SPINAL DEFORMITIES AFTER SELECTIVE DORSAL

Objective: Selective dorsal rhizotomy (SDR) used for spasticity treatment could worsen or develop spinal deformities. Our goal is to describe spinal deformities seen in patients with cerebral palsy (CP) after being treated by SDR. Methods: Retrospective study of patients operated on (SDR) between January/1999 and June/2012. Inclusion criteria: spinal Rx before SDR surgery, spinography, and assessment at follow-up. We evaluated several factors emphasizing level and type of SDR approach, spinal deformity and its treatment, final Risser, and follow-up duration. Results: We found 7 patients (6 males): mean age at SDR 7.56 years (4.08-11.16). Mean follow-up: 6.64 years (2.16-13), final age: 14.32 years (7.5-19). No patient had previous deformity. GMFCS: 2 patients level IV, 2 level III, 3 level II. Initial walking status: 2 community walkers, 2 household walkers, 2 functional walkers, 1 not ambulant, at the follow-up, 3 patients improved, and 4 kept their status. We found 4 TL/L laminotomies, 2 L/LS laminectomies, and 1 thoracic laminectomy. Six spinal deformities were observed: 2 sagittal, 3 mixed, and 1 scoliosis. There was no association among the type of deformity, final gait status, topographic type, GMFCS, age, or SDR approach. Three patients had surgery indication for spinal deformity at skeletal maturity, while those patients with smaller deformities were still immature (Risser 0 to 2/3) although with progressive curves. Conclusions: After SDR, patients should be periodically evaluated until they reach Risser 5. The development of a deformity does not compromise functional results but adds morbidity because it may require surgical treatment.


INTRODUCTION
Rhizotomy of the dorsal or posterior root to treat spasticity was performed for the first time at the beginning of the 20th century, 1 based on the hypothesis that the rigidity would disappear after section of the dorsal roots.
The surgical procedure can be accomplished using the techniques popularized by Peacock, in which laminectomies of L1 to L5 are performed, and by Fazano, which consists of a single laminectomy of T12 and L1. 2 A third variant is that of Park 3,4 involving less removal of bone.
Although the procedure is recognized as useful and approved for use, [5][6][7] there is not yet a universal consensus around patient selection criteria. 8,9Furthermore, little is known about the effect of rhizotomy on the development or the progression of spinal deformity.The treatment of spasticity by selective dorsal rhizotomy (SDR) could worsen or develop spinal deformities.
Our objective in this study was to describe the spinal deformities observed in a group of patients diagnosed with cerebral palsy, after having undergone selective dorsal rhizotomy.

METhODS
We conducted a retrospective evaluation of patients diagnosed with cerebral palsy, who had undergone laminectomies or laminotomies for selective dorsal rhizotomy between January 1999 and June 2012 (13 and a half years).The critical selection criteria were the existence of pre-rhizotomy spinal radiographs and spinography and a complete final follow-up assessment.(Figure 1) The following parameters were evaluated for each case: etiology, sex, topographical and physiopathological type of cerebral palsy, GMFCS classification, presence of pre-rhizotomy extraspinal orthopedic deformities, ambulatory state pre-rhizotomy and at the last control visit, age at the completion of surgery, pre-and post-rhizotomy spinal deformity, level of the laminectomy, post-rhizotomy spinal deformity treatment, appearance of orthopedic deformities following the rhizotomy, degree of bone maturation (according to the Risser sign) at the last control visit, and post-rhizotomy follow-up time.The Phelps, 10 Hoffer et al., 11 and Palisano et al. 12 classification systems were used.
Because this was an observational investigation with no linkable data and no patient risk, since only clinical records and complementary studies were used, and because the absolute protection of the privacy and total confidentiality of the subjects and their data were guaranteed, neither an approval by the Institutional Review Board nor a signed informed consent form were required by the institution where the study was conducted.

