A 70-year-old male presented with twelve hours of progressive lower limb weakness, saddle anesthesia and urinary incontinence. He had undergone a diagnostic lumbar puncture three days previous to the onset of symptoms. The lumbar puncture was performed as part of a diagnostic workup of progressive bulbar symptoms.

MR of the lumbosacral spine was performed. This demonstrated subarachnoid T2 hypointensity extending from the L3 vertebral body level to the filum terminale (see sagittal and axial T2 sequences). This subarachnoid lesion is T1 isointense to the spinal cord. There is severe compression of the nerve roots at this level. The appearances are consistent with an acute spinal cord subarachnoid hemorrhage with an associated cauda equina syndrome.