3D-FT MRI of the facial nerve

Abstract

Contrast-enhanced 3D-FT MRI of the intrapetrous facial nerve was obtained in 38 patients with facial nerve disease, using a 1.0 T magnet and fast gradient-echo acquisition sequences. Contiguous millimetric sections were obtained, which could be reformatted in any desired plane. Acutely ill patients, were examined within the first 2 months, included: 24 with Bell's palsy and 6 with other acute disorders (Herpes zoster, trauma, neuroma, meningeal metastasis, middle ear granuloma). Six patients investigated more than a year after the onset of symptoms included 3 with congenital cholesteatoma, 2 with neuromas and one with a chronic Bell's palsy. The lesion was found incidentally in two cases (a suspected neurofibroma and a presumed drop metastasis from an astrocytoma). Patients with tumours had nodular, focally-enhancing lesions, except for the leptomeningeal metastasis in which the enhancement was linear. Linear, diffuse contrast enhancement of the facial nerve was found in trauma, and in the patient with a middle ear granuloma. Of the 24 patients with an acute Bell's palsy 15 exhibited linear contrast enhancement of the facial nerve. Three of these were lost to follow-up, but correlation of clinical outcome and contrast enhancement showed that only 4 of the 11 patients who made a complete recovery and all 10 patients with incomplete recovery demonstrated enhancement. Possible explanations for these findings are suggested by pathological data from the literature. 3D-FT imaging of the facial nerve thus yields direct information about the of the nerve condition and defines the morphological abnormalities. It can also demonstrate contrast enhancement which seems to have some prognostic value in acute idiopathic Bell's palsy.

Neurofibroma in the Mastoid Segment of the Facial Canal

“…Interestingly, extensive tumour growth was described in this case, involving the jugular foramen as well. Two other publications, mentioning a neurofibroma in the mastoid part of the facial canal, refer to the same patient and have not been histologically verified [13,14]. The diagnosis was based on the coincidence of a facial canal tumour and the presence of NF1.…”

Clinical significance of quantitative analysis of facial nerve enhancement on MRI in Bell's palsy

“…Girard et al [1] reported that cases showing facial nerve enhancement on MRI may recover later than those without enhancement, and Yetiser et al [2] also showed a positive correlation between enhancement of facial nerve and the recovery time in patients with facial paralysis. However, many other reports have denied any relationship between the clinical prognosis and the extent, duration, pattern, and degree of facial nerve enhancement on MRI [3Á5, 12,15,17].…”

“…Nevertheless, there are still controversies regarding the enhancement pattern of the facial nerve on MRI and its correlation with anatomical characteristics, disease severity, electrophysiologic tests, and prognosis. Some authors reported that the presence of facial nerve enhancement on MRI is associated with delayed clinical recovery [1,2], while many others demonstrated the poor prognostic value of MRI in predicting disease severity or the recovery process [3Á5]. The controversial results of different studies may be due to the heterogeneity of subjects with different prognoses included in the study, various timings at which MRI was performed after the onset of facial palsy, or the different techniques and parameters of MRI applied.…”

MR-Volumetrie des N. trigeminus bei Patienten mit einseitigen Gesichtsschmerzen

“…Weist ein Patient mit Trigeminusneuralgie auf der betroffenen Seite einen um 20 % dünneren Nerv im Vergleich zur gesunden Gegenseite auf, so ist dieser Befund auch mit bloßem Auge zweifelsfrei zu erkennen. Dies setzt jedoch voraus, dass bei diesem Krankheitsbild hochauflösende Sequenzen verwendet werden, mit denen solch dün-ne Strukturen wie Hirnnerven differenziert beurteilt werden können [11,12]. Ebenso wie beim asymmetrischen Enhancement gesunder Nerven nach i. v. Kontrastmittelgabe [13] spielen auch bei der Einschätzung von Volumina bei Nerven dieser Größen-ordnung Partialvolumeneffekte mit zunehmender Schichtdicke eine Rolle [14].…”