![]() ![]() However, the knowledge of the anatomy of the inner ear and the IAC from the external auditory canal corridor is important to be totally oriented during middle-ear surgery. In daily practice, this surgical corridor is seldom employed, especially if specific diseases and the patient’s features are contemporarily present. In the latter case, the IAC can be reached via the external auditory canal corridor using an endoscopic transcanal transpromontorial approach. Recently, endoscopic techniques have been introduced also in lateral skull base surgery, either as assistance to microscope-based procedures or as an exclusive mini-invasive approach. The advantages of endoscopic visualization and the possibility to work around the corner represent great advantages during ear surgery approaches. Since the introduction of the endoscope in the otologic field, there has been a progressive development in term of indications for transcanal endoscopic approaches. All of these procedures are based on the use of the operative microscope and are defined “open techniques,” due to the extensive bone work, the brain or cerebellar retraction, or the facial nerve re-routing to reach the affected area. Moreover, despite the benign nature of the vast majority of lesions located in the IAC, extensive surgical approaches are often required to reach that area, like transpetrous routes (e.g., translabyrinthine, transotic, transcochlear), the retrosigmoid route, and the middle cranial fossa techniques. These exposures may be used in combination.The surgery of the internal auditory canal (IAC) represents a challenge for otolaryngologists and neurosurgeons because of the important anatomical relationships of this noble area with other structures, like the internal carotid artery and the facial nerve. Transmastoid or middle cranial fossa surgical approach are generally used. The surgical management depends on the size, the segments of facial nerve involved by tumor and the patient´s hearing status. Cystic changes or heterogeneity may alsoīe observed in large tumors. It is heterogeneously hyperintense on T2-weighted images, and it enhances brightly and homogeneously after administration of gadolinium. MR imaging shows a well-circumscribed extraaxial mass that is mildly hypo- or isointense relative to brain on Labyrinthine segment of the facial nerve, widening of internal auditory canal and geniculate fossa, opacification of the mesotympanum by soft-tissue mass with scalloping of the apex of the petrous CT scans show a benign bone remodeling secondary to tumor, consisting of enlargement of the bony canal for the Other less common symptoms are tinnitus, otalgia and hemifacial spasms. Sensorineural hearing loss is due to internal auditive canal, CPA or both Conductive hearing loss is due to tympanic segment involvement and ossicular compression. The most common symptom is facial paresis followed by hearing loss. The clinical presentation is variable and depends on the size and the location of the tumor. The age range at time of imaging is 10-70 ![]() These lesions may demonstrate a dumbbell appearance due to extension from the CPA-IAC through the labyrinthine segment into the geniculate fossa. Uncommonly it may extend projecting up into the middle cranial fossa (upward spread through the roof of the temporal bone or anterior spread through the facial From there the tumor may extend proximally (involving labyrinthine portion) orĭistally (involving tympanic portion). The most common location is the geniculate ganglion. Multiple contiguous segments are affected. These tumors may arise anywhere along the course of the facial nerve, from the cerebellopontine angle to The mass wasįacial nerve Schwannomas are uncommon tumors that come up from the Schwann cell sheath. There is opacification of the epitympanum and mesotympanum by invading soft-tissue mass (hypotympanum and Prussak space are not affected) which also contacts the ossicular chain. Axial and coronal CT scans show the enlargement of the internal auditory canal, labyrinth and geniculateįossa. ![]() After administration of gadolinium it enhances brightlyĪnd homogeneously, displaying a hypointense peripheral capsule which represents duramater. ![]() The mass is hypo- or isointense relative to gray matter on T1-weighted images and heterogeneously hyperintense on T2-weighted images. The labyrinthine, tympanic and intracanalicular portions of the facial nerve, with anterior spread through the facial hiatus and upward spread through the tegmen tympani involving the middle cranialįossa. MR images show a well-defined extraaxial mass in the right cerebellopontine angle extending into the geniculate ganglion and At physicalĮxamination there was no evidence of peripheral facial nerve neuropathy. The patient also referred night tinnitus for the last three months. A 26-year-old man shows a one and a half year history of progressive right-sided sensorineural hearing loss. ![]()
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