Pediatric Emergency Medicine POCUS
Created in 2020 by series editor, Dr. Margaret Lin-Martore, this series focuses on point-of-care ultrasonography (POCUS) for pediatric emergency medicine (PEM).
Read this tutorial on the use of point of care ultrasonography (POCUS) for pediatric ocular ultrasonography for optic nerve evaluation. Then test your skills on the ALiEMU course page to receive your PEM POCUS badge worth 2 hours of ALiEMU course credit.
Madeline is a 15-year-old female presenting to the Emergency Department with chief complaint of a headache for 1 week. She has been struggling with headaches for more than a year. The headache has been intermittent and tends to develop close to the end of the day, but it does improve with sleep. She denies photophobia, but has been complaining of blurry vision over the last week for which she is scheduled to see an ophthalmologist. Her medications include ibuprofen as needed for the headache and a daily medication for her acne.
|Heart rate||78 bpm|
|Oxygen saturation (room air)||100%|
|Weight||200 lbs (90.1 kg)|
Overall she is well appearing. She has a normal cardiac, respiratory, abdominal, and neurological examination including the cranial nerves.
On ocular examination, she has normal extra-ocular movements and a pupillary examination.
Given your examination findings, you request an ophthalmology evaluation and consider head imaging. While waiting, you decide to perform an ocular point of care ultrasound (POCUS) examination.
Ocular POCUS can be performed for various complaints, and it can provide valuable information. This especially is true in cases where the physical examination is difficult to perform such as from lack of patient cooperation, sensitivity to light, or pain. In resource-limited settings and when access to advanced diagnostic imaging or an ophthalmologist could be delayed or unavailable, ocular POCUS can be easily performed and provide information within minutes.
Indications to performing ocular POCUS include:
IMPORTANT NOTE: Ocular POCUS should not be performed when there is a concern for globe rupture to avoid applying pressure on the eye and exacerbating loss of intraocular contents.
Pro Tip: A tegaderm placed over a closed eye could be used to keep the gel from going into the eye. A tegaderm placed over a closed eye could be used to keep the gel from going into the eye depending on the patient’s preference.
Pro Tip: If your POCUS machine does not have an ocular preset, a musculoskeletal or small parts preset could be used after turning down the dynamic range and mechanical index. Figure 3 is an example of how this could be done on a Mindray TE7 ultrasound machine.
Pro Tip: If the optic nerve cannot be seen, ask the patient to move the eye from one side to another. The optic nerve will move in the opposite direction (opposite to the patient gaze).
The optic disc is where the optic nerve enters the eyeball. On POCUS, it normally appears smooth and in-line with the retina. Sometimes a small elevation is noted at the optic disc. This is called Optic Disc Elevation (ODE). It can be measured from the base of the optic disc to its peak at the widest area. It normally measures < 1 mm (figure 7). If the ODE is > 1 mm, this indicates papilledema and increased ICP. Of note, normal ranges are still an active area of study, see table in Ocular POCUS: Facts and Literature Review section for more information.
Pro Tip: ONSD normative values are not well established in pediatrics. Multiple studies attempted to set normal cutoffs for ONSD in various age groups. While measurement more than 5 mm in adults is considered abnormal, a value of 4 mm for infants and 4.5 mm in older children is used as the cut off . The are different cutoffs that are used in the literature with variable sensitivity and specificity. See literature review section. ONSD is also highly operator dependent. An inappropriate technique in measuring the ONSD can lead to under- or over-estimation of the diameter.
When ODE is >1 mm, it suggests papilledema, which is concerning for an increased ICP. The following figures and videos below illustrate abnormal ODE measurements. Note that normal ODE ranges are an active area of study.
Assessment of the optic nerve can provide information about intracranial pressure. Increased ICP is suggested when you see an enlarged ONSD.
Pro Tip: Pseudopapilledema (anomalous elevation of one or both optic discs without edema of the optic nerve) is a mimicker of papilledema and can be caused by a number of conditions including:
In these mimic cases, the POCUS ODE is typically <1 mm, whileas true papilledema is ≥1 mm. If the findings are equivocal, providers should perform additional evaluation for papilledema and elevated ICP.
Ocular POCUS has been used in the Emergency Department for detection of various ocular conditions, including increased ICP. The American Academy of Pediatrics (AAP) supported its use for ocular evaluation in its policy statement .
ODE has been reported as a method for detection of increased ICP with decent accuracy. There has been multiple attempts to assess the quantitative measurement of ODE and its correlation with increased ICP (table 1). This is an area of ongoing research with early studies limited by small sample sizes.
|Teismann et al 2013 ||At 0.6 mm cut off: 82%|
(95% CI 48-98%)
At 1 mm cut off: 73%
(95% CI 39-94%)
|At 0.6 mm cut off: 76% (95% CI 50-93%)|
At 1 mm cut off: 100% (95% CI 81-100%)
|Sample size: 14 adults|
These measurements were compared to ophthalmology-performed fundus exam. Only 6 of 14 patients had papilledema.
|Tessaro et al 2021 ||At 0.66 mm cut off (for mean of ODE of both eyes): 96% |
(95% CI 79–100%)
|93% (95% CI 79–100%)||Sample size: 40 children (mean age 11.4 years)|
26/40 patients had increased ICP.
Normal values for ONSD have been established in adults . It is still a controversial topic in children. The current standard is that an ONSD >4 mm in infants and 4.5 mm in children older than 1 year is considered abnormal, based on pediatric study of 102 healthy children . There have been multiple studies to assess the sensitivity and specificity of this exam (table 2).
|Study||Abnormal ONSD if||Sensitivity||Specificity||Comments|
|Blaivas et al 2003 ||>5 mm||100%||95%||Sample size: 34 adults|
This is an adult study comparing ONSD on POCUS with CT results.
|Le et al 2009 ||>4 mm for infants|
>4.5 mm for children >1 year old
|83% (95% CI 60-94%)||38% (95% CI 23-54%)||Sample size: 64 children|
24/64 patients had confirmed ICP based on CT, MRI, or direct ICP monitoring.
|Marchese et al 2018 ||>4.5 mm||90% (95% CI 67–98%)||57% (95% CI 43–70%)||Sample size: 76 children|
20/76 patients had concern for optic nerve swelling on ophthalmology exam. The test characteristics of ONSD changed with increasing or decreasing cutoffs or adding ODE as another marker for increased ICP.
You perform an ocular POCUS exam with a linear probe. The following image was obtained. What do you see?
This patient’s POCUS showed optic disc swelling with optic disc elevation and an enlarged optic nerve sheath diameter suggesting elevated ICP. The brain MRI was normal without signs of hydrocephalus. Ophthalmology evaluation confirmed the presence of papilledema. After consulting with neurology, an ultrasound-assisted lumbar puncture (LP) was performed. The patient’s opening pressure was 35 mm H2O. CSF was removed until a goal pressure of 25 mm H2O was achieved. The patient was diagnosed with idiopathic intracranial hypertension (formerly known as pseudotumor cerebri). The patient symptoms were resolved after the LP. She was admitted for further evaluation and management.
The patient was evaluated by neurology while on the inpatient unit. She was started on acetazolamide and discharged home. After multiple follow-up visits at the neurology clinic, her symptoms continue to be well-controlled.