EM Reflections – October 2017

Thanks to Dr Joanna Middleton for leading the discussion this month

Edited by Dr David Lewis

Top tips from this month’s rounds:

  1. Imaging reports can underestimate the clinical impact of an incidental finding

  2. Neuro ICU in the Emergency Department?

 


Imaging reports can underestimate the clinical impact of an incidental finding

Not all benign conditions have a benign outcome. A CT report will occasionally underestimate the clinical impact of an incidental finding. Its always worth reviewing the images yourself.

For example – a report might read – “No acute bleed or infarct, incidental finding of frontal bone fibrous dysplasia” –  may sound innocuous and unrelated to the patient’s headache, until you review the scans yourself:

 

Fibrous dysplasia is a benign condition which can present with new craniofacial asymmetry. Whilst the condition itself may be benign, the location and speed of growth can result in symptoms, especially headache and even cranial nerve compression.

Clinical Guidelines for managing craniofacial fibrous dysplasia

 


Neuro ICU in the Emergency Department?

 

Management of Intracranial Hemorrhage in the Emergency Department can be complex. The diagnosis is usually straightforward with CT (providing it has been considered as a possibility – subarachnoid hemorrhage can present with syncope alone) and the broad category of bleed determined by the history, patient age, CT appearance, etc.

ED Management will depend on the category of bleed (Primary ICH, Subdural, Epidural, Traumatic SAH, Spontaneous SAH).

From ALIEM.com, click here for the full article

 

Initial management of intracranial hemorrhage can be simplified / summarized as follows:

Airway – ET Intubation if GCS < 9

Breathing – Ventilate if GCS < 9 (SaO2 >94%, ETCO2 35-45 mmHg)

Circulation

  1. Stop the bleeding
    1. Neurosurgery (see here for indications)
    2. Reverse anticoagulation
    3. ?Tranexamic acid
  2. Maintain an adequate cerebral perfusion pressure (CPP) to ensure adequate tissue oxygenation
    1. CPP = Mean Arterial Pressure (MAP) – Intracranial Pressure (ICP)
      1. Seems simple enough? – ensure the patient’s blood pressure is high enough to overcome the ICP
    2. However, the optimal CPP following acute brain injury is not known (general consensus suggest 50-70 mmHg)
      1. In the normal brain CPP is maintained by autoregualtion
      2. Autoregulation is less effective after brain injury
      3. If the CPP is too low brain hypoxia occurs
      4. If the CPP is too high there may be a risk of hematoma expansion
    3. However, it’s not easy to measure the ICP
      1. Methods of non-invasive ICP estimation:
        1. Level of consciousness
        2. Papilledema
        3. CT appearances
        4. Transcranial doppler
        5. Sonographic Optic Nerve Sheath Diameter
        6. Lots of others
        7. None of these are perfect
      2. Invasive ICP measurement
        1. External Ventricular Drain – Neurosurgical procedure
        2. Setting up the EVD and measuring ICP requires experienced nursing staff (see below)
    4. Even measuring the MAP is not without its own problems in the ED
      1. MAP = (Systolic BP + 2(Diastolic BP))/3
      2. However non invasive measurement of MAP (based on SBP and DBP peripheral sphygmomanometry) is not accurate.
      3. An accurate measurement of MAP requires invasive monitoring via an arterial line.
    5. Assuming that we are able to accurately measure ICP and MAP, there is then the question of how to adjust these values reliably via therapeutic interventions.
      1. ICP Management (Normal = 0-15, Goal < 20)
        1. Patient position, head up
        2. Sedation and paralysis, if patient aggitated
        3. Mannitol – potential risk of acute kidney failure in prolonged use
        4. Hyperventilation – will also reduce cerebral blood flow – so PaCO2 no lower than 35 mmHg
        5. CSF Drainage : 
        6. Hypothermia
      2. MAP Management
        1. IV Fluid (crystalloid vs colloid?)
        2. Diuretics / Antihypertensives vs Inotropes
        3. A very detailed guide to blood pressure management in stroke can be viewed here: BP-Stroke


I suspect that most emergency physicians/nurses are wondering whether this level of care falls within their remit. In most hospitals the answer will be NO, these cases are stabilised and managed in an Intensive Care Unit. However, there are occasions when this level of care is required prior to transfer to another unit/hospital, in which case it is likely that the care will be directed by the local neurosurgeon / neurointensivist and the receiving specialists.


