There is no simple answer to a rare complication of inferior petrosal sinus sampling.

Bilateral inferior petrosal sinus sampling is the most reliable test to differentiate Cushing’s disease from ectopic adrenocorticotropic hormone (ACTH) production. Catheters, whether preshaped polyethylene or coaxial Tracker systems, are supple and atraumatic. Retrograde venograms are gentle procedures performed only to document catheter position at the time of sampling. And yet, as reported by Bonelli et al (page 306) in this issue of the American Journal of Neuroradiology, we continue to see the rare ischemic/hemorrhagic complication associated with this procedure. It is appropriate to report these rare complications to our colleagues; the question remains whether anything can be learned about their cause or prevention. Historically, it is of interest to note that the first large reported series of patients who underwent petrosal sinus sampling were studied by a tip-deflecting catheter guidewire handle system (1). Using this method, a probing guidewire was never advanced beyond the tip of the 4-French sampling catheter, and the sampling site tended to be relatively proximal in the inferior petrosal system. No complications were encountered in 312 consecutive procedures, and the sensitivity for distinguishing Cushing’s disease from ectopic ACTH-dependent hypercortisolism was 100% after corticotropin-releasing hormone (CRH) administration. Production of this catheter guidewire handle was discontinued in the late 1980s. Petrosal sinus sampling is currently performed with flexible catheters introduced over supple glidewires. Some groups routinely enter the petrosal system with only coaxial Tracker catheters, but both techniques involve probing for the inferior petrosal sinuses with guidewires over which the sampling catheter is subsequently positioned. Conversion to the use of finer wires and catheters permits more selective catheterization, but increases the risk of engaging small bridging veins that occasionally connect the inferior petrosal sinus with the brain stem. All reported ischemic/hemorrhagic complications of petrosal sinus sampling have occurred with such probing-wire catheters. One wonders whether more proximal sampling of the inferior petrosal sinuses might not lessen the risk of these ischemic/hemorrhagic complications with, in our experience, no loss of diagnostic sen-