Progression of Scoliosis in Patients with Spastic Quadriplegia after the Insertion of an Intrathecal Baclofen Pump

Purpose: Many orthopaedic surgeons who treat spastic quadriplegic patients have noticed a trend of marked scoliosis progression after the administration of intrathecal baclofen (ITB) via subcutaneous pump and catheter. The purpose of this study is to quantify scoliosis progression in this patient population before and after baclofen administration and compare this to published natural history data.

Methods: To document the magnitude and rate of scoliosis progressions after the placement of an ITB pump, the charts and radiographs of eighteen consecutive nonambulatory patients with spastic quadriplegia and an ITB pump. To document rate of scoliosis progression, each patient had at least two pre- and two post-pump insertion spinal radiographs made. All radiographs were made with the patients in the supine position without orthoses. A board certified orthopaedic surgeon reviewed these radiographs. Skeletal maturity was assessed using Risser grading. Catheter tip location and rate of baclofen administration were recorded. Statistical analysis was done using Wilcoxon signed rank test for paired data.

Results: Average Cobb angles were 10.2 degrees before pump insertion and 25 degrees at an average of 31.6 months after pump insertion (p<0 .0001). The eighteen patients with at least two pre- and post-pump insertion radiographs had a mean rate of change their Cobb angles 1.825 degrees/year before pump 10.95 an average 34.6 months after (p="0.024)." These results represent six-fold increase in the curve progression insertion. There was no relationship between catheter tip location or Baclofen infusion on progression.

Discussion: In published data, the rate of progression of scoliosis in skeletally immature nonambulatory patients with cerebral palsy was 4.5 degrees/year. In this study, the average rate of progression of the scoliosis for the immature was 9.02 degrees/year. For the skeletally mature bed-ridden patients, the worst-case natural history progression was 4.4 degrees/year. The comparable rate of change in skeletally mature (Risser 5) nonambulatory patients (n=6) in this study was 28.4 degrees/year. This study demonstrates a significant increase in the rate of curve progression after ITB pump placement when compared with published natural history data. The evidence of the beneficial effects of ITB on spasticity has been confirmed, and as larger, prospective, randomized studies are conducted, the authors believe that support for continued use of this treatment will increase. However, early bracing and spinal fusion may be warranted to prevent significant increases in spinal deformity if scoliosis is anticipated to progress more than 10 degrees per year for patients with spastic quadriplegia and an ITB pump. The authors are now performing spinal fusions for curves that exceed 40 to 50 degrees in the presence of an ITB pump as recommended by previous reviews of scoliosis and accompanying quadriplegia.