A 71-year-old male with lumbar spinal stenosis developed exacerbation of lower back pain and leg paresthesias while attempting to undergo a spinal magnetic resonance imaging (MRI) scan in the supine position. After undergoing sedation for the MRI, he developed an acute cauda equina syndrome that required surgical decompression. MRI may be contraindicated in the supine position for patients with spinal stenosis and back pain exacerbated by mild-to-moderate extension, since it may further compress the neural tissue.