Abstract
BackgroundTo test the hypothesis that optic nerve sheath diameter (ONSD) correlates with real-time changes in intracranial pressure, we performed ultrasound measurements of the ONSD in ambulatory patients undergoing elective lumbar puncture (LP). We conducted a prospective cohort study, including adult patients undergoing LP in a non-emergent setting. We measured ONSD perpendicular to the optic nerve at 3 mm behind the globe in both eyes in the traverse and sagittal planes, with the patient supine. The primary outcome was change in ONSD from pre-LP to post-LP. We calculated association of opening and closing LP pressures with changes in the pre- and post-LP ONSD measurements.ResultsThe mean patient age was 49.0 years (SD = 37–61, range 19–67) with 21 females (72.4%) and 26 (89.7%) white American (not Hispanic or Latino). The average opening pressure and closing pressures were 20.4 cm and 13.5 cm with a difference of 6.9 cm, (95% CI 3.9–10.0 cm). Pressures between the participants with baseline ONSD measurement > 5 mm (average opening pressure = 21.3 cm) to those < 5 mm (20.2 cm) differed by 1.1 cm (95% CI − 5.7 to 8.0). Linear regression revealed no association between the sagittal, transverse, average, and change in ONSD measurements with the observed LP opening pressure, change in LP pressure, or volume of cerebral spinal fluid (CSF) drained.ConclusionsIn this study of ambulatory patients undergoing rapid decreases in ICP via elective LP, we detected no acute changes in ultrasonographic measurement of the ONSD.
Highlights
To test the hypothesis that optic nerve sheath diameter (ONSD) correlates with real-time changes in intracranial pressure, we performed ultrasound measurements of the ONSD in ambulatory patients undergoing elective lumbar puncture (LP)
Our primary research question was to determine if the optic nerve sheath diameter demonstrates a measurable change via ultrasound assessment in real time for patients undergoing elective lumbar punctures correlated with changes in intracranial pressure
This study provides evidence that the use of ONSD measurement via ultrasound (2D/B mode imaging with measurement of the ONSD 3 mm posterior to the globe in supine patients) does not correlate with real-time changes in intracranial pressure (ICP) in ambulatory patients undergoing an elective lumbar puncture
Summary
To test the hypothesis that optic nerve sheath diameter (ONSD) correlates with real-time changes in intracranial pressure, we performed ultrasound measurements of the ONSD in ambulatory patients undergoing elective lumbar puncture (LP). Optic nerve sheath diameter (ONSD) measurement by ultrasonography is a promising method to detect elevated intracranial pressure (ICP) [1, 2] and is gaining popularity as a beside assessment of ICP in critically ill patients [3]. This may be of particular benefit to undifferentiated patients presenting to the emergency department with concerns for elevated ICP and where Point-of-care ultrasound (POCUS) has a significant role in patient care. Different studies report variable inter-rater agreement and wide confidence intervals in measurements, suggesting caution-pending larger and more comprehensive studies [3, 11, 12]
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