The keyhole concept in neurosurgery.

OBJECTIVE: Improvements in preoperative diagnostic imaging as well as in microsurgical techniques significantly advanced the development of transcranial neurosurgery, allowing the treatment of complicated diseases through smaller and more specific approaches.
METHODS: In this article, authors overviewed their experience in transcranial endoscope-assisted microsurgery, using limited-sized keyhole craniotomies. Over a 10-year period, authors treated more than 3000 patients according to the transcranial endoscope-assisted microsurgery concept, advanced by the pioneer of minimally invasive neurosurgery, Axel Perneczky. RESULTS AND
CONCLUSION: In all cases, meticulous preoperative planning was done for determining the site, size, and optimal placement of the craniotomy as well as the trajectory toward the surgical target. Most importantly, the surgical approach was performed either completely or at least under permanent presence of the responsible senior surgeon from the moment of patient positioning until wound closure. The minimally invasive keyhole approaches allowed safe intraoperative control and adequate dealing with intracranial lesions. Essential preconditions for keyhole surgery were 1) careful selection of cases, 2) accurate preoperative planning, 3) placement of the craniotomy tailored to the individual case, and 4) intraoperative use of transcranial endoscope-assisted microsurgery techniques. Advantages of intraoperative endoscopic visualization were increased light intensity, extended viewing angle, and clear depiction of details even in hidden parts of the surgical field.