Cogan syndrome is a very rare autoimmune inner ear disorder that is temporally associated with an inflammatory eye disease, usually interstitial keratitis, and is thought to be mediated by a hypersensitivity response to infectious agents associated with vasculitis.

Clinical hallmarks:

• Cogan syndrome is characterized by an acute, subacute, or recurrent onset of inner ear loss of function resembling Meniere disease (tinnitus, vertigo, and gradual hearing loss). The resultant hearing loss typically is sensorineural, bilateral, and progressive. This is temporally related to the onset of keratitis manifested as pain, redness, and blurry vision in the affected eye. Systemic vasculitis features are marked by large-vessel vasculitis and can occur in up to 10% of patients. Medium-vessel vasculitis resembling polyarteritis nodosa to small-vessel vasculitis manifestations are possible.
• Constitutional: Fever, headache, weight loss, malaise.
• Ocular: Redness, pain, photophobia, and blurred vision as a result of interstitial keratitis (72%-100%). Scleritis or episcleritis (23%). The gap between involvement of audiovestibular and ocular symptoms is usually 1 to 6 mo and not more than 2 yr.
• Hearing/vestibular: Hearing loss progressing to deafness, usually bilateral (100%), vertigo (90%), and tinnitus (80%). Imbalance may be associated with nausea and vomiting.
• Cardiovascular: Aortitis, aortic aneurysm, aortic insufficiency.
• Musculoskeletal: Arthralgia, arthritis, myalgia.
• Neurologic: Hemiparesis and hemiplegia.
• Gastrointestinal: Abdominal pain (13% to 16%), diarrhea, melena.
• Renal: Hematuria (7%), glomerulonephritis (3%).
• Dermatologic: Cutaneous nodules, rash.

The exact etiology of Cogan syndrome is unknown. Evidence of an autoimmune mechanism includes binding of autoantibodies from patients with Cogan syndrome to the cochlea of mice in passive transfer studies. Autopsy specimens show nonspecific lymphocytic and plasma cell infiltration. Infection is thought to be a trigger. Some human leukocyte antigen (HLA) loci, including HLA-B17, HLA-A9, HLA-Bw35, and HLA-Cw4, correlate with the disorder.

• Infectious diseases:
  1. Syphilis
  2. Tuberculosis, Lyme disease, chlamydia, leprosy, brucellosis, mumps, EBV, herpes zoster, and herpes simplex; rubeola should be considered in the differential for interstitial keratitis
• Rheumatology:
  1. Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis: Granulomatosis with polyangiitis (formerly Wegener granulomatosis)
  2. Takayasu arteritis
  3. Giant cell arteritis
  4. Rheumatoid arthritis with vasculitis
  5. Polyarteritis nodosa
  6. Behçet disease
  7. Sarcoidosis
• Neurology:
  1. Susac syndrome
  2. Occlusive nonvasculitis vasculopathy
• Neoplastic:
  1. Lymphoma (CNS)
• Miscellaneous:
  1. Vogt-Koyanagi-Harada syndrome
  2. Inflammatory bowel disease (Crohn disease)

• Diagnosis of Cogan syndrome is usually made on clinical evidence.
• Inflammatory markers are often elevated, including the erythrocyte sedimentation rate (ESR) and C-reactive protein.
• CBC count with differential; may show leukocytosis.
• ANCA serology test to evaluate for ANCA-associated vasculitis.
• Serologic test result should be negative for syphilis.
• Antiheat shock protein (Hsp) 70 antibodies have been suggested as possible markers of typical Cogan syndrome (also found in other forms of autoimmune sensorineural hearing loss).

• Initial tone audiogram shows a hearing loss, especially at high frequencies.
• MRI with gadolinium of the brain to rule out non-inner-ear causes for acute or subacute hearing loss and vestibular dysfunction. Brain MRI can range from normal to gadolinium enhancement of the vestibular-cochlear structures.
• MRA of the aorta and its proximal branches may be used to assess for vascular inflammation that may support the diagnosis of large-vessel vasculitis.

Cochlear implant

• Treatment guidelines are based on grade C (fair evidence from ancillary studies) recommendations. Table E1 summarizes treatment modalities for Cogan syndrome.
• Early treatment is critical for a favorable prognosis.
• Eye symptoms: Unlike audiovestibular symptoms, ocular manifestations typically respond to topical corticosteroids. Mydriatics may be considered.
• Vestibuloauditory symptoms: Divided doses of prednisone 1 to 2 mg/kg PO daily.
• Vasculitis symptoms: Divided doses of prednisone 1 to 2 mg/kg PO daily. PO or IV cyclophosphamide should be considered for life-threatening features.

• Methotrexate, cyclophosphamide, or azathioprine may be considered as steroid-sparing agents.
• Treatment options such as TNF-alpha inhibitors (infliximab and etanercept), plasmapheresis, rituximab, tocilizumab, cyclosporine, and mycophenolate mofetil have been reported in the literature.

• Ocular outcomes are good.
• Hearing loss may occur in up to 50% of cases.

• Ophthalmology for complete ocular examination, including slit-lamp examination
• Rheumatology/immunology for all patients with suspected disease
• Audiology for complete hearing assessment
• Otolaryngology for confirmation of sensorineural hearing loss