✓ A laboratory technique that allows strain measurements of the skull is described. Holographic interferometry allows the entire surface displacement of the skull to be mapped within 1/10 of the wavelength of light. Holographic interferometric pictures are presented following various stress applications to the skull. The method, besides being exquisitely sensitive, allows strain measurements simultaneously in any desired direction over the entire skull. No physical contact with the skull is required, and the experimental set-up is simple.
Robert F. Spetzler and Hartmut Spetzler
Arteriovenous malformation grading system
Robert F. Spetzler
Robert F. Spetzler
✓ A new fixation technique for bone flaps is described. This technique avoids the use of hardware external to the skull in hairless areas where it may prove unsightly in patients with a thin scalp. The insertion of pins into the middle table of the skull firmly fixes bone flaps at one edge, eliminating the need for external plates at that site.
Robert F. Spetzler and Nader Sanai
Smaller operative exposures, endoscopic approaches, and minimally invasive neurosurgery have emerged as a dominant trend in the modern era. In keeping with this evolution, the authors have recently eliminated the use of fixed retractors, instead employing dynamic retraction, with the use of handheld instruments. In the present study, the authors report the results of applying this strategy to challenging vascular and skull base lesions.
This 6-month study prospectively analyzed the use of retractorless surgery in a consecutive series of 223 patients with intracranial vascular or skull base lesions undergoing craniotomy. A single surgeon performed all operations.
The microsurgical approaches (in descending order of frequency) included an orbitozygomatic craniotomy (77 patients [35%]), frontal (36 patients [16%]), retrosigmoid (27 patients [12%]), interhemispheric (16 patients [7%]), and lateral supracerebellar (15 patients [7%]). The most common lesions were aneurysms (83 lesions overall [37%]), 18 of which required a bypass. Of 159 vascular lesions, there were also 46 cavernous malformations (29%). Meningiomas were the most common skull base tumors (37 cases [58%]). Of the 223 patients, 7 cases of various vascular and skull base lesions required fixed retraction. Therefore, 97% of the cases were successfully treated without a self-retaining retractor system.
Fixed retraction can be supplanted by dynamic retraction with surgical instruments, limiting the risk of retractor-induced tissue edema and injury. This quiet revolution has precipitated a major change in surgical techniques. Extensive dissection of arachnoidal planes, careful placement of the handheld suction device, patient positioning that enhances gravity retraction, the refinement of microsurgical instrumentation, and appropriate selection of the operative corridor all serve to obviate the need for fixed retraction in most intracranial procedures. Retractorless neurosurgery is an achievable goal, even when complex lesions of the vasculature and skull base are being treated.
Giuseppe Lanzino and Robert F. Spetzler
✓ An intraoperative aneurysm rupture due to a tear at the aneurysm neck can be a tricky complication to manage. The authors describe a simple technique found to be useful in such a case.
Timothy Mapstone and Robert F. Spetzler
✓ A case is described in which vertebral artery occlusion, caused by a fibrous band, occurred whenever the patient turned his head to the right side, resulting in vertigo and syncope whenever the head was turned to the right. Release of a fibrous band crossing the vertebral artery 2 cm from its origin relieved the patient's vertebral artery constriction and symptoms.