Monthly Archives: December 2012

Case- Abdominal pain

Patient with history of hypertension presents periumbilical abdominal pain radiating to the back. Minimal abdominal tenderness, no rebound or guarding, though  a pulsatile mass is felt.

The following ultrasound is obtained:

As the title suggests, the patient was diagnosed with an abdominal aortic aneurysm and vascular surgery was consulted.

We’re experimenting a bit with the GMEP.org system. It’s a great educational collaborative run by the folks who brought you Life in the Fast Lane. Worth checking out.

As you may know, we have a Vimeo channel with a growing video archive as well. Our goal is to make this site and its content as helpful and accessible a possible, so please let us know how we can improve!

Back to the Source

Screen Shot 2012 12 29 at 5.06.37 PM Back to the Source

With the proliferation of online educational modalities (blogs, educational websites, podcasts, twitter feeds) designed for rapid dissemination and translation of our basic Ultrasound knowledge to the bedsides around the globe, we must occasionally go back to the source – The Scientific Journal.

Listed below are several ultrasound-specific journals.

What is your favorite source for point of care ultrasound literature goodness?

What The Heck 1

This patient presented with right upper quadrant abdominal pain. There was RUQ tenderness on exam, but no fever, rebound or Murphy sign. A point-of-care ultrasound was performed to assess for signs of cholecystitis and the following image was obtained. This prompted the operator to ask, “What the heck?”

GB1 500x376 What The Heck 1
What structures are visible here? How could you differentiate them? More after the break!

Continue reading

AAMC article

logo aamc.gif data AAMC articleThe Association of American Medical Colleges (AAMC) has written an article about ultrasound education at the medical school level. In the current edition of their widely distributed publication The Reporter, they describe programs at the University of South Carolina School of Medicine, University of California (Irvine) School of Medicine, and the Mount Sinai School of Medicine.

The article notes,

With rapid advancements in ultrasound technology, such scenarios as this are becoming more commonplace, as a handful of the nation’s medical schools make ultrasound training a standard part of the curriculum. And there is a push to encourage more schools to use ultrasound.

The full article is available here.

Ultrasound Zen

ZenStone 500x333 Ultrasound Zen To image something which moves, you must remain still. To image something which is still, you must move.

If you think on this long enough, the point is self-evident and requires no explanation. Or, just see some examples below.

We are pretty well adapted to seeing three dimensions at a time. Thus when imaging a moving structure like the heart, we hold the probe in a fixed position to obtain standard views. This allows us to focus on the movement, and cardiac presets optimize temporal resolution at the expense of spatial resolution. We are then seeing two spatial dimensions and one temporal dimension (heart moving in time).

D Shaped Left Ventricle from Sinai EM Ultrasound on Vimeo.

It is very difficult to appreciate the anatomy and function of the heart, for example,  when the probe is moving.

In contrast, imaging the right upper quadrant for fluid in Morison’s pouch requires a slow fan through the liver, diaphragm, and kidney. This allows us to appreciate the entire potential space where fluid can collect. Abdominal imaging is optimized for spatial resolution at the expense of temporal resolution, so be sure to move the probe slowly. Fanning through the entire structure of interest will often reveal pathology which was missed with a single-plane scan. Small gallstones, small amounts of peritoneal or pleural fluid, saccular aneurysms, and other maladies can fool a novice sonographer who isn’t thorough. In this case we are seeing three spatial dimensions.

FAST1 RUQ pos from Sinai EM Ultrasound on Vimeo.

So, keep your audience in mind when you are creating scans. Should you fan through the static anatomy, or let the movement of the structures speak for themselves?

Lung Ultrasound Pitfalls

US lung consolidation Tsung 500x514 Lung Ultrasound PitfallsThoracic sonography is one of the most rapidly growing areas of emergency and critical care ultrasound. One very important emerging indication is to assess for lung consolidation. The characteristic appearance of consolidated lung is very sensitive and specific for pneumonia, but novices should heed some important pitfalls in making the diagnosis.

Special thanks to Jim Tsung, MD, MPH and Brittany Jones, MD for their tips, videos, and ongoing research in this important field! For further reading on this topic, please see this article.

Pitfall #1 – confusing thymus for a consolidation

Normal thymus in sagittal view:

Thymus (top half of screen) and heart (bottom right). Don’t confuse thymus for lung consolidation. Note there are no air bronchograms, but thymus has a faint speckled appearance.

Normal thymus in transverse view:

Thymus (top half of screen) and heart (bottom right). Don’t confuse thymus for lung consolidation. Note there are no air bronchograms, but thymus has a faint speckled appearance
Pneumonia adjacent to Thymus in transverse view:

Lung consolidation with air bronchograms (top left) adjacent to normal thymus (speckled appearance on top right) with heart (bottom right)

Pitfall #2 – mistaking spleen for consolidation.

This is an important pitfall for everyone to know about. The same issue applies to the liver & stomach. The sensitivity of lung US for pneumonia rises >90% if this mistake is avoided.

Left lower chest- sagittal view:

Be careful scanning the left lower chest (left anterior and left axillary line) – air in stomach and spleen may look like pneumonia if you don’t realize that you have scanned inferior to the diaphragm and past the end of the pleural line. Most common error by novices.