RESULTS
We identified 8 patients, of whom 7 could be completely evaluated: 1 female, 6 males, with an average age of 7 years 7 months at the time of surgery (ranging from 4 years 1 month to 11 years 2 months).
Given the small sample, it was impossible to draw statistically valid conclusions from the analyses.We were only able to give our impressions and identify certain trends.
Four patients had spastic diplegia, one had spastic triplegia, one had spastic quadriplegia, and one had mixed diplegia.None of the patients presented any spinal deformity prior to the rhizotomy.
Six of the 7 patients had suffered perinatal anoxia-hypoxia.According to the GMFCS, 2 patients were level IV, 2 were level III, and 3 were level II.The pre-rhizotomy ambulatory states of the patients were 2 community ambulatory (CA), 2 household ambulatory (HA), 2 functional ambulatory (FA), and 1 non-ambulatory (NA).At the end of follow-up, 3 patients had improved their ambulatory status and 4 had maintained theirs: 4 patients as CA, 1 as HA, and 2 as FA (1 HA progressed to CA, one FA progressed to CA, and 1 NA progressed to FA). (Tables 1 and 2) All had associated pre-rhizotomy extraspinal orthopedic deformities, but 5 also had deformities that appeared later.
The average post-rhizotomy follow-up was 6 years and 8 months (ranging from 2 years 2 months to 13 years) and the average age at end of follow-up was 14 years and 4 months (ranging from 7 years 6 months to 19 years).
At the end of follow-up, we detected significant spinal deformities in 6 of the 7 patients and an insignificant frontal curve (9 º ) in 1 of the 7 patients.Two patients had strictly sagittal deformities (one lumbar hyperlordosis of 90 º and one thoracolumbar hyperkyphosis of 75 º ), 3 patients had mixed deformities (    lumbar scoliosis of 17 º ]), one patient had a left lumbar scoliosis of 31 º , and the last patient had a right TL curve of 9 º .We found no obvious association between the type of deformity and the ambulatory state at the end of follow-up, or the topographical type of CP, or the GMFCS level, or the age at the time of the SDR, or the technique of approach for the SDR, or the level of the SDR approach.Two patients had to be treated surgically, 2 were treated with TLSO (one failed and was indicated for surgery and the other is still at Risser 1), and 3 received no treatment other than rehabilitation (patients with Risser 0 to 2/3).We found no association between age at the time of the rhizotomy and the type of curve, but the degree of bone maturation seemed to influence the degree of curve severity.Thus, if we compare the severity of the deformities (using the need for surgery as the criterion) against the degree of bone maturation (according to the Risser sign), we see that the 3 patients with severe deformities were rated Risser 4 or 5, while the remaining patients with less serious deformities were still skeletally immature (Risser 0 to 2/3), though 2 of these 3 had curves in a state of evolution.(Table 3)

DISCUSSION
Although selective dorsal rhizotomy (SDR) has been effective in reducing spasticity in children with spastic cerebral palsy, 5,[13][14][15][16][17] its long-term effects on the musculoskeletal are still unknown, 18 a fact that gains importance due to the permanence of the neurological change produced by the rhizotomy. 7As regards to the spine, hyperlordosis, scoliosis, spondylolysis, and spondylolisthesis have been documented following a rhizotomy. 19Hyperlordosis, present in one of our patients, is referenced as the most common and most difficult to manage secondary deformity. 2,20,21(Figure 2) It is not clear whether the prevalence of these conditions is greater than in children with spastic cerebral palsy who have not undergone rhizotomy, 22 but several retrospective 19,23 and prospective 21 studies appear to suggest it.
4][25] Turi and Kalen 23 reported scoliosis in 12 out of 42 patients, most of whom were non-ambulatory, and none of whom had a preexisting deformity.In our study, we observed spinal deformity in 6 out of 7 patients, all ambulatory, strikingly different from other studies. 22In our cases, sagittal deformities were the most common, whether standalone or associated with others.(Figure 3) Only one case presented a scoliotic curve without a more serious sagittal deformity.Like the Johnson et al. series, 21 there were no differences between the patients who underwent more or less conservative procedures (laminotomies versus laminectomies).

Table 2 .
Ambulatory state pre-rhizotomy and at end of follow-up.

Table 3 .
Relationship between age at performance of rhizotomy, severity of the deformity, and Risser at the end of follow-up.