Medical Excellence- Issue 1

such as benign paroxysmal positional vertigo (BPPV), the use of imaging and treatment with medications is not in accordance with best evidence [7]. In the NHAMCS study, prospectively defined “dangerous” diagnoses (various cardiovascular, cerebrovascular, toxic, meta- bolic, and infectious conditions in which the possibility of a poor outcome without treatment was likely) were found in 15% of patients, and this proportion increased with age [2]. The most common dangerous causes found were fluid and electrolyte dis- turbances (5.6%), cerebrovascular diseases (4.0%), cardiac ar- rhythmias (3.2%), acute coronary syndromes (1.7%), anemia (1.6%), and hypoglycemia (1.4%) [2]. Some rare causes of diz- ziness such as adrenal insufficiency [8], aortic dissection [9], carbon monoxide intoxication [10], pulmonary embolus [11], and thiamine deficiency [12] are treatable. How does this study compare to others? One older single- institution study analyzed 125 patients prospectively identified over a 16-month period [13]. Forty-three percent had a diagno- sis of a peripheral vestibular problem, and 30% had a “serious” diagnosis. Another larger prospective single-institution Chinese study of adult ED patients with dizziness reported results of 413 patients recruited over just 1 month [1]. A central nervous system (CNS) cause was found in 23 patients (6%). Two retrospective studies also provide relevant data. One was done in a German ED of 475 consecutive dizzy patients who were seen by a neurologist during the index ED visit [14]. The initial diagnoses assigned by the neurologists were benign in 73% of cases and serious (mostly cerebrovascular and inflammatory CNS disease) in 27% of cases. Overall, the two most common diagnoses were BPPV (22%) and stroke (20%). In follow-up by a neurologist blinded to the ED diagnosis, 44% of diagnoses (pre- viously made by a neurologist in the ED) were changed. Over half of these diagnostic changes were from a serious to a benign diagnosis, which errs toward patient safety but is more resource intensive than necessary. In about one patient in seven, the error was from benign to serious (five patients diagnosed with vestibu- lar neuritis and one with vestibular migraine, all reassigned to stroke), a dangerous misdiagnosis. The other study analyzed patients who had an ED triage di- agnosis of dizziness, vertigo, or imbalance as a primary symptom, collected over a 3-year period, and identified 907 patients (only 0.8% of all ED patients over that period of time), suggesting a very targeted selection (compared to other large studies) [15]. Of the 907 patients, one in five was admitted (68% to an inten- sive care unit [ICU]). The most common admitting services were medicine (41% of admissions), cardiology (32%), and neurology (24%). Of the 907 patients, most had benign conditions either peripheral vestibular problems, 32%, orthostatic hypotension (13%), or migraine (4%). A full 22% could not be diagnosed. Serious neurological disease was found in 49 patients (5%) of which 37 were cerebrovascular. Finally, only two patients with serious neurological disease presented with isolated dizziness. The incidence of important CNS disease in adult ED pa- tients with dizziness is approximately 5%. The high-end outlier is the Royl study that reported that 27% of patients have serious CNS causes which may be skewed by the fact that the study was conducted in a neurological ED [14]. Various studies have tried to identify risk factors for ED dizzy patients with CNS causes [1, 15–19]. One ED study of dizzy patients found that abnormal gait and subtle neurological deficits on neurological examination were associated with a CNS cause [16]. Overall, the risk factors include increasing age, vascular risk factors and history of pre- vious stroke, complaint of “instability,” and focal neurological findings (Table 1). Table 1: Risk factors for a central nervous system cause in emergency department patients with dizziness. Risk factor Cheung et al. [1] Navi et al. [15] Chase et al. [16] Kerber et al. [19] Age in years 6.15 for age > 65 5.7 for age > 60 Symptom of imbalance or ataxia 11.39 for “ataxia” 5.9 for “imbalance” 9.3 for “gait instability” Focal neurological symptoms 11.78 5.9 History of previous stroke 3.89 Vascular risk factors 3.57 for diabetes 0.48 (CI crossed 1) ABCD2 score 1.74 (scored as a continuous variable) HINTS testing 2.82 Other neurological deficits 8.7 for “subtle” neurological finding 2.54 Not every study reported on every variable; blank cells were not reported in that study. Numbers are odds ratios (when reported) HINTS head impulse, nystagmus, test of skew; CI confidence intervals 2  |  Issue-1 MEDICAL EXCELLENCE