VBI and the “5 Ds”: Dim, Dopey, Dumb, Dumber and Dumbest

This essay is by Jim Meadows, BScPT, MCPA, FCAMPT. It is the first in a series on clinical assessment of vertebrobasilar insufficiency.

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This is the first in a series of essays on VBI that outline a logical and scientifically based system of clinical assessment.

I am more and more frequently hearing about the 5 Ds as the diagnostic criteria for vertebral basilar ischemia in both Canada and the USA and I am more and more frustrated and annoyed at the dumbing down of what is an extremely important and complex clinical diagnosis. I don’t know if the instructors who are teaching this think that the students are too stupid to understand this topic or if they are too lazy to teach it properly or if they really believe that it is useful. But in all cases they really should stop teaching it if this is the best that they can do. The subject needs to be given a whole lot more respect than something cute but generally wrong. The following is a discussion based on the best scientific evidence of what is known of the signs and symptoms of VBI and why the 5 Ds do not in any important way reflect this science.

First it is worth noting that there is a difference in presentation between traumatic VBI and degenerative VBI, but I will keep this discussion to traumatic VBI as this is always the context in which the 5 Ds arises. Let’s first look at the 5 Ds — or at least the six or seven Ds that different students give me.

What Are the 5 Ds?

They are:

• Dizziness
• Diplopia
• Dysphagia
• Dysarthria
• Dysphasia
• Drop attacks

Actually the full spectrum of Ds that could be symptoms of VBI includes:

• Dysmetria
• Dysphonia
• Dysequilibrium
• Dysgeusia

So above there are 11 Ds — all of which may be due to VBI — and there seems to be no reason to select the seven above and exclude the four below. It’s not a matter of sensitivity and specificity; it’s just the cute idea of collecting everything starting with D, cutting it down to five, and a variable five at that.

But however dumb this idea might be, it becomes downright dangerous when the number of other symptoms and signs are excluded simply because they do not start with D. The most startling omission is headache — probably the second most common symptom of VBI after dizziness (Husni et al., JAMA, 1966). Traumatic VBI without headache is very unlikely. Other symptoms that may be caused by VBI — some of which are as common as the 5 Ds (excluding dizziness) — include:

• Hemilateral or partial facial paresthesia
• Hemilateral body paresthesia
• Perioral paresthesia
• Visual scintillations
• Blurred vision (which may or may not be diplopia)
• Photophobia
• Intermittent ptosis (Horner’s syndrome or less commonly CN 3 paresis)
• Tinnitus
• Hypoacusia
• Vomiting and nausea (may be described as dizziness)
• Phonophobia

Lateral Medullary Syndrome: The Most Common VBI Presentation

If we look at the most common syndrome of lateral medullary syndrome, we can compare it with the 5 Ds:

Symptom	Frequency
Vertigo/dizziness	91%
Gait ataxia	88%
Nausea/vomiting	73%
Horner’s sign	73%
Dysphagia	61%
Hoarseness (dysphonia)	55%
Facial sensory changes	85%
Hemibody sensory changes	94%

Source: Kim JS et al. Spectrum of Lateral Medullary Syndrome. Stroke. 1994;25:1405–1410.

If nausea and vomiting are considered as Type 2 dizziness when described by the patient, this brings dizziness up to near 100% sensitivity. The study did not include headache. It should be remembered that this study was on patients who had had a VB stroke — average age 59, trauma not listed as a risk factor — so it likely reflects non-traumatic stroke. Our clinical findings in transient cases may not exactly mirror the study, but at least this frequency rate is based on evidence, not on the cuteness of the 5 Ds.

Evidence From Traumatic VBI Studies

For traumatic VBI, here are the results of two relevant studies.

“The mean age was 48. Possible precipitating factors were identified in 14 patients (53%). Sporting activity and chiropractic manipulations were the most common (15% and 11% respectively). Headache and/or neck pain was the prominent feature in 88% of patients and was a warning sign in 53%, preceding onset of stroke by up to 14 days. The most common clinical features included vertigo (57%), unilateral facial paresthesia (46%), cerebellar signs (33%), lateral medullary signs (26%) and visual field defects (15%).”

Vertebral artery dissection: warning symptoms, clinical features and prognosis in 26 patients. Can J Neurol Sci. 2000;27(4):292–6.

From Medscape on traumatic VBI:

“The typical presentation of vertebral artery dissection (VAD) is a young person with severe occipital headache and posterior nuchal pain following a recent, relatively minor, head or neck injury. The trauma is generally from a trivial mechanism but is associated with some degree of cervical distortion. Focal neurologic signs attributable to ischemia of the brainstem or cerebellum ultimately develop in 85% of patients; however, a latent period as long as 3 days between the onset of pain and the development of CNS sequelae is not uncommon.”

Medscape — Vertebral Artery Dissection

The common symptoms of VAD include:

• Ipsilateral facial dysesthesia (pain and numbness) — most common symptom
• Dysarthria or hoarseness (CN IX and X)
• Contralateral loss of pain and temperature sensation in trunk and limbs
• Ipsilateral loss of taste (nucleus and tractus solitarius)
• Hiccups
• Vertigo
• Nausea and vomiting
• Diplopia or oscillopsia
• Dysphagia (CN IX and X)
• Disequilibrium
• Unilateral hearing loss

Why the 5 Ds Should Be Retired

The telling paragraph for this discussion is:

“Many patients present only at the onset of neurologic symptoms.”

This makes only dizziness the useful symptom of the 5 Ds if no neurological symptoms are present — and given the transient nature of VBI as we encounter it, this is likely what will present to us.

So if the originators of the 5 Ds were aiming for a protocol similar to the Canadian C-spine Rules or the Ottawa Rules for ankle fracture, they did not go about it in the right way. Those rules are all about sensitivity — erring on the safe side and ordering imaging even when the likelihood of pathology is low. We don’t have that here. Apart from dizziness, the majority of the Ds will not be present either because they are not part of lateral medullary syndrome or because the patient is not yet experiencing them. For sensitivity purposes, dizziness alone would serve excellently — it is just about 100% sensitive for VBI (see Husni and virtually any article on the subject) but has essentially no specificity. So as a protocol for identifying traumatic VBI, the 5 Ds are useless unless you want to refer every neck patient with dizziness — including nausea — to a physician.

As diagnostic criteria for traumatic VBI they fare no better. Leaving aside the fact that many are not part of lateral medullary syndrome and will not present in our patients until a stroke is established, they are too specific and too many are outliers.

Because of these scientific reasons — and because the 5 Ds preclude or at least remove the necessity to respect and learn about the condition — they should be dropped from all curricula and replaced with a knowledge of anatomy, physiology, pathology and the mechanics of blood flow in the system. Together, these will generate a rational subjective and objective examination framework. These topics will be covered in the essays that follow.

“Thus, when VAD is suspected, clinicians should evaluate patients for the presence of a unilateral headache and/or neck pain and vertigo, with or without objective neurologic signs.”

Medscape — Vertebral Artery Dissection

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VBI Series

1. VBI Screening: Why the 5 Ds Fail Physical Therapists (this article)
2. Vertebrobasilar Anatomy and Physiology for Physical Therapists
3. VBI and Dizziness: Clinical Classification for Physical Therapists