Stability-preserving decompression in degenerative versus congenital spinal stenosis: demographic patterns and patient outcomes.

Abstract Background Context: Although lumbar spinal stenosis often presents as a degenerative condition, some patients present with symptoms from lifelong narrowing of the spinal canal. These patients have congenital stenosis (CS) and present with symptoms of stenosis at a younger age. CS patients often have a distinct pathophysiology with fewer degenerative changes but present with multi-level involvement. In the setting of neurological symptoms, decompression-alone while preserving stability, has been proposed for both patient populations. Purpose The purpose of this study is to evaluate if the different etiology for narrowing in CS and DS results in a different natural history of pain progression, different locations requiring decompression, and different outcomes following a stability-preserving decompression procedure. Study Design/Setting Retrospective Cohort Study Patient Sample: We retrospectively reviewed consecutive patients of a single surgeon with degenerative stenosis or congenital stenosis who underwent surgical decompression without fusion between 2008-2014. Patients were excluded if they had undergone a previous lumbar surgical procedure (decompression and/or fusion) or follow-up less than 12 months. Outcome Measures Pre- and postoperative clinical outcome scores including Visual Analogue Scale (VAS) and Oswestry Disability Index (ODI) were recorded. Post-operatively, data was collected regarding complications, the presence of new radicular or myelopathic symptoms, and necessity of re-operation in the lumbar spine. Methods Demographic information included: age, sex, body mass index, smoking status, and Charleston Comorbidity Index (CCI). Pre-operative clinical symptoms as well as the presence of lower extremity radiculopathy and claudication were evaluated. Patients were determined to have a diagnosis of congenital stenosis by the treating surgeon if primary radiographs revealed shortened pedicles and decreased cross-sectional area of the spinal canal as detailed by previous studies. Binary outcomes were compared between congenital and degenerative cohorts using bivariate and multivariate logistic regression. Multivariate regressions controlled for baseline patient and operative characteristics. Results The average age of the degenerative stenosis cohort was 66.7 +/- 10.7 years, while 47.1 +/- 9.2 years for the congenital stenosis group. Average follow-up was 27.6 month. The degenerative stenosis patients had significantly more comorbidities as shown by the CCI (2.8 +/-1.6 vs. 0.5 +/- 0.6); p Conclusions CS and DS patients respond well to decompression-alone, without a supplemental fusion, despite differences in pain experience and presentation. The localization of pathology requiring decompression is similar. The DS patients were more susceptible to require another operation resulting in a fusion, which confirms the theory that initial microinstability can progress in DS, but is likely not part of the disease process in CS. At just over 2 years after decompression, CS patients may not need to be treated by a fusion in the setting of lower back pain, however longer-term follow up is necessary to further assess these outcomes.