Role of transcranial sphenoidotomy in skull base surgery: classification of surgical techniques based on the surgical anatomy of the sphenoid sinus

Abstract

OBJECTIVEAlthough sphenoidotomy is more commonly performed via the transnasal approach than via the transcranial approach, transcranial sphenoidotomy (TCS) remains indispensable for en bloc resection of locally advanced sinonasal malignant tumors (SNMTs) extending to the skull base. TCS also enables transsphenoidal transposition of the temporoparietal galeal flap (TPGF) to compensate for the lack of vascularized reconstructive tissue after endoscopic transnasal skull base surgery. The objective of this study was to review the authors’ surgical experience using TCS with an emphasis on the surgical anatomy of the sphenoid sinus and on the purpose of TCS. Relevant anatomy is further illustrated through cadaveric dissection and photo documentation.METHODSThe authors reviewed the records of 50 patients who underwent TCS at the Nagoya University Hospital, Fukushima Medical University Hospital, or Aichi Medical University Hospital over the course of 7 years (between January 2011 and November 2017). The authors also performed cadaveric dissection in 2 adult cadaveric skull base specimens.RESULTSOf the 50 patients included in this study, 44 underwent craniofacial resection (CFR) for en bloc resection of SNMTs involving the anterior and/or lateral skull base, and 6 underwent transsphenoidal transposition of the TPGF flap. The authors categorized the TCS procedures according to the portion of the sphenoid sinus wall involved (i.e., superior, lateral, and superolateral). Superior sphenoidotomy was used in patients requiring anterior CFR. Lateral sphenoidotomy was further divided into 2 subtypes, with type 1 procedures performed for the transsphenoidal transpositioning of the TPGF, and type 2 procedures used in patients requiring lateral CFR. Superolateral sphenoidotomy was used in anterolateral CFR.CONCLUSIONSTCS still represents a useful tool in the armamentarium of neurosurgeons treating central skull base lesions. The newly proposed surgical classification facilitates a profound understanding of TCS and how to incorporate this technique into clinical practice.

Skull Base Invasion Patterns of Malignant Head and Neck Tumors: A Neurosurgical Perspective

“…In our patients, such contraindications were distant metastasis and invasion of the sphenoid sinus, cavernous sinus, clivus, internal carotid artery, and sigmoid sinus. 9,10 The surgical strategy for handling head and neck tumors has been described previously. 9,10,[12][13][14][15] Briefly, the head and neck surgeons performed facial dissection of endoscopic endonasal dissection.…”

“…9,10 The surgical strategy for handling head and neck tumors has been described previously. 9,10,[12][13][14][15] Briefly, the head and neck surgeons performed facial dissection of endoscopic endonasal dissection. Surgical neck dissection was also performed in patients with cervical lymph node metastases.…”

“…This may have been because the maxillary sinus is the most common primary site of MHNTs in Japanese patients. 9,10 The maxillary sinus is close to the orbit and sphenoid bone pterygoid plate, and tumors originating in the maxillary sinus are characterized by frequent extension into these structures. Invasion of the orbit and the pterygoid plate tended to lead to invasion into the anterior skull base and lateral skull base, A2 and L1 regions in this study.…”

“…At our facilities, the multidisciplinary team of head and neck surgeons, neurosurgeons, and plastic surgeons perform craniofacial resection (CFR) and temporal bone resection (TBR) on MHNTs that invade the skull base. [9][10][11] The cranial resection of the tumor is performed by neurosurgeons, who aim to remove the lesion en bloc with a layer of normal tissue to prevent any tumor exposure and resulting metastasis. If the tumor does not reach the internal surface of the skull base, the skull base bone that is in contact with the tumor forms the safety margin.…”

Prospective Evaluation of Health-Related Quality of Life in Patients Undergoing Anterolateral Craniofacial Resection with Orbital Exenteration

“…6 At our hospital, we have performed craniofacial resection and reported favorable prognoses and acceptable complication rates in patients with locally advanced malignant skull base tumors. [5][6][7][8][9] The management of orbital invasion of malignant tumors, such as sinonasal carcinoma or skin cancer, remains controversial because of the considerable psychological impact on patients. It is well known that intraperiosteal orbital involvement is an important prognostic factor for malignant skull base tumors.…”