EXAM STUDY TIPS – DIZZINESS
Dizziness can be an overwhelming and broad topic to study for, let alone in clinical practice – where do you even begin?
Just like all major problems, you need to have a well-organized approach to dizziness to take a good history or answer exam questions. Dizziness can be caused by a problem with
the wiring (nerves, such as vestibular neuritis)
the processor (stroke, MS, tumour, migraine)
the balance sensors (BPPV, shingles in the otic system – Ramsay Hunt Syndrome which you should suspect if you see VZV vesicles in the ear)
the pipes (CVA, vasculitis),
what’s in the pipes (clot, dissection, prescription drug, or an over the counter drug or supplement or toxin)
…or what’s not in the pipes but should be (hemoglobin, oxygen, or volume due to bleeding or shock – so make sure you quickly think of and rule out the 5 kinds of shock for an unstable patient)
PEARLS FOR PRACTICE - DIZZINESS
By now you should also be able to differentiate presyncope from vertigo, and if it’s vertigo, a central vs. a peripheral cause of vertigo.* The HINTS exam (Head impulse test + nystagmus + test of skew) can be key and in fact was found to be better than MRI at ruling out a stroke in patients with acute vestibular syndrome – more on this below.
Alarm features are also important to know and should be reviewed before the exam. These are crucial distinctions that are usually easily distinguished with a good history, and can completely change your line of management and differential diagnosis. Vertigo is particularly suspicious for something serious (think bleed or stroke) if they have these alarm features:
Multiple prodromal episodes (these could be TIAs)
Can’t walk (vertigo with associated new gait instability is high risk for central but can happen with vestibular neuritis)
A sketchy history (risk factors for vasculopathy etc.)
Head impulse test normal if the patient has acute vestibular syndrome (95% specific for stroke, with a + LR of 18.39! This “virtually confirms a stroke”**)
Associated neck pain or headache
Associated other neurologic findings
Absence of tinnitus or hearing loss (tinnitus & hearing loss suggest a peripheral cause)
I have had a patient present with very vague symptoms which ended up being vertigo, but when I asked a few more questions he revealed he had neck pain that he didn’t initially mention and that he awoke with the symptoms (which can be equivalent to sudden onset). Because of these alarm features, and even more so due to his sudden inability to walk properly, I sent him to the ED where he was found to have suffered a vertebral artery dissection.
Knowing the alarm features can be a huge help on your exam, and more importantly, in practice.
Some useful resources referenced above:
* If you need to brush up, UpToDate has an outstanding table on acute vertigo that you can review or even pull up when you’re with a patient (subscription required). A useful tip- if you use UpToDate make sure you renew your discounted resident rate subscription right before you finish residency! As well DynaMed is free through the CMA.
THE HINTS EXAM
** An outstanding review of the evidence on this topic was published in 2011 in CMAJ, entitled “Does my dizzy patient have a stroke?” If you don’t know how to do a HINTS exam – I wasn’t taught this in med school – you can find videos about the head impulse test and test of skew on YouTube. If any one of the 3 portions of the HINTS exam is positive, the sensitivity and specificity for ruling out stroke were found to be 100% and 96% in a 2009 article in the journal Stroke.
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