Magnetic resonance investigations of non-acoustic petrous lesions

Can MRI replace a second look operation in cholesteatoma surgery?

The purpose of this paper is to investigate whether a magnetic resonance imaging (MRI) examination of the petrous bones could replace the conventional second look surgical procedure when a canal wall up tympanoplasty procedure has been performed during the first look surgery. Eighteen patients were examined with MRI prior to a second look surgical procedure. MRI was performed on a 1.5 T superconducting system. T2 weighted images before contrast and T1 weighted images after contrast (gadopentate dimeglumine) were obtained. Imaging results were compared with surgical findings. The poor radiosurgical correlation (50% and 61% after re-evaluation) suggests that, at the present time, MRI is not a valid alternative to a second look surgical intervention in the case of cholesteatoma treated by canal wall up tympanoplasty. In our study, MRI was not capable of differentiating small pearls of residual cholesteatoma from surrounding scar tissue.

Facial nerve neuromas: MR imaging. Report of four cases

Four cases of facial nerve neuroma were evaluated by computed tomographic (CT) scan and magnetic resonance imaging (MRI). The extension of the tumor in the petrous bone or the parotid gland was well defined by MRI in all cases. CT scan was useful to demonstrate bone erosions and the relation of the tumor to inner ear structures. In cases of progressive facial palsy, CT and MRI should be combined to detect a facial neuroma and to plan the surgical approach for tumor removal and nerve grafting.

Haemangioma of the petrous bone: MRI

Gd-DTPA-enhanced MRI provided accurate demonstration of the site and extension of a haemangioma of the petrous bone. Enhanced-MRI could allow early detection and differentiation from the other more common tumours of the geniculate ganglion area, thereby permitting the surgeon to remove the tumour, while preserving the facial nerve. CT is, however, required to display the characteristic ossification in these tumours.

Intratemporal facial nerve neurinoma without facial paralysis

A 38-year-old man was referred by his general practitioner to our department on 28 October 1991, with a 2-week history of vertigo. A left aural polyp was identified. The audiogram showed a moderate conductive loss on the left side. Computed tomography (CT) and magnetic resonance imaging (MRI) confirmed the presence of the expanding lesion in the descending portion of the facial nerve. However, there was no seventh nerve paresis. At operation, the neurinoma (Schwannoma) filled the middle ear cleft and extended from the genu to the stylomastoid foramen. The floor of the middle ear had been eroded, exposing the jugular bulb. Facial nerve paresis is the usual presenting feature of a facial neurinoma. The case is presented for the reason that the absence of facial palsy as a presenting feature is rather rare, especially in the cases with large tumor and extensive bone erosion.