Dysthyroid Orbitopathy and Myasthenia Gravis (Kennerdell Case 9, PPT)

History: A 74-year-old woman presented with an eight-month history of inability to move the right eye to the left and proptosis of the right eye. Her visual acuity was intact. Improved movement of the right eye medially following intravenous injection of Tensilon indicated that the right medial rectus was afflicted with Myasthenia gravis as well as thyroid eye disease. Right medial rectus function improved as myasthenia improved. Anatomy: Orbit; Medial rectus; Medial rectus muscle structure; Oculomotor muscles. Disease Diagnosis: Thyroid Associated Ophthalmopathy; Dysthyroid Orbitopathy; Myasthenia gravis. Pathology: The biopsy of the muscle taken because of the unusual nature of the presentation showing the disrupted myofibrils and the inflammatory cells in the interstitial tissue, which is consistent with Dysthyroid Orbitopathy. There are no findings on pathology to indicate Myasthenia gravis. Presenting Symptom: Inability to move the right eye to the left and proptosis of the right eye. Neuroimaging: The enlarged medial rectus muscle in the right medial orbit. Ocular Movements: Inability to move the right eye to the left. Treatment: injection with Tensilon.