Experimental intraoperative localization of retained intracerebral bone fragments using transdural ultrasound.

Precise intraoperative localization of retained bone fragments and foreign bodies avoids extensive brain disseciton, cerebral edema, damage to vital structures, incomplete debridement, and prolonged surgical procedures. Such localization after head trauma is often hampered by cerebral distortion, previous incomplete debridement, fragment migration, and surgical draping. Our intraoperative technique of transdural A-scanning using aspiration-biopsy transducers precisely localized 3.5-mm fragments without damage to underlying cortical tissue and vessles. Transdural A-mode echoencephalography was found to be more reliable for intracerebral depth estimations but epidural B-mode sonography was more useful for determining the size of fragments. Transdural ultrasound offered an intraoperative alternative to stereotaxic localization of retained bone fragments in experimental head trauma.