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Abnormal Skull
Published in Swati Goyal, Neuroradiology, 2020
Usually idiopathic, but reactivation of the herpes simplex virus or the varicella-zoster virus, with latent infection in the geniculate ganglion, can also be a cause. It is rapid in onset but normally resolves in 6−8 weeks. The age range of presentation is usually 15−45 years. Risk factors are pregnancy, diabetes mellitus, and hypothyroidism.
Head and Neck
Published in Rui Diogo, Drew M. Noden, Christopher M. Smith, Julia Molnar, Julia C. Boughner, Claudia Barrocas, Joana Bruno, Understanding Human Anatomy and Pathology, 2018
Rui Diogo, Drew M. Noden, Christopher M. Smith, Julia Molnar, Julia C. Boughner, Claudia Barrocas, Joana Bruno
The facial nerve (CN VII) follows a complicated course through the temporal bone, giving off several branches (Plate 3.16; described in detail in Section 3.3.1.7). It enters the internal auditory meatus and performs a hairpin turn behind the cochlea. At the anterior point of the turn, the geniculate ganglion is found. This is a sensory ganglion, whose axons carry information from the taste receptors of the anterior tongue and from the skin of the external auditory meatus. A branch of the facial nerve projects anteriorly from the geniculate ganglion, forming the greater petrosal branch of the facial nerve. These fibers emerge from the tegmen tympani of the temporal bone into the middle cranial fossa, and join the deep petrosal nerve to form the nerve of the pterygoid canal (Vidian nerve). They are preganglionic fibers running to the pterygopalatine ganglion. The next branch is the chorda tympani, which passes between the incus and malleus near the tympanic membrane and then exits the temporal bone through the petrotympanic fissure, just posterior to the mandibular fossa, to join the lingual nerve. The third branch goes to the stapedius muscle in the middle ear. The rest of the facial nerve is entirely motor and exits the temporal bone through the stylomastoid foramen.
Case 44
Published in Simon Lloyd, Manohar Bance, Jayesh Doshi, ENT Medicine and Surgery, 2018
Simon Lloyd, Manohar Bance, Jayesh Doshi
Facial nerve schwannomas most often occur at the geniculate ganglion. A more typical imaging appearance is shown below on a gadolinium-enhanced T1-weighted MRI image. This shows a lesion involving the right geniculate ganglion and the internal auditory canal.
Role of MPR image reconstruction in guiding the diagnosis and treatment strategy of facial nerve schwannoma
Published in Acta Oto-Laryngologica, 2022
Xiaoyu Li, Qiaohui Lu, Yang Liu
In patients 1-1 and 1-2, the lesions invaded the geniculate ganglion and tympanic segment. Patient 1-1 was treated in our department 7 years prior, and non-enhanced temporal bone CT scan at the axial position and non-enhanced cranial MRI showed otitis media, an atypical presentation. Facial palsy was absent and the patient was misdiagnosed with ‘otitis media’, before surgery. The patient underwent exploratory tympanotomy and was misdiagnosed with inflammatory granuloma during the surgery, which was resected. After surgery, the patient immediately developed facial palsy (grade HB-4) and was lost to follow-up. MPR was employed for source image data facial nerve reconstruction to discover bone canal defects from the geniculate ganglion to the horizontal segment of the facial nerve and a neoplasm with clear borders growing in the tympanum, suggesting a facial nerve schwannoma (Figure 1(B)). Patient 1-2 did not develop facial palsy and the lesion was confirmed through external auditory canal biopsy. Subsequently, the patient was observed and had no facial palsy within 13 months of follow-up.
Minimally invasive endoscopic removal of primary inner ear schwannomas
Published in Acta Oto-Laryngologica Case Reports, 2021
Safeer Mohammed, Seung Hyun Jang, Dong Hee Han, In Seok Moon
Because of intractable vertigo, she strongly wanted surgical removal and a minimally invasive modified Exclusive Endoscopic Transcanal Transpromontorial approach (mEETTA) was done [10]. Surgical procedures: 1) tympanomeatal flap elevation, all ossicles were removed, 2) facial nerve was demarcated from geniculate ganglion to proximal second genu, 3) transcanal endoscopic drilling of the promontory was done exposing basal turn filled with tumor and drilling continued inferiorly to expose the vestibule, 4) tumor was entirely removed, 5) promontory opening was plugged with soft tissue from tragal area, and 6) a tragal cartilage tympanoplasty was done (Supplement 1). The tumor was removed (Figure 1(B)) and histological diagnosis proved to be consistent with Intra labyrinthine schwannoma. The patient improved symptomatically and well-healed tympanic membrane was observed (Figure 1(C)) on regular follow up.
High-resolution computed tomography temporal bone imaging in achondroplasia
Published in Baylor University Medical Center Proceedings, 2021
Puneet S. Kochar, Priti Soin, Ayah Megahed
HRCT demonstrated upward tilted petrous ridges, giving a characteristic appearance of “towering” petrous ridges (Figure 1a). The IACs were also tilted upwards with an IAC-IAC angle of approximately 126° (normal 165°) (Figure 1b). Secondary to rotation, the orientation of the middle ear ossicle changes gave an appearance of a broader ice cream cone on axial images (Figure 1c, 1d). Bilateral geniculate ganglion had a “vertical” orientation due to rotation of the cochlea (Figure 2a, 2b). The oval windows were facing directly downwards (Figure 2c, 2d). Coronal CT at the level of the scutum demonstrated a downward-pointing scutum projecting inferior to the promontory (Figure 3a). The Körner septum was rotated horizontally (Figure 3b). Additionally, because of changes at the skull base, the carotid canals were foreshortened with distal ends approaching the midline (Figure 3c). Instead of being vertical, the proximal ascending portion of the carotid canals were angled medially toward the midline (Figure 3d).