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It wasn't that long ago, that when a patient was referred for vestibular testing, our option was limited to electronystagmography (ENG) or videonystagmography (VNG). Today we have a series of tests available to us including:
The question is, is there an optimal process for deciding which tests to perform, and in what order to make that decision?
We need to have an idea about the patient's most likely preliminary diagnosis, and the best indication of that preliminary diagnosis is based on the patient's history, and the bedside exams. In this presentation, we're going to explore the different options and decide about the best course of action based on some illustrative cases.
One of the main elements of the history taking has always been the reliance on the patient to describe the nature of their symptoms. But this has proven to be quite unreliable because the patients have difficulty in differentiating the type of symptoms that we're looking for.
Regardless, the types of symptoms are divided into several categories according to the classification of vestibular symptoms. This classification was developed and published by the Bárány Society's committees.
Vertigo is the sensation of self-motion, when no actual motion is occurring, or distorted self-motion during actual head or body movements.
Notice that this definition is broader than the traditional spinning sensation and includes the type of symptoms one might expect from otolith lesions and central pathways. These symptoms are often associated with peripheral or central vestibular causes of dizziness.
Syncope is transient loss of consciousness and presyncope is the sensation of impending loss of consciousness without that actually happening. These types of symptoms are often associated with dizziness that originates from vascular causes.
Unsteadiness is lack of postural stability. This category is often related to central causes, but it could be related to loss of bilateral vestibular function.
Another category is the false perception of visual surround. One example of that is oscillopsia. Here, the causes for this category vary quite a bit and it could be central or peripheral.
The final category includes light-headedness, and vague sensation of dizziness or distorted orientation. Again, there are multiple causes, but anxiety, PPPD, and similar diagnoses are a few to consider.
As I mentioned, recent evidence shows that this classification is of limited value, because of overlapping and hard to describe symptoms. And because sometimes we as clinicians, ask leading questions, which contaminate the patient's responses.
A more recent approach is to move away from the description of symptoms and to concentrate on the timing and triggers of the symptoms. This approach has been advocated by David Newman-Toker and his colleagues, and it's abbreviated to TiTrATE, which stands for timing, triggers, and targeted examination.
For example, for the timing, one can have a single event that's intense at the beginning, but begins to decline in intensity over several days or weeks. Another type is episodic, where the symptoms disappear, or at least they are reduced substantially, but they start up again after a period of time. Finally, in chronic cases, the symptoms continue without a significant change in intensity.
As for triggers, there are several possibilities, such as the change in the head or body position, or exposure to head trauma, infections, or certain medications.
When trying to come up with a preliminary diagnosis, consider what associated symptoms are present with the dizziness. For example, when you have auditory or neurological symptoms, they can guide you to the differential diagnosis.
Notice that when we're talking about diagnoses here, we're just trying to decide what's the best functional test to perform, and not necessarily to decide about the medical diagnosis.
This table shows a few examples for different timings and triggers:
|Acute / sudden onset persistent||Vestibular neuritis
|Traumatic labyrinthine concussion|
|Episodic / recurrent||Meniere’s disease
Posterior fossa mass
|Chronic / progressive||Cerebellar degeneration||Uncompensated vestibulopathy|
Some of these examples are serious or emergency cases that should not be missed, and others are less serious and not life threatening. Regardless, even less serious cases are still troubling for the patient and need to be identified.
An example of a non-triggered persistent vertigo is vestibular neuritis. But we need to be aware of the more serious cause, which is the stroke.
A triggered version of the persistent symptom is concussion, which is triggered by head trauma. This is usually serious and sometimes an emergent case.
An example of a non-triggered episodic vertigo is Meniere’s disease. But a more serious cause can be transient ischemic attack.
The triggered version can be BPPV, if that triggers the head or body movement, or more seriously tumors of the central nervous system which can mimic BPPV.
Examples of chronic or progressive cases can be cerebellar degeneration, or uncompensated vestibulopathy, where the patient may have blurry vision during head movements.
When we talk about triggers, such as head movements, we have to differentiate symptoms that are brought on by the trigger, like BPPV, or those that are not brought on but simply exasperated by head movements like different types of vestibulopathies.
At this point, we can narrow the choices for preliminary diagnosis by asking more targeted questions, and by performing specific types of bedside examinations.
First, identify obvious serious and emergency causes based on the associated symptoms, vital signs, mental status, and so on. Most of us do not encounter these cases unless we're working in an urgent care center or the emergency room. Still, we all should be aware of these cases that may have been missed, for whatever reason.
Next, classify the timing of the attacks to acute, episodic or chronic.
Ask about obvious triggers such as:
And so forth.
At that time, again, differentiate between more or less serious causes within a timing trigger category. And then use targeted history, associated symptoms, and bedside tests to narrow your choices.
That final step is beyond the scope of this presentation. At this time, you can decide which vestibular function tests are the most appropriate for this patient. Some of you may also have to decide which specialty you need to refer this patient to. There are approximately 63 disorders give or take a few that have dizziness as their primary symptom.