Case # 13: What Lies Beneath

Answer

Using ultrasound as an adjunct to your exam, you are able to tell the consultant that there is a normal appearing, reactive pupil and that the extra-ocular movements of the eye are intact. The consultant is appreciative over the phone and is happy to come in and see the patient whom after evaluation is discharged home with close outpatient follow up.

Learning Points

It is often the case where a patient suffers such significant facial trauma that a complete physical exam of the orbit due to periorbital swelling is not possible. Ultrasound can be a critical tool in these cases to provide useful information to assess for multiple potential pathologies. Previous studies have shown the ability of ocular ultrasound in trauma to detect elevated intracranial pressure (via optic nerve sheath diameter), retinal detachment, vitreous hemorrhage, and retrobulbar hematoma. It can also be used for early detection of muscular entrapment in the case of an orbital wall fracture, as well as performed serially for pupillary response in patients with significant neurological injury at risk for deterioration and potential herniation.

• To evaluate extraocular movements:
  • Prepare the patient by laying the bed backwards and having their face parallel to the ceiling,  supporting the patient's head and neck with a pillow or blanket.
  • (Optional) Place a tegaderm over the eye. If you do, ensure there is no air between the tegaderm and the eyelid.
  • Place a small amount of ultrasound gel on the closed eyelid  and prepare the linear probe with the gain turned almost all the way up.
  • Stabilize your hand on the patient's nasal bridge or zygoma, with the probe marker to your left, and place the probe transverse on the orbit with minimal pressure being applied directly to the eye. This is very important in trauma as the area is likely painful and theoretically the patient could have a ruptured globe.
  • Adjust the depth to ensure the optic nerve is just visualized at the bottom of the screen. The anterior chamber and lens should be used as visual landmarks to ensure you are in proper location.
  • Next, have the patient look left and right, then turn the probe to a sagittal orientation and have the patient look up and down. During these maneuvers you should be evaluating for symmetric movements of the orbit in each direction.
  • If you do not appreciate symmetric movements of the orbit in all directions then you may have entrapment of an extraocular muscle.
• To evaluate for pupillary response and shape:
  • Be sure to dim the lights in the room prior to performing this exam to allow for an adequate pupillary response.
  • Gently apply the linear probe with gel in a transverse plane just inferior to the eye, angling superiorly towards the patient's head (Depending on the location of the swelling around the eye, you can also place the probe superior to the eye, angling inferiorly towards the patient's feet).
  • Keep flattening out your probe angle relative to the skin until you have a cross section of the pupil and iris in view.
  • The pupil should be evaluated for symmetry as an asymmetric or oblong pupil could suggest globe rupture. You can then shine a light in the affected or non-affected eye (consensual light reflex) and observe the pupil for constriction.