Study objective: To determine whether lorazepam is more effective than dimenhydrinate in relieving the symptom of vertigo in the emergency department setting.
Methods: A prospective, randomized, double-blind trial of intravenous lorazepam versus dimenhydrinate therapy was conducted in the ED of a county-owned, university-affiliated hospital. All adult patients who presented between January 24, 1998, and May 23, 1999, with the symptom of vertigo were eligible for inclusion. The intervention was varying the intravenous treatment between lorazepam, 2 mg, and dimenhydrinate, 50 mg. All patients received intravenous infusion of Ringer's lactate solution at a rate of 100 mL/h. Adequacy of randomization to the 2 treatment groups was assessed by comparing the patients' relevant baseline history, physical examination, and symptoms. The predetermined primary outcome measurement was the patient's sensation of "vertigo with ambulation" 1 and 2 hours after treatment. Secondary outcome measurements included vertigo while lying, sitting, and turning the head, ability to ambulate as judged by the enrolling physician, and sensation of nausea and drowsiness 1 and 2 hours after treatment, and whether the patient was "ready to go home" per patient report or physician assessment 2 hours after treatment. All patient symptoms were reported on 10-point scales. Outcome measurements were compared between the 2 treatment groups with a 2-way repeated-measures analysis of variance, Student's t test, Mann-Whitney U, and chi(2) test as appropriate.
Results: Ten patients refused entry into the study, 16 were excluded, and 74 were enrolled, treated, and included in the analysis. One enrolled patient had evidence of vertigo of central origin. The pretreatment values of vertigo with ambulation were strongly correlated with the patient's ability to ambulate (P <.001), suggesting good internal validity. The patients randomly assigned to the lorazepam group were sicker based on their pretreatment symptoms and ability to ambulate, and this may have biased the study results. The patients' symptom of "vertigo with ambulation" decreased 1.5 units more (95% confidence interval [CI] 0 to 3.0) on average on a 10-point scale 2 hours after treatment in the dimenhydrinate group. All other measures of vertigo also decreased more in the dimenhydrinate group, although the differences were not statistically significant. At 2 hours after treatment, the patients' ability to ambulate was better in the dimenhydrinate group (P <.001), and 17% (95% CI -2 to 36) more patients in this group were "ready to go home." Patients in the lorazepam group experienced a 1.8-unit (95% CI 0.2 to 3.4) greater increase in drowsiness 2 hours after treatment.
Conclusion: Our results suggest that dimenhydrinate was more effective in relieving vertigo and less sedating than lorazepam at the intravenous doses administered in this study. Dimenhydrinate appears to be the preferred medicine for patients who present to the ED with vertigo likely to be of peripheral origin.