Otosclerosis: Symptoms, Types, Causes and Treatment

Otosclerosis is a complex ear disorder that primarily affects adults and is a leading cause of progressive hearing loss. As new research and technologies emerge, our understanding of otosclerosis continues to deepen, offering hope for earlier diagnosis, more effective treatments, and improved quality of life for those affected. This article explores the key aspects of otosclerosis—its symptoms, types, causes, and the latest treatment options—through an evidence-based lens.

Symptoms of Otosclerosis

Otosclerosis can manifest in a variety of ways, often beginning subtly and progressing over time. Recognizing its symptoms early is vital for timely intervention and management. Most individuals first notice hearing changes, but other symptoms can also signal the disease.

Symptom	Description	Prevalence/Severity	Sources
Hearing Loss	Gradual, usually conductive, sometimes mixed	Most common, progressive	1 2 4 8
Tinnitus	Ringing or buzzing in the ears	65–68% of patients, can be severe	2 3
Vertigo	Sensation of dizziness or imbalance	Higher in those with sensorineural loss	1
Depression/Anxiety	Emotional impact of chronic symptoms	Increased with severe vestibular issues	1

Table 1: Key Symptoms

Hearing Loss: The Hallmark of Otosclerosis

• Progressive Nature: Hearing loss in otosclerosis typically develops gradually. Early hearing loss is usually conductive, resulting from the fixation of the stapes bone, which impedes sound transmission. As the disease progresses, a mixed or sensorineural component may develop if the cochlea is involved 1 4 8.
• Bilateral or Unilateral: Hearing loss can affect one or both ears. Over time, many patients experience worsening in both ears.

Tinnitus: More Than Just a Nuisance

• Prevalence and Impact: Tinnitus, or the perception of ringing or buzzing, is reported by up to 68% of otosclerosis patients and is sometimes the very first symptom. For over half of those affected, tinnitus is a significant or severe problem, sometimes even more troubling than the hearing loss itself 2 3.
• Severity: Tinnitus severity can be moderate to severe, and its impact may be independent of the measured degree of hearing loss 2 3.

Vestibular Symptoms: Vertigo and Imbalance

• Vertigo: While less common than hearing loss or tinnitus, vertigo (a spinning sensation or imbalance) is reported more frequently in those with significant sensorineural hearing loss. The severity of vestibular symptoms, such as dizziness, increases as otosclerosis advances and more inner ear structures are affected. These symptoms can also negatively impact emotional well-being, contributing to depression or anxiety 1.

Emotional and Psychological Effects

• Depression/Anxiety: Chronic symptoms, particularly severe vertigo and persistent hearing loss or tinnitus, can lead to psychological distress, including depression or anxiety 1.

Types of Otosclerosis

Otosclerosis can present in several distinct forms, each with unique features and implications for diagnosis and treatment. Understanding these types is crucial for tailored patient care.

Type	Characteristics	Impact on Hearing	Sources
Fenestral	Involves the oval window and stapes footplate	Primarily conductive loss	4 8 12
Retrofenestral	Affects cochlear capsule (inner ear structures)	Mixed or sensorineural loss	4 8 12
Pure Cochlear	Only cochlear involvement ("labyrinthine otosclerosis")	Pure sensorineural loss	1 4

Table 2: Major Types of Otosclerosis

Fenestral Otosclerosis

• Definition: This is the most common form, where abnormal bone growth primarily affects the stapes footplate at the oval window—preventing its normal vibration.
• Clinical Manifestation: Results in conductive hearing loss because sound cannot efficiently pass into the inner ear 4 8.
• Treatment Approach: Most responsive to surgical intervention (stapedectomy or stapedotomy) 4 12.

Retrofenestral Otosclerosis

• Definition: Involves the bony capsule surrounding the cochlea (the inner ear).
• Clinical Manifestation: Causes a mixed (conductive and sensorineural) or purely sensorineural hearing loss, as the bone changes extend to inner ear structures, potentially damaging the cochlea 4 8.
• Treatment Approach: Less responsive to surgery; often requires medical management or cochlear implants in severe cases 4 12.

Pure Cochlear (Labyrinthine) Otosclerosis

• Definition: Also called “pure labyrinthine otosclerosis,” this rare type affects only the cochlea without involving the stapes or oval window 1 4.
• Clinical Manifestation: Results in sensorineural hearing loss alone, which may be harder to diagnose and manage 1.

Causes of Otosclerosis

Otosclerosis is a multifactorial disease, arising from a complex interplay of genetic predisposition and environmental influences. While much is still being learned, significant progress has been made in uncovering the roots of this condition.

