Dinosaur tail sign on spinal MRI in a patient with postdural puncture headache

Description

A 68-year-old man presented with cognitive impairment, urinary incontinence and short step gait. These symptoms, together with brain MRI finding, suggested idiopathic normal pressure hydrocephalus. After a spinal tap test to confirm the diagnosis, he suffered from postdural puncture headache. Despite an equivocal finding on spinal MR myelography (MRM), lumbosacral fat-suppressed T2-weighted image (FST2WI) clearly showed the characteristic 'Dinosaur tail sign' indicative of cerebrospinal fluid (CSF) leakage (figure 1).1 This pathognomonic sign disappeared on symptom improvement (figure 1).

Figure 1

Serial MRM and FST2WI before (A, D) and after a dural puncture (B, C, E, F). In contrast to subtle paraspinal hyperintensities on MRM (arrows, B), sagittal FST2WI shows characteristic dorsal epidural fat tissues demarcated by interspinous arched hyperintensities (dash lines, E) contributing to the 'Dinosaur tail sign' and slight epidural hyperintensity (arrowhead, E). Pathognomonic signal changes disappear on...

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