Ct Images Of Tympanic Membrane

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Figure 10.14 Left congenital supralabyrinthine petrous bone cholesteatoma with extension towards the apex. Otoscopy is negative. The patient complained of progressive facial nerve paralysis of 5 years' duration as well as conductive hearing loss.

Cholestoma Tempanic Membrane
Figure 10.16 CT scan of the case presented in Figure 10.14. Axial view showing cholesteatoma extending into the petrous apex.
Sclerotic Tympanic Membrane
Figure 10.15 CT scan of the case presented in Figure 10.14. Coronal view showing extension of the cholesteatoma into the internal auditory canal.
Tympanic Membrane Sclerosis

Figure 10.17 Right congenital infralabyrinthine apical petrous bone cholesteatoma in a 30-year-old female patient. In the posterosuperior quadrant a white retrotympanic view is observed. The patient had complained of right anacusis since childhood and instability of 1 year duration. The facial nerve was normal.

Figure 10.17 Right congenital infralabyrinthine apical petrous bone cholesteatoma in a 30-year-old female patient. In the posterosuperior quadrant a white retrotympanic view is observed. The patient had complained of right anacusis since childhood and instability of 1 year duration. The facial nerve was normal.

Figure 10.18 CT scan of the case presented in Figure 10.17. Coronal view demonstrating the involvement of the infralabyrinthine apical compartment by the cholesteatoma.

Figure 10.19 CT scan of the case presented in Figure 10.17. A more anterior coronal view at the level of the cochlea.

Infralabyrinthine Approach
Figure 10.20 Postoperative CT scan showing total removal of the cholesteatoma through the transcochlear approach and obliteration of the operative cavity using abdominal fat.

Figure 10.21 Polyp in the external auditory canal in a patient who had undergone a tympanoplasty (see CT scan, Fig. 10.22). The patient presented with otorrhea and hearing loss.

Infralabyrinthine Approach

Figure 1022 CT scan of the case presented in Figure Figure 10.23 Postoperative CT scan showing total removal

10.21. A large infralabyrinthine apical petrous bone cholesteatoma extending to the cavernous sinus and to the sphenoid sinus can be seen. Total removal was achieved using an infratemporal fossa approach type B.

Figure 1022 CT scan of the case presented in Figure Figure 10.23 Postoperative CT scan showing total removal

10.21. A large infralabyrinthine apical petrous bone cholesteatoma extending to the cavernous sinus and to the sphenoid sinus can be seen. Total removal was achieved using an infratemporal fossa approach type B.

Radical Mastoid Cavity

Figure 10.25 CT scan of the case presented in Figure 10.24 demonstrating cholesteatoma invading the labyrinth.

Figure 10.24 Left acquired petrous bone cholesteatoma of the massive type. The patient had complained of fetid otorrhea and hearing loss since early childhood. Six months before presentation, he started to experience facial nerve paralysis. A radical mastoidectomy was performed in another center with partial removal of the pathology. The second and third portions of the facial nerve can be observed in the mastoid cavity. The patient underwent surgery using a transcochlear approach to obliterate of the cavity with abdominal fat.

Figure 10.25 CT scan of the case presented in Figure 10.24 demonstrating cholesteatoma invading the labyrinth.

Cholestoma Tempanic Membrane

Figure 10.26 Left radical mastoid cavity. This patient was operated on using a combined middle cranial fossa and trans-mastoid approach for the removal of a petrous bone cholesteatoma. The facial nerve was left as a bridge in the middle of the cavity. On follow-up the patient complained of recurrent episodes of facial nerve paralysis due to accumulation of cerumen and debris in the cavity. Therefore, the patient underwent a second operation for obliteration of the cavity with abdominal fat and closure of the external auditory canal as cul-de-sac.

Figure 10.26 Left radical mastoid cavity. This patient was operated on using a combined middle cranial fossa and trans-mastoid approach for the removal of a petrous bone cholesteatoma. The facial nerve was left as a bridge in the middle of the cavity. On follow-up the patient complained of recurrent episodes of facial nerve paralysis due to accumulation of cerumen and debris in the cavity. Therefore, the patient underwent a second operation for obliteration of the cavity with abdominal fat and closure of the external auditory canal as cul-de-sac.

Summary

When a patient presents with hearing loss (sensorineural or mixed) and/or facial nerve paralysis with or without a retrotympanic mass, the probability of petrous bone cholesteatoma should be considered. In such cases, it is necessary to perform a high -resolution CT scan of the temporal bone. The ideal treatment for petrous bone cholesteatoma is radical surgical removal, although destruction of the labyrinth and rerouting of the facial nerve may be required. The status of the contralateral ear must also be considered.

