Medical Excellence- Issue 1

Importantly, half of those small strokes were not due to small vessel disease, but due to vertebral artery atherosclerosis or dis- section. Therefore, in patients with the AVS, the physical exami- nation is more sensitive than MRI. An Italian ED study (in which the emergency physicians used Frenzel lenses to test for nystagmus) exploited elements of this bedside exam and showed that it decreases both CT use and hospitalization [59]. However, another survey study found that many emergency physicians clearly do not understand or feel confident in HINTS testing and overuse CT [41]. This same study showed that emergency physicians tend to overvalue the dizziness type in making a diagnosis. Although traditional vas- cular risk factors underperform HINTS and neurological exam testing [19, 63], emergency physicians still value them over bedside testing [41]. Triggered Episodic Vestibular Syndrome (t-EVS) Patients with t-EVS have short-lived episodes of dizziness lasting seconds to a few minutes, depending on the underlying etiology. There is an “obligate” trigger, meaning that each time the spe- cific trigger occurs, the dizziness follows. Common triggers are changes in head position or body posture, especially arising from the lying or seated position to standing. Vomiting can occur and may lead patients to overestimate episode duration. Clinicians must distinguish triggers (provoke new symptoms not present at baseline) from exacerbating features (worsen preexisting base- line symptoms), since head movement will exacerbate acute vestibular dizziness of any cause. Common etiologies are BPPV and orthostatic hypotension. Dangerous causes include central (neurologic) mimics of BPPV and serious causes of orthostatic hypotension such as internal bleeding or sepsis with relative hypovolemia. Since the symptoms can be triggered, the physi- cian should be able to re-create them at the bedside. Benign paroxysmal positional vertigo, the most common vestibular cause of dizziness with a lifetime prevalence of 2.4% and increasing incidence with age [68], results frommobile crys- talline debris in one or more semicircular canals (“canaliths”). Classical symptoms are repetitive brief, triggered episodes of ro- tational vertigo lasting more than a few seconds and less than a minute [69, 70]; non-vertiginous symptoms are frequent [25]. The diagnosis is confirmed by reproducing symptoms using ca- nal-specific positional testing maneuvers (Table 5) [70–72]. Since the offending canal(s) are generally not known in advance, a se- quence of multiple diagnostic maneuvers is typically performed starting with the Dix-Hallpike maneuver because this tests the posterior canal, which is by far the most common involved [60]. A detailed recent review of these exam maneuvers includes in- structive video clips [27]. Despite the fact that BPPV is quite common, a majority of emergency physicians report that they do not use the Dix-Hallpike (diagnostic) or Epley (therapeutic) maneuvers in practice [41]. Once the correct canal is identified by these maneuvers, bedside treatment with canal repositioning maneuvers can follow [70]. Rarely, central paroxysmal positional vertigo (CPPV) mimics BPPV. This is usually caused by posterior fossa lesions including neoplasm, infarction, hemorrhage, and demyelination. Factors that help to distinguish BPPV from CPPV are summa- rized in Table 6 [73]. Orthostatic hypotension affects 16% of adults [74] and ac- counts for 24% of acute syncopal presentations [75]. Classical symptoms are brief presyncope on arising, but vertigo is common [24]. Orthostatic hypotension is a sustained decline in blood pressure of at least 20 mmHg systolic or 10 mmHg dias- tolic within 3 min of standing [76]. Recent work suggests optimal Table 5: Positional nystagmus findings in triggered, episodic vestibular syndrome (t-EVS). Positional tests in t-EVS BPPV (posterior canal) BPPV (horizontal canal) Central Dix-Hallpike test (diagnostic test) Upbeat-torsional a 5–30 s No spontaneous reversal None b Variable direction (downbeat or horizontal; almost never upbeat) Variable duration (often >90 s) No spontaneous reversal Supine roll test (diagnostic test) None b Pure horizontal c 30–90 s Spontaneous reversal typical Variable direction (downbeat or horizontal; almost never upbeat) Variable duration (often >90 s) No spontaneous reversal BPPV benign paroxysmal positional vertigo a The nystagmus of posterior canal BPPV will have a prominent torsional component, and the 12 o’clock pole of the eye will beat toward the down-facing (tested) ear. Although the nystagmus will reverse on arising from the Dix-Hallpike position, there will be no spontaneous reversal b Although the Dix-Hallpike test is fairly specific to posterior canal BPPV and the supine roll test to horizontal canal BPPV, the maneuvers may sometimes stimulate the other canal. If so, the nystagmus direction will depend on the affected canal, not on the type of maneuver eliciting the nystagmus. The nystagmus may be considerably weaker and less evident than when using the“correct”maneuver c The nystagmus of horizontal canal BPPV may beat toward the down-facing ear or away from it. The nystagmus will often crescendo and then slow down and reverse spontaneously even without moving the head. When the opposite side is tested, the nystagmus will usually beat in the opposite direction (e.g., if right-beating initially with the right ear down and then left-beating initially with the left ear down) Issue-1  |  9 MEDICAL EXCELLENCE