SHM Converge Scientific Abstract ePoster Gallery-A Dilemma of Managing Dueling Diagnoses: Giant Cell Arteritis and Concurrent Myasthenia Gravis

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This case highlights the diagnostic and treatment challenge of coexisting giant cell arteritis (GCA) and myasthenia gravis (MG). A 54-year-old man with prior stroke, seizures, neurogenic bladder, and spine surgery presented with progressive left-sided weakness, dysphagia, major weight loss, headaches, and diplopia. Exam showed bilateral upper-extremity weakness, ptosis, ocular palsy, and restricted eye movements. Workup was unrevealing except for a positive acetylcholine receptor antibody, confirming MG. He was started on pyridostigmine, IVIG, and eye patching.<br /><br />During MG treatment, he developed severe retro-orbital headaches with right temporal tenderness and elevated ESR/CRP, raising concern for GCA. Temporal artery ultrasound showed a bilateral halo sign, which is highly specific for GCA, so high-dose prednisone was started. Two days later, his respiratory and limb weakness worsened, suggesting steroid-triggered MG exacerbation. Steroids were stopped and his weakness improved. Temporal artery biopsy was negative, but inflammatory markers remained elevated. He was restarted on low-dose prednisone, with improvement in both headache and MG symptoms, and later discharged on pyridostigmine.<br /><br />The report emphasizes that corticosteroids can precipitate myasthenic worsening or crisis in 9–18% of MG patients, so clinicians should confirm GCA carefully before initiating high-dose treatment. Although temporal artery biopsy is the gold standard, it can be falsely negative; a bilateral halo sign on ultrasound may be sufficient for diagnosis when clinical suspicion is strong. After discharge, the patient improved further on efgartigimod and was started on tocilizumab with PJP prophylaxis for GCA.<br /><br />Overall, the case underscores the need to consider overlapping autoimmune diseases and to balance treatment of one condition against potential harm to the other.

Asset Subtitle

Nikitha Rajendran

Meta Tag

Author List Mohammad Baseem Shaikh, Nikitha Rajendran, Rani Chikkanna

Category Clinical Vignettes

Concept Myasthenia Gravis

Concept Giant Cell Arteritis

Concept Muscarinic Receptors

Concept Temporal Artery Ultrasound

Concept Temporal Artery Halo Sign

Distinguished Non-Finalist

Presenter Organization University of Kentucky College of Medicine

Presenting Author Nikitha Rajendran

Track Adult

Keywords

giant cell arteritis

myasthenia gravis

corticosteroid exacerbation

temporal artery ultrasound

halo sign

acetylcholine receptor antibody

pyridostigmine

prednisone

temporal artery biopsy

autoimmune overlap

Myasthenia Gravis

Giant Cell Arteritis

Muscarinic Receptors

Temporal Artery Ultrasound

Temporal Artery Halo Sign