CASES OF THE WEEK - “Cogan syndrome” by Dr Samy Zakout, Specialist Rheumatology & Dr Shwan Hameed, Consultant Otolaryngology, NMC Royal Hospital Sharjah

Cogan syndrome is a rare disorder of a probable autoimmune vasculitic origin first described in 1934. The age of onset seems to range from 3 to 50 years with an average age of disease onset at 29 years. It is characterised by audiovestibular dysfunction and ocular inflammation. The cause remains unknown and the epidemiology of the disease is purely based on case reporting. As of 2015, there were fewer than 250 case reports. Interestingly, it seems extremely rare in Arabic and Middle Eastern countries in which a new case has been recently diagnosed and is being reported in our hospital.

In January 2019, a 14-year-old girl of Middle Eastern origin first presented to the otolaryngologist with a 3-week history of balance problems, left tinnitus and sensorineural hearing loss in both ears worse on the left. She first received treatment for vestibular neuritis without experiencing any improvement. Two months later, she complained of bilateral red eyes and excessive lacrimation when diffuse interstitial keratitis was diagnosed by the ophthalmologist. An array of blood tests including a full autoimmune screen was arranged and a rheumatology opinion was sought.

The patient had a normal inflammatory response and her screen for antinuclear antibodies (ANA), extractable nuclear antigen (ENA), rheumatoid factor (RF) and antineutrophil cytoplasmic antibodies (ANCA) were all negative. A full virology screen was also negative. Having failed to respond to all supportive treatment modalities, a trial of a tapering two-week course of prednisolone starting at 25mg daily was instigated. The patient’s symptoms improved by more than 50% on glucocorticoids subsequent to which the diagnosis of Cogan syndrome was anticipated. As the patient’s symptoms relapsed when glucocorticoids were stopped, she was recommenced on prednisolone 25mg in line with azathioprine 100mg daily by her rheumatologist. The patient’s hearing, which was almost lost in the left ear, improved significantly by more than 70% initially, and then to normal hearing as stated by the patient supported by special ENT testing. Her balance problems and vertigo also improved remarkably. Her tinnitus, which was the last symptom to resolve, also responded to treatment. The patient has now successfully stayed away from glucocorticoids for more than 6 months and is currently on Azathioprine 50mg daily without developing any symptoms or signs of relapse. As guided by her rheumatologist, further reductions of azathioprine dose ought to be introduced in due course with a target to completely stop immunosuppressive treatment if at all possible.

The consistent clinical picture supported by the positive response to glucocorticoids especially in the absence of an alternative diagnosis would make the diagnosis of Cogan syndrome likely. Given the rarity of this disorder, there are no classification criteria as yet hence the ongoing need to case reporting. Moreover, there is no clear guidance on both the duration and regimes of immunosuppressive treatment of this condition.

Conclusion: