Study Examines Benefits of Neurosurgical Procedure

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A major study on selective dorsal rhizotomy – a complex, neurosurgery used to improve walking in some children with cerebral palsy – suggests that it may not be more effective than a series of orthopedic surgeries used to treat the same problem.

The Bloorview MacMillan study – the first to compare long-term outcomes of kids who had dorsal rhizotomies with those who didn’t – found children who had the surgery were four times less likely to need multiple orthopedic surgeries. But their walking ability was not better than that of children who had only orthopedic surgeries when the two groups were compared seven to eight years later.

Dr. Golda Milo-Manson, pediatrician and lead investigator of the study at Bloorview MacMillan Children’s Centre, reported the results of the study last month at the American Academy for Cerebral Palsy and Developmental Medicine Conference in New Orleans, La. She said the study begs for further research evaluating the costs and benefits of putting a child through one dorsal rhizotomy procedure or a number of orthopedic interventions aimed at improving walking. “Is it better to have one surgery at age four to six that involves intense rehabilitation and time away from family and school, or to have three surgeries with less recovery time between the ages of six and 12? We need to compare the complication rates and therapeutic price of dorsal rhizotomy to those associated with having a series of orthopedic surgeries.”

While previous studies demonstrated that dorsal rhizotomies significantly improve the walking ability of a select group of children with cerebral palsy, “they weren’t long-term, and we wanted to understand what happens to these children seven to eight years after undergoing this intensive procedure,” Dr. Milo-Manson says.

The purpose of a dorsal rhizotomy – “dorsal” means at the back and “rhizotomy” means to cut nerves – is to permanently reduce spasticity or tightness in the legs by cutting nerve roots at the back of the spinal cord. These roots transmit sensation from the muscles to the spinal cord. In typical children, the brain reduces the intensity of this information before sending messages back to the muscles about how to move. In children with cerebral palsy, the brain’s ability to inhibit sensory information is reduced, causing messages to be echoed back to the muscle repeatedly. This causes increased muscle tone or tightness, unintended movement, and an awkward walking gait.

A dorsal rhizotomy is a long, complex neurosurgery that involves identifying over-active nerves and cutting about half of the most problematic ones. The procedure is usually targeted to children with moderate cerebral palsy affecting only the legs, because good trunk control is necessary to achieve the best results. Following the surgery, children typically spend one week in an acute-care hospital, then six weeks as an inpatient or day patient at a rehabilitation facility, where they begin rigorous, daily physical and occupational therapy. This is followed by six months of multiple therapy visits a week. Intense rehabilitation is needed because “once the spasticity is removed, the child needs to learn how to use his or her muscles in a different way, and to rebuild underlying strength,” Dr. Milo-Manson says.

Her study compared 10 children who had dorsal rhizotomies at age four to six, with 10 who hadn’t. The children were similar in age (average age of 12 1/4 years during the study) and severity of cerebral palsy. Their current ability to perform skills such as sitting, standing, walking and running was evaluated using the Gross Motor Function Measure. All of the children had been scored using this outcome measure as young children, providing a baseline against which follow-up results seven to eight years later could be compared. In addition to evaluating their current level of functioning, researchers analyzed the children’s gaits and degree of spasticity, had parents fill out a questionnaire about their child’s abilities, and reviewed medical charts.

The study found that the walking abilities of both groups of children had improved significantly over the seven-to eight-year period studied, but “they tended to improve the same amount,” Dr. Milo Manson says. “There wasn’t a statistically significant difference between the groups in their ability to walk.”

What was striking was that the children who didn’t have dorsal rhizotomies were four times as likely to have received orthopedic surgeries. “A total of 16 orthopedic interventions were performed on nine of the 10 children in the control group, with most children receiving two surgeries and two receiving three,” says Dr. Milo-Manson. “In contrast, a total of four orthopedic surgeries occurred in the rhizotomy group, with four children receiving a single surgical procedure.”

The children who didn’t have rhizotomies had orthopedic surgeries that involved lengthening tendons and muscles and reconstructing hips – all in efforts to improve their ability to walk. Dr. Milo-Manson says that it’s likely that the children who didn’t have rhizotomies were walking as well as those who did “because of these orthopedic surgeries. Other factors would include the therapy they were getting and natural improvement we would expect over time.”

It’s also possible that improvements in the quality of how the children with rhizotomies walked weren’t picked up by the outcome measure used in the study. “The measure looks at whether or not a child can do a particular function – such as walk across the room – not whether the child stands straighter while walking, or walks more smoothly,” says Virginia Wright, outcome measures coordinator at Bloorview MacMillan, and one of the study’s investigators. “These are things that may well improve after a rhizotomy procedure.”

Dr. Milo-Manson notes that most families of children who had the rhizotomy felt their child had benefited from it, and that they would choose to do the procedure again.

She says the study will “make physicians more selective in the children they recommend for the procedure. Only those with good trunk control, who are already walking independently or with assistive devices, and who can comply with the intense rehabilitation needed, will be candidates. These are the children who will gain the most in improved function.”

What is needed now, she says, is a study comparing the costs and benefits of a dorsal rhizotomy with the typical orthopedic surgeries used to improve walking in children with cerebral palsy. The study would need to compare the complications, time away from school for rehabilitation, and impact on families associated with each.