Intraoperative transdural functional mapping. Technical note.

During craniotomy for supratentorial intraparenchymal space-occupying lesions, with the patient either under general anesthesia or awake, a smaller durotomy designed to expose only the region of resection may be desirable because of brain swelling. Similarly, during repeat craniotomy or craniotomy following cerebral injury or infection, pial-dural adhesions increase the risk of damage to essential cortex, making a limited dural opening desirable. Intraoperative transdural somatosensory evoked potentials and transdural cortical stimulation mapping permit localization of functional cortex prior to durotomy. These techniques can be combined with intraoperative transdural ultrasonography to identify topographical landmarks and borders of mass lesions.