The modified transcochlear approach is the most appropriate for the removal of petrous bone cholesteatoma. This approach offers direct lateral access to the petrous bone and allows the removal of all types of petrous bone cholesteatoma with their possible extension into the clivus or sphenoid sinus. In addition, it has the advantage of minimizing the occurrence of cerebral spinal fluid (CSF) leak and allows control of the different vital structures, including the internal carotid artery. Closure of the external auditory canal as cul-de-sac and obliteration of the operative cavity with abdominal fat avoids the risk of infection and the need for frequent toilet of a very deep cavity.

The middle cranial fossa approach and the radical mastoidectomy can be used in cases with noncom-

promised inner ear function. The former is utilized in small supralabyrinthine cholesteatoma, while the latter is utilized in small infralabyrinthine cholestea-toma with no involvement of the internal carotid artery.

11 Glomus Tumors (Chemodectomas)

The glomus body was first described by Guild in 1941 as a small highly vascular mass of epithelioid cells located in the region of the adventitia of the jugular bulb. In 1953, Guild described glomus formations along the tympanic branches of the glossopharyngeal and vagus nerves (Jacobson's and Arnold's nerves, respectively).

Glomus bodies are mainly found in the tympanic region, jugular bulb, at the carotid bifurcation, and related to the vagus nerve. They are classified as paraganglia that are derived from the neural crest. While the carotid and vagal bodies function as chemorecep-tors stimulated by the changes in the oxygen tension, tympanic and jugular bulb paraganglia do not exhibit this function.

The term glomus tympanicum is reserved for tumors that originate from the mesotympanum while the term glomus jugulare is attributed to those cases that arise from the jugular bulb or the hypotympanum with secondary invasion of the bulb. These tumors are highly vascular and they derive the blood supply mainly from the ascending pharyngeal artery. It is claimed that they have a hereditary transmission as autosomal dominant traits with penetrance that increases with age.

In the majority of cases, the initial symptoms are hearing loss (conductive, sensorineural, or mixed) and pulsatile tinnitus synchronous with pulse. The tumor can extend into the labyrinth, causing vertigo of peripheral origin; towards the jugular foramen, leading to deficits of one or more of the lower cranial nerves (IX-XI); or towards the occipital condyle, leading to hypoglossal nerve paralysis. Patients suffering from preoperative affection of the lower cranial nerves run a better postoperative course as compensation of the contralateral side would have already started. The contralateral vocal cord compensates by crossing the midline to meet the paralyzed cord, thereby markedly reducing the risk of aspiration pneumonia. On the other hand, patients with preoperative intact lower cranial nerves in whom the nerves are sacrificed during the operation suffer from deglutition problems in the postoperative course. Nasogastric feeding is used in such cases and oral feeding is resumed only when compensation from the contralateral side occurs. A useful alternative is vocal cord medialization either by Teflon injection or by medialization thyroplasty using cartilage or silicon.

The tumor can also extend into the petrous apex, leading to paralysis of the abducent nerve and trigem-inal neuralgia, or invade the mastoid, resulting in facial nerve paralysis. Further extension can also occur in the external auditory canal. Tumors occupying the exter nal auditory canal can lead to serous or purulent otor-rhea due to irritation of the skin and retention of squamae and epithelial debris. Hemorrhagic discharge rarely occurs.

Fisch classified glomus tumors into four classes based on location and extension seen on high-resolution CT scans (see Table 11.1 and Figs. 11.1-11.6).

On otoscopy, a retrotympanic pulsatile mass is usually seen in the inferior quadrants. The mass is red or bordeaux red. In some cases the mass may have a reddish-blue color due to the presence of middle ear effusion secondary to eustachian tube blockage. The tumor may be seen as a polyp in the external auditory canal either due to erosion of the floor of the canal or to the tumor breaking through the tympanic membrane.

The diagnosis can be made clinically (history and otoscopic findings). Computed tomography (CT) with contrast and magnetic resonance imaging (MRI) with gadolinium allow exact definition of the tumor extension. Radiology also helps to differentiate between glomus tumors and other lesions such as aberrant carotid artery, high jugular bulb, cholesterol granuloma, or meningioma extending into the middle ear. Carotid and vertebral angiography allows identification of the arteries supplying the tumor; and they should be embolized before surgery to avoid excessive intraoperative bleeding.

In cases in which the horizontal carotid artery is engulfed by the tumor, the balloon occlusion test is indispensable for studying the perfusion by the contralateral carotid artery as well as for the safety of the closure of the involved carotid.

Table 11.1 Classification of glomus tumors according to Fisch (1978)

Class A

Glomus tympanicum

Class B

Tympanomastoid

Class C

Glomus jugulare

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Responses

  • ian
    Where is the tympanic membrane on a CT scan?
    6 years ago
  • Isaias
    Can a perforated tympanic membrane be seen on CT scan?
    5 years ago
  • leevi
    Is it possible to have normal tympanic membrane on ct but have a perforated membrane?
    4 years ago
  • matthias
    Does ct scan of ear drum do tubes aswell?
    4 years ago
  • klaus
    Where is hypotypanum locatred on CT scan?
    1 year ago

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