Optic Nerve Sheath Ultrasound for Detecting Increased Intracranial Pressure (ICP)

In podcast 78 on the management of elevated ICP, I discussed ocular nerve sheath ultrasound. Here are some additional resources.

Key Aspects of the Technique

  • Must see lens or iris in the scan or you are scanning nerve off-axis. If off-axis, may underestimate OSND diameter.
  • Measure Outside Diameter (OD)
  • A good view of the nerve often necessitates moving the probe slightly to the temporal side and angulating the beam a little nasally.
from Broomedocs
from Broomedocs

optic nerve and visual pathways from grays anatomy


  • Crit Care 2008;12:150
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  • Review Article (Acta Anaesthesiol Scand 2011;55:644)


From Life in the Fast Lane

Update 5/31/14: This Blog and Podcast is the one you must immediately check out on optic nerve sheath for ICP, from the Broomedocs podcast.

There you will find this table from Dr. Leanne Hartnett:

from Broomedocs
from Broomedocs



From Ultrasound Podcast guys, a 1-minute tutorial

Link to Full Ultrasound Podcast on Ocular Nerve Sheath Exam





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  1. Karim says

    Hi, I’m wondering why the ETCO2 may not match the PaCO2 in a head injury patient (who is not in shock or has any underlying cardiovascular disease). Thanks!

    • says

      If they had none of those things, and no atelectasis, and no other trauma it would probably correlate fairly well–at first. Most TBI patients are not that isolated. One correlated set- of-samples doesn’t tell you that their lungs have not started to get bad later on. The TBI state leads to ALI and ARDS on its own without any coexisting external lung injury.

  2. Don Diakow says

    This just wants me to have a Pocket ultrasound machine when I’m on calls. Besides that this is excellent stuff thanks Ultrasound guys!

  3. A says

    I used this technique just last week to confirm an elevated ICP reading by a Codman. I didn’t have a Tegaderm handy, so I just cut a latex glove into sort of a square sheet which I draped over the patient’s closed eye, and then applied ultrasound gel over the latex, leaving the eye completely residue free. Perfect images. Great podcast!


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