Medical Excellence- Issue 1

In another study of 1091 dizzy patients in the U.S. EDs, emergency physicians documented some comment about nys- tagmus in 887 (80%) of whom nystagmus was documented to be present in 185 (21%) [26]. No other information beyond the presence or absence was recorded in 26% of the 185 patients, and sufficient information to be diagnostically useful was only recorded in ten patients (5.4%). Of patients given a peripheral vestibular diagnosis, the description of the nystagmus conflicted with that diagnosis. This illustrates a knowledge gap in emer- gency physicians’ understanding of nystagmus: what to look for, how to report it, and, most importantly, how to use the findings to their advantage. Reporting the presence or absence of nystagmus in a dizzy patient is not the key finding. In a patient with an AVS the find- ings of direction-fixed horizontal nystagmus versus direction- fixed vertical nystagmus versus direction-changing nystagmus have different significances (see below). A recent review illus- trates how to use the physical examination in dizzy patients [27]. Multiple studies find that patients with an AVS that superfi- cially appears to be a peripheral process in fact have posterior cir- culation strokes [28–30]. In one, almost 3% of patients referred to the ENT clinic for vertigo had a missed cerebellar stroke [29]. There are two major reasons that showed missed stroke is an important misdiagnosis. The first is that the underlying vascu- lar mechanism goes untreated, leaving the patient vulnerable to another stroke, and the second is that some patients will develop posterior fossa edema that can be fatal [5]. Although lost oppor- tunity for thrombolysis is often suggested as a third negative con- sequence of missing a posterior circulation stroke, many of these patients have minor deficits and are not necessarily thrombolysis candidates. Some have an NIHSS of zero [31]. Younger age and dissection as a cause were found to be risk factors for missed cerebellar stroke [32]. Posterior circulation lo- cation is a risk factor for stroke misdiagnosis in general [33–35]. To put these data into some context, only a very small proportion (0.18–0.63%) of patients who are seen in the ED diagnosed with a Table 2: Shortcomings of the original paper on the “symptom quality” approach. Methodological issues Tautological hypothesis   Their methods placed patients into one of four categories of dizziness by design   Related “appropriate” questions were only asked once the dizziness category was assigned   A diagnosis of a “peripheral vestibular disorder was typically applied to a patient who complained of unmistakable rotational vertigo” Lack of independent verification and blinding   A single individual assigned the final diagnosis; there was no independent verification of the diagnoses   The individual assigning of the diagnoses was not blinded to the data or the categories of symptom quality Small number of subjects with 25% drop-out rate after enrollment   125 total patients were enrolled (but 25.6% were excluded)   12 (16.8%) were excluded due to “inadequate data” obtained   9 (7.2%) were excluded because of “uncertain diagnosis”   2 (1.6$) were excluded because they were “inappropriate referrals” Selection bias   Only 125 patients were enrolled over a 2-year period   They had to be available to return on four different days for testing   They had to be fluent in English Lack of long-term follow-up of patients   There was no long-term follow-up to verify accuracy of diagnosis Unavoidable issues related to era in which study was performed Lack of modern imaging   When the study was done, neither CT nor MRI was available Lack of some diagnoses being established   Vestibular migraine (a common cause of s-EVS) had not yet been described   Posterior circulation TIA presenting as isolated dizziness was not recognized 4  |  Issue-1 MEDICAL EXCELLENCE