Acute Vestibular Syndrome: Causes and Differentiation

00:01 In this lecture, we're going to talk about the approach to the acute vestibular syndrome.

00:06 And this is a really important lecture.

00:09 This pathology we see all the time in the emergency department, urgent care, or in other clinics.

00:15 It can be very confusing to the untrained eye.

00:18 But if you know what to look for, for these patients or clinical vignettes, it can be very easy to sort through benign pathology from very severe conditions that must be recognized.

00:29 So what is the acute vestibular syndrome? Well, it's acute, meaning that it starts abruptly in seconds to minutes over the course of a short amount of time.

00:41 It is vestibular, meaning that the description of dizziness is that a vertigo.

00:47 Patients describe rooms spinning or spinning about the room, and it can often be associated with nausea, vomiting, gait instability, nystagmus, and head motion intolerance.

00:59 It is persistent.

01:00 And it often persists for a day or more.

01:03 Once it begins, it continues without episodes, without paroxysms, like other vertiginous, or vestibular disorders.

01:13 And it results from dysfunction of the peripheral vestibular system or the central vestibular system.

01:19 And differentiating between those two things is the critical job of the clinician when evaluating patients or vignettes.

01:29 When we think about the acute vestibular syndrome, there are two organs that are involved that caused this problem.

01:36 One is the peripheral vestibular system and apparatus.

01:40 This is the motion sensor.

01:42 The vestibular apparatus, which senses head movement, the vestibular nerve and vestibular nucleus in the brainstem.

01:50 That's receiving all of the input about head motion.

01:54 The second is the brainstem. And that's the motion analyzer.

01:58 It receives the input from the vestibular apparatus coordinates that with eye movement, with body movement, with arm and leg movement, and with where the head is positioned in space.

02:09 And problems in the central nervous system with that motion analyzer can be big problems that must not go unrecognized.

02:18 So when we think about the acute vestibular syndrome, there are two causes and the clinicians job is to differentiate between a peripheral process and a central process.

02:28 The peripheral acute vestibular syndrome is most commonly caused by vestibular neuritis.

02:34 And that is the prototypical syndrome that I'd like for you to remember when you think about a peripheral cause of the acute vestibular syndrome.

02:42 Vestibular neuritis is a self-limited viral or post-viral syndrome.

02:47 It's known by many names vestibular neuritis, vestibular neuronitis, peripheral vestibulopathy, it is benign, it is self limited, and most patients get better with supportive care.

02:59 We also see the word acute labyrinthitis which is very common and very similar.

03:03 Technically, labyrinthitis is what we would term when there's also superimposed ipsilateral hearing loss.

03:10 In addition to the vertigo, nausea, vomiting, and imbalance.

03:14 Causes of the peripheral acute vestibular syndrome are different than the central syndrome.

03:21 Causes of a central-AVS are brainstem stroke, cerebellar stroke, and other brainstem conditions like multiple sclerosis.

03:28 These are emergencies. A stroke is an emergency, and multiple sclerosis affecting the brainstem can be particularly problematic.

03:36 So they must not go unrecognized.

03:38 And again, the job of the clinician is to differentiate the peripheral from central acute vestibular syndrome.

03:46 So how do we do that? What are the clinical tools that we use to differentiate a central or peripheral cause of the acute vestibular syndrome? Well, physical exam is actually better than imaging.

03:58 And so the assessment starts after a good history to hone in on the problem being vertigo, with several physical exam techniques to differentiate between peripheral and central origin.

04:09 The things we think about: our first, a head impulse test, which we'll talk about what that test is and what the findings are? Then we look for nystagmus.

04:19 Nystagmus can be very difficult, and we'll break it down so that it can be understood.

04:24 And the last will be a test of skew.

04:26 And we'll look for a test of skew.

04:28 And these three exam techniques are actually better than MRI in evaluating patients with the acute vestibular syndrome and differentiating a central or peripheral cause.

04:40 We call these the HINTS of stroke because we're looking to rule out, to rule in stroke and these provide our HINTS.