A clinical approach to ocular myasthenia gravis

Myasthenia gravis is a common disorder of the neuromuscular junction characterized clinically by muscle weakness and fatigability. Ocular myasthenia is often misdiagnosed in the initial stages due to the fluctuating nature of ptosis and diplopia. Here, we describe the clinical characteristics of ocular myasthenia gravis along with the diagnostic difficulties in a tertiary eye care center in Nepal. We retrospectively reviewed the charts of the patients diagnosed as ocular myasthenia gravis in Neuro-ophthalmology clinic, BPKLCOS, from 2010 to 2013. The diagnosis of ocular myasthenia was based on the association of typical history and signs together with at least one of these features: unequivocal improvement of ocular signs after injection of neostigmine, positive response to electrophysiological tests and detection of serum antibodies to acetylcholine receptors. There were 24 cases of diagnosed ocular myasthenia gravis during the 3 years. Among them 11 cases (45.8%) were males and 13 cases (54.1%) were females. The mean age was 32.04±19.56 years with the age range from 9 years to68 years. The most common symptoms among patients were drooping of the lids (45.8%, n=11), followed by both double vision and drooping of the lids (37.5%, n=9) and only intermittent double vision in16.6% (n=4). In two patients (9.09%) CT-scan findings were suggestive of thymoma. The symptoms were resolved with anticholinesterases alone in 66.6% (n=16) and anticholinesterases were supplemented with immunosuppressive drugs in 33.3% (n=8) patients. Ocular myasthenia is often misdiagnosed in the initial stages due to its fluctuating nature. With a high index of clinical suspicion simple clinical tests accompanied by pharmacological tests can be useful in diagnosing the condition.DOI: http://dx.doi.org/10.3126/jcmc.v4i3.11931Journal of Chitwan Medical College 2014; 4(3): 5-8