The usefulness of MR imaging of the temporal bone in the evaluation of patients with facial and audiovestibular dysfunction

Imaging Anatomy and Pathology of the Intracranial and Intratemporal Facial Nerve

The facial nerve is one of the most complex cranial nerves, with motor, sensory, and parasympathetic fibers. A large spectrum of congenital, inflammatory, vascular, and neoplastic processes may affect one or more segments of the nerve. Customized use of computed tomography and magnetic resonance imaging combined with good understanding of the nerve anatomy and relevant clinical/surgical key points is crucial for appropriate assessment of facial neuropathy. This article reviews the anatomy of the intracranial and intratemporal facial nerve, and the imaging features of the most frequent disorders involving those segments of the nerve.

Temporal bone MRI with 3D-FIESTA in the evaluation of facial and audiovestibular dysfunction

PURPOSE

To evaluate the clinical usefulness of magnetic resonance imaging (MRI) of the temporal bone using three-dimensional fast imaging employing steady-state acquisition (3D-FIESTA) sequences in patients with facial and audiovestibular dysfunction.

METHODS

We retrospectively reviewed the MR images of 1263 patients who presented with hearing loss (n=429), peripheral facial palsy (n=96), tinnitus (n=341) or vertigo (n=397). There were 605 men and 658 women, with a mean age of 46.97±16.95 (SD) years (range: 2-83 years). Positive MRI findings that were responsible for clinical manifestations in individual patients were categorized according to the anatomic sites and etiologies of the lesions.

RESULTS

Positive MRI findings possibly responsible for clinical manifestations were found in 232/1263 (18.37%) patients, including 86/429 (20.05%) patients with hearing loss, 21/96 (21.88%) patients with facial palsy, 62/341 (18.18%) patients with tinnitus, and 63/397 (15.87%) patients with vertigo.

CONCLUSION

Although the use of MRI of the temporal bone using 3D-FIESTA shows positive findings in only 18.37% of patients, it provides important information in those with facial and audiovestibular dysfunction. However, for patients with normal MRI of the temporal bone, other etiological factors should be investigated in order to clarify or elucidate the cause of clinical manifestations.

Vascular loops at the cerebellopontine angle: is there a correlation with tinnitus?

BACKGROUND AND PURPOSE

Tinnitus is a common disorder, and the etiology remains mostly unclear. The purpose of this study was to investigate the causative effect of the vascular loop and compression of the vestibulocochlear nerve at the cerebellopontine angle in patients with unexplained tinnitus.

MATERIALS AND METHODS

This study was approved by our institutional review board. Written informed consent was obtained from all participants. Fifty-eight patients with unexplained tinnitus and 44 age- and sex-matched asymptomatic controls were examined with temporal MR imaging. Besides the tinnitus and control groups, a third group was formed by asymptomatic sides of patients with unilateral tinnitus. A 3D fast imaging employing steady-state acquisition (3D-FIESTA) sequence was performed in addition to the regular pre- and postcontrast axial and coronal sequences. The anatomic type of vascular loop, the vascular contact, and the angulation of the vestibulocochlear nerve at the cerebellopontine angle (CPA) were evaluated by 2 experienced neuroradiologists. The chi(2) test was used for statistical analysis.

RESULTS

No statistically significant differences were found between the patient and control groups for the anatomic type of vascular loop, the vascular contact, and the angulation of the vestibulocochlear nerve at the CPA (P > .05).

CONCLUSION

Although 3D-FIESTA MR imaging correctly shows the anatomic relationships of the vestibulocochlear nerve, its vascular compression cannot be attributed as an etiological factor for tinnitus.