My TBR Saraf

8/14/2019 My TBR Saraf

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This is the first of a five part series on how to differentiate stroke from inner ear disease in acutevertigo. The main symptoms of cerebellar stroke (CS) are dizziness, nausea, vomiting, gait instability(unsteadiness while walking) , and headaches. This presents some difficulty because thesesymptoms are most often associated with common benign disorders such as migraine or peripheralvestibular (inner ear) disease. Differentiation between these benign disorders and cerebellar stroke(CS) can be aided by quick and simple examination including evaluation of control of eye

movements, presence and pattern of nystagmus ( an involuntary rhythmic eye movement), andexamination of gait and coordination (more on that later).Stroke and TIA (transient ischemic attack) account for approximately 3% of dizziness complaints inthe Emergency Department. Cerebellar strokes (CS) are uncommon and account for only 3% of allstrokes. When the complaint of dizziness is isolated (e.g. no additional neurological complaints)stroke and TIA are responsible for less than 1% of patients with dizziness (Kerber, et al., 2006). Theaverage age of CS patients is 65 years, with two-thirds being male. Risk factors for CS are similar tothose associated with other stroke, and include: hypertension, diabetes, cigarette smoking,hyperlipidemia, atrial fibrillation, and history of stroke or transient ischemic attack (Edlow, Newman -Toker, & Savitz, 2008). Consequences of CS include death and permanent disability (Savitz,Caplan, & Edlow, 2006).

Retrospective studies of misdiagnosis of Cerebellar Stroke (CS) reveal that the most commonmedical errors include failure to perform appropriate screening exams, choosing a diagnosis that

does not explain all the presenting symptoms, failure to consider CS as a differential diagnosis

based on the patients age, and the ordering of the inappropriate neuro-imaging study . When the

risk factors, symptoms and clinical signs suggest the possibility of cerebellar or brainstem infarction,

specific neuro-imaging (CT or MRI scanning) can help verify this suspicion, but are pretty poor at

ruling them out.

Imaging

Patients presenting with dizziness and vertigo are often referred for Computerized Tomographic

(CT) scan of the brain. CT scans are frequently normal in the first few hours following acute

ischemic stroke, therefore, a normal CT scan cannot rule out CS. As many as 50% to 74% of CSpatients may be missed if the diagnosis is dependent on CT scanning (Simmons, Biller, Adams,

Dunn, & Jacoby, 1986; Chalela et al., 2007). CT studies are particularly poor for ruling out

brainstem stroke as that area is often poorly visualized due to surrounding bone structures. The

American College of Radiology recommends MRI of the head without and withcontrast as the

appropriate test for the complaint of vertigo with no hearing loss (ACR, 1996). Although MRI has

significantly higher sensitivity than CT, the examiner must not rely totally on MRI findings to identify

or rule out cerebellar stroke. Twelve percent of CS patients had normal MRI exams on initial

presentation, with abnormal exams a few days later (Kattah et al. 2009). Similarly, Chalela et al.

(2007) report that 17% of patients diagnosed with acute stroke had normal MRI exams on initial

presentation, commenting that there is a higher likelihood of a false-negative MRI exam when the

stroke is located in the brainstem. So the old adage, Lets get an MRI just to be sure, isnt such a

sure bet after all.

Because of the low incidence of dizziness caused by Cerebellar Stroke (CS), as well as theincreased cost and reduced availability of MRI scanners, screening protocols to determine whichpatients require MRI scanning should be developed and followed in both Emergency Departmentsand primary care settings.David Solomon, a noted neurologist at Johns Hopkins University, offers the following suggestions:Note: The items in quotes are from Dr. Solomon, the additional comments are mine (ALD).


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A patient presenting with acute vertigo should be referred for emergent neuro-imaging (MRI) whenaccompanied by:1. Unilateral or asymmetrical hearing loss Unilateral hearing loss may be the result of labyrinthinedisorders such as Menieres disease or labyrinthitis, but may also be the result of vestibularschwannoma or infarction of the anterior inferior cerebellar artery (AICA).2. Brainstem or cerebellar symptoms other than vertigo

3. Stroke risk factors (diabetes, hypertension, history of Myocardial Infarction).4. Acute onset associated with neck pain Neck pain associated with vertigo is considered a signof possible vertebral artery dissection .5. Direction changing spontaneous nystagmus Additionally, nystagmus that are vertical or do notdiminish with visual fixation suggest central involvement.6. New onset severe headache Migraine is known to cause episodic vertigo accompanied byheadache, however, Migraine patients typically have a history of prior headache .7. Inability to stand or walk This is often the most obvious clinical sign differentiating the patientwith acute labyrinthine vertigo from a patient with cerebellar or brainstem stroke. Even the mostseverely vertiginous labyrinthine patient can typically walk a few steps. If the patient cannot stand orwalk unassisted, stroke should be suspected .

