What is a WADA exam?

What is a WADA exam?

A WADA exam is also known as an intracarotid amytal test. It is one of the “non-invasive” tests used to determine which hemisphere is language dominant in epileptic patients and also assess the ability of the non-affected side to maintain memory when isolated. For example, if you were to remove the R hippocampus – could the L side support language and memory alone?

No test is perfect... here are a couple of the WADA Shortcomings:

1. If patient has a high flow AVM – reading can be inaccurate
2. A portion of the hippocampus that you are trying to shut down could get its blood supply from posterior circulation making it hard to tell how accurately the patient will respond with full resection.

How is it done?

1. Get angiogram (to assess cross flow – which is a contraindication to shutting down the side of primary supply)
2. Cath ICA (usually start on lesion side)
3. Ask pt to hold opposite arm in the arm as amobarbital is rapidly injected into the ICA
4. What should happen? An almost immediate flaccid exam of the arm that begins to wear off in about 8 minutes. If it wears off faster (around 2 minutes) you may think about a high flow AVM.
5. Assess language by asking pt to name objects and remember them
6. Assess memory by asking pt to recall as many of the objects as possible 15 minutes later
7. Procedure can be repeated on the other side if needed

Photo source: http://www.instantanatomy.net/headneck/vessels/articinskull.html
Source: Handbook of Neurosurgery, Greenberg 6th Ed

Aphasia

I have always found aphasia incredibly interesting and terrifying all at the same time. Imagine not being able to communicate with language as smoothly as you do everyday. It is something that many of us take for granted.

Definition:
the loss or defect of language (speaking fluency, reading, writing, understanding of written or spoke words)

What are the 4 types of aphasia?
1. Wernicke's 
2. Broca's
3. conduction
4. global

Potential causes:

• stroke
• brain trauma
• brain tumor
• alzheimer's disease

Wernicke's

-receptive, fluent aphasia

-pt has hard time comprehending written or spoken language

-fluid speech, but difficult to understand

Broca's

-expressive, nonfluent aphasia

-speech is slow and requires effort

-few words used

-good comprehension of language

Conduction

-disturbance in repetition

-pathology involves the connections between Wernicke's and Broca's

Global

-often associated with RIGHT hemiparesis

-defect in all areas of language

How to treat
-many recover spontaneously in 4-6 weeks
-speech therapy



Photo source: emedia.leeward.hawaii.edu
Source: Step Up to Medicine by Agabegi and Agabegi

ACA Stroke Basics

Anterior Cerebral Artery (ACA) Stroke

The Anatomy

What deficits might you expect to see in a patient?

• contralateral leg weakness (both motor and sensory), frontal lobe behavioral issues, +/- aphasia if prefrontal cortex involved, grasp reflex

Where does the ACA receive its blood supply from?

• Carotid arteries

Source: http://www.neuroanatomy.ca/stroke_model/aca_info.html
Photo sources: http://missinglink.ucsf.edu/lm/ids_104_cns_injury/response%20_to_injury/watershed.htm

Calculating and Interpreting ABI

http://www.strokescaninc.com/abi.htm

First things first...
What does ABI stand for? 

Ankle-Brachial Index

What arteries are you examining?

Brachial and Dorsalis pedis

How do calculate ABI?

R ABI = highest avg ankle pressure (R dorsalis pedis)/ highest avg arm pressure (either arm)
L ABI = highest avg ankle pressure (L dorsalis pedis)/ highest avg arm pressure (either arm)

http://www.mayoclinic.com/health/medical/IM04412

How do you interpret the #s?

ABI                     Interpretation

>0.90                   Normal LE flow

<0.89 - >0.60      Mild PAD

<0.59 - >0.40      Moderate PAD

<0.39                   Severe PAD

See more about the technique of gathering ABI data in an older ABI post of mine...



Source: Bates Pocket Guide of Physical Examination 6th Ed

Transcranial Doppler

How does a transcranial doppler work?

• uses low-frequency U/S to evaluate flow velocity in cerebral vessels

Why might you order a transcranial doppler?

1. evaluation of basal cerebral arteries
2. finding spasms intercranially
3. evaluating the patency of the MCA (you would look for this in patients with carotid stenosis)

What the upside to transcranial dopplers?

1. no radiation
2. fast
3. non-invasive
4. can evaluate the circle of willis/intercranial carotids

What is the downside?

1. the outcomes is dependent on the person doing the test - skill and bias can play a role

Transcranial Doppler Video (a little old school - but good information)

Pic source: http://spencertechnologies.com

Source: Ferri's Best Test: A practical guide to clinical lab and medicine diagnostic imaging, Fred Ferri

Cardiac Surgery Made Ridiculously Simple

Cardiac Surgery Made Ridiculously Simple is a good resource if you are heading into a Cardiac rotation. Below are some additional resources listed on this site:

A good reference is: Cardiac Surgery in the Adult 

by L. Henry Edmunds, Jr., MD which is available online http://www.ctsnet.org/book/

An online reference text “Cardiothoracic Surgery Notes” for residents 

is available at http://www.ctsnet.org/residents/ctsn/

An online Johns Hopkins Cardiac Intern Survival Guide is available at http://www.ctsnet.org/doc/2695

http://www.nhrmc.org/heartsurgery

Vasculitides

Vasculitides

Definition: immune-mediated inflammation of blood vessels
Classifications: by size of the vessel, anatomical location, and immunological findings

Large Vessel Vasculities

• Giant cell arteritis 
• usually > 50 yo
• inflammation of the temporal, vertebral, or ophthalamic arteries
• increased ESR
• histology = segmental
• Takayasu arteritis
• inflammation of the lg arteries branching from the aortic arch
• downstream ischemia causing blindness
• undetectable pulse in upper extremeties

Medium Vessel Vasculities

• Polyarteritis nodosa
• segmental nectrotizing inflammation of any vessel (most often kidney, heart, and liver)
•  affects young adults
• Kawasaki disease
• acute vasculitis
• primarily coronary vessels
• Thromboangiitis obliterans
• aka Buerger's disease
• acute and chronic inflammation
• inflammation that can spread to veins and nerves

Small Vessel Vasculities

• Wegener granulomatosis
• either acute or necrotizing
• prominent lung involvement
• Churg Strauss Syndrome
• necrotizing granulomatous
• affects vessels and surrounding tissues (usually heart and lungs)
• numerous eosinophils
• Microscopic polyangiitis
• usually affects the skin
• most caused by immune responses  

Photo source: http://www.wegenersgranulomatosis.net/5_autoimmune_vasculitis.php
Source: Hardcore: Pathology, Carter Wahl