What is Cogan syndrome?

Cogan Syndrome: An Autoimmune Disorder Affecting the Eyes and Ears

Cogan syndrome is a rare autoimmune vasculitis characterized by inflammation of the inner ear and eyes, particularly nonsyphilitic interstitial keratitis and audiovestibular dysfunction, which can lead to permanent hearing loss and vision impairment if not treated promptly. 1

Definition and Classification

• Cogan syndrome is classified into two subtypes:
  • Typical Cogan syndrome: Interstitial keratitis with audiovestibular symptoms occurring within a 2-year maximum delay between these organ involvements 2
  • Atypical Cogan syndrome: Inflammatory ocular disease without interstitial keratitis, with audiovestibular impairment and systemic manifestations occurring with a delay longer than 2 years between different organ manifestations 2

Clinical Manifestations

Ocular Manifestations

• Nonsyphilitic interstitial keratitis (in typical form) 1
• Other inflammatory eye conditions in atypical form, including:
  • Retinal vasculitis 3
  • Uveitis 3
  • Optic nerve swelling 3

Audiovestibular Manifestations

• Sensorineural hearing loss (often bilateral) 1, 4
• Tinnitus 3
• Rotatory vertigo 3
• Vestibular dysfunction 5

Systemic Manifestations

• Systemic vasculitis occurs in approximately 10% of cases 6
• Can affect vessels of all sizes (small, medium, and large) 5
• May present as:
  • Fever 6
  • Splenomegaly 6
  • Lymphadenopathy 6
  • Musculoskeletal complaints 6
  • Large vessel vasculitis (Takayasu-like) 6
  • Aortic valve involvement 6
  • Coronary artery involvement 6
  • Renal vasculature involvement 6
• Association with inflammatory bowel disease has been reported 5

Diagnosis

• Diagnosis is primarily clinical and one of exclusion 2
• No specific diagnostic criteria or biomarkers are currently available 2
• Key diagnostic elements include:
  • Presence of characteristic eye and ear symptoms 1
  • Audiometric testing to document sensorineural hearing loss 3
  • Ophthalmologic examination to identify ocular inflammation 3
  • Ruling out other conditions with similar presentations 2

Differential Diagnosis

• Bilateral sudden sensorineural hearing loss may be associated with:
  • Infections (viral, bacterial, mycoplasma, Lyme, tuberculosis, syphilis, fungal) 1
  • Autoimmune inner ear disease 1
  • Ototoxic medications 1
  • Trauma 1
  • Lead poisoning 1
  • Genetic disorders 1
  • Mitochondrial disorders 1
  • Stroke 1
  • Neoplastic conditions 1
  • Sarcoidosis 1
  • Hyperviscosity syndrome 1

Treatment

• First-line treatment is immunosuppressive therapy with corticosteroids 4, 3
• For refractory cases or as steroid-sparing agents:
  • Methotrexate 5
  • Tumor necrosis factor-α inhibitors 4
  • Other biological agents 4
• Early intervention is critical to prevent irreversible hearing loss 3
• For patients who develop profound bilateral sensorineural hearing loss:
  • Cochlear implantation is recommended early due to the risk of cochlear ossification from inflammation 4
  • Cochlear implants provide excellent hearing rehabilitation with high word and sentence recognition scores 4
• For ocular manifestations with retinal vasculitis:
  • Retinal photocoagulation may be necessary 3
  • Close monitoring for retinal neovascularization is required 3

Prognosis

• Disease prognosis is related to the risk of deafness and/or blindness as well as complications from systemic vasculitis 2
• Without timely treatment, hearing loss may become irreversible in approximately half of patients 4
• Early recognition and intervention can minimize disabling and irreversible damage 2
• Long-term follow-up in collaboration with multiple specialties (rheumatology, ophthalmology, otolaryngology) is essential 3

Special Considerations

• Hearing tests should be performed in patients with retinal vasculitis and systemic inflammation, even in the absence of subjective symptoms 3
• Regular monitoring for progression of audiovestibular and ocular symptoms is necessary 3
• Patients may require long-term immunosuppressive therapy to prevent recurrence 3