H74.3 Ossicular Ankylosis Middle Ear
H74.3 is the ICD-10 code for ankylosis of the ossicles of the middle ear, a condition that restricts sound conduction and can lead to conductive hearing loss.
Things worth knowing about "H74.3"
H74.3 is the ICD-10 code for ankylosis of the ossicles of the middle ear, a condition that restricts sound conduction and can lead to conductive hearing loss.
What is ICD-10 Code H74.3?
The ICD-10 code H74.3 refers to ankylosis of the ossicles of the middle ear. The three tiny bones of the middle ear – the malleus (hammer), incus (anvil), and stapes (stirrup) – are normally freely mobile and transmit sound vibrations from the eardrum to the inner ear. In ossicular ankylosis, these bones become fused or adherent to each other or to the walls of the middle ear cavity, reducing or eliminating their mobility and thereby impairing sound transmission.
Causes
Ankylosis of the ossicles can result from several underlying conditions:
- Otosclerosis: One of the most common causes, characterised by abnormal bone remodelling affecting the stapes footplate and surrounding structures.
- Chronic otitis media: Repeated or long-standing middle ear infections can produce scar tissue and adhesions that restrict ossicular movement.
- Trauma: Injuries to the middle ear may result in scarring and subsequent ankylosis.
- Congenital malformations: In rare cases, ossicular fixation is present from birth.
- Tympanosclerosis: Calcification of middle ear structures following chronic inflammation can fix the ossicular chain.
Symptoms
The hallmark symptom of H74.3 is conductive hearing loss, caused by the mechanical failure of sound transmission. Common complaints include:
- Gradually progressive hearing loss, often unilateral
- Muffled or dampened hearing quality
- Tinnitus (ringing in the ear), especially in otosclerosis-related cases
- Occasional dizziness or balance disturbance
- Usually no ear pain unless active infection is present
Diagnosis
Diagnosis is established through clinical examination and audiological testing:
- Otoscopy: Visual inspection of the ear canal and eardrum
- Tympanometry: Assessment of eardrum and middle ear mobility; ankylosis typically produces a flat (Type B) or stiff (Type As) tympanogram
- Pure-tone audiometry: Demonstrates an air-bone gap, confirming conductive hearing loss
- High-resolution CT scan of the temporal bone: Allows visualisation of ossicular fixation, calcifications, and structural abnormalities
Treatment
Treatment depends on the extent of ossicular fixation and the degree of hearing impairment:
Conservative Management
- Fitting of conventional hearing aids to compensate for hearing loss, particularly when surgery is contraindicated or not desired
- In otosclerosis: sodium fluoride has been used in some cases to attempt to slow disease progression, though evidence for its efficacy is limited
Surgical Management
- Stapedotomy or stapedectomy: Surgical removal or mobilisation of the fixed stapes with insertion of a prosthesis; highly effective in otosclerosis
- Ossiculoplasty (tympanoplasty type III/IV): Reconstruction of the ossicular chain using prostheses or grafts in cases of extensive adhesions or post-inflammatory damage
- Implantable hearing systems: Bone-anchored hearing aids (BAHA) or active middle ear implants may be considered when conventional approaches are insufficient
Prognosis
The outlook for patients with H74.3 depends on the underlying cause and the extent of ossicular involvement. When treated surgically at an early stage, particularly with stapedotomy, significant hearing improvement is achievable in many cases. In the presence of extensive ankylosis or concurrent sensorineural hearing loss, the prognosis is more guarded.
References
- World Health Organization (WHO): ICD-10 International Statistical Classification of Diseases and Related Health Problems, 10th Revision, Chapter VIII: Diseases of the ear and mastoid process (H60–H95). https://icd.who.int/browse10
- Merchant S.N., Nadol J.B. (eds.): Schuknecht's Pathology of the Ear. 3rd edition. PMPH-USA, Shelton 2010.
- Ruckenstein M.J. (ed.): Comprehensive Review of Otolaryngology. Saunders Elsevier, Philadelphia 2004.
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