coexistence of myasthenia gravis ( mg ) and thyroid disorders is well known for the past few decades . it has been postulated that mg frequently occurs in patients with autoimmune thyroid disease , as compared to the general population and is mostly seen with hyperthyroidism ( 50 times more common with graves disease ) . although autoimmune thyroid disorders are known to be present in 5 - 7.5% of the mg patients , mg is seen in only 0.2% of the patients with thyroid disease , commonly associated with thyrotoxicosis . we discuss herewith , a female patient presenting in a thyrotoxic state and thereafter developing ocular mg . a 22-year - old female presented to the neurology clinic with a history of a mild , dull aching headache in the occipital area , which progressively increased over the past two years . she also complained of diplopia in all directions for the past six months . a positive history of aura , neck pain , restriction of movement in the neck , vomiting , photophobia , seizures , and weakness of limbs was present . there was also a positive history of amenorrhea since four months , and a 10 kg weight loss over the last four months was documented . a general survey of the patient showed a thin built and poorly nourished female with pallor and pedal edema . vitals recorded : pulse  96/minute , regular , with normal volume and character ; blood pressure  130/90 mm of hg . systemic examination including neurological and all other systems documented no significant abnormality , except for decreased palpebral fissure of the left eye and lid lag noticed in the left eye [ figure 1 ] . based on the history and examination findings and a battery of relevant investigations ( tensilon test ) , diagnosis of ocular mg was made , and physostigmine was initially prescribed to the patient . the patient was then referred to internal medicine for further evaluation for suspicion of hyperthyroidism . thyroid function tests reported t3 levels of 3.4 ( 0.8 - 2.0 ) ng / ml , t4 levels of 20.2 ( 4.5 - 12.0 ) ug / dl , and tsh levels of < 0.005 ( 0.3 - 5 ) uiu / ml . finally , in view of the thyrotoxic status of the patient , carbimazole was started at a dose of 10 mg , eight hourly . the patient was discharged with an advice to continue carbimazole and review after one month . follow - up after one month showed both symptomatic and biochemical improvement , that is , left eye ptosis had decreased and t3 , t4 , and tsh levels were within normal range , respectively . the further plan was to discuss the alternative of thymectomy with the patient , on the next follow - up after two months . myasthenia gravis is an autoimmune disorder characterized by fluctuating weakness of the skeletal muscles caused by impaired neuromuscular transmission due to circulating antiacetylcholine receptor antibodies . mg has a high incidence of association with autoimmune diseases , most common being graves disease and autoimmune thyroiditis . graves disease is commonly associated with the ocular form of mg , which has been supported by the increased presence of thyroid antibodies in patients with ocular mg ( approximately 40% ) . this case report of ocular mg in conjunction with thyrotoxicosis supports the earlier reported association between the two entities . treatment of thyroid disorder in patients with mg leading to myasthenia regression , in approximately two - thirds of the patients , also strengthens this correlation . first , the possibility of immunological cross - reaction against epitopes or auto - antigens shared by the thyroid and the eye muscles . second , higher frequency of ocular myasthenia in autoimmune thyroid disease could be attributed to genetic linkage . human leukocyte antigen ( hla ) specificity ( b8 , dr3 , and bw46 ) between mg and thyroid disease has been reported . however , further studies to unearth the precise association between thyroid disease and mg is a must in the future , to understand the relation between both the entities . in a majority of patients ( ~75% ) with coexisting conditions , hyperthyroid symptoms our patient initially showed symptoms of thyrotoxicosis , that is , weight loss and amenorrhea , four months before developing left eye ptosis , lid lag , and diplopia . neuromuscular features are known to be associated with both the entities and the presentation of myasthenia . when it is present concomitantly with thyrotoxicosis , it is usually mild , and therefore , can get overlooked when considering differential diagnosis for a patient with hyperthyroid symptoms and muscular weakness . appropriate diagnosis of mg can be made by a complete history and thorough examination , with the supplementation of laboratory investigations such as edrophonium ( tensilon ) test , radioimmunoassay , and electromyography . a common treatment modality denotes the use of anticholinesterase medications supplemented by immunosuppression , plasmapheresis and/or thymectomy . it is also seen that any deviation from a euthyroid state will adversely affect mg and the treatment of thyroid dysfunction may alleviate the existing myasthenic symptoms when both disorders are present concomitantly . the presence of an enlarged thymus and thymic abnormalities have been seen in both thyrotoxic and mg patients . the beneficial effect of thymectomy in the management of mg , if done at an earlier stage in the disease course , has been documented . thymectomy not only aids in improving the symptoms of myasthenia , but it also reduces the morbidity in severe cases and where large doses of anticholinesterases are required on a daily basis . the main objective of this case is to highlight the importance of detecting a coexisting mild myasthenia gravis at an early stage in a patient with thyrotoxicosis with predominantly restricted ocular symptoms .
ocular myasthenia gravis in conjunction with thyroid disorders , although rare , has been reported in the past . however , the similarity in the presentation of both the entities and the tendency of myasthenia gravis to get overlooked easily , even by experienced clinicians , necessitates a thorough knowledge , a strong consideration , and a vigilant approach , to aid in its diagnosis . 
 we discuss a case of a female in a thyrotoxic state , with symptoms of ocular myasthenia gravis , and a brief overview of this entity .