Benign Tumors of the Skull Base Workup

  • Author: Mario J Imola, MD, DDS, FRCS, FACS, FRCS(C); Chief Editor: Arlen D Meyers, MD, MBA   more...
 
Updated: Apr 13, 2012
 

Imaging Studies

  • Diagnostic imaging is the most important component of an adequate workup following clinical assessment. CT scanning and MRI are complementary modalities in diagnosis and delineation of tumor extension. In certain circumstances, diagnostic imaging can accurately predict whether a tumor is benign or malignant and can narrow differential diagnoses.
  • CT scanning details bony structures, foramina, canals, and osteogenic lesions. Obtain contrast-enhanced axial and coronal 3-mm sections with bone and soft tissue window algorithms.
  • MRI has recently evolved into the single most useful imaging study of the skull base and provides highly accurate representation of soft tissue structures. Axial, coronal, and sagittal 3-mm sections with gadolinium enhancement are recommended using both T1- and T2-weighted modalities. T1-weighted images are not fat-suppressed; hence, adipose-containing structures are very bright, whereas structures containing water (eg, CSF) are dark. T2-weighted images are fat-suppressed, so fatty structures are dark and water is very bright. In both weightings, bone is visible as a very dark signal void, and muscle is of intermediate intensity. Tumor appearance varies depending on the histologic type and grade.
  • Angiography is indicated in selected tumors suspected of being hypervascular, (eg, hemangiomas, angiofibromas, glomus tumors, arteriovenous malformations, aneurysms). MR angiography is a good noninvasive technique but does not provide the detail of conventional intra-arterial angiography. When surgical resection is indicated, angiography combined with interventional preoperative embolization can be used to occlude the blood supply to vascular neoplasms, which possibly limits blood loss during subsequent surgery.[6]
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Diagnostic Procedures

  • Biopsy is the only diagnostic technique that allows tissue diagnosis of skull base tumors. In many cases, the clinical presentation and diagnostic imaging provide sufficient information upon which to base a treatment decision. Because surgical excision is the treatment of choice for the vast majority of benign skull base tumors, a histologic tissue diagnosis is unnecessary prior to definitive resection. However, an attempt at biopsy is indicated for cases in which diagnostic imaging has not sufficiently narrowed the diagnostic possibilities, in very slow-growing lesions for which observation is contemplated, or when the patient is not a good surgical candidate.
  • Depending on the tumor location, both open biopsy and needle biopsy have indications. Open biopsy of tumors manifesting with palpable masses close to the surface can be approached through a simple skin incision. Biopsy of sinonasal masses can be performed with endoscopic guidance. Needle aspiration biopsy using either CT or MRI guidance can be used to safely biopsy deeper skull base tumors.
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Contributor Information and Disclosures
Author

Mario J Imola, MD, DDS, FRCS, FACS, FRCS(C)  Consulting Staff, Department of Otolaryngology-Head and Neck Surgery, Center for Craniofacial and Skull Base Surgery, Colorado Facial Plastic Surgery

Mario J Imola, MD, DDS, FRCS, FACS, FRCS(C) is a member of the following medical societies: American Academy of Facial Plastic and Reconstructive Surgery, American Academy of Otolaryngology-Head and Neck Surgery, American Cleft Palate/Craniofacial Association, American Head and Neck Society, American Laryngological Rhinological and Otological Society, American Medical Association, AO Foundation, Canadian Academy of Facial Plastic and Reconstructive Surgery, Canadian Society of Otolaryngology-Head & Neck Surgery, College of Physicians and Surgeons of Ontario, Colorado Medical Society, and North American Skull Base Society

Disclosure: Nothing to disclose.

Specialty Editor Board

Douglas D Backous, MD  Director of Listen for Life Center, Department of Otolaryngology-Head and Neck Surgery, Virginia Mason Medical Center

Douglas D Backous, MD is a member of the following medical societies: American Academy of Otolaryngology-Head and Neck Surgery, American Auditory Society, American College of Surgeons, American Laryngological Rhinological and Otological Society, American Medical Association, Association for Research in Otolaryngology, North American Skull Base Society, Society for Neuroscience, and Washington State Medical Association

Disclosure: Nothing to disclose.

Francisco Talavera, PharmD, PhD  Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Medscape Salary Employment

Peter S Roland, MD  Professor, Department of Neurological Surgery, Professor and Chairman, Department of Otolaryngology-Head and Neck Surgery, Director of Clinical Center for Auditory, Vestibular and Facial Nerve Disorders, Chief of Pediatric Otology, University of Texas Southwestern Medical Center; Adjunct Professor of Communicative Disorders, University of Texas School of Human Development

Peter S Roland, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Otolaryngic Allergy, American Academy of Otolaryngology-Head and Neck Surgery, American Auditory Society, American Laryngological Rhinological and Otological Society, American Neurotology Society, American Otological Society, North American Skull Base Society, and Society of University Otolaryngologists-Head and Neck Surgeons

Disclosure: Alcon Labs Honoraria Speaking and teaching; Advanced Bionics Honoraria Board membership; Cochlear Corp Honoraria Board membership; Med El Corp travel grants Consulting; Foresight Consulting fee Consulting

Christopher L Slack, MD  Private Practice in Otolaryngology and Facial Plastic Surgery, Associated Coastal ENT; Medical Director, Treasure Coast Sleep Disorders

Christopher L Slack, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Facial Plastic and Reconstructive Surgery, American Academy of Otolaryngology-Head and Neck Surgery, and American Medical Association

Disclosure: Nothing to disclose.

Chief Editor

Arlen D Meyers, MD, MBA  Professor of Otolaryngology, Dentistry, and Engineering, University of Colorado School of Medicine

Arlen D Meyers, MD, MBA is a member of the following medical societies: American Academy of Facial Plastic and Reconstructive Surgery, American Academy of Otolaryngology-Head and Neck Surgery, and American Head and Neck Society

Disclosure: Covidien Corp Consulting fee Consulting; US Tobacco Corporation Unrestricted gift Unknown; Axis Three Corporation Ownership interest Consulting; Omni Biosciences Ownership interest Consulting; Sentegra Ownership interest Board membership; Medvoy Ownership interest Management position; Cerescan Imaging Consulting; Headwatersmb Consulting fee Consulting; Venturequest Royalty Consulting

References

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Internal anatomy of the skull base, lateral view, and base of the skull.
 
 
 
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