The lumbar sedimentation sign: spinal MRI findings in patients with subarachnoid haemorrhage with no demonstrable intracranial aneurysm.

We present a new MRI finding within the lumbar spine in a series of six patients admitted with CT proven subarachnoid haemorrhage (SAH) where cerebral angiography demonstrated no aneurysm and who had not had a lumbar puncture. A retrospective audit of 130 patients presenting to a regional neurosciences centre over a 13 month period with a suspected diagnosis of SAH was performed. Seven patients with proven SAH underwent MRI of the lumbar spine during the same admission. In six of these patients layering of haemorrhagic blood products was demonstrated within the lumbosacral spine. The process is analogous to the previously ubiquitous bedside erythrocyte sedimentation rate assay and has has been termed the "lumbar sedimentation" sign. This finding has not previously been reported in the literature in relation to SAH. While this is a small unselected group it may provide a useful adjunct in the diagnosis of SAH.