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 (p<0.05). Also, larger dural sac areas were determined in group H+ (1.90cm2) compared to Groups C (1.80 cm2) and D (1.60 cm2) but the difference reached no statistical significance (p=0.078). In preoperative JOA scores, there were no significant differences among groups (p>0.05). 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<0.05).
Conclusion: It seems that the narrower the preoperative dural sac area, the better the clinical symptoms of the patients with SEHs based on our new MRI-based classification system. This classification may be useful to predict the clinical status of these patients at one-year follow-up.
Level of Evidence: Level IV, Diagnostic study
Cite this article as: Merter A, Shibayama M. A new classification for spinal epidural hematoma following microendoscopic decompressive laminotomy: A prospective clinical and magnetic resonance imaging study of 245 patients. Acta Orthop Traumatol Turc 2020; 54(6): 596-603.