Archive | April, 2012

Spontaneous Cervical and Intracranial Arterial Dissections

26 Apr

(scroll to bottom for quick hits)

Background
-Arterial dissections can cause stroke in both young in old populations, and is the most common cause of stroke in the young

-Extracranial dissection is more common than intracranial dissection

-Stroke is generally caused by either diminished blood flow from intraluminal thrombus or embolized clot

Pathogenesis (stick with it)
-Dissection are believed to begin with a tear in the media of the vessel wall, leading to bleeding in the wall itself

-partially coagulated intramural blood can enter the lumen which activates platelets and
the coagulation cascade leading to intraluminal thrombus.

-Intramural blood can accumulate leading to compression of the lumen



Risk Factors
Connective tissue and vascular disorders are thought to be main risk factors:
(e.g. Ehlers-Danlos Syndrome (type IV), Marfan Syndrome, Polycystic kidney disease, cystic medial necrosis, Fibromuscular dysplasia)

-many are caused by trauma




Diagnosis
-based on radiologic criteria taken from the Strategies Against Stroke Study for Young Adults in Japan (SASSY) using CTA or MRI/MRA

-Primary rules are based on finding an intimal flap or double lumen on Angiogram or MRI/MRA, or repeated non-specific findings associated with dissection on multiple studies.



Symptoms
Head or neck pain

Horner Syndrome occurs when the sympathetic fibers on the ICA are stretched. It is usually just partial with ptosis and miosis but no anhidrosis.

Difference between Carotid and Vertebral Dissections
-Transient monocular blindness occurred only with internal carotid dissection

-Ischemic stroke is more common in vertebral dissections

Neck pain and recent minor cervical trauma are more common in vertebral dissections

-Proportion of men and a recent infection are more common in ICA

Treatment
Antithrombotic therapy (antiplatelet or anticoagulation) is the primary initial treatment for ischemic stroke and TIA caused by arterial dissection

-For intracranial dissection, antiplatelet therapy is often the treatment of choice

-For extracranial dissection, anticoagulation initially followed by 6 months of warfarin therapy as opposed to antiplatet therapy is often chosen

Endovascular and surgical therapy are generally only reserved for recurrent ischemic events

BOTTOM LINE:
arterial dissection is more common cause of stroke in the young
extracranial (vertebral, carotid) more common than intracranial dissection
-sx: headache, neck pain, stroke-like symptoms, Horner’s syndrome (for ICA)
-risk factors: connective tissue disorders, trauma
-dx: angiography, MRI/MRA
-tx: antithrombotics/anticoagulation (aspirin, heparin, coumadin, etc.); surgical/endovascular for recurrent events

Submitted by J. Grover.


Reference(s): Caplan, LR and Biousse V. “Cervicocranial Artery Dissections.” J Neuro-Opthalmol. 2004; 24:299-305. Maruyama, H et al. “Spontaneous Cervicocephalic Arterial Dissection with Headache and Neck Pain as the Only Symptom.” J Headache Pain (2012) 13: 247-253. “Spontaneous Cerebral and Cervical Artery Dissection: Treatment and Prognosis”. Uptodate.  “Spontaneous Cerebral and Cervical Artery Dissection: Clinical Features and Diagnosis”. Uptodate., picture

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octreotide in sulfonylurea overdose

24 Apr

BASIC IDEA:
Octreotide inhibits the secretion of several neuropeptides, including insulin
–if someone overdoses on a sulfonylurea (e.g. glipizide), would giving octreotide help reduce the hypoglycemia problem?

(straight to the) BOTTOM LINE:
–limited studies out there, but reviews tend to say the same thing…
octreotide is probably safe and beneficial in sulfonylurea overdose/hypoglycemia

Reference(s): http://www.ncbi.nlm.nih.gov/pubmed/17764782 , http://www.ncbi.nlm.nih.gov/pubmed/16356235, http://www.ncbi.nlm.nih.gov/pubmed/17652687, http://www.ncbi.nlm.nih.gov/pubmed/20352540

fat pad on x-ray

19 Apr

WHAT IS THE FAT PAD?
–might be only subtle sign of a fracture on x-ray

–broken bones leak fat & blood, which also moves existing soft tissue



COOL TRICK:
–courtesy of EM News article (check out the pic on their website)
–if you’re aspirating a joint (e.g. knee effusion), and you aspirate blood, take a look under a light, look for the sheen of fat on top (suggests fracture)

–might want to get a CT or MRI next, if those x-rays were negative

Reference(s): EM News article with picture, x-ray, diagram, oil&water

hydrofloric acid burns

18 Apr

HYDROFLUORIC ACID:
one of the strongest inorganic acids
–can cause significant systemic toxicity due to fluoride poisoning.

–is used mainly for industrial purposes (eg, glass etching, metal cleaning, electronics manufacturing)–may be found in home rust removers.

