A new classification for spinal epidural hematoma following microendoscopic decompressive laminotomy: A prospective clinical and magnetic resonance imaging study of 245 patients

Objective: The aim of this study was to develop a new radiological classification system for postoperative spinal epidural hematoma (SEH) using magnetic resonance imaging (MRI) and to determine the correlation of this classification system with clinical and radiological outcomes. Methods: This prospective study included a total of 245 consecutive patients (126 females, 119 males; mean age=72 years; age range=39-91 years) with single level spinal stenosis who were treated by microendoscopic decompressive laminotomy (MEDL). MRI was performed for all patients 24 hours postoperatively and at 12 months. SHEs were categorized into four grades using our new MRI-based classification system based on the measurement of dural sac area: Grade A, small hematoma with a round shape; grade B, small hematoma that show no round shape; grade C, moderate hematoma; grade D: severe hematoma. Patients were then divided into four groups according to their hematoma grades, Group A, 107 patients with grade A hematomas; group B, 47 with grade B; group C, 67 with grade C; group D, 24 with grade D. Also, patients who had neurological deterioration or who pain resistant to medical treatment were treated surgically, and those were assigned to group H+(14 patients). The study, therefore, contained five groups. Clinical evaluation was done using Japanese Orthopaedic Association (JOA) score preoperatively and at 12 months postoperatively. Results: No significant difference existed among groups in the preoperative median measurement of the dural sac area, which were 0.90 cm2 in group A, 0.80 cm2 in group B, 0.70 cm2 in group C, 1.1 cm2 in group D, and 0.80 cm2 in group H+ (p=0.076). At the postoperative 12-month measurement, no significant difference was noted among groups A (2.05 cm2), B (1.80 cm2 ), and H+ (1.90cm2) (A vs B: p=0.891, A vs H+: p=0.089, B vs H +: p=0.933). The measurements were greater in groups A and B than in groups C and D (p0.05). At 12-month JOA scores, no significant difference was observed between groups A and B (p=0.061) and between groups C and D (p=0.511). The scores were higher in groups A and B than in groups C and D (p

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