Vertigo: is it caused by peripheral lesions or the brain stem?

A patient is feeling unsteady or dizzy. She has difficulty in describing what she feels exactly: the room feels as if it is spinning or she is spinning while the room stands still. This is obviously illusory. She finds it difficult to maintain her balance as she has difficulty in judging the vertical dimensions of her surroundings or sometimes the horizontal dimensions. She feels unsteady and needs to hold onto a chair or table or feels that her head is spinning or that her eyes will not focus properly. In the subcontinent the word most often used to describe this feeling is “chakar” or sensation of spinning.

What is causing her to have any or all of these symptoms?

The commonest reason for vertigo is related to inflammatory lesions of the middle ear i.e. vestibular neuronitis. The common cold if severe can cause vertigo and the onset of migraine can be a cause. Travel sickness is a common cause and is usually accompanied by nausea and vomiting. Postural stability can be affected in patients with vertigo. The vestibular nuclei send signals to the vestibulospinal tract, which in turn stimulates anti-gravity muscles that maintain posture. When symptoms are less pronounced, particularly when there is pronounced nystagmus out of proportion to the severity of vertigo, think of a brainstem rather than a peripheral lesion.

Some patients may have an illusion that their body is upside down or tilted to one side. This tilt illusion, in which patients feel that they and their environment are tilted with respect to gravity, usually reflects damage to otolithic organs (utricle and saccule) or their central connections. Otolith dysfunction may also cause lateropulsion or the tendency to fall to the side of the lesion. A sudden drop to the ground without warning can occur and is called the drop attack. Drop attacks can be caused by epileptic seizures specially in older patients, or cardiogenic syncope or have a vestibular pathology.

Oscillopsia, a visual illusion of to-and-fro environmental motion and blurred vision whenever the head is in motion, is a manifestation of an impaired vestibuloocular reflex (VOR).

Impaired balance without vertigo — This is a common manifestation of acute simultaneous bilateral vestibular loss such as that occurring with aminoglycoside antibiotic toxicity. Vertigo does not occur because there is no marked vestibular asymmetry. Most patients have oscillopsia during passive head movement, as when walking or riding in a car over rough terrain. Imbalance is most marked in the dark when visual cues to position in space are not available.

How are you going to set about determining why your patient is having problems with their balancing apparatus? Take a detailed history specially of associated symptoms current or in the recent past specially related to ear, nose and throat. Ask about drugs used medicinally and for leisure. Ask about associated conditions such as diabetes, hypertension, epilepsy, past history of stroke or ischemic heart disease. Inquire about aggravating and provoking factors.

Examine the patient for nystagmus, eye movements, balance and gait. Do the DixHallpike and HINT tests, check the cranial nerves, motor and sensory systems, check the hearing clinically.

Keep in mind that vertigo comes and goes and is not a permanent symptom, Association with nystagmus and persistence of vertigo tends to occur in in stroke and brain stem lesions.

Acute onset, sustained vertigo: common diagnoses in this setting include vestibular neuritis, demyelinating disease, and a stroke in the brainstem or cerebellum.

Very brief episodes of isolated vertigo that are precipitated by predictable movements or positions of the head are often caused by benign paroxysmal peripheral vertigo (BPPV).

The Dix-Hallpike maneuver can help confirm this diagnosis. With the patient sitting, the neck is extended and turned to one side. The patient is then placed supine rapidly, so that the head hangs over the edge of the bed. The patient is kept in this position until 30 seconds have passed if no nystagmus occurs. The patient is then returned to upright, observed for another 30 seconds for nystagmus, and the maneuver is repeated with the head turned to the other side. The latency, transience, and fatigability, coupled with the typical mixed upward vertical and torsional direction, are important in diagnosing BPPV due to posterior canalithiasis.
The lack of evidence to support performance of the HINTS exam by EPs does not prove we cannot use it successfully.

