The ability to define the nerves in the internal auditory canal in the parasagittal plane may provide greater sensitivity and specificity in identifying abnormalities of this anatomic structure. Similar anatomy was demonstrated by MR imaging. The anatomy of the nerves differed among the specimens. An otic artery segmental anteroposterior anastomotic artery similar to persistent trigeminal and hypoglossal has been postulated to traverse the inner ear to connect with the carotid but has never been conclusively demonstrated to exist. The vestibulocochlear nerve entered the canal as a tubular structure but became crescent shaped in cross section in the middle portion of the canal and separated into individual nerves only in the most lateral portion of the canal. On cadaveric specimens, the facial nerve coursed superior and anterior to the vestibulocochlear nerve as a tubular structure throughout the length of the canal. The anatomy depicted on MR images was compared with the cadaveric anatomy. Fourteen canals in 12 patients were examined with T2-weighted two-dimensional fast spin-echo oblique parasagittal MR imaging and 12 canals in 8 patients were examined with T2-weighted three-dimensional turbo spin-echo MR imaging. Ten specimens underwent limited dissection. Thirty-eight formalin-fixed cadaveric temporal bones were examined with 1-mm-thick contiguous parasagittal CT sections to determine the anatomy of the nerves in the internal auditory canal. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.To define the anatomy of the facial and vestibulocochlear nerves in the internal auditory canal on parasagittal CT scans of cadaveric specimens and to compare this anatomy with findings on in vivo T2-weighted two-dimensional fast spin-echo and three-dimensional turbo spin-echo MR images. For the developmental research the left-right asymmetry might be a field of research. For the physician this differentiation represents a clinical and radiological challenge. The differentiation between benign and malign lesions in the CPA and IAC is important, as it requires diverse treatment protocols. In view of the sparse literature on treatment of single intracanalicular metastases, the review is broadened to the current treatment recommendations of single brain metastases. We address the issue of a possible regulation of CPA lesion laterality by asymmetrically expressed genes. Intracanalicular metastases of adenocarcinoma are documented, but a primary adenocarcinoma remains unreported. The discussion focuses on the incidence of extra-axial CPA and IAC lesions with their clinical presentations and their radiological findings. Background: Despite the relatively frequent occurrence of multiple primary tumors, namely, 10 of intracranial tumors, metastasis is a rare occurrence within the internal auditory canal (IAC) and cerebellopontine angle (CPA). The patient was treated with intrathecal chemotherapy. MRI showed an increase of the residual tumor and meningeosis carcinomatosa, and cerebrospinal fluid (CSF) examination was positive for tumor cells. This is the first of a two-part review that provides a practical approach to understanding temporal bone anatomy, localizing a pathologic process with a focus on inflammatory and neoplastic processes, identifying pertinent positives and negatives, and formulating a differential diagnosis. Green: internal auditory canal (IAC) light blue: cochlear aqueduct (CA) purple: bony. The patient's condition deteriorated gradually. The greater superficial petrosal nerve (GSPN) follows the genicu- late ganglion and the labyrinthine segment of the facial nerve into the fundus of the internal. A 3D model based on segmentation from temporal bone HRCT (right side). The investigations for the primary tumor site were all negative. Histological examination revealed blennogenic cylindrical adenocarcinoma. Due to progressive headaches and dizziness, the patient underwent a left transtemporal craniotomy with subtotal tumor resection. The follow-up MRI showed an unchanged pattern of contrast enhancement. Magnetic resonance imaging (MRI) showed an extra-axial mass most likely representing a left-sided vestibular schwannoma with characteristic contrast enhancement in the IAC. He presented 8 months later with left-sided tinnitus, progressive hearing loss, and attacks of vertigo. Cranial computed tomography scan revealed bilateral nonspecific periventricular and subcortical vascular lesions. We provide a review of uncommon lesions in the IAC and describe to our knowledge the first instance of a primary adenocarcinoma.Ī 60-year-old man presented with nausea and vomiting. Despite the relatively frequent occurrence of multiple primary tumors, namely, 10% of intracranial tumors, metastasis is a rare occurrence within the internal auditory canal (IAC) and cerebellopontine angle (CPA).
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |