CP that affects the legs more than the arms are the most common candidates for SDR. Sometimes called “borderline ambulators,” spastic diplegics can take a few steps forward without assistance, often on their tiptoes.
Spastic diplegics who undergo SDR virtually always experience reduced spasticity, and recurrence of spasticity is extremely rare. For these children, SDR can improve gait and leg function.
Severe spastic quadriparetics/quadriplegics. In certain cases, SDR can increase the physical comfort and independence of severe spastic quadriparetics or quadriplegics. Parents report that caretaking tasks, like diaper changes and mealtimes, are less challenging after SDR surgery. However, for this group, SDR has a lower success rate and higher risk of spasticity recurrence.
How Can I know if SDR is Right for My Child?
SDR is not right for every child with spastic CP, so a team of specialists will screen your child to determine whether the surgery is appropriate. This team can include a pediatric neurosurgeon, a pediatric orthopedic surgeon, a physical therapist, an occupational therapist, a rehabilitation medicine physician, and/or a nurse, depending on your hospital. When evaluating your child’s spasticity, they may order MRI brain scans, visits with a pediatric neurologist, or other pre-op tests as necessary.
Even if the team concludes that SDR is not right for your child, their evaluation can provide useful information about his or her therapy program and care. Some children who are not immediate candidates for SDR are invited to return in several months for reevaluation.
What Should I Expect if My Child Undergoes SDR Surgery?
Prior to surgery, patients will have a series of pre-op appointments with their doctor. On the date of the procedure, surgery typically lasts 3-4 hours. The patient will spend about 3-5 days recovering, closely monitored by nurses. After this period, comprehensive rehabilitation begins.
Because SDR reduces muscle spasticity permanently, patients must learn to walk and move differently than before. Physical and occupational therapists help patients learn basic self-care and motor skills, as well as helping to increase strength, alignment, and balance. Regular physical therapy sessions – usually several times per week – continue for several months after your child comes home. Doctors set a schedule of follow-up appointments to periodically evaluate your child’s progress.