Prognostic predictors of remission in ocular myasthenia gravis.

Background: Ocular myasthenia gravis (OMG) constitutes 15% of all myasthenia gravis patients.

Methods: One hundred eight patients with OMG followed-up for over 36 months were retrospectively evaluated regarding factors associated with remission. Demographic features, neuro-ophthalmologic findings at onset, acetylcholine receptor (AChR Ab) and muscle-specifc tyrosine kinase antibodies (MuSK Ab), thymic status, single fiber electromyography (SFEMG) results were the variables considered.

Results: Median age of disease onset was 57 years (range 18-82 years). Clinical features at onset was isolated ptosis in 55 (50.9%) and isolated diplopia in 33 (30.6%) patients. Combined ptosis and diplopia were present in 20 (18.5%) patients. Among 75 patients with ptosis, it was unilateral in 65 (86.7%) and bilateral in 10 (13.3%). AChR Abs were found in 66 (61.1%) and MuSK Abs in 2 (1.9%) patients. SFEMG abnormality was detected in 74 (68.5%) patients. Thymoma was present in 16 (14.8%) and thymic hyperplasia in 6 (5.6%) patients. Forty-one patients (37.9%) had been treated with pyridostigmine alone. Sixty-seven (62%) patients were given immunosupressive drugs. In 53 (49.1%) prednisone was used and in 14 (12.9%) patients it was combined with azathioprine. Thymectomy was performed in all 16 patients with thymoma. Complete stable remission (CSR) was achieved in 49 (45.4%) patients. Fifty-nine (54.6%) patients had reached minimal manifestation (MM) status; 32 (29.6%) having a status of MM-1 and 27 (25%) a status of MM-3.

Conclusions: The presence of AchR Abs (p = 0.034) and an abnormal SFEMG (p = 0.006) at onset as increased risk factors for the presence of ongoing signs necessitating medical treatment.