Tympanosclerosis, also known as tympanic hyaline degeneration, refers to the deposition of patchy collagenous tissue in the submucosal epithelium of the tympanic cavity. It commonly occurs on the tympanic membrane mucosa and ossicles. When it occurs on the tympanic membrane, it is still referred to as calcific plaque. This condition transforms the tympanic mucosa into a milky substance that covers the ossicles, oval window, and round window, adhering to the bone as if coated with a membranous layer. The involvement is more severe in the epitympanum and milder in the hypotympanum, with the malleus, incus, stapes, and tendons being the most frequently affected, often resulting in deafness. This condition was first discovered by Cassebohm in the 18th century but did not receive significant attention until modern times (1955), when extensive microscopic otologic surgeries brought it to clinical awareness.

bubble_chart Etiology

1. Commonly seen in acute necrotizing otitis media, due to extensive destruction of the mucous membrane cilia and glands, the exudate cannot be discharged. Later, it undergoes organization and hyaline degeneration, forming hard dissipating ecchymosis masses.

2. Cases caused by chronic otitis media are rare, accounting for about 10%. It is more common in young and middle-aged adults, with a higher incidence in women. The induction of collagen tissue proliferation may be related to the severe destruction of cilia and glandular secretion by otitis media. The affected tissue is mesodermal connective tissue, occasionally causing bone resorption. The tissue structure is similar to keloid, but the disease cause is entirely different. There is neither an allergic constitution nor specific bacterial or viral infection. Microscopically, patch tissue is divided into two types: ① Soft, cheese-like shell fragments that are not heavily adherent to the bone and can be peeled off like onion skin. ② Firm, white hard masses tightly adhered to the bone, difficult to remove, and prone to recurrence shortly after removal. The patch consists of hyaline-degenerated collagen tissue, devoid of cells and blood vessels, covered by a thin layer of flattened epithelium. Ossicular necrosis appears moth-eaten and often leads to ossicular chain disruption and fixation. Harris (1961) classified tympanosclerosis into two types: ① Superficial sclerosing mucous membrane inflammation, which does not damage the deep mucous membrane or periosteum. ② Deep osteoclastic mucous membrane periostitis, which can destroy deep bone tissue. Some oppose this view, arguing that tympanosclerosis is a non-active sexually transmitted disease change without the ability to destroy bone tissue. The observed bone destruction may result from ischemic necrosis caused by compression and surrounding by hard dissipating ecchymosis. Electron microscopy reveals extracellular collagen fiber proliferation, degenerative changes, and calcium deposition. Gibb (1976) reported an analysis of patch generation and transformation, with the main component being calcium phosphate salts.

Gibb reported 138 cases, all with a history of chronic otitis media. 80% had dry ears, and 84% had large perforations in the tense part of the tympanic membrane. The surface of the tympanic membrane showed scar tissue in varying sizes of gray-white patches. Sometimes, through large perforations, gray-yellow hard patches could be seen on the tympanic annulus, the surface of the promontory, behind the handle of the malleus, and around the stapes, directly affecting the movement of the tympanic membrane and ossicles. Pure-tone audiometry indicated conductive deafness, with hearing levels ranging from 30 to 50 dB. When the tympanic membrane was intact, impedance audiometry showed normal middle ear pressure, with a type As tympanogram. Mastoid X-rays revealed interstitial or sclerotic mastoid cells.

bubble_chart Diagnosis

Based on medical history, otoscopy, and impedance audiometry, the diagnosis is not difficult. However, it should be differentiated from otosclerosis and adhesive otitis media. Otosclerosis has no history of otitis media, a normal tympanic membrane, and progressive deafness, making differentiation straightforward. However, distinguishing it from adhesive otitis media can be challenging, and sometimes surgical exploration is necessary for a definitive diagnosis.

bubble_chart Treatment Measures

A tympanotomy is performed through a postauricular or endaural incision. Under the microscope, the sclerotic tissue is carefully peeled off based on the extent of the hard dissipating ecchymosis. The epitympanum and the area around the ossicles are common sites of sclerosis, which is removed layer by layer using hooks and elevators. The long process of the incus and the stapes arch often exhibit necrosis and may be absent, necessitating ossicular reconstruction with a prosthesis when appropriate. Calcified dissipating ecchymosis on the tympanic membrane can be excised by making an incision at the annulus and dissecting it from the fibrous layer. Perforations may be repaired using a fascial graft. Sclerotic lesions on the promontory and around the oval and round windows are difficult to remove completely and are prone to recurrence postoperatively.