Lecture Notes
This is the second part of a two part series on dizziness. Part one can be found at http://www.blog.numose.com/emed-cc/dizziness
When approaching an undifferentiated patient, it is important to create a differential of critical or can’t miss conditions off of the chief complaint. The critical differential guides what questions to ask in your HPI, what physical exam findings to focus on, what labs/imaging to order in your workup, and skeletonizes the medical decision-making portion of your note. This organized approach is especially helpful initially when there is diagnostic uncertainty or when patients present with vague or multiple complaints.
In the undifferentiated patient it is often easier to figure out what is NOT going on, than it is to figure out the final diagnosis. Think of it as trying to solve a case with limited clues or leads, it is hard initially but once you obtain more data you begin to get a better idea of what is going on. Sometimes the uncertainty can be paralyzing and you will not know where to start your workup. This is why we advocate focusing on the acute chief complaint and using that to build a critical differential of diseases you can’t miss (patients with multiple chief complaints may have many chronic complaints and only one acute complaint that caused them to come to the ER).
Once you have initiated the workup, you then methodically rule out life-threatening conditions using an evidence-based approach. After you have convinced yourself that you have ruled out a life-threatening process, you can focus on building a differential of common diseases from the chief complaint, focusing now on what most likely is going on.
Doctors don’t get to use the words dizziness or lightheaded as they do not convey any medical information. If someone presents with the chief complaint of dizziness you must determine if they mean:
- Syncope/Presyncope
- Vertigo/disequilibrium
The initial part of your encounter should focus on helping the patient define what they by dizziness or lightheaded. Ask them to describe what they feel without using the words dizzy or lightheaded. If they cannot describe it to you in an open-ended manner, then provide them with multiple choice options.
Patients usually present in the following 3 scenarios:
- Clear-cut symptoms of syncope/presyncope.
- Clear-cut symptoms of vertigo/dysequilibrium.
- A mixture of both syncope and vertigo.
- If your patient reports both, try to determine if what they feel is more likely syncope or more likely vertigo.
- For these patients you may have to workup both entities simultaneously, but early on you should develop a feel for which one of the two is more likely.
Vertigo/Disequilibrium
Vertigo is much more than the room spinning. The true definition of vertigo is an abnormal sensation of movement. Have you ever gone skiing/snowboarding only to come home and feel like you are still on the mountain when you are trying to go to sleep. You are experiencing vertigo. Patients that report the sensation that they are on a boat, or on a rollercoaster are experiencing vertigo.
If your patient reports mostly or only vertigo/disequilibrium then your job is to determine if this is more of a vestibular (peripheral) or neurologic (central) issue. The sensation of vertigo results from a mismatch between any combination of our visual, vestibular, and proprioceptive systems. Our brain gets confused when the signals we receive from these systems are not congruent and it interprets that issue as vertigo/disequilibrium. The encounter for patients with vertigo centers around convincing yourself that your patient has clear-cut peripheral vertigo signs and symptoms. You should memorize the following characteristics of peripheral vertigo (reassuring findings):
- The symptoms are sudden in onset
- The symptoms are intense (patient will look very sick)
- The symptoms are paroxysmal or intermittent
- The symptoms are extinguisable
- The symptoms positional
- The patient may be very nauseous or diaphoretic
- The patient may exhibit unidirectional horizontal nystagmus
- The neurologic examination should be normal and have good truncal tone
It can be hard to keep track of what symptoms constitute peripheral versus central vertigo, so it is easiest to memorize all of the qualities of one so you do not mix them up. I would suggest you memorize all the characteristics of peripheral vertigo (listed above) since it is more common. This is the one the few places in medicine where the sick looking patient actually has a benign etiology
A High-Stakes Decision
Deciding whether your patient has peripheral or central vertigo is a high-stakes game because the dispositions are so radically different. Patients with peripheral vertigo don’t require much in the form of a workup and management centers around symptomatic treatment with antihistamines/anticholinergics or benzodiazepines. Patients with peripheral vertigo very rarely require admission. Whereas patients with central vertigo require emergent imaging to rule out a cerebellar or posterior circulation stroke AND require an extensive workup with admission to the hospital. Missing peripheral vertigo is not the end of the world, but discharging a patient with central vertigo could be catastrophic. If you miss an acute stroke in the cerebellum or posterior circulation the patient is a risk for uncal herniation from the subsequent brain edema. You do not want to discharge patients with central vertigo. This is why it is important to confirm that your patient has an airtight story for peripheral vertigo and convince yourself that a central process is not occurring. If you cannot confidently convince yourself that your patient has peripheral vertigo because the patient is a poor historian, difficult to examine or has a mixed picture presentation with qualities of BOTH central and peripheral vertigo then you must err on the side of caution and default to ruling out central vertigo with an MRI of the brain (or CT head with neurology consult if MRI is unavailable). I do not mean to scare you into obtaining a million dollar workup on every patient with vertigo, I simply want to emphasize the importance of your decision making so that you take it seriously.
