What Is Mastoiditis?
Mastoiditis is infection and inflammation of the mastoid. The mastoid bone is located behind the ears. If you slide your hand up the neck behind the ear you will feel it as a bony prominence. The inside of the mastoid bone is aerated. This means that it is hollow. It is not like the long bones of the extremities that are solid. It is more like the bones of the face which house the sinuses. In fact, the mastoid is essentially the sinus of the ear. Sound resonates in the air-filled spaces of the ear including the mastoid. The spaces are lined with mucosa like the lining of your mouth, lungs, or stomach.
Similar to a sinus infection or ear infection, mastoiditis occurs when bacteria infect the lining of the mastoid. However, these infections are less common than sinusitis or otitis. Mastoiditis can be divided into different types such as acute mastoiditis, chronic mastoiditis, serous mastoiditis, and radiologic mastoiditis. When doctors use the term mastoiditis without specifying a type, they are referring to acute mastoiditis.
Serous mastoiditis refers to sterile fluid in the mastoid. This occurs in children and adults with Eustachian tubes that do not effectively ventilate the ear and mastoid. Sometimes these situations lead to inflammation and remodeling of the ear and mastoid. This occurs over months to years. This is called chronic mastoiditis and may be associated with cholesteatoma.
Acute mastoiditis is bacterial infection of the mastoid. Imaging such as CT scan cannot always distinguish the types. Undistinguished mastoiditis based on imaging is called radiologic mastoiditis.
What Are the Symptoms of Mastoiditis?
Acute mastoiditis causes ear symptoms and systemic symptoms. The ear symptoms include ear pain, hearing loss, tenderness to touch, swelling, and redness. The swelling makes the ear look like it is protruding outward. There may be drainage from the ear canal. Systemic symptoms include fever, loss of appetite, fatigue, and malaise.
Why Does This Occur?
Mastoiditis typically follows an untreated ear infection. First, the patient is infected with a virus causing cold-like symptoms. This impairs ear mucosa defenses and bacteria are able to cause infection. Inflammation, infection, and pus build up behind the ear drum. If this goes unrecognized or untreated, the infection spreads to the mastoid cavity which is connect to the space under the ear drum by a narrow tunnel called the isthmus.
How Does My Doctor Test for Mastoiditis?
When a patient gives their doctor a history of ear pain and fever, the evaluation begins. A hearing test will show a conductive hearing loss initially. This is because the infection impairs the ability of sound to get to the inner ear. Examination of the ear drum will reveal pus behind it under pressure, causing the ear drum to bulge. Sometimes the ear drum will rupture and the physician will note a hole in the ear drum. This is why some patients get drainage from the ear canal. Examination of the skull behind the ear will reveal bulging. This is because the infection is breaking out of the bone and is causing an abscess under the skin. These findings are confirmed with lab tests and imaging. These will reveal an elevated white blood cell count and fluid in the mastoid with erosion of the air-filled spaces in the mastoid. Imaging will also show a fluid collection (abscess) under the skin behind the ear.
What Are the Complications of Mastoiditis?
If mastoiditis develops and treatment is not given, the infection can progress. It may enter the inner ear and cause profound hearing loss and vertigo. It may infect the facial nerve and cause a facial droop. It can spread into the neck and cause infection of the muscles of the neck resulting in neck abscess. It can spread into the veins of the skull and cause an infected blood clot. Blockage of the veins may cause elevated pressure in the brain. The infection may spread to the lining of the brain causing meningitis. It may spread to the brain itself causing encephalitis or brain abscess. Though more common in the past, these complications rarely occur today due to access to antibiotics. If they do occur they are very serious.
How Is Mastoiditis Treated?
Treatment of mastoiditis begins with prevention. Recognition and proper treatment of early ear infections (otitis) with oral antibiotics are important. Assurance of cure is necessary, and resistant infections can be treated by placing a tube in the ear drum to drain and culture the infection.
When mastoiditis occurs, aggressive therapy is important to prevent complications. Intravenous antibiotics are given. To prevent resistant infections, cultures are needed. Surgical relief of the infection is necessary as antibiotics cannot effectively treat infections that have progressed to abscess formation. A tube is placed in the ear drum and cultures are taken. An incision behind the ear is used to drain the abscess and provide access to the mastoid. A mastoidectomy is performed and the infection is removed to prevent progression to more serious complications. A drain is left in the skin for 1-2 days to prevent bacteria from causing a relapse. Antibiotics are continued for 1-2 weeks to ensure complete resolution.