EVD Drainage System and ICP Monitoring

 

Suggest ICP Protocol from Vancouver General ICU

Download (PDF, 110KB)

 


 

CME QUIZ

 

ED Reflections - CME Quiz - Oct 2017

ED Reflections – CME Quiz – Oct 2017

 


 


Click Print, PDF or Email to save a record of this CME

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ED Rounds – May 2016

Imaging Decisions in Vascular Disease

Presented by Dr. Dylan Blacquiere (Neurologist)

 


 

Download (PDF, 11.39MB)

 


New Imaging Recommendations. Dr Jake Swan (Radiologist)

After meeting with Dr. Blacquiere and the ER department regarding stroke management and SAH management, I’m recommending the following based on new literature and evolving management in “high risk” patients.

1) High risk TIA patients, such as those who had a profound motor / speech deficit that is resolving should have a CTA carotid / COW as well as their standard CT head.

2) SAH patients should have CT done prior to LP due to false positive LP rates.  If there is any question about vascular malformation / aneurysm, follow with a CTA. The CTA isn’t necessary for every headache patient, etc, just those with a positive bleed on the unenhanced CT.


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HINTS exam in Acute Vestibular Syndrome

The eyes are the window to the brain: HINTS exam in acute vestibular syndrome

Resident Clinical Pearl – January  2016

Jacqueline MacKay, PGY2 iFMEM, Dalhousie University, Saint John, New Brunswick

Reviewed by: Dr Joanna Middleton and Dr David Lewis

 

Acute vestibular syndrome (AVS) is the rapid onset of vertigo, nausea/vomiting, and gait unsteadiness combined with head-motion intolerance and nystagmus that lasts days-weeks. Often these dizzy patients have a benign, self-limiting cause for their symptoms, however it is estimated that up to 25% of AVS presentations to emergency departments are due to posterior circulation infarcts.

 

CT scan has low sensitivity for identifying acute infarct, especially in the posterior fossa. MRI is not always available, and will often have false-negative results in acute posterior circulation strokes. Are bedside predictors able to identify central causes of acute vestibular syndrome?

 

The HINTS exam is a bedside test that carefully assesses eye movements. HINTS stands for Head Impulse-Nystagmus-Test of Skew.


Untitled

Head Impulse: test of vestibulo-ocular reflex function. A normal Head Impulse test (HIT) strongly indicates a central localization for the AVS. An abnormal HIT usually indicates a peripheral lesion.


Untitled1

Nystagmus: bilateral nystagmus which changes direction on eccentric gaze or primarily vertical nystagmus is predictive of central pathology.


Untitled2

Skew Deviation: a vertical ocular misalignment that is assessed by alternate cover testing


Watch the video! A short and excellent description of the exam with good examples of normal and abnormal:

https://vimeo.com/133033089 (Courtesy of EMCrit)


 

Interpretation

A benign HINTS exam is defined as abnormal HIT + direction-fixed horizontal nystagmus + absent skew.

A dangerous HINTS exam is defined as any one of:

  • Normal/untestable HIT
  • or direction-changing horizontal nystagmus present/untestable
  • or skew deviation present/untestable

(Untestable refers to those patients with obvious oculomotor pathology or lethargy in whom the tests were unable to be completed).

 

The acronym INFARCT can be used to remember what constitutes a dangerous HINTS exam:

Impulse Normal

Fast-phase Alternating

Refixation on Cover Test.

 

A dangerous HINTS result was found to be 100% sensitive and 96% specific for the presence of a central lesion when applied to patients with acute vestibular syndrome (continuous vertigo and nystagmus) with at least one stroke risk factor. In fact, the HINTS exam is more accurate than MRI to diagnose stroke in patients with AVS in the first 48 hours!


 

Bottom Line:

In the acutely dizzy patient with at least one stroke risk factor, remember the HINTS to an INFARCT

 


References:

  1. Kattah, J. C., Talkad, A. V., Wang, D. Z., Hsieh, Y. H., & Newman-Toker, D. E. (2009). HINTS to diagnose stroke in the acute vestibular syndrome three-step bedside oculomotor examination more sensitive than early MRI diffusion-weighted imaging. Stroke, 40(11), 3504-3510. DOI: 10.1161/STROKEAHA.109.551234
  2. EMCrit http://emcrit.org/misc/posterior-stroke-video/ – original source of the videos is http://novel.utah.edu/Newman-Toker/collection.php

 

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