Factor	Description	Role/Contribution	Sources
Genetic	Multiple loci identified; some familial cases	Major risk factor; complex inheritance	5 6 7 8 9
Environmental	Viral (measles), possible fluoride influence	Possible triggers/modifiers	9 11
Bone Metabolism	Abnormal bone remodeling in otic capsule	Central disease mechanism	4 9 11
Immune Response	Inflammation, autoimmunity (HLA associations, T-cell involvement)	Possible pathogenic role	6 9 11

Table 3: Key Contributing Factors in Otosclerosis

Genetics: The Foundation

• Inheritance Patterns: Otosclerosis often runs in families, most commonly as an autosomal dominant trait with reduced penetrance. However, large multi-generational families are rare—most cases are sporadic or involve small families 5 6 7 8 9.
• Genetic Loci Identified: At least five genetic loci (OTSC1–OTSC5) have been mapped to specific chromosomes, though the precise genes involved are still being discovered 5 6 7 8. Recent studies suggest that T cell receptor beta may play a role in familial otosclerosis 9.
• Complexity: The genetic landscape is complex, involving both rare, high-impact mutations and more common, lower-risk variants 7 8 9.

Environmental Factors

• Viral Infections: Measles virus infection has been implicated as a potential environmental trigger, possibly initiating or accelerating the disease in genetically susceptible individuals 9 11.
• Fluoride and Other Factors: There is some suggestion that environmental fluoride levels may influence risk, but evidence is not definitive 9 11.

Bone Metabolism and Immune Response

• Pathology: The disease is characterized by disordered bone remodeling within the otic capsule, leading to areas of bone overgrowth and fixation 4 9.
• Immunological Involvement: Associations with specific HLA types and evidence of immune activity in affected bone suggest that immune mechanisms, including autoimmunity, may contribute to disease progression 6 9 11.

Treatment of Otosclerosis

Treatment for otosclerosis has evolved, offering patients a range of options from surgical intervention to advanced hearing devices and, in select cases, pharmacological therapies. The choice of treatment is guided by the type and stage of the disease, patient preference, and overall health.

Treatment Type	Main Approach / Option	Indication/Effectiveness	Sources
Surgery	Stapedectomy/Stapedotomy (microscopic or endoscopic)	Gold standard for conductive loss	4 10 12 13
Hearing Devices	Hearing aids, cochlear implants	Alternative or adjunct	12 4
Pharmacological	Fluorides, Vitamin D, Bisphosphonates, Anti-inflammatories	Mixed/limited evidence, mainly for retrofenestral/sensorineural cases	1 4 11
Symptom Management	Tinnitus therapies, vestibular symptom control	Supportive, variable efficacy	1 2 3 11

Table 4: Main Treatment Options

Surgical Intervention

• Stapedectomy/Stapedotomy: Surgery to remove or bypass the immobilized stapes bone, replacing it with a prosthesis, is the gold standard for fenestral otosclerosis. This procedure can be performed using microscopic or endoscopic techniques, with both approaches offering excellent outcomes and low complication rates 4 10 12 13.
  • Endoscopic Approach: Recent advances have made endoscopic stapes surgery a safe and effective alternative, with comparable audiological results to traditional microscopic surgery and minimal risks 10 13.
  • Outcomes: Surgery can restore conductive hearing loss in over 90% of cases, with most patients experiencing significant improvement in hearing thresholds 10 13.

Hearing Devices

• Hearing Aids: For those who are not surgical candidates or prefer non-invasive options, hearing aids can compensate for conductive or mixed hearing loss 12.
• Cochlear Implants: In cases of advanced retrofenestral otosclerosis with profound sensorineural loss, cochlear implants may be considered. Preoperative imaging is essential to assess cochlear patency 4 12.

Pharmacological Treatments

• Fluorides and Vitamin D: Some studies report that a combination of sodium fluoride, calcium gluconate, and vitamin D can help stabilize hearing and control vestibular symptoms, particularly in retrofenestral or sensorineural cases. Side effects are generally mild and reversible 1 4.
• Bisphosphonates: Although promising as anti-osteoporotic agents, current evidence for their use in otosclerosis is limited 11.
• Anti-inflammatories & Other Agents: Corticosteroids or NSAIDs may help in early, inflammatory stages, but long-term use is limited by side effects. Future therapies may target bone metabolism and immune pathways 11.

Management of Persistent Symptoms

• Tinnitus and Vertigo: Symptom management remains crucial, especially for those with persistent tinnitus or balance problems. Some patients benefit from specific therapies or medications aimed at reducing tinnitus severity or controlling vertigo, but results can vary 1 2 3 11.

Conclusion

Otosclerosis remains a significant cause of hearing loss in adults, but ongoing research and innovation are improving the lives of those affected. Early recognition of symptoms, precise diagnosis of the type, understanding the underlying causes, and a tailored approach to treatment are key to successful management.

Summary of Main Points:

• Otosclerosis typically presents with progressive hearing loss, often accompanied by tinnitus and, less commonly, vertigo or emotional distress.
• There are several types of otosclerosis, with fenestral and retrofenestral being the most recognized, each impacting hearing differently.
• The causes are multifactorial, involving both genetic and environmental factors, with abnormal bone metabolism at the core of the disease process.
• Surgical treatment—especially stapedectomy or stapedotomy—is the gold standard for fenestral disease, while hearing aids, cochlear implants, and limited medical therapies offer options for other types.
• Future advances may further improve outcomes, particularly through better understanding of the genetic and immunological underpinnings of the disease.

With continued research and patient-centered care, individuals with otosclerosis can look forward to better outcomes and enhanced quality of life.