Selective Dorsal Rhizotomy, 5/1994

A number of pediatric neurological surgeons are utilizing a surgical procedure to diminish spasticity (increased muscle tone) in children with cerebral palsy. The goals of the procedure are improvement in walking, increase in range of motion, and better body positioning; this latter for non-ambulatory persons requiring assistance with hygiene for body care.

The surgical procedure is done in the lower back region, principally to diminish tone in spastic muscles of the lower limbs. It involves identifying sensory nerve fibers just dorsal (posterior) to the spinal cord and then selectively cutting those nerve fibers (rhizotomy) ---"selective dorsal rhizotomy." The nerve fibers selected for cutting during surgery are those which when stimulated electrically are reported to generate unusual electrical activity. After part of its nerve supply is cut, the muscle usually has less tone (is less spastic) and may show temporary or permanent weakness. The surgery is always followed by other clinical procedures, often a program of intensive physical therapy for periods of three to six months.

Surgeons who use this procedure find it important that an expert team use specified criteria to evaluate any child being considered for surgical treatment of spasticity. The presurgical evaluation team is usually multi-disciplinary and uses a combination of clinical, laboratory and behavioral guidelines for evaluating the child. It generally requires assurances of the parent or other caregiver to adhere to the program of follow-up therapy. The presence of muscle-tendon contractures, a history of previous surgery, and/or hip displacement are considered by some physicians as contraindications to rhizotomy, particularly if the purpose of rhizotomy is to improve function such as walking.

A number of side effects of the procedure have been reported. One side effect is sensory loss, numbness or uncomfortable sensations in limb areas which the cut nerve supplied; however, these usually disappear. Another reported side effect is hip dislocation in children who had previous problems in hip alignment. Also, there are some reports of difficulty in bladder and/or bowel control after surgery. An important post-operative problem is patient discouragement, usually due to the length and intensity of the follow-up program of physical therapy.

Several "case series" have been published by individual pediatric neurosurgeons and physical medicine specialists on their clinical experience in using selective dorsal rhizotomy. There have also been a number of medical symposia in which these case series have been discussed. Most series report a decrease in muscle tone; however, there are mixed reports about the long term effects of selective dorsal rhizotomy on function. Some specialists report that if the patient is selected properly and follow-up therapy is adequate, the clinical results in their patients are good; other specialists report that limited clinical improvement in their patients does not justify the risks or complications of the surgery.

Controversial issues include: What is the biological rationale explaining why the procedure should be clinically useful? What are the characteristics of the person for whom the procedure should be used (age, contractures, previous therapy, neuromuscular laboratory findings, etc.)? Is there a meaningful and long term diminution in spasticity after surgery? Does the diminution in spasticity provide for improved function such as ambulation? What are the respective contributions to improvement of function of the surgical procedure and of the intensive follow-up care?

The majority of articles published about selective rhizotomy indicate its effectiveness in reducing muscle tone. However, there is still debate as to whether the long term benefits of the procedure justify the risks, cost, and expenditure of family resources. At this time, the available data indicate that selective dorsal rhizotomies decreases muscle tone (spasticity); however, there are inadequate data to support or reject the usefulness of selective rhizotomy to improve long term function in patients with disabilities due to cerebral palsy.

Some investigators are evaluating the usefulness of this procedure in controlled clinical trials of their patients. However, proper evaluation will probably require a larger number of persons participating in a trial than can be enrolled in any single institution. The UCP Research & Educational Foundation has urged the pediatric neurosurgical community to undertake a national cooperative study to evaluate the role and place of this neurosurgical procedure. Until an adequate controlled clinical trial is done, we won't know if selective dorsal rhizotomy is useful in the treatment of persons with disability due to spasticity associated with cerebral palsy.