Acute Mastoiditis: Pearls and Pitfalls

Author: Kristen Kann, MD (EM Staff Physician, SAUSHEC, USAF) // Edited by: Jennifer Robertson, MD, MSEd and Alex Koyfman, MD (@EMHighAK, EM Attending Physician, UTSW / Parkland Memorial Hospital)

CASE

A 14 year-old otherwise healthy female presents to the Emergency Department (ED) complaining of left ear pain. She had been diagnosed with Acute Otitis Media (AOM) the day prior and was placed on Cefpodoxime. She was also prescribed ibuprofen and acetaminophen for pain control. She re-presents to the ED with her mother due to concerns about worsening pain and new purulent drainage from the left ear, despite antibiotic therapy. She denies fevers, chills, or other systemic symptoms. She does note left sided ear pain and an associated headache.

Her exam reveals the following vital signs: Blood pressure (BP) 110/70 and a a heart rate (HR) of 68. She is afebrile and has a normal respiratory rate and oxygen saturation.  Her exam is normal except for her head, ears, nose and throat (HEENT) exam, which reveals a mildly swollen external ear canal. The tympanic membrane is red and cloudy with inferior perforation and purulent drainage. The auricle itself is not erythematous or tender to manipulation. The left mastoid is mildly tender to palpation with minimal overlying erythema. There is no mastoid bogginess or swelling. Her neurologic exam reveals intact cranial nerves, no meningismus, and no focal deficits. She is alert and attentive with no obvious global neurologic deficits.

Due to a concern for acute mastoiditis, the patient is given a dose of intravenous (IV) vancomycin.  A computed tomography (CT) scan of the head and temporal bones is also obtained and results reveal “opacification of the bilateral left greater than right mastoid air cells and middle ear cavities without osseous dehiscence”. No intracranial abnormalities are found on the CT. Otolaryngology (ENT) is consulted for further management of acute mastoiditis.

BACKGROUND

AOM is an infection of the middle ear that affects an estimated 85% of all children at least a once in their lifetimes. The usual presentation involves fever with associated otalgia and a red, bulging, cloudy tympanic membrane. While most AOM follows a relatively benign course, there are important complications for the Emergency Physician (EP) to be aware of.  These complications can be intracranial or extracranial. Intracranial complications may include meningitis, brain abscess, subdural empyema, epidural abscess, or sinus thrombosis. Extracranial complications may include mastoiditis, postauricular abscess, petrous apicitis, labyrinthine fistula, facial nerve paralysis, or acute suppurative labyrinthitis). AOM and its complications almost always occur in the first two decades of life, with those 6 years of age or younger most commonly affected.

Mastoiditis can be divided into acute, masked, and chronic. Acute mastoiditis is the most common suppurative complication of AOM, and often is the first complication that develops. The most common causative agents of acute mastoiditis include staphylococcus, streptococcus, and pseudomonas species. Acute mastoiditis can also be non-coalescent or coalescent, which refers to the absence or presence of breakdown of the bony septa within the mastoid. Coalescent mastoiditis is what is classically referred to as “mastoiditis.”

Masked mastoiditis is a chronic focus of infection within the mastoid air cells that tends to produce milder symptoms than acute mastoiditis. This is usually seen in patients who have received multiple courses of antibiotics in whom the middle ear and most of the mastoid have responded, but a small area of infection remains.

SIGNS/SYMPTOMS

Acute mastoiditis usually presents 2-6 days after the onset of symptoms of AOM. Signs and symptoms include retro-auricular pain and erythema and tenderness over the mastoid. There also may be swelling of the soft tissues over the mastoid, which can cause auricular protrusion. While fever, ear pain, and otorrhea are also symptoms of AOM, any abnormal findings over the mastoid should alert the EP to the possibility of acute mastoiditis.

A full history and physical exam is always important when evaluating these patients. Some clues that may help determine any complications of AOM include:

  • Loss of usual anatomy of the mastoid/posterior auricle: subperiosteal abscess
  • Retro-orbital pain: petrositis / petrous apicitis (akin to osteitis of the petrous temporal bone)
  • Vertigo: labyrinthitis or labyrinthine fistula
  • Facial paralysis: involvement of facial nerve
  • Headache, meningismus, or altered mental status: meningitis
  • Focal neurologic signs or seizure: brain abscess

WORK UP

Any patient who is suspected of having complications of AOM should receive imaging and laboratory testing. Some argue that the diagnosis of acute mastoiditis should be made clinically in those patients with histories of AOM and exams consistent with mastoiditis. However, as noted above, about a quarter of patients may have other complications as well. Thus, the EP should have a low threshold for imaging.

Computed Tomography (CT) is the imaging study of choice. A non-contrast CT scan of the temporal bones will show fluid in the mastoid air cells and reveal any bony breakdown. A contrast study, however, is ideal since it will better evaluate for peri-dural and intracranial complications such as abscess. Laboratory evaluation should also be considered, and usually a CBC and chemistry will be sufficient.

MANAGEMENT

Acute mastoiditis can be managed medically or surgically. In the patient who only has mild erythema and tenderness over the mastoid, a CT without evidence of coalescence, and normal laboratory tests, an argument could be made for outpatient oral therapy. However, the available literature supports admission and IV antibiotics for any patient with acute mastoiditis, coalescent or not. IV antibiotics alone may be sufficient to begin treatment in a patient with acute mastoiditis without evidence of coalescent mastoiditis or abscess, with consideration for operative management in 1-2 days if no improvement is noted. Any patient with coalescent mastoiditis and/or subperiosteal abscess should trigger an ENT consult for tympanostomy, IV antibiotics, and possible mastoidectomy. In any patient with an intracranial complication of AOM, neurosurgery consultation should also be considered.

Initial antibiotic therapy should cover for streptococcus and staphylococcus. Pseudomonas coverage should be considered in patients with recurrent AOM or recent antibiotic use. For patients who have not taken antibiotics recently or have recurrent infections, IV vancomycin alone is usually sufficient. However, patients with recurrent infections and/or recent antibiotic use should receive broader coverage with medications such as vancomycin plus piperacillin-tazobactam.

SUMMARY

Acute mastoiditis is the most common, and usually the initial, complication of AOM. The diagnosis can be confusing due to differing uses of the term “mastoiditis”. Radiographic mastoiditis simply refers to fluid in the mastoid air cells, which can occur with any AOM due to communication between the middle ear and the mastoid air cells. However, acute mastoiditis for the EP involves clinical evidence of mastoid inflammation such as erythema, tenderness to palpation, bogginess, and swelling over the mastoid bone. A clinical diagnosis of acute mastoiditis necessitates treatment with IV antibiotics with a consideration for tympanostomy and mastoidectomy. Occasionally, a CT scan with IV contrast should be considered to evaluate for additional complications such as abscess.

References / Further Reading

-Bailey’s Head and Neck Surgery – Otolaryngology (1-60913-602-0, 978-1-60913-602-4), 5th ed. / Johnson, Jonas T.

-Cummings Otolaryngology – Head and Neck Surgery (1-4557-4696-7, 978-1-4557-4696-5), Sixth edition. / Flint, Paul W.

-Luntz M, Brodsky A, Nusem S, et al. Acute mastoiditis – the antibiotic era: a multicenter study. Int J Pediatr Otorhinolaryngol 2001; 57:1.

http://www.ncbi.nlm.nih.gov/pubmed/25662802

http://www.ncbi.nlm.nih.gov/pubmed/23915604

http://www.ncbi.nlm.nih.gov/pubmed/23034496

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