LO51: Does my dizzy patient need a computed tomography of the head?

Abstract

Introduction: Dizziness is among the most common presenting complaints in the emergency department (ED). Although the vast majority of these cases are the result of a benign, self-limiting process, many patients undergo computed tomography (CT) of the head. The objective of this study was to define the yield of and diagnostic accuracy of CT in dizziness in addition to defining high-risk clinical features predictive of an abnormal CT. Methods: At a tertiary care ED we performed a medical records review from Jan 2015-2018 including adult patients with a triage complaint of dizziness (vertigo, unsteady, lightheaded), excluding those with symptoms >14days, recent trauma, GCS < 15, hypotensive, or syncope/loss of consciousness. Five trained reviewers used a standardized data collection sheet to extract data. Our outcome was a central cause defined as: cerebrovascular accident (CVA), brain tumor (BT) or intracranial haemorrhage (ICH) diagnosed on CT or magnetic resonance imaging. Univariate analysis/logistic regression were performed and odds ratios reported. A sample size of 796 was calculated based on an expected prevalence of 5% with an 80% power and 95% confidence interval to detect an odds ratio greater than 2. Results: 2310 patients were recruited, 800 (35%) underwent CT head, 471(59%) female and a mean age of 62.8 years (+/−17.5 years). The top three diagnoses for patients undergoing CT were peripheral vertigo/benign positional vertigo (153 – 19%), vertigo not-otherwise-specified (137 – 17%) and dizziness not-otherwise-specified (137 – 17%). The number of CT scans considered abnormal was 30 (3.7%). The top three diagnoses for patients with an abnormal CT were CVA (22 – 75%), BT (9 – 26%) and ICH (6-17%). High risk clinical findings associated (p < 0.001) with an abnormal head CT were dysmetria, objective motor neurological signs, positive Rhomberg, ataxia and inability to walk 3 steps. Objective motor neurological signs (OR 8.4 [95% CI 3.27-21.72]) and ataxia (OR 3.4 [95% CI 1.62-7.41]) were both independently associated with an abnormal CT. Patients without any high risk findings on exam had a 0.7%(3/381 – 2 CVA,1 Tumour) probability of an abnormal CT. Sensitivity of CT for a central cause of dizziness was 71.43%(95%CI 55.4-84.3%), specificity 100%(95%CI 99.5-100%). Conclusion: Current rate of imaging in dizziness is high and inefficient. CT should be the first imaging test in those with high-risk clinical features, but a normal result does not rule out a central cause.