Ischemic syndromes causing dizziness and vertigo

Abstract

Dizziness/vertigo and imbalance are the most common symptoms of vertebrobasilar ischemia. Even though dizziness/vertigo usually accompanies other neurologic symptoms and signs in cerebrovascular disorders, a diagnosis of isolated vascular vertigo is increasing markedly by virtue of recent developments in clinical neurotology and neuroimaging. It is important to differentiate isolated vertigo of a vascular cause from more benign disorders involving the inner ear, since therapeutic strategies and prognosis differ between these two conditions. Over the last decade, we have achieved a marked development in the understanding and diagnosis of vascular dizziness/vertigo. Introduction of diffusion-weighted magnetic resonance imaging (MRI) has greatly enhanced detection of infarctions in patients with vascular dizziness/vertigo, especially in the posterior-circulation territories. However, well-organized bedside neurotologic evaluation is even more sensitive than MRI in detecting acute infarction as a cause of spontaneous prolonged vertigo. Furthermore, detailed evaluation of strategic infarctions has elucidated the function of various vestibular structures of the brainstem and cerebellum. In contrast, diagnosis of isolated labyrinthine infarction still remains a challenge. This diagnostic difficulty also applies to isolated transient dizziness/vertigo of vascular origin. Regarding the common nonlacunar mechanisms in the acute vestibular syndrome from small infarctions, individual strategies may be indicated to prevent recurrences of stroke in patients with vascular vertigo.

Introduction

Dizziness/vertigo and imbalance are the most common symptoms of vertebrobasilar ischemia, that comprises about 20% of all ischemic strokes (Savitz and Caplan, 2005, Paul et al., 2013). Recent prospective studies using a large database reported dizziness as a presenting symptom in 47–75% of patients with posterior-circulation stroke (Akhtar et al., 2009, Searls et al., 2012). Even though dizziness/vertigo is usually accompanied by other neurologic symptoms and signs in cerebrovascular disorders, the diagnosis of isolated vascular vertigo is increasing markedly by virtue of recent developments in clinical neurotology and neuroimaging (Kim et al., 2015). It is important to differentiate isolated vertigo of a vascular cause from more benign disorders involving the inner ear, since therapeutic strategies and prognosis differ between these two conditions. Misdiagnosis of an acute stroke may result in significant morbidity and mortality, while overdiagnosis of vascular vertigo would lead to unnecessary costly work-ups and medication (Choi et al., 2013b).

Over the last decade, our anatomic and pathophysiologic understanding of vascular dizziness/vertigo has markedly expanded (Baloh et al., 2012). Introduction of diffusion-weighted magnetic resonance imaging (MRI) has greatly enhanced the detection of infarctions in patients with vascular dizziness/vertigo, especially due to impaired posterior circulation (Lee et al., 2006). However, well-organized bedside neurotologic evaluation is even more sensitive than MRI, including diffusion-weighted imaging, in detecting acute infarction as a cause of spontaneous vertigo lasting more than 24 hours, especially during the first 48 hours (Kattah et al., 2009, Newman-Toker et al., 2013a, Saber Tehrani et al., 2014). Furthermore, detailed evaluation of patients with strategic infarctions restricted to specific anatomic sites has enabled us to better understand the function of vestibular structures and define various ischemic vestibular syndromes in humans (Kim et al., 2015).

However, diagnosis of isolated labyrinthine infarction remains a challenge, since no confirmatory tool other than a postmortem study is currently available (Kim et al., 1999). We still lack the technology to image infarctions restricted to the labyrinth. A similar diagnostic difficulty applies to isolated transient dizziness/vertigo of vascular origin, which is a common variant of vertebrobasilar ischemia (Grad and Baloh, 1989, Hoshino et al., 2013, Paul et al., 2013). Furthermore, the current diagnostic criteria of transient ischemic attacks do not readily include dizziness/vertigo as a focal symptom (Furie et al., 2011). Since nonlacunar mechanisms are more common (47%) than previously thought in the acute vestibular syndrome (AVS) from small infarctions, customized therapies may be indicated to prevent recurrences of stroke in patients with vascular vertigo (Jackson and Sudlow, 2005, Saber Tehrani et al., 2014).