Head impulse test — The head impulse test (or head thrust test) is performed by instructing the patient to keep his or her eyes on a distant target while wearing his or her usual prescription eyeglasses. The head is then turned quickly and unpredictably by the examiner, approximately 15°; the starting position should be approximately 10° from straight ahead.

The normal response is that the eyes remain on the target (figure 3). The abnormal response is that the eyes are dragged off of the target by the head turn (in one direction), followed by a saccade back to the target after the head turn; this response indicates a deficient VOR on the side of the head turn, implying a peripheral vestibular lesion (inner ear or vestibular nerve) on that side


The HINTS (Head Impulse, Nystagmus, Test of Skew) exam has been shown to accurately identify central causes of vertigo when performed by neuro-ophthalmologists on patients with acute vestibular syndrome (Stroke 2009; 40:3504). To compare the accuracy of HINTS exams performed by emergency physicians (EPs) and neurologists for identifying central causes of vertigo, researchers performed a systematic review and meta-analysis. Inclusion criteria were adult patients with acute vestibular syndrome (constant vertigo, nystagmus, ataxia) evaluated with a HINTS exam performed by any clinician, with neuroimaging as the gold standard.
In the five studies identified, overall risk of bias was moderate. In most studies, HINTS exams were performed by neurologists or neuro-ophthalmologists, with a sensitivity of 97% and specificity of 95%. Only one study included EPs, and they were fellowship-trained in vascular neurology. That study also included neurologists, and for the EPs and neurologists combined, sensitivity was 83% and specificity was 44%.

COMMENT
The aim of this study was to further confirm high accuracy of the HINTS exam when performed by neurologists and neuro-ophthalmologists. It also highlights that the little available evidence suggests EPs do not perform the exam with the same sensitivity and specificity. Despite the limited evidence, I believe EPs can learn to perform the HINTS exam accurately. The most common mistake I see is performing it on patients who don’t have vestibular syndrome. If the patient doesn’t have constant vertigo with nystagmus, they don’t have vestibular syndrome, and the HINTS exam should not be used.

(April 3, 2020 Accuracy of the HINTS Exam for Vertigo in the Hands of Emergency Physicians. Benton R. Hunter, MD reviewing Ohle R et al. Acad Emerg Med 2020 Mar 13)

MRI of the brain is indicated in selected patients when the history and examination suggest either a central cause of vertigo or a vestibular schwannoma (acoustic neuroma). CT scans are significantly less sensitive for the diagnosis of cerebellar infarction and for pathologies affecting the brainstem or vestibular nerve.

Electronystagmography and video nystagmography — ENG uses electrodes to record eye movements. VNG uses video cameras to record eye movements. These techniques record and quantify both spontaneous and induced nystagmus. Most balance disorder centers and many specialists use ENG or VNG to assess vestibular function and ocular motility.

Vestibular evoked myogenic potentials — VEMPs are a new means of assessing otolith function.

Brainstem auditory evoked potentials — BAEPs have a 90 to 95 percent sensitivity for detecting acoustic neuromas but are not used routinely in the diagnostic workup.

By now you have a fairly accurate idea as to how to work up a case of vertigo. Keep in mind that vestibular neuronitis is the commonest cause but you may pick up a brainstem or cerebellar tumor or infarct in the course of your patient examination. Do not forget demyelinating diseases.

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shaheenmoin

I am a Professor of Medicine and a Nephrologist. Having served in the Army Medical College, Pakistan Army for 27 years I eventually became the Dean and Principal of the Bahria University Medical and Dental College Karachi from where I retired in 2016. My passion is teaching and mentoring young doctors. I am associated with the College of Physicians and Surgeons Pakistan as a Fellow and an examiner. I find that many young doctors make mistakes because they do not understand how they should answer questions; basically they do not understand why a question is being asked. My aim is to help them process the information they acquire as part of their education to answer questions, pass examinations and to best take care of patients without supervision of a consultant. Read my blog, interact and ask questions so that I can help you more.

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