What is the role of selective dorsal rhizotomy (SDR) in the treatment of spasticity?

Updated: Jun 28, 2019
  • Author: Krupa Pandey, MD; Chief Editor: Stephen A Berman, MD, PhD, MBA  more...
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Selective dorsal rhizotomy (SDR) is performed under general anesthesia, involves the cutting of selective nerve roots between the levels of L2 and S1 or S2, the fibers lying just outside the vertebral column that transmit nerve impulses to and from the spinal cord. "Dorsal" or "posterior" indicates that the target nerve roots enter the posterior spinal cord. These fibers carry sensory information to the cord from muscle. [46]

Sensory nerves are targeted because of the probable role they play in generating spasticity. SDR is thought to improve spasticity by partially restoring the proper physiologic balance between the disinhibited sensory nerves and the resulting excess physiologic muscle tone.

The surgery is employed only when less-invasive procedures are unable to control spasticity adequately. The candidate nerve rootlets are stimulated electrically and those that lead to abnormal responses are cut; usually 25-50% of all tested rootlets are cut.

SDR has been performed mostly on children with cerebral palsy and less often in adults with spasticity from cerebral palsy or other etiologies. Studies have shown that most children with cerebral palsy experience a reduction in spasticity and an increase in range of motion that occurs immediately after SDR and persists for at least a year.

Cole et al emphasized the importance of applying strict selection criteria when considering children for SDR, as this is more likely to result in encouraging results. Of 53 children referred for SDR, only 19 (35%) fulfilled their selection criteria. These children showed improvement in cosmesis of gait, clinical examination, and temporal, kinetic, and kinematic parameters of gait analysis. [47]

Physical and occupational therapy are important postsurgical interventions to achieve the best outcome in patients who have undergone SDR. Most often, therapy is recommended 5 times per week for 6 months after the operation.

The relatively few longer-term follow-up studies that have been done on SDR indicate that tone reduction may last for a number of years. Reduction of spasticity can in some instances improve function, with most studies showing some benefit in mobility for subjects with spastic diplegia but less for those with spastic quadriplegia.

The extent of functional improvement after SDR therefore varies. Positive prognostic factors include the extent of mobility before the operation, underlying strength and balance, availability of regular physical therapy after SDR, and the patient's motivation and ability to undertake the rehabilitation process.

The possible complications from the surgery include those involving general anesthesia. Pain, altered sensation, and fatigue may continue for a number of weeks after the operation, as may changes in sleep and bladder or bowel function. Rare, long-term complications include low back pain, scoliosis or kyphosis (ie, spinal curves), and hip displacement.

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