Yes, History & Exam Really Matter
A thoughtful provider will spend a bulk of his/her time asking the questions on the list above and performing a thorough HEENT and neurologic examination. We utilize the HINTS (Head impulse, Nystagmus, Test of Skew) exam to help us differentiate peripheral from central vertigo in patients who are actively symptomatic. The HINTS exam is not helpful and should not be performed in patients that are asymptomatic at the time (will explain why in a little bit).
The HINTS Exam
Just as before it is important to remember what findings are reassuring in a patient and are suggestive of a peripheral cause of vertigo. The 3 components of the HINTS exam and their reassuring findings include:
- Head Impulse Test: an abnormal exam (presence of a corrective saccade) is reassuring
- Nystagmus: Absence of nystagmus or presence of unidirectional horizontal nystagmus is reassuring
- Test of Skew: a normal exam is reassuring
It is probably easiest if you search for videos to illustrate each of these examinations so that you can familiarize yourself with normal and abnormal findings. Please only perform this test on an actively symptomatic patient. If your patient is not actively symptomatic then it is more likely you are dealing with peripheral vertigo because by definition the symptoms are intermittent and extinguishable. Vertigo from a stroke is unlikely to resolve spontaneously (it is not like the stroke just magically fixes itself in the acute phase).
The Head Impulse Test determines the function of the vestibulo-ocular reflex. You have the patient keep their eyes on your nose while you move their head in the horizontal plane to the left and right in an unpredictable manner. You are looking to see if the patient has a corrective saccade (where the patient has to re-fixate on your nose after movement of their head along the horiztonal plane). The corrective saccade is an abnormal finding. A normally functioning vestibulo-ocular reflex will allow the patient’s eyes to remain on target because the vestibular system will identify any head movement and rapidly send the appropriate corrective movement to the eyes in a way that is seamless (no corrective saccade needed). Remember we are testing a reflex. A reflex is an action that is performed as a response to a stimulus without conscious thought (aka your brain is not involved in the process). The reflex is managed via the peripheral vestibulocochlear nerve. When the vestibular system is not working, as is the case in peripheral vertigo, the subconscious reflex loop is interrupted and no longer works. When the reflex loop is broken the brain acts as a backup system getting involved by creating a temporary fix that you see in the form of a corrective saccade. It seems paradoxical to call an abnormal finding on a test reassuring, but that is the case in this test (as it is due to a dysfunction of a PERIPHERAL nerve). In central vertigo the injury occurs at the level of the brain (from a cerebellar or posterior circulation stroke) and does not affect the peripheral vestibulocochlear nerve reflex loop. This results in a normal exam (which is BAD). The reason you only perform a HINTS exam on patients that are actively symptomatic from vertigo is because if I were to test your Head Impulse Test right now you would have a normal exam. Does that mean you have central vertigo and you should get an MRI? NO!
This is precisely why when you report your HINTS exam findings you should state whether the findings are suggestive of central or peripheral vertigo and DO NOT say:
- “The HINTS exam was positive”
- “The HINTS exam was negative”
Remember that words matter and we use them to communicate with other people, if you say the HINTS exam is positive or negative that does not tell me anything.
Nystagmus may be very subtle and it may be helpful to use a specific smartphone application to help you record/slow down the patient in primary, right, and leftward gaze. Only no nystagmus or unidirectional horizontal nystagmus is reassuring. Any other type of nystagmus should scare you.
The Test of Skew examination helps you determine brainstem involvement in patients presenting with vertigo. The presence of skew is highly suggestive of a central lesion. To perform this test you sit in front of your patient and have them look at your nose while you cover one of their eyes. You then rapidly uncover the eye to see if there are any signs of eye realignment on the patient. You perform this test on each eye.
ddxof.com Algorithm for Vertigo:
Full ddxof.com article and algorithm on Dizziness can be found at https://ddxof.com/dizziness-and-vertigo/
For more on Dizziness check out part one of our two part series on Dizziness. Part one can be found at http://www.blog.numose.com/emed-cc/dizziness
If any one of the above tests does not result in a reassuring finding when performed on an actively symptomatic patient you must obtain a full workup.
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