Tumors of the anterior skull base

Abstract

A variety of histologic tumor types are present in the anterior skull base. Primary tumors of this area may be derived from the bone, paranasal sinuses, nasopharynx, dura, cranial nerves, pituitary gland and brain. Symptoms are caused mostly through mass effect but, if the tumor becomes aggressive, also through invasion. Selection of surgical approaches to the anterior skull base is based upon balancing risk reduction with maximizing extent of resection. Here we review a spectrum of neoplastic entities found in the anterior skull base in adults and discuss clinical and radiographic presentation, treatment options, and outcomes. Surgical resection remains the mainstay in treatment of these tumors, particularly in the hands of experienced surgeons exercising proper patient and case selection.

Keywords::

• anterior skull base
• craniopharyngioma
• endonasal surgery
• endoscopic surgery
• esthesioneuroblastomas
• meningioma
• minimally invasive surgery
• non-neuroendocrine sinonasopharyngeal tumors
• pituitary adenoma
• radiotherapy
• sinonasal undifferentiated carcinoma

Financial & competing interests disclosure

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending or royalties.

No writing assistance was utilized in the production of this manuscript.

Key issues

• The anterior skull base is the site of numerous tumors, most of which are benign but they can cause symptoms due to compression of surrounding sinonasal and intracranial structures.

• Over recent years, anterior skull base surgery has drastically evolved by the multidisciplinary improvements in equipment and surgical techniques.

• The development of smaller brain exposing osteotomies through narrow corridors, endoscopic surgery, infection prevention methods and new and improved techniques for reconstruction allow surgeons to perform biopsies and resections on most skull base masses.

• With the addition of multiple adjuvant therapies including improved radiosurgery, better long-term control rate have been achieved.

• Traditional open approaches to the anterior skull base include bifrontal craniotomies, extended bifrontal craniotomies, pterional craniotomies as well as complex transfacial operations. These approaches, while adequate, require a large incision, and significant brain exposure and retraction that places critical structures at risk and increases recovery time. This exposure can also cause cosmetic defects in the forehead resulting from the incisional scar, depression of the bone flap, inadequate repair of burr holes and/or temporal muscle atrophy.

• With the recent application of concepts from endonasal sinus surgery, neurosurgeons, working with otolaryngologists, can obtain access with a direct anatomical route to the lesion with a minimal opening that limits brain exposure and minimize iatrogenic trauma. Proponents argue that, in contrast to the various transcranial approaches, the minimally invasive approaches: devascularize the skull base blood supply before tumor resection and decompress structures like the optic apparatus from below.