 
TREATMENT TOOLBOX:
–can be soaked in magnesium hydroxide containing solutions (e.g. Mylanta) or soaked in ice water to help decrease the amount of absorption. 

decontaminateappropriately and wash with water. 

–apply 2.5% calcium gluconate gel to burn (10% Ca Gluconate solution in 3 times the volume of KY gel) and place hand into latex glove. 

–if pain persists >30 minutes and not on fingers, infiltrate margins of burn with 10% calcium gluconate solution. 

–if severe burns, can inject 10ml of 10% Ca gluconate in 40ml of D5 intra-arterially over 4 hours. 

–repeat as necessary.  For oral, ocular, or inhalation burns, calcium will also have to be given in different concentrations. 

–Consult Toxicology. 

–Treat pain with opioids.

Submitted by T. Boyd.

Reference(s): http://emedicine.medscape.com/article/773304-treatment, picture

bedside ultrasound vs. supine chest x-ray for pneumothorax

13 Apr

RAGING HYPOTHETICAL:
trauma patient, worried about pneumothorax
–how good is the bedside ultrasound? (sliding lung sign)

YOUTUBE ASSIST:

STUDY 1 (176 patients):

  • sensitivity (CXR): 75.5%
  • sensitivity (US): 98.1%
  • specificity (CXR): 100%
  • specificity (US): 99.2%

STUDY 2 (120 patients):

  • sensitivity (CXR): 82.7%
  • sensitivity (US): 89.7%
  • specificity (CXR): 100%
  • specificity (US): 97%

REVIEW ARTICLE (4 articles, 606 patients):

  • sensitivity (CXR): 28-75%
  • sensitivity (US): 86-98%
  • specificity (CXR): 100%
  • specificity (US): 97-100%  

BOTTOM LINE:
bedside ultrasound vs. supine CXR for pneumothorax
both are very specific
ultrasound is more sensitive than supine CXR

Submitted by S. Lee.

Reference(s): youtube video, study 1, study 2, review article, picture

decision rule for subarachnoid hemorrhage?

12 Apr

THOSE CANADIANS ARE AT IT AGAIN:
–study by Ottawa docs, Perry et al. reviewed nicely in an AAEM/Common Sense article (see reference)
–tried to identify a set of clinical characteristics to make a decision rule for those who need SAH workup

BASIC STRUCTURE:
–1,999 patients, 130 diagnosed with SAH
–SAH diagnosis defined by +CT, xanthrochromia, or >5 x 10^6/L RBCs + aneurysm/AVM on cerebral angiography

–included:

  • adults (>16 yo)
  • chief complaint = headache
  • GCS 15
  • non-traumatic
  • peak intensity of HA within 1 hr

–excluded:

  • >2 wks after symptom onset
  • prior SAH
  • previous CT and/or LP workup
  • 3 similar HA’s within past six months
  • papilledema/focal neuro symptom
  • prior hydrocephalus or cerebral neoplasm

RULES THEY CAME UP WITH:
–all have sensitivity 100%, but specificity sucked (28-39%)

the rules (each set works to help rule-out SAH):

  • age >40, neck pain/stiffness, witnessed LOC, DBP > 100mmHg
  • arrival by EMS, age>45, vomiting, DBP > 100
  • arrival by EMS, age 45-55, neck pain/stiffness, SBP > 160

BOTTOM LINE:
–nice study, helps think about why we do what we do, but isolated population
–the extra H&P details (age, BP, vomiting, neck pain/stiffness, etc.) are not very specific for SAH, but together might be sensitive (reminds me of appendicitis)
not ready for primetime just yet, but food for thought

Submitted by S. Lee.

Reference(s): AAEM/RSA review, picture

what’s a TAVI?

11 Apr

vck8sm5h Transcatheter Aortic Valve Implantation (TAVI) Reduces Mortality Rate Compared to Standard Therapy

RAGING HYPOTHETICAL:
–Hypotensive, elderly gentleman presents to your ED, records show he’s had a TAVI

–You nod your head with a reassurring look, then run to google…

–Next time you won’t need to – because you read this post.

WHAT’S A TAVI?

Transcatheter Aortic-Valve Implantation (TAVI) for patients with severe aortic stenosis who are not candidates for surgery.

What it looks like:

kdaesp1huv Transcatheter Aortic Valve Implantation (TAVI) Reduces Mortality Rate Compared to Standard Therapy

How it is placed: (so cool and worth watching)
The implantation procedure involves accessing a femoral artery, performing balloon valvuloplasty, then advancing the device across the native valve. During rapid right ventricular pacing, a balloon is inflated to deploy the valve and the frame.

Video animation: http://youtu.be/_eiI6S62zOs

Evidence it works:

At one year, the rate of death from any cause was 30% with TAVI vs. 50.7% with standard treatment (balloon aortic valvuloplasty and or medical therapy)

Not so good: TAVI had a higher incidence of strokes and major vascular complications compared to standard treatment, however this was included in rate of death.

Now you know 🙂

Submitted by S. Morris.