Spinal subdural and epidural haematoma
Spinal subdural haematoma due to trauma, or occurring as a result of lumbar puncture in patients who are anticoagulated or thrombocytopaenic, are rare causes of acute cord compression.
Spontaneous epidural haematoma, usually occurring in the thoracic region (Hernandez et al. 1982) is also rare, but is a surgical emergency; sometimes bleeding is due to a vascular malformation and sometimes no cause is ever discovered.
Haematomas more than a few days old produce a characteristic high signal on T1-weighted MR images due to the paramagnetic effects of methaemoglobin.