New Evidence on Outcomes of Selective Dorsal Rhizotomy

Most treatments for cerebral palsy (CP) are initially directed toward children.   What is not clearly established is the long- term effects of such treatments.  Many appear helpful in the short term but prove to be disadvantageous in the long run. Selective dorsal rhizotomy (SDR) is a permanent, irreversible neurosurgical procedure for reducing spasticity in cerebral palsy.  Parents contemplating SDR for their child would like assurance that that there will not be harmful complications from it as the child ages into adolescence and adulthood. We now have new evidence to address this concern.

SDR was first described in the medical literature more than 100 years ago but was largely forgotten until the 1960’s when it was modified and popularized, first in France, Italy, and South Africa, then subsequently in North America.

Normally, when a muscle is stretched, sensors in that muscle detect this change and inform a pool of nerve cells in the spinal cord via sensory nerve fibers. An immediate reflexive response is sent back to the muscle causing it to contract. This is a safety mechanism to prevent overstretching of the muscle, much like the rapid withdrawing of a hand when a hot stove is touched. The brain dampens this reflex so that the muscles are not overly sensitive to changes in movement.

However, in the spastic type of cerebral palsy, the inhibitory input from the brain to the spinal cord is reduced resulting in high muscle tone and muscles that are overly reactive to stretch and movement. This leads to difficulties with walking, reaching, and self-care as well as joint contractures.  SDR interrupts the excessive flow of nerve impulses to the muscles that causes stiffness and over-reaction to stimulation and position changes.

In SDR, the neurosurgeon gains access to the sensory fibers going into the dorsal (back) side of the spinal column. About 50-70% of the nerve roots are cut, often guided by response of certain nerve roots to electrical stimulation. By cutting these nerve roots, the amount of sensory stimulation coming from the muscles into the spinal cord is reduced, thereby reducing the degree of reactive muscle contraction and, therefore, spasticity.

There is marked variability with SDR across surgical centers and among neurosurgeons in patient selection, operative procedures, complications, and in immediate and long term follow-up care. While most agree that the best candidates for SDR are individuals with spastic diplegia (predominantly high tone in the lower extremities), some surgeons have expanded the procedure to include those with quadriplegia (high tone in upper as well as lower extremities). Individuals with the dystonic type of CP (sustained muscle contractions with twisting and repetitive movements) are not candidates for SDR.

Determination of which and how many nerve roots to cut, how to gain access to the nerve roots and at what spinal cord levels, can vary markedly from medical center to medical center. These decisions can affect the type and degree of post-operative discomfort and complications that occur. Some patients go home very quickly after the procedure; others remain hospitalized for several weeks. Weeks of recuperative physical therapy are required to overcome weakness and to regain (and hopefully attain new) mobility capabilities.

Studies of SDR, though limited because of the variability of surgical techniques and outcome measures, have generally been positive. The procedure clearly reduces spasticity and improves range of movement in the lower extremities. For most individuals, there is better sitting and walking ability, improvements in self-care and performance of activities of daily living, some improvement in upper limb use, and sometimes a reduced need for orthopedic surgery.

Fortunately, serious complications from SDR have been rare. Because the operation requires disruption of sections of the spinal column, there appears to be a possible increased risk of spinal deformity (such as scoliosis or twisting of the spine) resulting from SDR in a population already at high risk for this problem, especially among those with spastic quadriplegia.

Dr. Hurwitz at the University of Michigan evaluated medical outcomes, interventions, satisfaction with life and subjective impressions about SDR in older adolescents and adults who underwent the procedure as children. He found that the majority of adults would recommend SDR to others. Very few reported negative impressions of the procedure. Levels of satisfaction with life were generally high. However, despite the SDR, additional surgical and nonsurgical interventions were necessary in the majority of patients.

Although SDR has typically been performed on children with CP, there is some experience with the procedure in adults. Dr. Matthew Reynolds at the St. Louis Children’s Hospital published a report on adults with spastic diplegia. In a short term follow-up, patients reported less spasticity and improved ambulatory ability, coordination, joint range of motion, and independence.

The following are recommendations for those considering SDR for their child with spastic CP or for themselves.

  • Once SDR is mentioned as a possible option for yourself or your child, prepare for a discussion of SDR by reading about its rationale, selection process, operative procedures, complications, and outcomes from outside sources so that you are ready to ask detailed questions about a particular center’s methods.
  • Consider a center with an experienced, interdisciplinary diagnostic and management team that might include: neurosurgeon, orthopedic surgeon, physical and occupational therapists, orthotist, developmental pediatrician, pediatric neurologist, and physiatrist.
  • Ask about details of the procedure at this center and how they might differ from other centers, expected post-operative course, length of hospitalization, and type and extent of physical and occupational therapies, cost and insurance coverage.
  • Ask whether and why you or your child fit the candidate criteria for SDR.
  • Ask about other treatment options and why SDR is indicated at this time. What are the expected outcomes specifically for you or your child? Take time to consider alternative options.

 

References:

1. Hurvitz EA, Marciniak CM, Daunter AK, et al. Functional outcomes of childhood dorsal rhizotomy in adults and adolescents with cerebral palsy. J Neurosurg Pediatr. Published online February 8. 2013.

2. McLaughlin J, Bjornson K, Temkin N. Selective dorsal rhizotomy: Meta-analysis of three randomized controlled trials. Dev Med Child Neurol 2002;44:17-25.

3. Nordmark E, Josenby AL, Lagergren J, et al. Long-term outcomes five years after selective dorsal rhizotomy. BMC Pediatr 2008;8:54-69.

4. Reynolds MR, Ray WZ, Strom RG. Clinical outcomes after selective dorsal rhizotomy in an adult population. World Neurosurg 2011;75(1):138-144.

5. Steinbok, P. Selective dorsal rhizotomy for spastic cerebral palsy: A review. Childs Nerv Syst 2007;23:981-990.

6. Tedroff K, Lowing K, Jacobson DNO, et al. Does loss of spasticity matter? A 10-year follow-up after selective dorsal rhizotomy in cerebral palsy. Dev Med Child Neurol 2011;53:724-729.