Surgical approaches to central skull base and postsurgical imaging

Imaging in Endoscopic Cranial Skull Base and Pituitary Surgery

Endoscopic endonasal approaches have widely accepted techniques for managing benign and malignant processes along the entire ventral skull base with similar or better results compared with open procedures, but with lower rates of complication. Managing pathology affecting the skull base can be challenging because of complex anatomy and the proximity of critical neurovascular structures. Postoperative imaging can be challenging, because of surgical alterations of normal anatomy and the now common use of complex reconstruction techniques. Understanding the normal imaging appearance of skull base reconstruction is important for accurate postoperative interpretation and delineation between normal reconstructive tissue and recurrent neoplasm.

Objective assessment of olfaction after transsphenoidal pituitary surgery

BACKGROUND

Transnasal endoscopic pituitary surgery has proven to be a safe and effective method for removing pituitary tumors. Direct and angled endoscopy at the site of dissection provides excellent visualization without external incisions. However, olfactory loss has been documented after surgical approaches to the pituitary and is accompanied by a significant detriment to quality of life.

STUDY DESIGN

A prospective cohort study.

METHODS

Subjects 19 years and older who were undergoing transnasal endoscopic pituitary surgery were recruited for this study. The University of Pennsylvania Smell Identification Test (UPSIT) was administered preoperatively and then at 3-4 months. Data regarding demographics, reconstructive technique, and complications were recorded. The patients had skull-base reconstruction with a Medpore implant or a vascularized nasoseptal flap.

RESULTS AND DISCUSSION

A total of 33 subjects were recruited, with 18 completing the study. The mean (SEM) age was 58.2 ± 2.4 years, with 12 females and 6 males. The majority of patients (89%) had nonfunctioning macroadenomas, and six individuals had reconstruction by using a vascularized nasoseptal flap. Matched mean (SEM) preoperative and postoperative UPSIT scores for this cohort were not significantly different (31.3 ± 0.4 versus 30.5 ± 0.5, respectively; p = 0.54). In addition, there was no significant difference between the mean preoperative and postoperative UPSIT scores of the patients who had nasoseptal flaps (29.4 ± 1.1 vs. 28.6 ± 1.3 respectively; p = 0.87).

CONCLUSIONS

In the current study, pre- and postoperative UPSIT scores were not significantly different in patients who underwent endoscopic transnasal pituitary surgery. The use of a nasoseptal flap also did not adversely affect postoperative UPSIT scores.

Management Strategies for Skull Base Inverted Papilloma

Objective

Inverted papilloma attached to the ventral skull base presents a surgical dilemma because surgical removal of the bony pedicle is critical to decrease risk of recurrence. The objective of this study is to evaluate the effectiveness of endoscopic management of skull base inverted papilloma.

Study Design

Case series with planned data collection.

Setting

Tertiary medical center.

Subjects

Patients with skull base inverted papilloma.

Methods

Over 7 years, 49 patients with skull base inverted papilloma were referred for surgical resection. Demographics, operative technique, pathology, complications, recurrence, and postoperative follow-up were evaluated.

Results

Average age at presentation was 57 years. Twenty-six patients (53%) had prior attempts at resection elsewhere, and 5 had squamous cell carcinoma (SCCA) arising in an inverted papilloma. Six patients (12%) suffered major complications, including skull base osteomyelitis in 2 previously irradiated patients, cerebrospinal fluid leak with pneumocephalus (n = 1), meningitis (n = 1), invasive fungal sinusitis (n = 1), and cerebrovascular accident (n = 1). The mean disease-free interval was 29 months (range, 10-78 months). One patient with SCCA recurred in the nasopharynx (overall 2% recurrence rate). He is disease-free 3 years following endoscopic nasopharyngectomy. Three patients with SCCA had endoscopic resection of the skull base, while 1 subject with inverted papilloma pedicled on the superior orbital roof had an osteoplastic flap in conjunction with a Draf III procedure. All others received endoscopic resection.

Conclusions

Removal of the bony pedicle resulted in excellent local control of skull base inverted papillomas. Our experience demonstrates that disease eradication with limited morbidity is attainable with this approach.

