On the basis of the patient's history, symptoms, and physical examination findings, a thorough differential diagnosis was developed. The most probable conditions in the differential were giant cell arteritis (GCA), myasthenia gravis, transient ischemic attack (TIA), and partial cranial nerve III (CN III) palsy.
This patient's initial presentation raised suspicion for GCA. His hypertension and hypercholesterolemia, as well as his prolonged history of smoking, combined with physical symptoms of left-sided temporal headache and vision changes, made GCA seem like a possibility. However, GCA is an autoimmune condition that causes an inflammatory response in large arterial vessels. Although the patient's medical conditions could irritate his vascular system, whether these conditions could elicit an autoimmune response is unknown. Furthermore, physical examination of the patient showed that the temporal artery was soft, pulsatile, and palpable. In contrast, a patient with GCA would have a rigid temporal artery. Moreover, patients with GCA have jaw pain and an acute loss of vision on the affected side rather than diplopic symptoms. In fact, studies show that diplopic symptoms develop in only 5.9% of patients with GCA. Thus, GCA was ruled out as a potential diagnosis, and corticosteroid therapy and a temporal artery biopsy were deemed unnecessary.
Myasthenia gravis is well known to cause diplopia. This is an autoimmune condition in which antibodies bind to acetylcholine receptors, causing symptoms of cholinergic toxicity, such as muscle weakness and fatiguability.  Myasthenia gravis should be treated immediately because of the possibility of respiratory failure. The first-line treatment is the acetylcholinesterase inhibitor pyridostigmine. This drug prevents the breakdown of acetylcholine, allowing an increase in the availability of acetylcholine molecules to compete with antibodies for acetylcholine receptors. If this therapy fails, patients undergo either plasmapheresis or intravenous immunoglobulin therapy; however, the results of these interventions can vary from patient to patient. Although the patient in this case has diplopic symptoms, the diplopia associated with myasthenia gravis has a more gradual onset compared with the sudden onset in this patient. In addition, the patient's lack of other symptoms associated with the disease make myasthenia gravis a less probable diagnosis.
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Cite this: Muthunivas Muthuraj, Shailesh Rajguru. Facial Spasms in a Man Recently Released From the Hospital - Medscape - May 05, 2022.