Institutional members access full text with Ovid®

Share this article on:

Hypoglossal Nerve Palsy Missed and Misinterpreted: The Hidden Skull Base

Learned, Kim O. MD*; Thaler, Erica R. MD; O’Malley, Bert W. Jr MD; Grady, M. Sean MD; Loevner, Laurie A. MD*†‡

Journal of Computer Assisted Tomography: November/December 2012 - Volume 36 - Issue 6 - p 718–724
doi: 10.1097/RCT.0b013e318268ec18
Neuroradiology

Objective: Dysarthria and tongue swelling may be seen with hypoglossal nerve palsy, and on cross-sectional imaging studies, tongue denervation can be misinterpreted as a primary base-of-tongue mass. Understanding radiological patterns of tongue denervation is important to prevent misinterpretation. Close evaluation of the skull base is critical as hypoglossal palsies resulting from pathology here are often overlooked.

Methods: Neck and brain magnetic resonance imaging studies obtained in 7 adult patients referred to our institution with clinically and/or radiologically suspected tongue base masses were retrospectively reviewed. Outside imaging evaluations were misinterpreted as base-of-tongue tumors in 3 patients, incorrectly read as normal in 2, and skull base pathologies were missed in 5.

Results: All 7 patients showed magnetic resonance imaging findings typical of tongue denervation: T2-weighted hyperintensity of involved hemitongue, protrusion of the tongue into oropharynx, variable fatty infiltration. All 5 skull base masses involved hypoglossal canal (4 metastases, 1 multiple myeloma; 4 newly diagnosed cancers). Two patients had internal carotid artery dissections at the skull base.

Conclusions: To avoid misinterpretation of tongue denervation for tongue base mass, understanding of tongue innervations and classic imaging findings of hypoglossal denervation are essential. Careful inspection of skull base is paramount to avoid overlooking these hidden pathologies.

From the *Division of Neuroradiology, Department of Radiology, Deparments of †Otorhinolaryngology: Head and Neck Surgery, and ‡Neurosurgery, University of Pennsylvania School of Medicine, Philadelphia, PA.

Received for publication May 19, 2012; accepted July 5, 2012.

Reprints: Laurie A. Loevner, MD, Division of Neuroradiology, Department of Radiology, University of Pennsylvania Health System, 3400 Spruce St, 2 Dulles Bldg, Philadelphia, PA 19104 (e-mail: laurieloevner@aol.com).

Presented at the ASHNR 43rd Annual Meeting, New Orleans, LA, October 2009.

The authors have no conflicts of interest to declare.

© 2012 Lippincott Williams & Wilkins, Inc.