Infectious Diseases

Mastoiditis

OVERVIEW: What every practitioner needs to know

Are you sure your patient has mastoiditis? What should you expect to find?

  • Acute mastoiditis is diagnosed by pain and tenderness over the mastoid bone. Signs of acute otitis media (AOM) including fever, ear pain, and hearing loss are usually present or have preceded infection of the mastoid.

  • Signs of acute mastoiditis include postauricular swelling, erythema, and tenderness over the mastoid bone. Protrusion of the pinna is most evident by viewing the patient from the front and comparing the position of the diseased versus the normal side in unilateral disease. A purulent discharge may be evident in the external canal following perforation of the tympanic membrane.

How did the patient develop mastoiditis? What was the primary source from which the infection spread?

  • The mastoid consists of a honeycomb of aerated cells lined with modified respiratory mucosa. The mastoid is connected to the middle ear by a narrow passage, the antrum. Most cases of AOM are likely accompanied by invasion of the mastoid air cells through the antrum but the inflammation of the mastoid usually resolves with normalization of the middle ear infection. If there is more extensive invasion of the mastoid, inflammation of the mastoid air cells occurs with hyperemia and edema and serous and purulent exudate. Pressure of the purulent exudate may result in necrosis of the walls of the mastoid cells with the development of an abscess in the mastoid bone.

  • Acute mastoiditis is the most common suppurative complication of AOM. Mastoiditis occurs in patients of all ages and is particularly frequent in patients who are predisposed to severe and recurrent AOM. Patients at risk include those who are immunocompromised, have anatomic or physiologic defects of the middle ear system, or belong to an ethnic or racial group (eg., American Eskimo, Native Americans, and Aboriginal Australians) who are prone to severe AOM.

Beware: there are other diseases that can mimic mastoiditis:

  • Postauricular swelling may be caused by external otitis and postauricular lymphadenitis and may be confused with acute mastoiditis.

What laboratory studies should you order and what should you expect to find?

Results consistent with the diagnosis

  • Nonspecific tests of response to infection including peripheral white blood cell count, sedimentation rate, or C-reactive protein level do not assist in the diagnosis of acute mastoiditis.

Results that confirm the diagnosis

  • Cultures of purulent exudate in the external ear canal reflect the pus from the mastoid and middle ear. Cultures of pus may also be obtained by tympanocentesis, needle aspiration of the middle ear through the tympanic membrane.

What imaging studies will be helpful in making or excluding the diagnosis of mastoiditis?

  • Radiologic studies of the mastoid show a loss of the integrity of the cell walls of the mastoid. Computed tomography may demonstrate the extent of the disease in the mastoid and surrounding structures.

What consult service or services would be helpful for making the diagnosis and assisting with treatment?

If you decide the patient has mastoiditis, what therapies should you initiate immediately?

  • The bacteria responsible for acute mastoiditis are the same as those that cause AOM. Thus, the choice of antimicrobial drug is the same as that outlined for AOM.

  • Tympanocentesis, incision of the tympanic membrane, achieves drainage of the middle ear and mastoid pus and is warranted if the patient with signs of mastoiditis has toxic symptoms fails to improve while on appropriate antibiotics, or is immunologically deficient.

  • Tympanocentesis usually provides pus for culture and relieves the pressure of the abscess on the mastoid and middle ear structures. Mastoidectomy may be necessary when radiologic studies indicate the loss of cell structure and development of an abscess. These surgical procedures require consultation with an otolaryngologist.

Key principles of therapy

1. Anti-infective agents

If I am not sure what pathogen is causing the infection what anti-infective should I order?

The bacterial pathogens responsible for acute mastoiditis are the same as those for AOM, including Streptococcus pneumoniae and non-typable Haemophilus influenzae. On occasion, Staphylococcus aureus, S. pyogenes, or Moraxella catarrhalis may be responsible for acute mastoiditis.

2. Next list other key therapeutic modalities.

  • Most important in management of acute mastoiditis is early diagnosis, appropriate antimicrobial therapy, and, when necessary, incision and drainage of the mastoid abscess.

What complications could arise as a consequence of mastoiditis?

  • The proximity of the mastoid air cells to the brain may result in breakdown of the overlying bone and development of osteomyelitis, septic thrombosis of the lateral sinus, meningitis, or brain abscess.

What should you tell the family about the patient's prognosis?

  • The prognosis is excellent if the disease is diagnosed and managed before complications develop.

How can mastoiditis be prevented?

  • Since mastoiditis is a complication of AOM, it is likely that steps to prevent AOM will lead to a decreased incidence of mastoiditis. At present, in 2012, the 13 valent pneumococcal vaccine is recommended for all infants and for selected adults.

What's the Evidence?

"American Academy of Pediatrics Subcommittee on Management of Acute Otitis Media: Diagnosis and management of acute otitis media". Pediatrics. vol. 113. 2004. pp. 1451.

(Guidelines for management of acute otitis media and its complications including mastoiditis.)

Stankovic, KM, Eskandar, El, Khoury. "A 20-year-old man with recurrent ear pain, fever, and headache". N Engl J Med. vol. 368. 2013. pp. 267-277.

(An excellent discussion of suppurative complications of acute otitis media including mastoiditis from the Case Records of the Massachusetts General Hospital.)

Goldstein, NA, Casselbrant, ML, Bluestone, CD, Kurs-Lasky, M. "Intratemporal complications of acute otitis media in infants and children". Otolaryngol Head Neck Surg. vol. 119. 1998. pp. 444-54.

(An excellent review by members of the pediatric otolaryngology program at Children’s Hospital of Pittsburgh of the pathogenesis and management of suppurative complications of acute otitis media including mastoiditis.)

Ghaffar, FA, Wordemann, M, McCracken, GH. "Acute mastoiditis in children; a seventeen year experience in Dallas, Texas". Pediatr Infect Dis J. vol. 20. 2001. pp. 376-380.

(Report of an extensive experience of mastoiditis in children in the era prior to the introduction of the pneumococcal conjugate vaccine.)
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