Timothy C. Hain, MD • Page last modified: May 1, 2022


Mastoiditis is an inflammation of the sinus behind the middle ear (Mastoid sinus) (Sahi et al, 2022). Mastoiditis (inflammation) is distinguished from mastoid effusion (fluid), as there is an implication as one has inflammation but the other doesn't. Both are easily seen on imaging studies such as MRI (see below). Often the same term ("mastoiditis") is used for both conditions as frequently the source of the fluid is unknown.

Right sided mastoiditis (white blotch on the left side of this image). On MRI films, the right side of the head is shown on the left side of the image. This is mild.
mastoid fluid
Mastoid fluid on MRI scan (coronal) -- Right side of image corresponding to L mastoid. On the more normal right side, the inner ear can be seen (loops just below temporal lobe of brain).
mastoid CT
Mastoid fluid on axial view of CT scan, again right side of image. This is the same patient as the image above On the left side, the more normal right mastoid is full of air (e.g. is black)

Mastoid fluid (whether from inflammation or not) can be seen on imaging studies (see above). Often this is unaccompanied by any symptoms referable to the ear.

Mastoid fluid (seen on imaging) is usually not treated or referred because of the high prevalence of fluid seen on imaging, but a relatively low prevalence of symptoms. However, this cannot be done 100% of the time.

Generally speaking, while it is clear that there is fluid in the mastoid (from imaging), it is not known whether the fluid is from inflammation or not, because inflammation is defined by data that is not available -- the presence of inflammatory cells in the fluid. We would not want a situation where fluid was being obtained using punctures of the ear drum, just to answer an academic question. So we have a situation where there are opinions being offered concerning whether fluid in the ear is from inflammation (i.e. mastoidits) or not (i.e. mastoid effusion), without strong evidence.

There is also a logical problem with many studies -- patients are divided into mastoid effusions (i.e. incidental), and mastoid infections based on clinical course rather than any evidence as to what was in the mastoid.

How often is Mastoid fluid seen ?

Mughal et al (2022) reviewed 16 studies. They stated "The selection criteria were mastoid opacification found on computed tomography (CT) or magnetic resonance imaging (MRI) as incidental findings. The prevalence of IMO was significantly higher in studies with children (17.2%, 95% CI 10.9-24.6) than those with adults (6.1%, 95% CI 3.3-9.6)". They concluded that "The term "mastoiditis" on radiology reports based on IMO does not indicate a clinical diagnosis of mastoiditis". Hm. One wonders how "incidental" (IMO) was determined.

Sayal et al (2019) reported that " Physical examination revealed that only 14 of 160 patients (8.8%) had clinical evidence of otologic disease." They took this to suggest that mastoid fluid is usually "incidental".

Wilkinson et al (2017) reported on 468 CT scans of the head, and noted that 13% of them had Mastoid and/or middle ear opacification. They called these "incidental temporal bone disease". They recommended: "Data from this study suggests that incidental findings in an asymptomatic individual do not necessitate referral or further intervention. Furthermore, it is the author's recommendation that radiological findings be closely correlated with clinical examination to reduce false diagnosis and inappropriate referral to ENT." So in other words, don't consult ENT with the 13% of CT scans that show mastoid fluid, as long as they are "incidental".

Meredith and Boyev (2008) wrote on mastoiditis on MRI, and suggested that the term is most often applied to the observation of fluid in the mastoid, which may be clinically insignificant. Again, this doesn't address the question as to whether the fluid is from inflammation.

Abbas et al (2018) reported that 5.8% of individuals who underwent MRI for asymmetrical hearing loss or tinnitus had "mastoiditis." Note here that they were scanning people with hearing symptoms, unlike Meredith and Boyev (2008) who were reporting on "asymptomatic volunteers". It would seem to us that again, individuals with hearing symptoms seem to have more fluid in their mastoid sinus than normal people. Abbas et al. stated "An incidental finding of high signalling in the mastoid region on magnetic resonance imaging is highly unlikely to represent actual clinical disease. In patients who are scanned for other reasons and who do not complain of otological symptoms, such findings are unlikely to require otolaryngology input."

There are several types of Mastoiditis

Mimickers of mastoiditis

Mimickers of mastoiditis are rare.

