P51. The effect of structural spinal deformities on the effectiveness of spinal cord stimulators

BACKGROUND CONTEXT Neural modulation via spinal cord stimulators (SCS) has become an accepted technique for the treatment of a variety of chronic pain syndromes. A concept akin to the placement of these devices (regardless of manufacturer) in most cases is the desire to ensure accurate midline positioning of the paddle lead in the thoracic spine. Midline positioning allows for flexibility of unilateral or bilateral coverage of pain patterns in patients. The presence of structural spinal deformities such as scoliosis or kyphosis often implies some degree of coronal, sagittal and rotatory deformity. To date, no study has examined the relationship of thoracic scoliosis/kyphosis and outcomes after permanent SCS placement. PURPOSE This study looks to ascertain if the presence of structural thoracic deformities affects outcomes of permanent SCS placement. STUDY DESIGN/SETTING This retrospective chart review included patients who underwent permanent SCS placement at our suburban hospital. Spinal imaging for each patient was reviewed, and scoliosis and thoracic kyphosis angles were recorded. The effect of each structural deformity on the change in NRS, ODI, and narcotic medication usage from baseline was analyzed. PATIENT SAMPLE Only patients with lumbar radiculopathy who were treated with a SCS placed by a fellowship trained orthopedic surgeon or neurosurgeon were included in our study. Patients who had previous SCS placed, were having other surgeries while having their SCS placed, or did not have spinal imaging taken that allowed the angular measurement of structural curves were excluded. OUTCOME MEASURES For each patient, demographic information, numerical rating system (NRS) pain scores, Oswestry Disability Index (ODI) scores, and narcotic medication usage as reported by our online state narcotic drug monitoring program were recorded at baseline and after permanent stimulator placement. METHODS Spinal imaging for each patient was reviewed, and scoliosis and thoracic kyphosis angles were recorded. The effect of each structural deformity on the change in NRS, ODI, and narcotic medication usage from baseline was analyzed. RESULTS A total of 100 patient charts were included in our cohort. Sixty percent of our population was female, with a roughly even age distribution ranging from 37 to 90 years of age. The average scoliotic Cobb angle was 11.0 degrees and kyphotic scoliotic angle was 39.2 degrees. Overall, 43% of our cohort had scoliosis and 30% had thoracic kyphosis. There was no significant difference in change in NRS scores, ODI scores, or narcotic usage between patients with scoliosis and those without scoliosis (p=0.86, p=0.81, p=0.64) or patients with kyphosis and those without (p=0.71, p=0.31, p=0.62). Univariate linear regression analysis showed that scoliotic angle and kyphotic angle were not significant predictors of change in NRS score (p=0.46, p=0.12), ODI score (p=0.48, p=0.06), or narcotic usage (p=0.93, p=0.56). Multivariate linear regression also showed that scoliotic angle and kyphotic angle were not significant predictors of NRS (p=0.482, p=0.304), ODI (p=0.116, p=0.161), or narcotic pain usage (p=0.644, p=0.735) either. CONCLUSIONS Spinal cord stimulators can be effective options for treating lumbar back pain and radiculopathy, even in patients with structural deformities such as thoracic scoliosis or kyphosis. Our study suggests that the presence of structural deformities does not adversely affect outcomes of permanent SCS placement and as such should not preclude this population from benefiting from such therapies. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.