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Cholesteatoma is a destructive and expanding growth consisting of keratinizing squamous epithelium in the middle ear and/or mastoid process. Cholesteatomas are not cancerous as the name may suggest, but can cause significant problems because of their erosive and expansile properties. This can result in the destruction of the bones of the middle ear (ossicles), as well as growth through the base of the skull into the brain. They often become infected and can result in chronically draining ears. Treatment almost always consists of surgical removal.
The temporal bones are situated at the sides and base of the skull, and lateral to the temporal lobes of the cerebral cortex.
Conductive hearing loss (CHL) occurs when there is a problem transferring sound waves anywhere along the pathway through the outer ear, tympanic membrane (eardrum), or middle ear (ossicles). If a conductive hearing loss occurs in conjunction with a sensorineural hearing loss, it is referred to as a mixed hearing loss. Depending upon the severity and nature of the conductive loss, this type of hearing impairment can often be treated with surgical intervention or pharmaceuticals to partially or, in some cases, fully restore hearing acuity to within normal range. However, cases of permanent or chronic conductive hearing loss may require other treatment modalities such as hearing aid devices to improve detection of sound and speech perception.
Facial nerve paralysis is a common problem that involves the paralysis of any structures innervated by the facial nerve. The pathway of the facial nerve is long and relatively convoluted, so there are a number of causes that may result in facial nerve paralysis. The most common is Bell's palsy, a disease of unknown cause that may only be diagnosed by exclusion of identifiable serious causes.
The mastoid antrum is an air space in the petrous portion of the temporal bone, communicating posteriorly with the mastoid cells and anteriorly with the epitympanic recess of the middle ear via the aditus to mastoid antrum. These air spaces function as sound receptors, provide voice resonance, act as acoustic insulation and dissipation, provide protection from physical damage and reduce the mass of the cranium. The roof is formed by the tegmen antri which is a continuation of the tegmen tympani and separates it from the middle cranial fossa. The lateral wall of the antrum is formed by a plate of bone which is an average of 1.5 cm in adults. The mastoid air cell system is a major contributor to middle ear inflammatory diseases.
Mastoiditis is the result of an infection that extends to the air cells of the skull behind the ear. Specifically, it is an inflammation of the mucosal lining of the mastoid antrum and mastoid air cell system inside the mastoid process. The mastoid process is the portion of the temporal bone of the skull that is behind the ear. The mastoid process contains open, air-containing spaces. Mastoiditis is usually caused by untreated acute otitis media and used to be a leading cause of child mortality. With the development of antibiotics, however, mastoiditis has become quite rare in developed countries where surgical treatment is now much less frequent and more conservative, unlike former times.
A skull fracture is a break in one or more of the eight bones that form the cranial portion of the skull, usually occurring as a result of blunt force trauma. If the force of the impact is excessive, the bone may fracture at or near the site of the impact and cause damage to the underlying structures within the skull such as the membranes, blood vessels, and brain.
The tympanic cavity is a small cavity surrounding the bones of the middle ear. Within it sit the ossicles, three small bones that transmit vibrations used in the detection of sound.
The asterion is a meeting point between three sutures between bones of the skull. It is an important surgical landmark.
The transverse sinuses, within the human head, are two areas beneath the brain which allow blood to drain from the back of the head. They run laterally in a groove along the interior surface of the occipital bone. They drain from the confluence of sinuses to the sigmoid sinuses, which ultimately connect to the internal jugular vein. See diagram : labeled under the brain as "SIN. TRANS.".
The mastoid part of the temporal bone is the posterior (back) part of the temporal bone, one of the bones of the skull. Its rough surface gives attachment to various muscles and it has openings for blood vessels. From its borders, the mastoid part articulates with two other bones.
The petrous part of the temporal bone is pyramid-shaped and is wedged in at the base of the skull between the sphenoid and occipital bones. Directed medially, forward, and a little upward, it presents a base, an apex, three surfaces, and three angles, and houses in its interior, the components of the inner ear. The petrous portion is among the most basal elements of the skull and forms part of the endocranium. Petrous comes from the Latin word petrosus, meaning "stone-like, hard". It is one of the densest bones in the body. In other mammals, it is a separate bone, the petrosal bone.
The petrosquamous suture is a cranial suture between the petrous portion and the squama of the temporal bone. It forms the Koerner's septum. The petrous portion forms the medial component of the osseous margin, while the squama forms the lateral component. The anterolateral portion (squama) arises from the mesenchyme at 8 weeks of embryogenesis while the petromastoid portion develops later from a cartilaginous center at 6 months of fetal development.
The mastoid cells are air-filled cavities within the mastoid process of the temporal bone of the cranium. The mastoid cells are a form of skeletal pneumaticity. Infection in these cells is called mastoiditis.
A Le Fort fracture of the skull is a classic transfacial fracture of the midface, involving the maxillary bone and surrounding structures in either a horizontal, pyramidal or transverse direction. The hallmark of Lefort fractures is traumatic pterygomaxillary separation, which signifies fractures between the pterygoid plates, horseshoe-shaped bony protuberances which extend from the inferior margin of the maxilla, and the maxillary sinuses. Continuity of this structure is a keystone for stability of the midface, involvement of which impacts surgical management of trauma victims, as it requires fixation to a horizontal bar of the frontal bone. The pterygoid plates lie posterior to the upper dental row, or alveolar ridge, when viewing the face from an anterior view. The fractures are named after French surgeon René Le Fort (1869–1951), who discovered the fracture patterns by examining crush injuries in cadavers.
The epitympanic recess is the portion of the tympanic cavity situated superior to the tympanic membrane. The recess lodges the head of malleus, and the body of incus.
A mastoidectomy is a procedure performed to remove the mastoid air cells, air bubbles in the skull, near the inner ears. This can be done as part of treatment for mastoiditis, chronic suppurative otitis media or cholesteatoma. In addition, it is sometimes performed as part of other procedures or for access to the middle ear. There are classically 5 different types of mastoidectomy:
Tympanosclerosis is a condition caused by hyalinization and subsequent calcification of subepithelial connective tissue of the tympanic membrane and middle ear, sometimes resulting in a detrimental effect to hearing.
Neuroendocrine adenoma middle ear (NAME) is a tumor which arises from a specific anatomic site: middle ear. NAME is a benign glandular neoplasm of middle ear showing histologic and immunohistochemical neuroendocrine and mucin-secreting differentiation.
An otic polyp is a benign proliferation of chronic inflammatory cells associated with granulation tissue, in response to a longstanding inflammatory process of the middle ear.
References
- ↑ Göksu, N; Kemaloğlu, YK; Köybaşioğlu, A; Ileri, F; Ozbilen, S; Akyildiz, N (May 1997). "Clinical importance of the Korner's septum". The American Journal of Otology. 18 (3): 304–6. PMID 9149822.
- ↑ Gaurano, JL; Joharjy, IA (2004). "Middle ear cholesteatoma: characteristic CT findings in 64 patients". Annals of Saudi Medicine. 24 (6): 442–7. PMID 15646162.
- ↑ Kwong, Y; Yu, D; Shah, J (August 2012). "Fracture mimics on temporal bone CT: a guide for the radiologist". AJR. American Journal of Roentgenology. 199 (2): 428–34. doi:10.2214/AJR.11.8012. PMID 22826408.
- ↑ {{Körner's Septum (Petrosquamosal Lamina) and Chronic Ear Disease E Ozer et al. Surg Radiol Anat. 2004 Apr.}}
