Mastoid cells, sometimes called mastoid air cells, refer to the air pockets formed by the honeycomb-shaped bone structure of the mastoid process. A projection of a portion of the temporal bone in the skull, the mastoid process is located behind the ear. These cells may be of different sizes, depending on where they are positioned within the mastoid.
Very small mastoid cells are located in the apex or tip of the mastoid process and in the lower portion of the mastoid. Some of the smallest cells are filled with marrow. They are usually uniform in size and shape.
Large and irregularly shaped mastoid cells are often referred to as mastoid air cells. Pockets of air collect in the open spaces inside each of these big cells. Most large cells are found in the upper portion of the mastoid process, while the others are located toward the front of the bone.
A computerized tomography (CT) scan of the mastoid process reveals the air cells as small, dark spaces separated by lighter areas of dense bone cells. Inflamed or infected cells will appear as gray or white areas on the scan where the darkened spaces would be expected to be located. When these abnormal looking cells are present, they are called mastoid cell opacification.
Many people with acute otitis media (AOM), a middle ear infection, develop a condition called mastoiditis. Inflammation of the mastoid process can occur if the infection spreads beyond the middle ear. Bacteria can travel through the mastoid antrum, a small cavity lined with mastoid cells adjacent to the mastoid process, and begin to colonize.
Early symptoms of mastoiditis mimic a middle ear infection. The area behind the ear can swell and become painful to the touch. A person may develop a fever as the infection settles into the cells. Treatment for this painful condition usually requires a round of antibiotics and careful observation by a medical professional.
Infected mastoid cells that do not respond to treatment with antibiotics may need to be surgically removed. Due to the close proximity of the mastoid process to the brain, a non-responsive infection could lead to meningitis, an inflammation of the membrane around the brain. A mastoidectomy is performed under general anesthesia and usually requires an overnight stay in the hospital for observation.
The simple mastoidectomy involves a small incision, through which a growth or infected area of mastoid cells are removed. A radical mastoidectomy removes nearly all of the mastoid process and may include the excision of small portions of some middle ear structures. The incision is then sutured together, and a regimen of antibiotics started to prevent an infection.