Contemporaneous Presentation of Ocular Myasthenia Gravis With Pituitary Apoplexy: A Diagnostic Dilemma

Pituitary apoplexy is a life-threatening condition caused by a rapid expansion of the pituitary tumor due to hemorrhage or infarction. It usually presents with acute onset severe headache and can also be associated with visual field defects and ophthalmoplegia. Similarly, ocular myasthenia gravis, which is an autoimmune condition causing muscle fatiguability, also presents with ophthalmoplegia, commonly ptosis and diplopia. A 53-year-old male patient with a past history of adrenal insufficiency presented with acute onset headache. On examination, he had bilateral asymmetrical partial ptosis and left-side medial rectus palsy with mild fatiguability. He had normal visual fields and sparing of the pupils. Acetylcholine receptor antibodies were positive but failed to demonstrate a decremental response in nerve conduction studies. The patient was started on neostigmine on clinical suspicion of ocular myasthenia gravis. A magnetic resonance imaging (MRI) scan of the brain was arranged to look for any intracranial pathology for persistent headache and it revealed evidence of pituitary apoplexy with compression of optic chiasm and partial obliteration of bilateral cavernous sinuses. In view of MRI findings, a diagnosis of pituitary apoplexy with third cranial nerve involvement was considered the first differential diagnosis, and the patient was started on replacement hormones while temporarily withholding neostigmine. Following multidisciplinary input, it was decided to manage the patient conservatively. A repeat MRI brain was planned to assess the evolution which revealed resolution of pituitary apoplexy. Despite this, the patient continued to have ophthalmoplegia and fatigable partial ptosis. Pyridostigmine was restarted following which the patient fully recovered, confirming the diagnosis of ocular myasthenia gravis presenting concomitantly with pituitary apoplexy.