Clinical Decision-Making Case: A Giant Headache.

Audience: This certifying exam practice case is intended for emergency medicine residents and medical students rotating through emergency medicine. Introduction: Giant cell arteritis (also known as GCA, temporal arteritis, cranial arteritis, or Horton's disease) is the most common systemic vasculitis.1 Patients commonly present with a new and unique headache, often with tenderness in the temporal region. Patients may present with associated jaw claudication and transient visual loss. Constitutional symptoms such as fever and fatigue are common and proximal muscle weakness may be present with concurrent polymyalgia rheumatica.1 These symptoms are thought to be a result of an exaggerated immune response to vascular injury with lymphocyte proliferation and giant cell formation which can lead to luminal narrowing and even ischemia.2The incidence varies among various demographics. It is highest in Scandinavia (21 per 100,000) and lowest in East Asia (less than one per 100,000). Globally, it is estimated to be 10 per 100,000 and in the US roughly 19 per 100,000.2,3 Recent studies have shown increasing incidence in Hispanic and African American populations while showing it to still be rare in Middle Eastern and Asian populations.4 It is most common in patients who are 70-79 years old and almost never presents in those under 50.1Left untreated, GCA can result in significant morbidity - vision loss.4 Treatment is not benign - there are adverse effects of long-term glucocorticoid therapy. The cost to the healthcare system in the US is expected to increase dramatically by 2050 due to the aging population and cost of treatment.3Given its relatively low incidence but high morbidity, giant cell arteritis is a rare diagnosis that Emergency Medicine residents may not encounter in training but is an important differential diagnosis to consider in the appropriate clinical context. Educational Objectives: By the end of this clinical decision-making case, learners will be able to: 1) demonstrate increased knowledge pertaining to ABEM's clinical decision-making case, 2) communicate the differential diagnosis of a new acute onset headache in patients over the age of 50 and the importance of giant cell arteritis in that differential, 3) acquire an appropriate history and physical exam in this clinical setting, 4) verbalize, interpret, and justify the appropriate diagnostic testing for this clinical case (at minimum CT head, complete blood count (CBC), basic metabolic panel (BMP), comprehensive metabolic panel (CMP), erythrocyte sedimentation rate (ESR), and 5) explain the appropriate treatment and disposition of a patient with temporal arteritis. Educational Methods: This session was structured after the clinical decision-making case that was introduced by the American Board of Emergency Medicine (ABEM) in the instructional videos on the ABEM Qualifying Exam Part 2 released in December 2024. The materials used were modeled after the samples that were provided in the supplemental material for the clinical decision-making case. Slides were provided to the instructor concerning clinical presentation, differential diagnosis, and management for the debriefing following the session. This case was tested using 18 resident volunteers PGY 1-2 in an ACGME (Accreditation Council for Graduate Medical Education) accredited emergency medicine residency program. Research Methods: Using a score sheet, evaluators assessed the residents' performance in acquiring appropriate clinical information, interpreting diagnostic tests, providing a differential, and justifying their management. Residents were asked to evaluate the educational value of the case. Results: Nine PGY1 residents and nine PGY2 residents completed the case, scoring 19.7/25 with four failures and 21.4/25 with three failures, respectively. Reasons for failing included scoring less than 19/25 or missing a critical action. Of the 17 residents that completed the post-survey, the educational value was reported to be 4.7/5 with all residents stating it increased their medical knowledge. Almost all of those residents stated that this experience made them more comfortable with the new ABEM clinical decision-making case. Discussion: This educational case focusing on giant cell arteritis (GCA) was effective in enhancing resident knowledge and clinical skills. All participating residents reported increased knowledge following the exercise and rated the case highly in terms of educational value. Performance outcomes further supported the case's efficacy. All residents successfully completed critical actions related to obtaining an adequate history, performing a focused physical exam, and ordering appropriate diagnostic tests. The only resident who failed the critical action of starting steroids was also the only resident to miss the critical action of diagnosis, which supports the close association of these two critical actions. This positive feedback supports the use of this case to expose learners to a rare but high-risk diagnose which they are unlikely to encounter during clinical training. Topics: Giant cell arteritis, temporal arteritis, headache, vasculitis, ophthalmologic disorders.