Episode 45: NYGH EM Update Conference 2014


This past May in Toronto, the largest and, in my opinion, best Canadian EM conference, North York General Hospital’s Emergency Medicine Update Conference, attracted ‘Captain Cortex’ himself, Stuart Swadron, a Toronto native to talk about his approach to vertigo, which highlights how not to miss a posterior circulation stroke. For the  seventh year running the EMU conference was proud to have one of the worlds most well known EM educators, Amal Mattu who presented the most important Cardiology Literature from the past year. This podcast includes edited versions of their talks with commentary and summaries.

Blogpost & Summary Prepared by Dr. Keerat Grewal, June 2014

Chapter 1 – Dr. Stuart Swadron – An Approach to Vertigo

From North York General’s Emergency Medicine Update Conference, May 2014

An Approach to Vertigo

VIDEO LINK for HINTS exam: http://emcrit.org/misc/posterior-stroke-video/

Go here to see a video Scott Weingart explaining how to use an iphone to help interpret the Head Impulse Test for your HINTS exam.

Paucis Verbis: Acute vestibular syndrome and HINTS exam.  Academic Life in Emergency Medicine

An excellent review of the HINTS exam by Andrew Petrosoniak on Boring EM

GET STUART SWADRON’S BEST CASE EVER

Update 2015: Should HINTS be used on all patients with vertigo in the ED? Check out this critical appraisal of the HINTS exam on SOCMOB.

Chapter 2 – Dr. Amal Mattu – Cardiology Literature

From North York General’s Emergency Medicine Update Conference, May 2014

Cardiology Literature

Dr. Amal Mattu’s screencast on Sgarbossa Criteria at Emergency ECG Video of the Week: Episode 114

GET AMAL MATTU’S BEST CASE EVER

Summary of Full Episode

lbbb-algorithm

Fig 1: LBBB Algorithm (Cai et al., 2013) (4)

ST-S-ratio-Sgarbosa

Fig 2: ST/S Ratio (Cai et al., 2014) (4)

Quote of the Month

“Everything should be made as simple as possible, but not simpler” – Albert Einstein

Now Test Your Knowledge

Question 1: What is the sensitivity and specificity of the Dix-Hallpike Maneuver for BPPV?

Answer: The accuracy of the Dix-Hallpicke maneuver for BPPV may differ between specialty and nonspecialty clinicians, but a sensitivity of 82% and specificity of 71% for the Dix-Hallpike maneuvers in BPPV has been reported for specialty clinicians, and in the primary care setting, a positive predictive value for a positive Dix-Hallpike test of 83% and a negative predictive value of 52% has been reported. So, a negative Dix-Hallpike maneuver does not necessarily rule out a diagnosis of BPPV, but it can be helpful as one important data point in deciding whether or not a patient has BPPV or a posterior circulation stroke causing their vertigo.

Question 2: What should we look for on head CT when we are evaluating a patient with acute Vertigo?

Answer: Besides the usual signs of stroke on CT which are difficult to visualize early in the course of illness and difficult to visualize in the cerebellum and brain stem, look for obliteration or near obliteration of the 4th ventricle indicating cerebellar edema and impending herniation.

Question 3: How does the HINTS exam compare to diffuse weighted MRI for diagnosing acute posterior circulation stroke?

Answer:  The HINTS exam has a better accuracy than MRI for diagnosing acute posterior circulation stroke.  The presence of any one of the three dangerous signs of the HINTS exam had a sensitivity of 100%  and a specificity of 96% for stroke (negative likelihood ratio 0.00, 95% CI 0.00–0.12)

Question 4: What are the new Sgarbossa criteria for diagnosing acute MI in the setting of LBBB?

Answer: Excessive discordance (ST/S ratio < -0.25). The Modified Sgarbossa Criteria which includes this 3rd criteria of more than 25% of the R or S wave discordant deviation is more sensitive than the original Sgarbossa Criteria for predicting AMI in the presence of LBBB, but don’t forget that this needs an external validation study before we can begin to apply it. If you have ST deviation in a discordant direction that is more than 25% the size of the q wave or the s wave in a patient who presents with symptoms consistent with an MI in a LBBB, then consider activating your cath lab or giving lytics.

