Introduction: Use of interspinous process devices is relatively new, less invasive surgical method managing mild-moderate lumbar stenosis symptoms (LSS). Symptomatic relief is not seen in all undergoing this procedure. MRI parameters (dural cross-sectional area and nerve root sedimentation) used to predict success of clinical outcomes in patients with symptomatic LSS. We determined feasibility of nerve root sedimentation signs to predict long-term clinical outcomes in interspinous process device implanted patients with LSS.
Methods: Prospective multicenter FDA IDE (Superion™ and X-STOP®) database used. Interspinous process implanted patients (n=177) were aged >45, suffered moderate symptoms of neurogenic intermittent claudication secondary to diagnosis of LSS at one or two contiguous levels from L1 to L5. Axial T2 weighted MRI images used to find nerve root sedimentation sign. Positive nerve root sedimentation sign is absence of normal nerve root sedimentation in at least one axial T2 weighted MRI sequence image (at level above or below). Preoperative, 1 and 2 year postoperative clinical outcomes measured using Oswestry Disability Index (ODI). Patients grouped based on nerve root sedimentation (positive/negative) and compared clinical outcomes.
Results: Group 1 had positive sign: absent nerve root sedimentation(n=116); Group 2 had negative sign: normal nerve root sedimentation (n=61). No statistical difference in preoperative ODI values seen between groups. High clinical and statistically significant ODI improvement seen from preoperative to 2 year follow-up for Group 1 (17 point gain; p<0.0001) and Group 2 (22 point gain; p=<0.0001). Six-week, 1 and 2 follow-ups, statistical difference between Group 1 and Group 2 (p=0.012, p=0.04, p=0.039, respectively) seen, but differences just reached statistical significance and mean difference in ODI values small, at ~ 6, which is at edge of clinical relevance.
Conclusions: Good clinical improvement in ODI from preoperative occurred in both with and without positive nerve root sedimentation sign. Differences between groups, although statistical, were not clinically meaningful.
Patient Care: If nerve root sedimentation signs, then the surgeon will be able to predict the clinical outcome of the patient and provide better care and treatment.
Learning Objectives: By conclusion of the session, participants should be able to know,
1.Clinical improvement was noticed in both abnormal and normal nerve root sedimentation patients in patients who were managed by interspinous process devices for symptomatic lumbar stenosis.
2. Thought the clinical improvement was statistically different between both abnormal and normal nerve root sedimentation patients, but clinically not meaningful.