What is the maximum patient age at which an interventional radiologist should attempt to use ultrasound to complete a lumbar puncture in a child after other modalities have not been successful?—KIRBY MEYER, PA-C, Seattle

I spoke with two neurointerventionalists, and neither knew of a maximum age for the use of ultrasound in the event of unsuccessful lumbar puncture. Although primarily used in neonates, in capable hands ultrasound can be used in patients older than age 18 years.

The clinician is simply looking for the interlaminar space, and bone can easily be seen on ultrasound. Fluoroscopy is often the imaging modality of choice for difficult cases.—Deborah Semmel, FNP-BC, Duke University Medical Center, Division of Interventional Radiology, Durham, N.C. (185-3)



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