#Internal auditory canal ct series

#Internal auditory canal ct series

In this series of 19 cases, we report the abnormalities of the vestibule and semicircular canals and provide a comprehensive description of their CT and MR imaging findings. Its characteristic CT findings, including bulbous dilation of the internal auditory canal and absence of the modiolus with the interscalar septa present, have been well-recognized. Be sure to check out the additional videos on other head and neck topics.Incomplete partition type III, also referred to as X-linked deafness, is a rare genetic inner ear malformation. Thanks for checking out this quick video on the internal auditory canal. This should make you think of unusual pathology such as lymphoma, sarcoidosis, metastatic disease, perineural spread of tumor, and Lyme disease. Red flags in the IAC include nodular enhancement and multiple cranial nerves enhancing. The geniculate and mastoid portions of the facial nerve can enhance in normal cases, so in those cases you must consider the symmetry.

Imaging can often be normal, but if you see linear enhancement in the distal auditory canal this can be a sign of Bell’s palsy. They look cystic on T2 and can be close to CSF, but their key distinguishing feature is hyperintensity on DWI.īell’s Palsy is an idiopathic facial paralysis on one side. Dural tails, or linear areas of tumor tracking along the dura, can be helpful, but schwannomas can also have them.Įpidermoids are relatively uncommon non-enhancing masses of the CP angle and IAC. Key clues that they are not schwannomas are a center outside of the IAC.

They are also solid enhancing masses near the IAC. Meningiomas are the second most common solid mass. They can sometimes be quite small but still symptomatic. With these tumors, you will see an enhancing mass with pretty homogeneous enhancement centered in the IAC with extension into the porus acousticus. They usually arise from the inferior vestibular nerve, and have previously been referred to as “acoustic neuromas”. Vestibular schwannomas are the most common tumor affecting the IAC. Vascular malformations are a rare cause of symptoms, but if you see an unusual tangle or cluster of vessels in the region you should If you see it, you can be descriptive about which portion of the nerve is involved. Smaller loops of the anterior inferior cerebellar artery are more controversial but has been previously described as associated with hemifacial spasm. If you see mass effect, this is particularly possible. Sometimes an arterial branch can compress the nerves as they enter the IAC. Contains the muscles of mastication, the mandible, branches of the trigeminal nerve, lymph nodes, and minor salivary glands. oral cavity includes the lips, teeth, hard and soft palate, gingiva, retromolar trigone, the buccal mucosa, and anterior 2/3 of the tongue. The oropharynx includes the tonsils (both lingual and palatine), the squamous mucosa of the pharynx, the uvula, and the vallecula. This can be remembered by the mnemonic “7up, Coke down”. On a sagittal view, the anterior portion of the canal contains the facial nerve (superior) and cochlear nerve (inferior). The most easily seen structures are the facial (cranial nerve VII) and vestibulocochlear (cranial nerve VIII) nerves. Review of internal auditory canal (IAC) anatomy.