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The Facial Nerve
Published in R James A England, Eamon Shamil, Rajeev Mathew, Manohar Bance, Pavol Surda, Jemy Jose, Omar Hilmi, Adam J Donne, Scott-Brown's Essential Otorhinolaryngology, 2022
Christopher Skilbeck, Samuel MacKeith
The course of the facial nerve is shown in Figure 21.1 and can be divided into intracranial, intratemporal and extratemporal portions. The intracranial portion is approximately 24 mm long and courses through the cerebellopontine angle (CPA) cistern to the porus of the internal auditory meatus (IAM). The intratemporal portion is 28–30 mm long. This includes the meatal segment, which runs in the IAM. The labyrinthine segment then runs laterally to the first genu and the geniculate ganglion, the tympanic segment runs posteriorly from the geniculate ganglion to the second genu and the vertical segment runs from the second genu to the stylomastoid foramen. The extratemporal segment runs forward into the parotid gland where it divides into upper and lower branches.
Otorhinolaryngology (ENT)
Published in Gozie Offiah, Arnold Hill, RCSI Handbook of Clinical Surgery for Finals, 2019
Investigation➣ Audiology (unilateral SNHL)➣ MRI of the Internal auditory meatus
Anatomy of the Skull Base and Infratemporal Fossa
Published in John C Watkinson, Raymond W Clarke, Christopher P Aldren, Doris-Eva Bamiou, Raymond W Clarke, Richard M Irving, Haytham Kubba, Shakeel R Saeed, Paediatrics, The Ear, Skull Base, 2018
The posterior aspect of the petrous bone is perforated by the internal auditory meatus (IAM), through which pass the VII and VIII cranial nerves, together with the superior and inferior vestibular nerves and the labyrinthine artery, an internal auditory branch of the basilar artery. Just behind the IAM, a small slit leads to the aquæductus vestibuli containing the endolymphatic duct.
Tinnitus following COVID-19 vaccination: report of three cases
Published in International Journal of Audiology, 2022
Daniela Parrino, Andrea Frosolini, Chiara Gallo, Romolo Daniele De Siati, Giacomo Spinato, Cosimo de Filippis
A 37-year-old woman was referred to our department complaining of sudden onset of right tinnitus 7 hours after her first dose of COVID-19 vaccine. She reported short-term dizziness, but she did not notice hearing loss. Local pain at injection site was reported as another vaccine side effect. Her previous medical history was relevant for glaucoma and undifferentiated connective tissue disease. She denied any previous audio-vestibular disorder except for an episode of transient tinnitus related to unremembered side acute otitis media 20 years previously. She was not taking any home medications and had no known allergies. She did not report any previous COVID-19 diagnosis. Otoscopy examination was normal bilaterally. Spontaneous nystagmus was absent as well as other focal neurological symptoms. PTa revealed bilateral normal hearing with slight asymmetry on the right ear. The Psychoacoustic Measures of Tinnitus resulted in a 20 dB pure tone at 10000 Hz. The THI score was 90/100. A 10-day course of oral corticosteroid therapy with tapering regimen was started. PTa performed after treatment showed no significant changes. The Psychoacoustic Measures of Tinnitus and THI score slightly improved (78/100), but the patient still complained of tinnitus and an accompanying bilateral ear fullness sensation. A second line therapy was started. A magnetic resonance imaging (MRI) of the internal auditory meatus or cerebellopontine angle ruled out any possible abnormality.
Optic Neuropathy Revealing Severe Superficial Siderosis in the Setting of Long-standing Low-grade Intracranial Neoplasm
Published in Neuro-Ophthalmology, 2022
Coralie Hemptinne, Adrienne Coche, Thierry Duprez, Philippe Demaerel, Christian Raftopoulos, Antonella Boschi
The vestibulo-cochlear nerves, the cerebellar cortex and the brainstem are especially vulnerable to haemosiderin incrustation in SS, with symptoms of sensorineural hearing loss, gait ataxia, dysmetria and myelopathy. This susceptibility probably derives from their specific ability to synthesise ferritin in response to haem, which is later stored in the form of haemosiderin. This ability is likely due to Bergmann glia in the cerebellum and to microglia in CNS tissues, and only exists in CNS tissues.9,10 This may explain the susceptibility of the vestibulo-cochlear nerve, in which the transition from CNS to peripheral nervous system occurs near the internal auditory meatus rather than near the brainstem as is the case for cranial nerves III, IV, V, VI, VII, IX, X and XII. In Koeppen at al.’s experiments, cranial nerves incrusted with haemosiderin included the vestibulo-cochlear nerves, as well as the olfactory tracts, the optic nerves and chiasm, which fully consist of CNS tissue. The facial nerves, adjacent to the vestibulo-cochlear nerves, were devoid of the iron stain.9
Combined transmastoid/middle fossa approach for a petrous bone cholesteatoma: A case report and literature review
Published in Acta Oto-Laryngologica Case Reports, 2021
Kiyotaka Miyazato, Yohei Hokama, Hideki Nagamine, Akira Ganaha, Mikio Suzuki, Shogo Ishiuchi
This case progressed favorably as a result of the resection using the combined transmastoid/middle fossa approach to treat right petrous bone cholesteatoma. The combined transmastoid/middle fossa approach is used to treat petrous bone cholesteatoma and other cerebellopontine angle tumors, such as acoustic schwannoma [3–5]. The choice depends on various factors, including tumor progression, tumor size, degree of hearing loss, and the extent of increased intracranial pressure [3]. With the translabyrinthine approach alone, surgery can be performed without applying pressure to the brainstem. However, this method causes deafness and is, therefore, only appropriate in cases in which hearing preservation is unnecessary. In combination with the middle fossa approach, the internal auditory meatus can be operated without passing through the labyrinthine [6].