ST-S-ratio-Sgarbosa

Question 5: What is the new ECG definition of ST-elevation for STEMI?

Answer:

STEMI is defined by STE > 1 mm in at least two contiguous leads, with the exception of leads V2-V3

§ _STEMI is defined by STE > 2 mm in leads V2-V3 in men > 40 years of age

§ _STEMI is defined by STE > 2.5mm in leads V2-V3 in men < 40 years of age § _STEMI is defined by STE > 1.5 mm in leads V2-V3 in women

Question 6 : Why should we repeat ECGs in patients suspected of ACS/MI in the ED?

Answer:

• 11% of patients diagnosed with STEMI had an initial non-diagnostic ECG

• 72% of these patients had a diagnostic (STEMI) ECG within 90 minutes

The shape of the ST segment may change (eg straighten) BEFORE the ST segment elevates in STEMI, so the ST elevation may not be apparent immediately, and only show up on subsequent serial ECGs.

Dr. Helman, Dr. Mattu and Dr. Swadron have no conflicts of interest to declare.

KEY REFERENCES

1. Clinical practice guideline: Benign paroxysmal positional vertigo. Bhattacharyya, n et al. Otolaryngology-Head and Neck Surgery 2008; 139: 47-81. Abstract

2. Does my dizzy patient have a stroke? A systematic review of bedside diagnosis in acute vestibular syndrome. Tarnutzer, MD et al. CMAJ 2011; 183(9):571-592. Free Full Text

3. HINTS to diagnose stroke in the Acute Vestibular Syndrome: Three-step beside oculomotor examination more sensitive than early MRI diffusion-weighted imaging. Kattah, JC et al. Stroke 2009; 40: 3504-3510. Free Full Text

4. The left bundle-branch block puzzle in the 2013 ST-elevation myocardial infarction guideline: From falsely declaring emergency to denying reperfusion in a high risk population. Are the Sgarbossa Criteria ready for prime Time? Cai Q et al. American Heart Journal 2013; 166(3): 409-413. Free Full Text

5. 2013 ACCF/AHA Guideline for the management of ST-elevation myocardial infarction. O’Gara PT et al. Journal of the American College of Cardiology 2013; 61(4): 78-140. Free Full Text

6. Diagnostic time course, treatment, and in-hospital outcomes for patients with ST-segment elevation myocardial infarction presenting with nondiagnostic initial electrocardiogram. Riley RF et al. American Heart Journal 2013; 165(1): 50-56. Free Full Text

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About the Author:

Dr. Anton Helman is an Emergency Physician at North York General in Toronto. He is an Assistant Professor at the University of Toronto, Division of Emergency Medicine, the Education Innovation Lead at the Schwartz-Reisman Emergency Medicine Instititute and is on the advisory board of The Teaching Institute. He is the founder and host of Emergency Medicine Cases.

2 Comments

  1. Elisha Targonsky June 10, 2014 at 5:27 pm - Reply

    Really great episode with two fantastic talks. I enjoyed hearing Stuart Swadron’s simplified approach to vertigo. One thing I wanted to point out, which may have been lost in the podcast (non-visual and edited) format, is that the HINTS battery of tests really must be applied to a specific patient population and only that population. The Acute Vestibular Syndrome is distinct from other vertigo, as described by Dr Newman-Toker in his CMAJ article in 2011:
    “When dizziness de velops acutely, is accompanied by nausea or vomiting, unsteady gait, nystagmus and intolerance to head motion, and persists for a day or more, the clinical condition is known as acute vestibular syndrome.”

    Thus the vertigo really must be persistent for several hours (and according to the above definition, > 24hr). Don’t apply HINTS to your brief vertiginous patients. Otherwise the tests don’t perform as they should, and for example, the ER doc may be over-calling the stroke due to the normal head thrust.

    Great episode as usual.

    • Anton Helman June 10, 2014 at 5:35 pm - Reply

      Thanks Elisha for clarifying. BPPV is still the most common cause of vertigo that we see in the ED, and the HINTS exam does NOT apply to BPPV. It is specifically to help differentiate acute vestibular syndrome (which presents with constant vertigo for hours-days) vs stroke. If only the Dix-hallpike was as specific for BPPV as the HINTS is for stroke!

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