Rates of CT myelography epidural contrast extravasation at puncture site by spinal needle type

BackgroundEpidural contrast extravasation (ECE) at the level of lumbar puncture site during CT myelography (CTM) is a noted phenomenon without determined clinical relevance. While prior randomized studies in spinal analgesia have shown benefits of pencil-type spinal needles compared to cutting-type for dural punctures, rates of ECE on imaging have not been closely studied, and no prior study has investigated the effect of spinal needle type technical factors on ECE rate.MethodsAll CTM cases over an 8-year period for any indication (e.g., spontaneous intracranial hypotension CSF leak evaluation) were retrospectively reviewed. A large series of cases (n = 276) were reviewed by two independent neuroradiologists for presence of puncture site ECE (n = 63), ECE extending at least one vertebral body level (n = 15), or no ECE (n = 198). Rates were compared by several technical factors including spinal needle type, gauge, and puncture site level.ResultsPencil-type spinal needles had significantly greater rates of any ECE (32%) versus cutting-type (25%, p = 0.030) and for ECE at puncture site only (25% vs. 20%, respectively) and ECE with extension greater than one vertebral body level (7% vs. 4%, respectively, p = 0.004). The rate of ECE did not differ by needle gauge, needle type/gauge combinations, or level accessed (p > 0.05). The need for post-dural puncture targeted epidural blood patch did not differ by presence of ECE (p = 0.190).ConclusionsThe rate of ECE in CTM was common (28% of cases) and occurred with slightly greater frequency with pencil-type spinal needles. As CTM and the use of pencil-type spinal needles become more prevalent in the investigation of spinal CSF leak, it is important to convey that asymptomatic ECE can be a common expected post-dural puncture finding with both pencil-type and cutting-type spinal needles and should not be confused for the site of leak when evaluating patients for spontaneous spinal CSF leak. Further, our results that immediate ECE do not correlate with symptomatic post-dural puncture headache differ from a recent retrospective series, and the imaging finding alone of ECE does not warrant further evaluation in an asymptomatic patient.