This checklist is something I came up with at the suggestion of a local family practice physician thatsaid, Can you give me a checklist of the things I should be looking for, with management

recommendations? A word of caution, this checklist is currently just an idea and has not been

validated in any way.

Since the sensitivity and specificity of categorizing a patient as peripheral versus central is greatly

increased when the screening tests are viewed in combination, it is helpful to use a checklist. As you

view the checklist will note two columns. The column on the left represents findings considered to be

highly specific to peripheral vestibular (labyrinthine) disorders. The column on the right represents

physical signs associated with brain stem or cerebellar dysfunction. As the screening exam is carried

out, the examiner should mark the appropriate box. If the examiner finds that items on the left are

marked, and the right column is unmarked, it is highly likely that the patient suffers from a peripherallabyrinthine disorder. To a large degree, a brain stem or cerebellar pathology has been effectively

ruled out by identifying that the patients complaints are most likely of peripheral labyrinthine origin.

Conversely, if any of the physical signs listed in the right column are noted, brain stem or cerebellar

stoke should be investigated by neuro-imaging or neurologic consultation. Physical findings in the

left column suggest peripheral labyrinthine etiology. Findings in the right column suggest cerebellar

or brain stem etiology. Note: My apologies for the formatting below. The columns should be side by

side., but I am posting this on Memorial Day and decided not to bother the IT folks. You get the

idea. A properly formatted checklist can be found in my new book on page 58.

Initial Examination Checklist for Vertigo

Peripheral versus Central

Name _______________________________________________ Date ___________________

Equivocal

No nystagmus

Peripheral

Central


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Direction Fixed Nystagmus

Nystagmus decrease w/ fixation

Ambulates unassisted

Positive Head Thrust exam

Headshake nystagmus

Transient Positional Nystagmus

(positive Dix-Hallpike)

Direction Changing Nystagmus

No decrease w/ fixation

Ataxiaunable to walk unassisted

Ocular Misalignment

Vertical Skew Deviation

Focal Neurologic Deficit

(hemiplegia, dysarthria, limb ataxia)

New Onset Severe Headache

Refer for vestibular exam

Refer for Neuro-Imaging

Refer for Neurologic Consult

HINTS to diagnosing cerebellar stroke

A simple eye exam more sensitive than MRI? Part V-

Final Installment

Kattah et al. (2009) describe a bedside eye movement exam thought to be very sensitive in

differentiating acute vertigo patients with CS from those with peripheral vestibular disorders. The

brief exam includes a combination of Head Impulse (Head Thrust) testing as described below, a

review of nystagmus pattern , and examination for ocular misalignment (vertical skew deviation)

using the cross cover test. The cross cover test involves having the patient look at an object in the

distance, then alternately covering each eye. If there is a consistent eye movement to regain fixation

on the object, then ocular misalignment is suspected. Some physicians use a Maddox Rodto


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provide a more objective evaluation of ocular misalignment.

This combination of eye exams, described asHINTS (Head Impulse test - NystagmusTest

ofSkew) is reported to be more sensitive than MRI in early identification of CS.

Head Thrust testing is almost always positive in patients with acute vertigo of labyrinthine origin, and

almost always (approximately 90%) negative in patients suffering vertigo related to CS. Direction

changing horizontal nystagmus is sometimes (approximately 20%) present with CS, but nystagmusis almost always direction fixed in acute labyrinthine disorders. Vertical skew deviation (ocular

misalignment) is present in some (25%) of CS patients, but very rare (4%) in labyrinthine patients.

When a patient presents with the combination of: 1. Normal Head Thrust exam, 2. Direction

changing horizontal nystagmus, and 3. Positive Skew Deviation, there is a high probability (100% in

the recent study) of brain or brainstem abnormality. Conversely, when this combination of exams is

considered benign (e.g. positive head thrust, no nystagmus or direction fixed nystagmus, and

negative test for skew deviation) there is a very small chance (4%) of central involvement. This

exam has significantly better sensitivity (100% versus 72%), and comparable specificity (96% versus

100%) when compared to immediate MRI (Kattah et al., 2009). Because this exam can be done in

one or two minutes and requires minimal equipment (infrared video or Frensel glasses), there is

great interest in expanding and independently duplicating these findings. This concludes the five

part series on acute vertigo and stroke. Next week we will take a look at recording techniques for

nystagmus.

References:

Kattah, J., Talkad, A., Wang, D., Hsieh, Y., & Newman-Toker, D. (2009). HINTS to diagnose stroke

in the acute vestibular syndrome: three-step bedside oculomotor examination more sensitive than

early MRI diffusion-weighted imaging. Stroke,3504-3510

v
http://hearinghealthmatters.org/dizzinessdepot/2011/acute-vertigo-could-it-be-a-stroke-part-v/maddox/http://hearinghealthmatters.org/dizzinessdepot/2011/acute-vertigo-could-it-be-a-stroke-part-v/maddox/

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