Inaccurate Assessments of Anterior Cranial Base Malignancy Following Nasoseptal Flap Reconstruction

Objective The nasoseptal flap (NSF) provides vascularized tissue for repair of skull base defects of various etiologies. However, the NSF repair after skull base resection for anterior cranial base malignancies may demonstrate radiologic findings confusing for recurrent or residual disease on postoperative surveillance imaging. The objective of the current study was to review neuroradiologic misinterpretations of NSF reconstruction following anterior cranial base malignancies. Methods A multicenter review of patients reconstructed with the NSF after endoscopic resection of anterior cranial base malignancies from 2008 to 2013 was performed. Data were collected regarding etiology, surgical technique, locoregional control, and postoperative radiologic assessments. Only patients with at least one postoperative surveillance scan with inaccurate assessment of residual or recurrent malignancy were included in the study. Results Over 5 years, 13 patients were identified who had erroneous reporting of malignancy due to NSF reconstruction. On average, two neuroradiologists interpreted the NSF as persistent or recurrent malignancy over this time period (range: 1-7). The key findings suspicious for recurrence were enhancement and soft tissue thickening of the NSF. These findings were present in at least one postoperative scan in all patients. Conclusion Neuroradiologists and rhinologists performing surveillance on patients with a history of skull base malignancy with NSF reconstruction should maintain collaborative efforts to accurately interpret radiologic findings of the NSF during postoperative imaging.

The use of image-guidance during transsphenoidal pituitary surgery in the United States

BACKGROUND

Intraoperative image guidance is a useful modality for transsphenoidal pituitary surgery. However, the outcomes associated with this technology have not been systematically evaluated.

OBJECTIVE

The purpose of the study was to quantify complication rates with and without the use of image guidance during transsphenoidal pituitary surgery using a nationwide database with broadly applicable results.

METHODS

A retrospective analysis of the Nationwide Inpatient Sample was performed from 2007 to 2011. Transsphenoidal pituitary resections for adenomas were identified by International Classification of Diseases-9th Revision, Clinical Modification code. The effect of image guidance on cerebrospinal fluid (CSF) leak complications and cost-benefit was analyzed.

RESULTS

A total of 48,848 transsphenoidal pituitary resections were identified, of which 77.5% were partial resections and 22.5% were complete. Pathologic indications included benign (89.3%), malignant primary (0.6%), and malignant secondary (0.4%). Complications included same-stay death (0.4%), CSF leak (8.8%), postoperative CSF rhinorrhea (1.9%), diabetes insipidus (12.4%), and meningitis (0.4%). Image guidance was employed in 7% (n = 3401) of all cases. When analyzed by modality, computed tomography (CT)-assisted procedures had lower CSF rhinorrhea rates (1.1%) compared with cases with no image guidance (1.9%), whereas magnetic resonance (MR)-assisted procedures had the highest rates (2.7%, χ2 p < 0.001). Rates of CSF leak demonstrated a similar pattern (CT 6.4%, no image guidance 8.9%, MR 9.2%, χ2 p < 0.001). CT-assisted surgery had significantly shorter length of stay (2.9 days) versus no image guidance (3.7 days, p < 0.001), lower total charges ($47,589 versus $62,629, p < 0.001), and lower total cost ($16,748 versus $20,530, p < 0.001).

CONCLUSIONS

CT-assisted surgery is associated with a lower rate of CSF leak, shorter length of stay, and lower cost compared with patients without image guidance. Further studies that control for severity and extent of disease are warranted to confirm this finding.

Endoscopic resection of anterolateral maxillary sinus inverted papillomas

OBJECTIVES/HYPOTHESIS

Endoscopic medial maxillectomy (EMM) has become the surgical procedure of choice for resection of maxillary sinus inverted papillomas (IPs). Traditionally, IPs pedicled on the anterior and/or lateral walls of the maxillary sinus have required an adjuvant Caldwell-Luc approach due to decreased visualization with transnasal endoscopy in these locations. The objective of the current study is to evaluate outcomes following endoscopic resection of anterolateral maxillary sinus IPs.

STUDY DESIGN

Prospective case series.

SUBJECTS AND METHODS

Over 6 years, a total of 35 patients underwent EMM for maxillary sinus IPs located on the anterolateral maxillary wall. Demographics, operative technique, pathology, complications, recurrence, and postoperative follow-up were evaluated.

RESULTS

The majority of patients were male (71%) with a mean age of 56 years (range 27-83). Most patients (71%) were referred for recurrence after previous attempts at surgical resection. Adequate visualization was obtained following EMM in the majority of patients with use of a 70-degree endoscope and angled instrumentation. The addition of transseptal surgical access was critical to the removal of IPs in 16 patients. No Caldwell-Luc approaches were required. Pathologic dysplasia was identified in nine patients, and three had carcinoma. There were no recurrences with a mean disease-free interval of 29 months (10-72 months).

CONCLUSION

In the present study, EMM provided excellent surgical access to anterolateral maxillary sinus IPs. The transseptal approach allowed enhanced visualization to this challenging location, previously considered accessible only with external procedures.