Mastoiditis · What Is It, Causes, Signs and Symptoms, and More

Mastoiditis is a severe infection that affects the mastoid air cells within the mastoid bone. It is the most common complication of acute otitis media, a painful infection of the middle ear generally caused by bacteria. 

Mastoiditis occurs when a middle ear infection spreads to the mastoid process of the temporal bone. The mastoid process is a closed bony compartment filled with tiny air spaces called mastoid air cells. With mastoiditis, bacteria from the middle ear invade the mastoid bone leading to the formation of pus. The tympanic membrane prevents pus from draining through the middle ear, so pus accumulates within the mastoid bone, thereby causing the destruction of the mastoid air cells. Spreading of the infection through the bony walls can result in a brain abscess, meningitis, or other intracranial complications. 

Mastoiditis is usually caused by the same pathogens that cause acute otitis media, including Streptococcus pneumoniae or Haemophilus influenzae. It is more common in children under the age of two years because of a higher incidence of otitis media and immaturity of the immune system.

Signs and symptoms of mastoiditis include recurrence of fever and ear pain after initial improvement of the otitis media, along with tenderness, redness, or swelling behind the ear. In many cases, swelling of the mastoid process causes the ear to protrude out and towards the face. Examination with an otoscope may reveal an inflamed tympanic membrane, sometimes associated with a tympanic perforation. Fluid accumulation in the middle ear may result in hearing loss which often resolves after the infection is cleared.

If left untreated, mastoiditis can spread to the surrounding bone, leading to osteomyelitis. More rarely, the infection can invade nearby tissues causing intracranial complications, including meningitis, a brain abscess, or thrombosis of the cerebral venous sinuses. These complications are more common in young children and in those with more severe disease or a weakened immune system. 

Diagnosis of mastoiditis is often suspected in children with a history of acute otitis media along with tenderness or swelling over the mastoid process. Imaging tests like a CT scan or MRI of the temporal bone may be performed in cases where there is a high risk of intracranial complications or in those who do not improve after 48 hours of antibiotic treatment. Finally, laboratory tests, blood cultures, and ear swabs may be completed to determine the severity of the condition and underlying causative organism. 

Most cases of mastoiditis can be treated with intravenous (IV) broad-spectrum antibiotics that can be tailored and de-escalated after the culture identifies the causative organism. In addition to antibiotic therapy, surgery may be done to help drain excess fluid from the middle ear. Surgery may involve creating an opening of the tympanic membrane, called a myringotomy, which is sometimes combined with the placement of a small ear tube (i.e., tympanostomy tube) to create an opening between the middle and outer ear. Tympanostomy tubes generally fall out on their own after 6 to 12 months. Finally, in severe or refractory cases of mastoiditis, surgery to remove the mastoid bone may be necessary to clear the infection.

Mastoiditis is a severe complication of otitis media characterized by infection of the mastoid bone. Symptoms of mastoiditis include tenderness, redness, or swelling behind the ear, as well as ear drainage or hearing loss. Diagnosis is made clinically based on the signs and symptoms. Additionally, imaging tests may be ordered to rule out complications. Treatment involves antibiotic therapy and in severe cases, surgery to drain the middle ear. Left untreated, mastoiditis can cause infection of the surrounding bone, or even progress and invade the adjacent brain tissue, causing intracranial complications.