Spontaneous Spinal Epidural Hematoma: A Study of 55 Cases Focused on the Etiology and Treatment Strategy.

Background Spontaneous spinal epidural hematoma (SSEH) is a rare neurologic emergency of the spinal cord. Its cause and treatment strategy remain controversial. This study aimed to evaluate a significant cause of SSEH and to discuss the treatment strategy according to the clinical outcomes of patients in 2 institutions. Methods Fifty-five cases of SSEH treated at our institutions between February 2002 and February 2016 were retrospectively analyzed. Results The mean age of the first SSEH onset was 31.8 years. The follow-up rate was 72.7%, with 28 patients (70%) showing satisfactory clinical outcomes. Forty patients received preoperative spinal digital subtraction angiography. Spinal epidural (extradural) arteriovenous fistula was detected in 6 patients (15%), 5 of whom showed 1 type of special slow-flow shunt. Nineteen patients (34.5%) suffered from multiple episodes until they underwent invasive treatments or last follow-up. Rebleeding was confirmed in 8 patients. None of the patients had a subsequent episode or rebleeding after invasive treatment. The risk factors for poor clinical outcome included advanced age at initial onset ( P  = 0.020), a short progression interval ( P  = 0.030), no symptom relief after admission ( P  = 0.011), hypesthesia ( P  = 0.017), complete spinal cord injury ( P  = 0.001), and hematoma below the T4 level ( P  = 0.014). Conclusions Spinal epidural (extradural) arteriovenous fistula is a significant cause of SSEH. Standard spinal digital subtraction angiography is necessary for patients with SSEH. Conservative treatment could not prevent occurrence of multiple episodes or rebleeding in patients. Microsurgery should be recommended as the preferred treatment strategy for SSEH. Endovascular embolization is also recommended if applicable.