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

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 5Ds as the diagnostic criteria for vertebral basilar ischemia in both Canada and the USA and 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 5Ds 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 as I will keep this discussion to traumatic VBI as this is always the context in which the 5Ds arises. Let’s first look at the 5Ds, or at least the six or seven Ds that different students give me.

They are:

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

Actually the full spectrum of Ds that could by symptoms of VBI include:

• Dysmetria
• Dysphonia
• Dysequilibrium
• Dysgeusia

So above there are 11Ds all of which may be due to VBI and there seems to be no reason to select out of the seven above and the four below so it’s not a matter of sensitivity and specificity just the cute idea of collecting everything starting with D and 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 that are excluded because they do not start with D. The most startling omission is that of headache which is probably the second most common symptom of VBI after dizziness (Mechanical Occlusion of the Vertebral ArteryA New Clinical Concept Elias A. Husni, MD; Herbert S. Bell, MD; John Storer, MD JAMA. 1966;196(6):475-478). That traumatic VBI without headache is very unlikely (not true for non-traumatic VBI by the way). Other symptoms that may be caused by VBI some of which are as common as the 5 (or seven or eight) 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

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

• Vertigo/dizziness (91%)
• Gait ataxia (88%)
• Nausea/vomiting (73%)
• Dysphagia (61%)
• Hoarseness (dysphonia (55%)
• Horners sign (73%),
• Facial (85%) and hemibody (94%) sensory changes (including paresthesia)

(Spectrum of Lateral Medullary Syndrome Correlation Between Clinical Findings and Magnetic Resonance Imaging in 33 Subjects Jong S. Kim, MD et al. Stroke: 1994;25:1405-1410)

If nausea and vomiting are considered as type 2 dizziness if so described by the patient, then they are a form of dizziness and this brings dizziness up to near 100% sensitive. The study did not include headache. It should be remembered that this study was on patients who had had a VB stroke and given that the average age was 59 years and trauma was not listed as a risk factor in this group it is reasonable to assume that this was a non-traumatic stroke, in addition given that we deal with transient issues our clinical findings may not exactly mirror the study’s, but at least this frequency rate is based on evidence and not on the cuteness of the 5Ds. It is likely that presence of headache was not mentioned in this study either because it was absent (this being non-traumatic VBI) or it was ignored by the researchers.

For traumatic VBI here are the results of a couple of studies.

Vertebral artery dissection: warning symptoms, clinical features and prognosis in 26 patients. Vertebral artery dissection: warning symptoms, clinical features and prognosis in 26 patients. Can J Neurol Sci.  2000; 27(4):292-6 (ISSN: 0317-1671)

“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%).”

This is from Medscape (http://emedicine.medscape.com/article/761451-clinical) 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. Delays of weeks and years also have been reported. Many patients present only at the onset of neurologic symptoms. 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.

• Ipsilateral facial dysesthesia (pain and numbness)6: Most common symptom
• Dysarthria or hoarseness (cranial nerves [CN] IX and X)
• Contralateral loss of pain and temperature sensation in the trunk and limbs
• Ipsilateral loss of taste (nucleus and tractus solitarius)
• Hiccups
• Vertigo
• Nausea and vomiting
• Diplopia or oscillopsia (image movement experienced with head motion)
• Dysphagia (CN IX and X)
• Disequilibrium
• Unilateral hearing loss

Rarely, patients may manifest the following symptoms of a medial medullary syndrome:

• Contralateral weakness or paralysis (pyramidal tract)
• Contralateral numbness (medial lemniscus)”

The telling paragraph for the current discussion is this:

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

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

So if the originators of the 5Ds were going for a protocol similar to the Canadian Cspine Rules or the Ottawa Rules for an ankle fracture then they did not go about it in the right way. These protocol or rules are all about sensitivity, that is erring on the safe side and getting imaging studies done if one or more of the relevant symptoms are present even though the likelihood is that the studies will turn out to be negative. 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 experiencing. In addition, how common are the symptoms that are excluded because of their alphabetic lack of character. So if they symptoms of the 5Ds are not part of the most common syndrome then they can’t be argued to add to the sensitivity of the protocol but actually subtract from it. For sensitivity purposes dizziness alone would serve excellently as it would appear that it is just about 100% sensitive (see Husni and just about any article on the subject) for VBI but has just about no specificity. So as a protocol for avoiding the problem of treating a patient with traumatic VBI the 5Ds are useless unless you want to send to the physician every neck patient with dizziness including nausea.

So are the 5Ds any good as diagnostic criteria of traumatic VBI. Not really, leaving out the fact that many if not most of them are are not part of lateral medullary syndrome or will not be present in our patients until a stoke is established they are too specific and many of these are outliers (again think in terms of the most common syndrome).

Because of these scientific reasons and because the 5Ds precludes or at least removes the necessity to respect and learn about the condition it should be dropped from all curriculums and replaced with a knowledge of anatomy, physiology, pathology and the mechanics of blood flow in the system that together will generate a rational subjective and objective examination system. These topics will be covered over the next few weeks and will build on the paragraph below (also from Medscape).

“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.”

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