Chronic mastoiditis is a long-term infection or inflammation affecting the mastoid bone, the prominent, honeycomb-like bony structure located directly behind the ear. The mastoid process is part of the temporal bone of the skull and contains numerous small air-filled spaces called mastoid air cells. This condition typically develops as a complication of a persistent or recurring middle ear infection (otitis media). Because the mastoid bone is close to the brain and other vital structures, this chronic inflammation poses a serious health risk if not addressed.
Understanding Chronic Inflammation
The distinction between acute and chronic mastoiditis lies primarily in duration. Acute mastoiditis is a sudden, severe infection that usually resolves with prompt antibiotic treatment. Chronic mastoiditis represents a persistent, often low-grade inflammatory process that continues for months or years. This long-standing infection is frequently linked to Chronic Suppurative Otitis Media (CSOM), where the middle ear infection fails to clear completely.
The persistence of bacteria and inflammation causes a destructive process within the mastoid air cells. Over time, the internal bony partitions are eroded, a process known as osteitis or coalescent mastoiditis. This bone destruction may be followed by the formation of dense, abnormal bone tissue, referred to as sclerosis. This inflammatory cycle leads to the development of granulation tissue, which harbors deep-seated infections difficult for antibiotics to penetrate. The result is a chronically infected, damaged mastoid structure that fails to drain properly, allowing the low-grade infection to continue.
Persistent Signs and Symptoms
The manifestations of chronic mastoiditis are often more subtle than the severe pain and high fever associated with the acute form. A common complaint is persistent, foul-smelling ear discharge (chronic otorrhea), which may last for weeks or months. This discharge results from the ongoing infection within the middle ear and mastoid cavity, often indicating a perforated eardrum.
Patients frequently experience a gradual or significant reduction in hearing, categorized as conductive hearing loss. This occurs because the infection and inflammation damage the delicate structures responsible for transmitting sound, such as the eardrum and the tiny middle ear bones (ossicles). A deep, dull ache or tenderness located behind the ear may also be present, contrasting with the intense, throbbing pain typical of acute cases. Unlike the acute form, systemic signs like fever are often absent, which can sometimes delay recognition of the condition.
Diagnostic Tools and Underlying Factors
Confirming a diagnosis of chronic mastoiditis begins with a thorough physical examination using an otoscope. The physician looks for signs of long-term infection, such as a perforated eardrum, chronic drainage, or abnormal tissue within the ear canal. If suspected, a sample of the ear discharge may be collected for a culture to identify the specific bacteria, which helps guide initial antibiotic therapy.
For definitive confirmation and to understand the extent of bone damage, high-resolution imaging is necessary. A Computed Tomography (CT) scan of the temporal bone is the standard method used to visualize the mastoid air cells and surrounding structures. The CT scan reveals the degree of bony erosion, the presence of sclerotic bone, and any soft tissue involvement that might indicate an abscess or complication.
A common underlying factor that sustains chronic infection and necessitates imaging is the presence of a cholesteatoma. This is a noncancerous, abnormal growth of skin cells that forms a sac behind the eardrum, often stemming from long-term middle ear problems. As the cholesteatoma grows, it sheds skin cells and keratin debris, creating an environment ripe for infection and blocking normal drainage pathways. The enzymes released by this growth actively erode the surrounding bone, including the mastoid partitions, sustaining the chronic inflammatory cycle.
Treatment Options and Surgical Intervention
The initial management of chronic mastoiditis involves aggressive medical therapy aimed at controlling the infection and inflammation. This typically includes a course of systemic antibiotics, sometimes administered intravenously if the infection is severe or complications are suspected. Topical antibiotic eardrops are also prescribed to target the infection locally through the ear canal.
Due to the presence of diseased bone and granulation tissue, chronic mastoiditis often requires surgical intervention to eradicate the problem. The standard procedure is a mastoidectomy, which involves drilling into the mastoid bone to remove infected air cells, granulation tissue, and any cholesteatoma. The purpose of this surgery is to create a clean, dry, and safe ear by removing the source of the chronic disease.
Depending on the extent of the disease, the surgeon may perform a simple mastoidectomy or a more extensive procedure. The goal of the operation is not primarily to restore hearing, but to eliminate the infection and prevent its spread to nearby structures, such as the facial nerve or the brain. Removing the diseased tissue and creating a wider, self-cleaning cavity significantly reduces the risk of serious, potentially life-threatening complications like meningitis or brain abscess.