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Wednesday, November 07, 2007

Current issue of Mayo Clnic Proceedings critical of ED docs handling of vertigo and current diagnostic paradigm

Ever since I heard Dr. Martin Samuel's classic lecture on vertigo, I took his advice and tried to become fairly knowable about vertigo so I could really look forward to seeing my "next dizzy patient".

Part of his approach is incorporation of the widely used classification proposed in 1972 by Drachman and Hart in which four categories are outlined.

non-specific, or lightheadedness ( what Samuels calls "true vertigo")

In the Nov. 2007 issue of the Mayo Clinic Proceedings, several authors are rather critical of the manner in which ED docs approach and manage vertigo patients. (Full text is available after registration on their site).

The editorialist comments that ED doc training seems lacking in neurological matters and in his analysis of a number of missed diagnosis of cerebellar infarction that histories were incomplete, neurological exams were inadequate and there was undue reliance on CT scans. I would like to hear what ED docs think of that ( if any read this).

One article suggested that the emphasize on "quality of symptoms" ( which is basically over emphasizing the above mentioned classification) may lead to missing diagnoses, the most important of which is cerebellar hemorrhage which in some instance is treatable by surgery. So not only are ED docs (just ED docs?) accused of screwing up, the paradigm taught for years and used by many is also under attack by this multi-institutional cadre of authors.

In a rather complicated article based on a survey of 505 ED attendings and residents the authors ( it seeemed to require 12 authors to interprete the results) concluded that "the dominant paradigm...is the quality of symptoms approach ....the standard approach ..suggests a potential link to misdiagnosis".

I think they are saying that over reliance on a simplified approach to vertigo/dizziness may lead to missed diagnosis of brain stem strokes and cerebellar infarcts or hemorrhages. The simplified approach they think is being used involves the following thought chain: vertigo--->vestibular--->otolaryngology type cause. The reasoning I thought was applicable was vertigo--->vestibular or central (brain stem or cerebellar cause.) In other words, one has to differentiate between peripheral and central causes of vertigo.

What always bothered me was "Don't miss cerebellar hemorrhage" and to that end I think the following points are valid and helpful,some of which the Proceeding's authors make.

Vertical nystagmus within a single bout of prolonged vertigo almost always means a central cause.

Head motion or positional trigger of vertigo usually means peripheral BUT cerebellar stroke related vertigo can also be made worse by head movement.

The typical head CT done in ED does not rule out a cerebellar hemorrhage and MR may be needed.

If the patient is so vertiginous or disqulibrated ( probably not really a word) that he cannot walk you had better really worry about a cerebellar stroke.

Absence of headache does not exclude a cerebellar hemorrhage.

You really need to do a history and a neurological exam. Brain stem strokes almost always have other neurological findings-diplopia,cranial nerve palsies ,dysarthria, etc-but midline cerebellar disease may only have vertigo, nausea and inability to walk so intense is the disequilibrium.So absence of cerebellar signs-upper extremity- dysmetria,past-pointing etc-does not exclude a cerebellar stroke.

I blogged about cerebellar hemorrhage before here.

In that posting I referenced an article written by an ED physician who missed a cerebellar hemorrhage and with more than a little courage discussed in detail how it happened.

The Proceeding authors' thesis is, in part, that more emphasis should be place on the timing or duration of the symptom(s) and on the triggers. Perhaps so but whether or not their survey indicates a major and widespread defect in diagnostic reasoning is unclear. David Drachman in a 2000 Annals of Internal Medicine editorial said that the physician needs to evaluate vision,vestibular function,motor function and search specifically for certain conditions. In other words, evaluate the patient,try and make sense of clinical findings and search particularly for potentially serious and treatable conditions. Rigid adherence to his categories was never intended.

Drachman's decades old outline is just that, an outline, a reasonable broad category checklist to consider in the evaluation of the dizzy patient not a rigid algorithm that would use a patient's description of symptoms as a mechanism for premature closure.

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