Mastoiditis pathophysiology

Mastoiditis Microchapters
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Differentiating Mastoiditis from other Diseases
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Mehrian Jafarizade, M.D [2]

Overview

Mastoiditis is the infection in the cavities of mastoid process of temporal bone that occurs after otitis media. At birth, the mastoid consists of a single cavity, which is connected to the middle ear by a canal. As the child grows, the mastoid bone becomes pneumatized, resulting in a series of connected cavities, lined by a mucosa diverted from respiratory epithelium. There is a relationship between the middle ear, eustachian tube, and the mastoid. This connection has a fundamental role in the pathogenesis of mastoiditis. In the setting of acute otitis media the mucosa that lines the middle ear and also mastoid air cells becomes inflamed. In majority cases of acute otitis media inflammation resolves, but some persist leading to bacterial and fluid accumulation within the mastoid air cells. Gradually, as a result of pressure rising in the mastoid, air cell septae may be destroyed and mastoiditis could be proceed to periostitis, cavity abscess and osteomyelitis. Mastoid is near vital organs in head and neck and mastoid infection may cause serious complications. There is evidence of genetic predisposition to recurrent otitis media and therefore mastoiditis, with statistically significant evidence that it has high heritability. The following genes have been identified as having potential pathogenic qualities for otitis media: CAPN14, GALNT14, BPIFA3, BPIFA1, BMP5, GALNT13, NELL1, TGFB3. Up-regulation of the genes correlated to recurrent otitis media pathogenesis contribute to individual susceptibility to mastoiditis.

Pathogenesis

Mastoiditis is the infection in the cavities of mastoid process of temporal bone that occurs after otitis media.

At birth, the mastoid consists of a single cavity, which is connected to the middle ear by a canal. As the child grows, the mastoid bone becomes pneumatized, resulting in a series of connected cavities, lined by a mucosa diverted from respiratory epithelium. There is a relationship between the middle ear, eustachian tube, and the mastoid. This connection has a fundamental role in the pathogenesis of mastoiditis. In the setting of acute otitis media the mucosa that lines the middle ear and also mastoid air cells becomes inflamed. In majority cases of acute otitis media inflammation resolves, but some persist leading to bacterial and fluid accumulation within the mastoid air cells. Gradually, as a result of pressure rising in the mastoid, air cell septae may be destroyed and mastoiditis could be proceed to periostitis, cavity abscess and osteomyelitis.

• Mastoid is near important structures like the facial nerve, sternocleidomastoid muscle, jugular vein, internal carotid artery, sigmoid sinus, brain, and meninges; as a result of this proximity, spreading infection to these places may cause complications.

Transmision

Mastoiditis results from extension of adjacent infection in middle ear.

Genetics

• There is evidence of genetic predisposition to recurrent otitis media, and thereby mastoiditis, with statistically significant evidence that it has high heritability.
  • Hereditary factors comprising 45-75% of risk factors for recurrent otitis media, as revealed by heritability studies involving twins and triplets.
• The following genes have been identified as having having potential pathogenic qualities for recurrent otitis media and mastoiditis:
  • 2p23.1
    • CAPN14
    • GALNT14
  • 20q11.21
    • BPIFA3
    • BPIFA1
  • Those that interact with the TGFβ pathway:
    • BMP5
    • GALNT13
    • NELL1
    • TGFB3
• Up-regulation of the genes correlated to recurrent otitis media pathogenesis contribute to individual susceptibility to mastoiditis.

Associated Conditions

• Mastoiditis is often associated with other upper respiratory conditions caused by the nasopharyngeal pathogen
  • Common cold
  • Strep throat
  • Sinusitis
• Allergies-related conditions, such as allergic rhinitis are also associated with mastoiditis.

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Gross Pathology

• Gross pathology refers to macroscopic or larger scale manifestations of disease in organs, tissues and body cavities. The term is commonly used by pathologist to refer to diagnostically useful findings made during the gross examination portion of surgical specimen processing or an autopsy.
• This section is a good place to include pictures. Search for copyleft images on The Pathology Wiki [3] and Ask Dr. Wiki [4].
• For an example of this section, click here.

Microscopic Pathology

• Microscopic pathology is the disease process as it occurs at the microscopic level.
• This section is a good place to include pictures. Search for copyleft images on The Pathology Wiki [5] and Ask Dr. Wiki [6].
• For an example of this section, click here.