Relative cerebral blood flow (CBF) < 30% has been identified as a predictor of infarct core on computed tomography perfusion (CTP). We investigated the relationship between CTP-predicted infarct core and diffusion-weighted imaging magnetic resonance imaging (DWI MRI). We conducted a retrospective analysis comparing infarct core (CBF < 30%; RAPID iSchemaView) and post-revascularization DWI MRI (ADC < 620 cc; RAPID iSchemaView) in patients with internal carotid artery (ICA) or proximal middle cerebral artery (MCA) stroke between November 2016 and May 2019. Included subjects had a modified Thrombolysis in Cerebral Infarction (mTICI) score of 2b or better and presented within 24 h of last known well (LKW) time. Two hundred one cases were identified. Mean duration from LKW time to CTP and MRI was 4.3 and 28.6 h, respectively. Median ischemic core volume was 8 cc, and median MRI infarct volume was 17 cc. CTP core volume showed fair correlation with MRI infarct volume (r = 0.294, p < 0.0001). There was a stronger association between CBF < 30% and DWI MRI in subjects presenting beyond 6 h (r = 0.359, p = 0.011). In a multivariate analysis, greater volumetric difference was associated with younger age (p = 0.001), longer duration from LKW time to revascularization time (p < 0.020), and longer CTP to revascularization time (p < 0.0001). Reduced relative CBF < 30% is a fair measure of infarct size within 24 h of anterior circulation, large artery occlusion (LAO) stroke when adequate reperfusion is achieved.
BACKGROUND
Elevated body mass index (BMI) is a well-known risk factor for surgical complications in lumbar surgery. However, its effect on surgical effectiveness independent of surgical complications is unclear.
OBJECTIVE
To determine increasing BMI’s effect on functional outcomes following lumbar fusion surgery, independent of surgical complications.
METHODS
We retrospectively analyzed a prospectively built, patient-reported, quality of life registry representing 75 hospital systems. We evaluated 1- to 3-level elective lumbar fusions. Patients who experienced surgical complications were excluded. A stepwise multivariate regression model assessed factors independently associated with 1-yr Oswestry Disability Index (ODI), preop to 1-yr ODI change, and achievement of minimal clinically important difference (MCID).
RESULTS
A total of 8171 patients met inclusion criteria: 2435 with class I obesity (BMI 30-35 kg/m2), 1328 with class II (35-40 kg/m2), and 760 with class III (≥40 kg/m2). Increasing BMI was independently associated with worse 12-mo ODI (t = 8.005, P < .001) and decreased likelihood of achieving MCID (odds ratio [OR] = 0.977, P < .001). One year after surgery, mean ODI, ODI change, and percentage achieving MCID worsened with class I, class II, and class III vs nonobese cohorts (P < .001) in stepwise fashion.
CONCLUSION
Increasing BMI is associated with decreased effectiveness of 1- to 3-level elective lumbar fusion, despite absence of surgical complications. BMI ≥ 30 kg/m2 is, therefore, a risk factor for both surgical complication and reduced benefit from lumbar fusion.
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