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Anatomy and Physiology of Hearing
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
Ananth Vijendren, Peter Valentine
The middle ear consists of the tympanic cavity (TC), Eustachian tube (ET) (see Chapter 8) and the mastoid air cell (MAC) system. The mastoid antrum is an air-filled sinus within the petrous temporal bone that communicates with the middle ear by way of the aditus. The MAC system is largely developed by the age of 6.
Case 37
Published in Simon Lloyd, Manohar Bance, Jayesh Doshi, ENT Medicine and Surgery, 2018
Simon Lloyd, Manohar Bance, Jayesh Doshi
The diagnosis is otogenic brain abscess. The opacified mastoid antrum can be seen in the first CT scan. The second brain window scan shows a rim-enhancing lesion in the temporal bone, confirmed by the MRI, which also shows the surrounding oedema. The most common site of an otogenic abscess is the temporal lobe followed by the cerebellum. Subdural empyema may also form but is less common.
Anatomy and Embryology of the External and Middle Ear
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 mastoid antrum is an air-filled sinus within the petrous part of the temporal bone. It communicates with the middle ear by way of the aditus and has mastoid air cells arising from its walls. The antrum, but not the air cells, is well developed at birth and by adult life has a volume of about 2 mL. The roof of the mastoid antrum and mastoid air cell space form the floor of the middle cranial fossa, while the medial wall relates to the posterior semicircular canal. More deeply and inferiorly is the dura of the posterior cranial fossa and the endolymphatic sac. The latter emerges through the operculum on the posterior surface of the petrous bone and derives from the endolymphatic duct, which has passed through the vestibular aqueduct. Posterior to the endolymphatic system is the sigmoid sinus, which curves downwards only to turn sharply upwards to pass medial to the facial nerve and then becomes the dome of the jugular bulb in the middle ear space. The posterior belly of the digastric muscle forms a groove in the base of the mastoid bone. The corresponding ridge inside the mastoid lies lateral not only to the sigmoid sinus but also to the facial nerve and is a useful landmark for finding the nerve itself. The periosteum of the digastric groove on the undersurface of the mastoid bone continues anteriorly and part of it becomes the endosteum of the stylomastoid foramen and subsequently of the facial nerve canal.
Examination of risk factors for postoperative vestibular symptoms in patients with cholesteatoma
Published in Acta Oto-Laryngologica, 2022
Takaaki Kobayashi, Shusuke Iwamoto, Toshihito Sahara, Yujiro Hoshi, Anjin Mori, Hajime Koyama, Takeshi Fujita, Mitsuo P. Sato, Yasuhiro Osaki, Katsumi Doi
Pathologically, it is not considered that exposure of the dura mater causes vestibular symptoms. However, because it was the greatest risk factor, we hypothesised that the narrowing of the working space around the mastoid antrum in mastoidectomy may be a background factor in cases with exposure of the dura mater. Therefore, as an additional study, the shortest distance from the prominence of the lateral semicircular canal to the middle cranial fossa dura was measured in the coronal image of the temporal bone CT of all cases in this study. It was confirmed that the length was significantly shorter in the exposed dura group than in the non-exposed group (p < .01) (Table 7). In addition, in cases with cholesteatoma in the mastoid area and need to remove epithelial tissue from the bony surface adjacent to the superior semicircular canal, we thought that by thinning the bony wall adjacent to the superior semicircular canal, the procedure might also threaten the vestibular function by stimulating the superior semicircular canal. We measured the length from the superior semicircular canal to the bony edge. However, as a result of the examination, no correlation was found between the thickness of the bony wall and the occurrence of vestibular symptoms (p = .53) (Table 8).
Canal wall-down procedure with soft posterior meatal wall reconstruction in acquired cholesteatoma: focus on postoperative middle ear status*
Published in Acta Oto-Laryngologica, 2018
Tomoyasu Tachibana, Shin Kariya, Yorihisa Orita, Michihiro Nakada, Takuma Makino, Yasutoshi Komatsubara, Yuko Matsuyama, Yuto Naoi, Kazunori Nishizaki
Surgical procedures in the present study are as follows. After placement of a retroauricular incision, the skin and periosteum of the auditory meatus were elevated from the posterior bony EAC wall, preserving the intact parts of the tympanic membrane (TM) and EAC wall skin as much as possible. The posterior bony EAC wall was then removed to eliminate cholesteatomas in the middle ear and mastoid antrum. Appropriate reconstruction of a functional sound-conduction mechanism was performed according to the individual situation. Finally, defects in the TM and posterior EAC wall skin were reconstructed with fascial sheet collected from the postauricular temporalis muscle. In the follow-up, we performed a CT scan every 6 months for first 2 years and once a year for next 3 years.
Cerebellopontine angle epidermoid with ipsilateral external ear atresia: an embryological association or a coincidence?
Published in British Journal of Neurosurgery, 2023
Khursheed Alam Khan, Rashim Kataria, Mohnish Grover, Virendra Deo Sinha
A true epidermoid has its nidus of squamous epithelium present at birth and often affect the temporal bone when the term congenital cholesteatoma may be used. They may arise from the cerebellopontine angle (CPA), petrous pyramid, jugular fossa, middle ear cavity or mastoid antrum.2,3