Dizziness is the third most common major medical symptom reported in general medical clinics1 and accounts for about 3%–5% of visits across care settings.2 In the United States, this translates to 10 million ambulatory visits per year because of dizziness,3 with roughly 25% of these visits to emergency departments.2 Many patients have transient or episodic symptoms that last seconds, minutes or hours, but some have prolonged dizziness that persists continuously for days to weeks.4
In this article, we use the term “dizziness” to encompass vertigo, presyncope, unsteadiness, and other nonspecific forms of dizziness. When dizziness develops acutely, is accompanied by nausea or vomiting, unsteady gait, nystagmus and intolerance to head motion, and persists for a day or more, the clinical condition is known as acute vestibular syndrome.5,6 We define isolated acute vestibular syndrome (with or without hearing loss) as occurring in the absence of focal neurologic signs such as hemiparesis, hemisensory loss or gaze palsy. Transient dizziness has a differential diagnosis distinct from that of acute vestibular syndrome, and the approach to diagnosis should differ accordingly.7 In this review, we focus on acute vestibular syndrome, whether isolated or not.
Most patients with acute vestibular syndrome have an acute, benign, self-limited condition presumed to be viral or postviral. The condition is usually called vestibular neuritis but is sometimes referred to as vestibular neuronitis, labyrinthitis, neurolabyrinthitis or acute peripheral vestibulopathy.5,6 Some authors distinguish between labyrinthitis and vestibular neuritis based on the presence of auditory symptoms at presentation;8 however, this distinction is inconsistently applied, and the terms are often used interchangeably. In this article, we include labyrinthitis and vestibular neuritis together as peripheral causes of acute vestibular syndrome — that is, pathology localized to the inner ear (labyrinth) or eighth cranial (vestibular) nerve — as distinguished from central causes affecting vestibular connections in the central nervous system. Although peripheral causes are more common, dangerous central causes, particularly ischemic stroke in the brainstem or cerebellum, can mimic benign peripheral causes closely.6,9–13
The evidence base for diagnosing the cause of dizziness is limited.14 There is growing evidence that the cause of acute vestibular syndrome is misdiagnosed in many patients15–19 and that frontline physicians are eager for diagnostic guidelines.20,21 Regional variation in diagnostic practice is probably common,3 but little is known about factors influencing diagnostic accuracy (e.g., access to technology, availability of consultants, nature of training, cultural or linguistic differences).
Narrative reviews have highlighted the importance of accurately assessing the risk of dangerous disorders, particularly ischemic stroke in the posterior fossa, and have emphasized the utility of a focused history and physical examination in these patients.5,22–24 However, we are unaware of any systematic reviews, practice parameters or fully validated clinical decision rules applicable to unselected patients with acute, prolonged dizziness that offer evidence-based guidance for the diagnosis and management of acute vestibular syndrome. We therefore performed a systematic review and synthesis of the medical literature, focusing on bedside diagnostic predictors.