Imaging findings of spontaneous spinal epidural hematoma.

The imaging studies of 12 patients with spontaneous spinal epidural hematomas (SSEHs) who were treated from 1987 to 1995 at Chang Gung Memorial Hospital were retrospectively analyzed. The advantages and disadvantages of myelography, computed tomographic myelography (CTM) and magnetic resonance imaging (MRI) in diagnosing SSEH were evaluated. We found that in subacute and chronic stages of SSEH, MRI was the diagnostic choice because of its pathognomonic magnetic resonance signal changes. However, in the first 24 hours of SSEH, the MRI signal changes of hematomas were confused with those of epidural metastatic tumors or abscesses. In this situation, enhancement was not an absolute sign to rule out hematomas, because gadolinium enhancement of a hematoma did occur in one of our patients. CTM was helpful in this stage because a hyperdense epidural mass was always noted. In conclusion, we found that MRI offers a noninvasive and specific diagnosis of SSEH, though it has some pitfalls in the first 24 hours of SSEH. CTM with sagittal reformations also provides a specific diagnosis, especially when a hyperdense mass is seen. By combining these diagnostic imaging modalities and clinical manifestations, an early diagnosis of SSEH is possible.