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Paper 4
Published in Amanda Rabone, Benedict Thomson, Nicky Dineen, Vincent Helyar, Aidan Shaw, The Final FRCR, 2020
Amanda Rabone, Benedict Thomson, Nicky Dineen, Vincent Helyar, Aidan Shaw
Cholesteatoma are middle ear masses, which unlike other masses in this region demonstrate restricted diffusion. They are T1 hypointense and T2 hyperintense and do not typically enhance. They most commonly affect the superior tympanic membrane (pars flaccida) occurring in the attic, otherwise known as Prussak’s space. They can erode the scutum and displace the ossicles and in this location displace them medially. When cholesteatomas less commonly involve the pars tensa, the ossicles are displaced laterally.
Ear, Nose, and Paranasal Sinus
Published in Swati Goyal, Neuroradiology, 2020
Two patterns of spread: Pars flaccida cholesteatoma (Attic type)The lesion initiates anterosuperiorly in Prussak’s space (the area just below the scutum), and then extends laterally toward the ossicular chain and into the epitympanum.Pars tensa cholesteatoma (Sinus type)The cholesteatoma begins posterosuperiorly, then extends posteriorly toward the facial recess and the tympanic sinus, and medially toward the ossicular chain.
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 middle ear mucosa is essentially mucus-secreting respiratory mucosa bearing cilia on its surface.20 The extent of the mucociliary epithelium varies in normal middle ears, being more widespread in the young. Three distinct mucocilary pathways can be identified – epitympanic, promontorial and hypotympanic, the latter being the largest. Each of these pathways coalesces at the tympanic orifice of the Eustachian tube.21 The mucous membrane lines the bony walls of the tympanic cavity, and it extends to cover the ossicles and their supporting ligaments in much the same way as the peritoneum covers the viscera in the abdomen. The mucosal folds also cover the tendons of the two middle ear muscles and carry the blood supply to and from the contents of the tympanic cavity. These folds separate the middle ear space into compartments. As a result, the only route for ventilation of the epitympanic space from the mesotympanum is via two small openings between the various mucosal folds – the anterior and posterior isthmus tympani. Likewise, the Prussak space is found between the pars flaccida and the neck of the malleus, bounded by the lateral malleolar fold. This space can play an important role in the retention of keratin and subsequent development of cholesteatoma. The mucosal folds have been described in detail by Proctor22 and are depicted in Figure 46.15.
Fully endoscopic laser stapedotomy: is it comparable with microscopic surgery?
Published in Acta Oto-Laryngologica, 2018
Since the introduction of classical stapes surgery, surgical microscopes play an important role. Under a microscope, surgeons cannot easily see the anterior crus of the stapes, which then necessitates the partial removal of the posterior bony wall of the external ear canal and the manipulation of the chorda tympani nerve. Endoscopy has been used in otologic surgery for approximately 20 years, and it provides a better view of important structures in the middle ear, especially that of the oval window niche, without the need for any bone removal [4]. Karchier et al. [6] reported that visualization of the footplate, sinus tympani, and Prussak’s space (the major sites related to cholesteatoma and otosclerosis) was significantly better with an endoscope than with a microscope. However, they reported no significant difference between the endoscope and microscope when used for the visualization of the orifice of the Eustachian tube and the hypotympanum. Surmelioglu et al. [7] concluded that endoscopic stapes surgery has many benefits, such as good visualization and easy accessibility of the stapes, oval window niche, and facial nerve. Removal of the scutum and manipulation of the chorda tympani nerve are less frequent with the endoscopic technique. In their study, the incidence of scutum removal and chorda injury was 4.5% in the endoscopic group, compared to 33.3% in the microscopic group.
Improvement of otoendoscopic surgery for epitympanic cholesteatoma invading the mastoid
Published in Acta Oto-Laryngologica, 2019
Nan Wu, Fangyuan Wang, Zhaohui Hou, Shiming Yang
Surgery always starts from the acoustic meatus approach. An incision is made on the acoustic meatus under an otoendoscope to lift the skin flap. The margin is 2 cm away from the tympanic anulus (Figure 1(a)). The tympanic membrane is lifted and separated from the manubrium of malleus. The flap is turned downward to the hypotympanum cavity and fixed, so that the cholesteatoma in the mesotympanum and posterior tympanum can be eliminated under the otoendoscope. If a retraction pocket is formed in Prussak’s space and is located outside the incudomalleolar joint and the backward extension range of cholesteatoma is limited within the tympanic antrum, the mastoid does not need to be opened. Scutum bones should be removed to expose edges of the epitympanum above the incudomalleolar joint. Cholesteatoma at the external side of the ossicular chain is eliminated downward along the edges under an angular otoendoscope (Figure 1(b)).If the epitympanic cholesteatoma is located in the inner side of the ossicular chain and extends into the mastoid, scutum bones should only be partly removed under an otoendoscope through the acoustic meatus. Then, the incus and head of malleus are taken out. A limited incision behind the ear is made, and the lesion in the mastoid is eliminated under an otoendoscope or microscope. Scutum bones close to the zygoma are drilled. Thus, the anterior epitympanic recess (AER) can be exposed from the direction of the mastoid as much as possible (Figure 1(c)). Given the removal of the head of malleus and incus, a space is available for the insertion of the 45° otoendoscope into the epitympanum from the mastoid. Under the direct view of the otoendoscope, cholesteatoma in the epitympanum can be eliminated completely from the back forward (Figure 1(d)).If surgeons cannot accurately judge whether the cholesteatoma invades the mastoid by routine CT of temporal bone before operation, a key hole will be made on the back wall of the acoustic meatus. The bone at approximately 1.5–2 cm above the short process of malleus is drilled to expose the tympanic antrum inside. The key hole directly faces the lateral semicircular canal. After making a 6-mm key hole, a 45°otoendoscope with 3 mm-diameter can be inserted to observe the epitympanum, tympanic antrum, and mastoid. Surgeons can judge the invasion scope of cholesteatoma in the early stage of operation (Figure 1(e)).Although the improvements aim to reduce or avoid drilling on the scutum, cholesteatoma usually erodes the scutum before surgery. The repair using full-thickness cartilage is needed at the end of the operation.