Retractorless Surgery: Strokes, Edema, and Gliosis Outcomes Following Skull Base Surgery

 

Background There is a growing trend toward retractorless surgery. It is assumed that the use of fixed retractor systems can lead to tissue ischemia, edema, and injury leading to the development of gliosis/scar. However, the clinical impact of fixed retraction on the brain and the radiographic changes that occur over time remain unclear. Anterior skull base meningiomas are deep-seated skull base tumors where surgery can be performed with and without fixed retraction. We evaluated the radiographic changes over time after surgical resection of these tumors with and without fixed retractor systems.

Methods All adult patients undergoing primary resection of an anterior skull base World Health Organization grade I meningioma through a craniotomy at a single academic tertiary-care institution between 2010 and 2015 were retrospectively reviewed. Preoperative scans were first evaluated if a retractor could be used for surgery, and only cases where a retractor could be used were included. Magnetic resonance imaging (MRI) scans were reviewed and contrast-enhanced tumor and fluid-attenuated inversion recovery (FLAIR) volumes were measured. Comparisons in pre-, peri-, and postoperative characteristics between patients who underwent retractor-assisted and retractorless surgery were made. Values with p < 0.05 were considered significant.

Results Sixty-six (49%) and 70 (51%) patients underwent retractorless and retractor-assisted resection of tumors, respectively, where 32 (24%) were olfactory groove, 48 (35%) planum sphenoidale, 27 (20%) tuberculum sella, and 29 (21%) anterior clinoid meningiomas. The only significant preoperative differences between the two cohorts were that patients who underwent retractorless surgery had larger preoperative tumor (23.2 vs. 9.8 cm³, p = 0.0001) and FLAIR volumes (1.3 vs. 0.8 cm³, p = 0.08) that trended toward significance. Despite this increase in preoperative tumor and FLAIR volumes, there were no differences in the postoperative tumor (0 vs. 0 cm³, p = 0.55) as well as the postoperative (11.2 vs. 11.3 cm³, p = 0.26) and 3-month FLAIR (0.05 vs. 2.55 cm³, p = 0.92) volumes between the two groups. Patients, however, who underwent retractorless surgeries had more often undergone skull base approaches (46 [70%] vs. 31 [44%], p = 0.003), less strokes (2 [3%] vs. 11 [16%], p = 0.02), more frequent FLAIR resolution (61% vs. 40%, p = 0.03), and shorter median times to FLAIR resolution (5.2 vs. undefined, p = 0.004) than retractor-assisted surgery. Even after matched-pair analysis was performed to control for potential differences in age, preoperative tumor, and FLAIR volumes, patients who underwent retractorless surgery versus retractor-assisted surgery still had less strokes (0 vs. 11%, p = 0.05), more frequent FLAIR resolution (48 vs. 29%, p = 0.02), and shorter median times to FLAIR resolution (5.2 vs. 12 months, p = 0.02).

Conclusion The use of retractors may be associated with more strokes and longer-term changes on the brain such as edema and eventually gliosis. The clinical significance of this has yet to be determined. However, if possible, the results from this study advocate for retractorless surgery in the anterior skull base when possible.