Wong et al (2021) reviewed 35 studies, and wrote "In children, 11 diseases were reported to mimic mastoiditis, including solid tumors, hematologic diseases, and autoimmune/inflammatory diseases. The most common disease in children was Langerhans cell histiocytosis, followed by rhabdomyosarcoma and acute myelogenous leukemia. In adults, 8 additional diseases were reported. The most common disease in adults was squamous cell carcinoma, followed by nasopharyngeal carcinoma and Langerhans cell histiocytosis."

Autoimmune disease appears to be very rare -- For example, Barnado and Cunningham (2014) reported an IgG4 related disease, successfully treated with immunsuppressants, refractory to several mastoidectomies. Other examples are Wegeners granulomatosis (Moussa et al, 1998).

There are several treatment approaches to mastoiditis/mastoid effusion--

If there are no ear symptoms, usually the observation of fluid in the mastoid is just noted but not treated.

If there are symptoms, conservative measures (such as antihistamines, decongestants, nasal saline irrigations) are currently favored as the initial approach in individuals who are not extremely ill. Then might follow a trial of antibiotics and PE tubes. There may be attempts open the eustachian tube with decongestants or maneuvers to "pop" the ears.

For more severe cases, Kaufman et al (2022) reviewed management of acute complicated mastoiditis and wrote "There were greater reductions in TNC, ECC, IT, intracranial complications, subperiosteal abscess and lateral sinus thrombosis at discharge and follow-up among surgical patients compared with conservative patients." (TNC -- total # complications, ECC -- extracranial complications, IT -- infratemporal complications).

Complications of Mastoiditis

Facial Paralysis associated with mastoiditis

An acute lower motor neuron facial palsy is rare even though dehiscence of the facial canal (i.e. exposure of the facial nerve to fluid in the middle ear) is very common. When there is acute facial nerve palsy combined with mastoiditis, common recommendations include myringotomy with PE tube placement, Infectious disease consultation, intravenous antibiotics, and consideration of mastoidectomy. Once the infection resolves, facial nerve function usually recovers over several months. If one looks at things from the perspective of how many patients with Bells palsy or Ramsay Hunt (A zoster version of Bell's palsy) have mastoid effusions, Choi et al (2021) says that the incidence of effusion is "higher" in Ramsay Hunt.

Lateral sinus thrombosis

A rare complication of mastoiditis is thrombosis of the lateral sinus. This is mainly reported in children, but adults are not entirely spared (Palma et al, 2014). According to Ghosh and others (2011), clinical features include headache, vomiting, fever, diplopia, papilledema, sixth nerve palsy, seventh nerve palsy, and unilateral cerebellar ataxia. Mastoiditis is often appreciated from postauricular (behind the ear) swelling, redness or tenderness, protrusion of the auricle, and fever. Diagnosis is generally with imaging (contrast MRI or CT scan), showing lack of the usual flow in the venous sinuses of the brain. The MRV study is usually the best as one can directly visualize the venous structures. Of course, there should also be fluid in the mastoid. Treatment primarily includes antibiotics (Palma et al, 2014).

Labyrinthitis associated with mastoiditis

This comes in several stages.

  • Serious labyrinthitis - -toxins from fluid in the middle ear enter the inner ear and cause vertigo and mild hearing loss.
  • Purulent labyrinthitis occurs as bacteria enter the inner ear.
  • Labyrinthitis ossificans -- occurs when the inner ear fills with scar tissue

In patients believed to have labyrinthitis associated with acute otitis media, one should image the brain, obtain a lumbar puncture, place a PE tube, administer IV antibiotics, and consider mastoidectomy.

Gradenigo's syndrome (Petrous apicitis)

The symptoms of Gradinego's include severe frontal headache, eye pain, diplopia, dizziness, nausea, and 6th nerve palsy (basically double vision and inability to look to the side with one eye). There should be otitis media seen on otoscopy. MRI shows inflammation of the petrous apex and mastoids (i.e. fluid). CT may show bone erosion in the petrous apex.

Treatment recommended is with myringotomy with PE tube, and culture-directed IV antibiotic therapy (Burston et al, 2005), although surgical treatment may also be required (Colpaert et al, 2013).