Pediatric Mastoiditis Workup

Updated: Feb 25, 2016
  • Author: Itzhak Brook, MD, MSc; Chief Editor: Russell W Steele, MD  more...
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Workup

Laboratory Studies

Specimens from the mastoid cells obtained during surgery and myringotomy fluid, when obtained, should be sent for cultures for aerobic and anaerobic bacteria, fungi, and mycobacteria and Gram and acid-fast staining.

If the tympanic membrane is already perforated, the external canal can be cleaned, and a sample of the fresh drainage fluid taken. Care must be taken to obtain fluid from the middle ear and not the external canal.

Gram stains of the specimen can initially guide empiric antimicrobial therapy. Culture and susceptibility testing of the isolates can assist in modifying the initial empiric antibiotic therapy. The results of properly collected culture for both aerobic and anaerobic bacteria should guide the definite choice of therapy.

Blood cultures should be obtained. The baseline complete blood count (CBC) and erythrocyte sedimentation rate (ESR) are determined to permit subsequent assessment of the effectiveness of therapy.

Obtain cerebrospinal fluid (CSF) for evaluation if an intracranial extension of the process is suspected.

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Computed Tomography

Computed tomography (CT) of the temporal bone is the standard in the evaluation of mastoiditis. [34] The sensitivity of CT scanning in acute mastoiditis is 87-100%. It may be overly sensitive because any acute otitis media (AOM) has a component of mastoid inflammation. Immediate CT scanning is warranted whenever intracranial extension or complications are suspected.

Evidence of mastoiditis is illustrated by appearance of haziness or destruction of the mastoid outline and cortex and a decrease or loss of the sharpness of the mastoid air cells bony septa (coalescent mastoiditis). In cases in which CT scanning reveals cloudiness of the air cells, a technetium-99 bone scan is helpful in detecting osteolytic changes.

Clouding of the middle ear and mastoid cells is a nonspecific finding that may be present early in the illness, and it is often observed in patients with AOM without mastoiditis.

Other findings include periosteal thickening, disruption of the periosteum, and subperiosteal abscess.

Plain radiographic findings of acute mastoiditis are similar to CT findings: clouding of the mastoid or coalescence of the mastoid air cells. [1, 2]

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Radiography

Plain radiography is unreliable in this setting, and the findings lag behind clinical symptoms. In areas of the world where CT scanning is not immediately available, plain radiography of the mastoids reveal clouding of the air cells with bone destruction in acute surgical mastoiditis (ASM). In the vast majority of cases, radiography is adequate to establish the diagnosis but lacks sensitivity in differentiating the stages of the disease and fails to reveal the petrous apex in any great detail. [35]

The following findings are used to differentiate AOM or acute mastoiditis without osteitis from chronic mastoiditis:

  • Clouding or haziness of the mastoid air cells and middle ear may be present. This is due to the inflammatory swelling of mucosa and the collected fluid.

  • Loss of sharpness or visibility of mastoid cell walls due to demineralization, atrophy, or necrosis of bony septa

  • Haziness or distortion of mastoid outline, possibly with visible defects of the tegmen or mastoid cortex

  • Enhancement of areas of abscess formation

  • Elevation of the periosteum of the mastoid process or posterior cranial fossa

  • Osteoblastic activity in chronic mastoiditis

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Magnetic Resonance Imaging

Magnetic resonance imaging (MRI) is used more often in patients with clinical symptoms or CT findings suggestive of intracranial complications. However, MRI is not routinely used to evaluate the mastoid.

MRI is the standard for the evaluation of contiguous soft tissue, in particular, the intracranial structures, and for detecting extra-axial fluid collections and associated vascular problems. In addition, it is helpful in planning effective surgical treatment.

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Tympanocentesis and Myringotomy

Tympanocentesis and myringotomy may be performed before the initiation of antibiotic therapy. Culturing middle-ear fluid before antimicrobial therapy is imperative. Although use of an operating microscope and specifically designed suction traps facilitate sampling from the middle ear, an otoscope, spinal needle, and syringe are equally helpful.

Sterilize the canal with an antiseptic. With the child restrained, aspirate fluid from the anterior half of the tympanic membrane.

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Other Tests

Audiometry

Audiometry is seldom appropriate or useful in children with acute mastoiditis but must be performed after patients recover from the acute phase and in children with chronic mastoiditis. In the population at risk (ie, children younger than 2 years), thresholds for air and bone conduction under headphones are only rarely determined.

Lumbar puncture

Perform a lumbar puncture and spinal tap if intracranial extension of the infection is suspected.

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