Abstract
Purpose: :
We previously reported prednisone reduced the frequency of generalized myasthenia (GMG) and controlled diplopia, without major adverse effects at 2 years, in patients with ocular myasthenia gravis (OMG). Questions remain whether study subjects had long standing disease-biasing results towards a steroid benefit and if prednisone merely delayed GMG onset.
Methods: :
Record review of a referral neuro-ophthalmology service OMG database for patients who had follow up > 4 years or until GMG developed. We studied the effect of prednisone on GMG incidence and control of ocular symptoms. Generally, patients with diplopia were recommended for prednisone therapy. Most remained on daily 2.5-10 mg to prevent diplopia. We compared the results for prednisone-treated and ‘untreated’ (pyridostigmine only) patients.
Results: :
Of 87 patients, 55 were in the prednisone-treated and 32 were in the ‘untreated’ groups. GMG developed in 7 (13%) of prednisone-treated (OR 0.41; 95 % CI: 0.22, 0.76) and in 16 (50%) of ‘untreated’ (OR 2.78; 95% CI: 1.68, 4.60) patients. After OMG onset, GMG developed at a mean of 5.8 years and 0.22 years in prednisone and ‘untreated’ groups. Diplopia was present at the last exam in 27% of prednisone-treated (mean 7.2 years) and in 57% of ‘untreated’ (mean 4.6 years) OMG patients. For 48 prednisone-treated patients who did not develop GMG, OMG treatment failure occurred in 13.
Conclusions: :
Prednisone delays the onset of GMG and has sustained benefit of reducing the incidence of GMG and controlling diplopia. Without prednisone, GMG develops in 50% of OMG patients, typically within 1 year.
Keywords: neuro-ophthalmology: diagnosis • eye movements