Loveren, Harry R. van

OBJECTIVE The principal tenet of minimally invasive neurosurgery is to limit approach-related tissue trauma, and a major assumption is that shorter incisions and smaller openings, in addition to protecting the brain, also have some perceptible benefits for the patient. This study tests the assumption of patient benefit and tries to define its significance. METHODS Procedures that fit the inclusion criteria of minimally invasive transcranial "keyhole" surgery were sought in the principal investigator’s archives. Each case was then paired with a classic procedure performed within the study time frame by the two senior authors, matched for pathology, size, location, and complexity. These pairs were then compared using a statistical tool (i.e., the Wilcoxon signed-rank test) designed for matched samples. Differences in estimated blood loss, duration of surgery, and length of hospital stay were examined. The narcotic needs during hospitalization were also examined as morphine milligram equivalent (MME). RESULTS Ninety patients were included in this study, evenly split between the minimally invasive surgery (MIS) and classic cohorts. Comparison of the 45 pairs showed no significant difference in estimated blood loss, though the operative times favored the MIS cohort significantly (mean ± SEM 310 ± 17 minutes vs 383 ± 24 minutes, p = 0.02). The length of stay was shorter for MIS, but the difference reached statistical significance only when cases with complications were excluded. The most important finding was that significantly less narcotic was needed during hospitalization in the MIS cohort (83 ± 15 MME vs 257 ± 47 MME). CONCLUSIONS The large difference in narcotic needs points to enhanced recovery from MIS techniques. While the difference in operative time did not lead to significantly shorter hospital stays, data suggest that minimally invasive technique may benefit the patient during recovery. This inspires further investigations to define the potentially positive impact on hospital and healthcare systems.

Object Historically, surgery to the petrous apex has been addressed via craniotomy and open microscopic anterior petrosectomy (OAP). However, with the popularization of endoscopic approaches, the petrous apex can further be approached endonasally by way of an endoscopic endonasal anterior petrosectomy (EAP). Endonasal anterior petrosectomy is a relatively new procedure and has not been compared anatomically with OAP. The authors hypothesized that the EAP and OAP techniques approach different portions of the petrous apex and therefore may have different applications. Methods Four cadaveric heads were used. An OAP was performed on one side and an EAP was performed on the contralateral side; the limits of bony resection were defined. The extent of bony resection was then evaluated using predissection and postdissection thin-slice CT scans. The comparative resection was then reconstructed using 3D modeling on Brainlab workstations. Results The average resection volumes for EAP and OAP were 0.297 cm 3 and 0.649 cm 3 , respectively, representing a comparative percentage of 46% (EAP/OAP). An EAP and OAP achieved resection of 29% and 64% of the total petrous apex volume, respectively. Indeed, EAP addressed the inferior portion of the petrous apex located adjacent to the petroclival suture more completely than OAP, where 45% of the bone overlying the petroclival suture (petroclival angle to the jugular foramen) was resected with the EAP, while 0% was resected with the OAP. Conclusions In anatomically normal cadavers, OAP achieved nearly a 50% larger volumetric resection than EAP. Furthermore, while OAP appears to completely address the superior portion of the petrous apex, EAP appears to have a niche in approaches to lesions in the inferior petrous apex. Given these results, the authors propose that OAP be redefined as the “superior anterior petrosectomy,” while EAP be referred to as the “inferior anterior petrosectomy,” which more clearly defines the role of each approach in anterior petrosectomy.