Left lower chest- transverse view:

Be careful scanning the left lower chest (left anterior and left axillary line) – air in stomach and spleen may look like pneumonia if you don’t realize that you have scanned inferior to the diaphragm and past the end of the pleural line.

Pitfall #3- missing pleural effusion

Here are a few examples to refresh your memory.

Left pleural effusion:

Identify:

  • Pleural effusion (anechoic wedge just beneath ribs and pleura)
  • Lung
  • Diaphragm
  • Spleen
  • Air in stomach

Do not confuse spleen and air in stomach for pneumonia.

Right pleural effusion:

Identify:

  • Pleural effusion
  • Lung
  • Diaphragm
  • Liver

Papilledema and the Crescent Sign

 

What’s abnormal in this image?

 

Screen shot 2012 08 09 at 6.27.44 PM1 230x300 Papilledema and the Crescent Sign

Here’s a hint.  Here is an example of normal.

 

Screen shot 2012 08 09 at 6.18.41 PM1 256x300 Papilledema and the Crescent Sign

When evaluating for possible elevation in intracranial pressure, it has been shown that optic nerve sheath diameter (ONSD) measurements correlate with elevated intracranial pressures.(1,2)  The optic nerve attaches to the globe posteriorly and is wrapped in a sheath that contains cerebral spinal fluid.  The optic nerve sheath is contiguous with the dura mater and has a trabeculated arachnoid space through which cerebrospinal fluid slowly percolates.

Eye Sono 261x300 Papilledema and the Crescent Sign

ONSD Normal Ranges

Normal Adults < 5 mm
Children >1 yr < 4.5 mm
Infants < 1 yr <4 mm

 

The ONSD is measured 3 mm posterior to the globe for both eyes.  A position of 3 mm behind the globe is recommended because the ultrasound contrast is greatest.  It is best to average two measurements of each eye.  An average ONSD greater than 5 mm is considered abnormal and elevated intracranial pressure should be suspected.

 

ONSD large Papilledema and the Crescent Sign

ONSD Measurement

 

Crescent Sign

In severe cases of elevated ICP, one can see an echolucent circle within the optic nerve sheath separating the sheath from the nerve due to increased subarachnoid fluid surrounding the optic nerve.  Ophthalmologists refer to this as the crescent sign.

 crescent 2 Papilledema and the Crescent Sign

 

 The Case

40 yo female patient presents with several months of frontal headache associated with photophobia and blurry vision.  Symptoms have gotten much worse over the last few days and she has had difficulty reading and watching TV because of her visual symptoms.  She denies fevers, chills, nausea, vomiting, or focal weakness.   Pt is hypertensive 170/100.  Her vital signs are otherwise normal.

  • Visual acuity - 20/30 OD, 20/70 OS
  • CT head is normal
  • Bedside point of care ultrasound

papilledema cropped from Sinai EM Ultrasound on Vimeo.

Papilledema 2 cropped from Sinai EM Ultrasound on Vimeo.

This patient had enlarged ONSD (measurements were 6 mm bilaterally) as well as papilledema(arrow).

 

Papilledema arrow Papilledema and the Crescent Sign

Arrow notes papilledema

 

Lumbar puncture was performed.  Opening pressure was 44.  30 cc’s of CSF was drained and the closing pressure was 11.  The patient’s headache and visual symptoms improved .  She was started on acetazolamide and admitted to the neurology service.  MRI brain prior to lumbar puncture showed posterior scleral flattening bilaterally with protrusion of the optic nerve in the the globes bilaterally consistent with increased ICP.

This patient’s papilledema and increased ONSD correlated with a markedly increased opening pressure during lumbar puncture and suggests that ocular ultrasound may play a role in the ED management of patients with suspected pseudotumor cerebri.

Pseudotumor cerebri

Elevated intracranial pressure in the abscence of intracranial mass lesion.  Most common in young, over weight women. If the diagnosis is missed, persistently elevated intracranial pressure can lead to optic atrophy and blindness.

Treatment

  • Lumbar puncture to drain CSF to a normal opening pressure.
  • Medical:  Diomox (acetazolamide), high dose steroids
  • Surgical : Optic nerve sheath fenestration, VP shunt

Summary

The ability to diagnose papilledema using bedside sonography is useful to emergency physicians, as many non-ophthalmologist clinicians do not feel confident in their ability to perform an accurate nondilated fundoscopic examination. (3)  Ultrasound provides a useful alternative means of determining the presence or absence of papilledema in a patient in whom fundoscopy cannot be adequately performed.

 

 

[1] Geeraerts T, Launey Y, Martin L, et al. Ultrasonography of the optic nerve sheath may be useful for detecting raised intracranial pressure after severe brain injury. Intensive Care Med 2007;33(10):1704-11 [electronic publication 2007 Aug 1]. PMID: 17668184

 

[2] Kimberly HH, Shah S, Marill K, Noble V. Correlation of optic nerve sheath diameter with direct measurement of intracranial pressure. Acad Emerg Med 2008;15(2):201-4. PMID: 18275454

 

[3] Wu EH, Fagan MJ, Reinert SE, Diaz JA. Self-confidence in and perceived utility of the physical examination: a comparison of medical students, residents, and faculty internists. J Gen Intern Med 2007;22 (12):1725-30 [electronic publication 2007 Oct 6].  PMID: 17922165