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Neuroradiology Case of the Week

Case 70

Ravinder Sidhu MD, Leena Ketonen MD, PhD
and P-L Westesson MD, PhD, DDS

Clinical Presentation: A 15-year-old post-partum patient with eclampsia had epidural anesthesia and presented with sudden onset right lower extremity weakness.

Radiological Findings:  Sagittal T1-weighted MR image of lumbar spine showed a focal isointense lesion of approximately 1x1 cm size posteriorly at L3/4 level and is seen to compress upon the cauda equina (Fig.1A). Sagittal T2-weighted MR image revealed the lesion to be of hypointense nature (Fig.1B).

Diagnosis: Spinal epidural hematoma

Discussion:  Spinal epidural hematoma is a rare condition which can present with acute spinal cord compression. Spinal hematoma may be spontaneous or related to trauma, anticoagulant therapy, blood dyscrasias, vascular malformations, epidural anesthesia, surgery or lumbar puncture. Rarely, spinal epidural hematoma may be associated with cervical spondylosis and systemic lupus erythematosis [1]. There is no sexual predilection. The estimated incidence of spinal epidural hematoma is 1 in 150,000 following epidural anesthesia and 1 in 220,000 after spinal anesthesia [2].
    The pathogenesis of spinal epidural hematoma is controversial, however, it is postulated that the valveless nature of rich venous plexus in epidural space predispose them to bleed with minor trauma. Spinal epidural hematomas may present with back pain, radiculopathy, weakness or spinal cord compression. There is however no distinctive clinical signs pathognomic for epidural hematoma.
    Prior to the advent of MR imaging, myelography and CT were used to evaluate spinal epidural hematoma. The findings mimicked those of a large extruded or free fragment disk herniation. MR imaging can differentiate between the adjacent but dissimilar tissues and can image in three planes. MR imaging is considered as the modality of choice. Sagittal MR imaging typically shows hematoma in the posterior epidural space with well-defined borders tapering superiorly and inferiorly. The dura matter separates the hematoma from the spinal cord on T1 and T2-weighted images [3]. In acute stage (within 24 hr of onset), the epidural hematoma is usually iso-intense on T1-weighted image. On T2-weighted image, there may be homogeneous high-signal or inhomogeneous areas of mixed high and low-signal. After 24 hours, there is usually a high-signal on T1-weighted images; T2-weighted images in most cases give the same signal as that of cerebrospinal fluid [2].
    Spinal epidural hematoma needs to be differentiated from epidural metastases, epidural abscess and extruded or migrated disk fragment. A careful history and MR imaging findings may help to narrow the differential diagnosis. Prompt surgical evacuation is the treatment of choice in spinal epidural hematomas.

References:

1. Ng WH, Lim CC, Ng PY, Tan KK. Spinal epidural haematoma: MRI-aided diagnosis. J Clin Neurosci. 2002; 9:92-4.
2. Haljamae H. Thromboprophylaxis, coagulation disorders, and regional anaesthesia. Acta Anaesthesiol Scand. 1996; 54:1024-40.
3. Dorsay TA, Helms CA. MR imaging of epidural hematoma in the lumbar spine. Skeletal Radiol 2002; 31:677-685.