Quantitative Analysis of Surgical Working Space During Endoscopic Skull Base Surgery

Objectives Selective dissection of intranasal anatomy may improve visualization and maneuverability at the skull base. We aimed to quantify the dimensions of working space and angles achieved following sequential removal of intranasal structures using an endoscopic transphenoidal approach to the skull base. Methods Cone beam computed tomography scans of four cadaveric heads were obtained for registration of an optical tracking system. Each head was sequentially dissected: (1) sphenoidotomy and limited posterior septectomy, (2) unilateral partial middle turbinectomy, (3) bilateral partial middle turbinectomy, and (4) wide posterior septectomy. The maximal craniocaudal and mediolateral distance (mm) and angle (degrees) reached were calculated at the sphenoid face and sella. Data were analyzed using descriptive statistics and tests of statistical significance. The significance level was set at p ≤ 0.05. Results A significant improvement in both dimensions of working space was observed with each stage of dissection at the level of the sphenoid face. Maximal working space was achieved following bilateral middle turbinectomy and wide posterior septectomy with a 38 and 29% increase in working space in the mediolateral and craniocaudal dimensions, respectively. The largest stepwise increase in working space was observed with unilateral middle turbinectomy (mediolateral: 24 ± 3 mm and craniocaudal: 20 ± 3 mm). A trend toward improved degrees of visualization was observed with each stage of dissection but was not statistically significant. Conclusion Approaches to the skull base can be enhanced by selective unilateral/bilateral partial middle turbinectomy and posterior septectomy being performed to improve visualization and maximize surgical working freedom.

Rathke’s Cleft Cysts

Cystic lesions involving the sella have a distinct differential diagnosis including Rathke cleft cyst, cystic pituitary adenoma, craniopharyngioma, arachnoid cyst, and epidermoid among other entities. Workup includes not only cranial imaging but also endocrine evaluation for pituitary dysfunction and ophthalmologic evaluation to assess for visual deficits that may not be immediately apparent to the patient at presentation. Rathke cleft cysts are common and may be found in 20% of autopsy specimens. However, symptomatic Rathke cleft cysts are rare, and surgical decisions should be made judiciously based on preoperative symptoms and workup. Endonasal transphenoidal approach for cyst fenestration is a common surgical management technique for symptomatic lesions. Complete resection of the Rathke cleft cyst wall is not required.

Endoscopic endonasal transsphenoidal approach for pituitary adenomas: technical aspects and report of casuistic

OBJECTIVE: Analyse technical aspects, effectiveness and morbidity of the endoscopic endonasal transphenoidal approach for pituitary adenomas. METHOD: From January 2005 to September 2008, 30 consecutive patients underwent endoscopic endonasal resection of pituitary adenomas with a follow up from 3 to 36 months. Their medical charts were retrospectively analysed. RESULTS: There were 18 women and 12 men, mean age 44 years (range 17-65 yr). Among the 30 patients, 23 had macroadenomas and 7 microadenomas. Twelve patients had non-functioning tumors, 9 had ACTH-secreting tumors, 8 had GH-secreting tumors and 1 prolactinoma. Complete resection and hormonal control was achieved in all microadenomas. Macroadenomas were completely removed in 6 patients, subtotal resection in 6 and partial resection in 11. Three patients had diabetes insipidus and 5 had CSF leaks treated with lumbar drainage. CONCLUSION: The endonasal endoscopic approach for pituitary tumors is effective and has low morbidity.