Use of an eye ultrasound may quickly and safely identify children with brain drainage tube failure in the emergency department, according to a new study. The research will be presented at the Pediatric Academic Societies (PAS) 2024 Meeting, held May 3-6 in Toronto.
A ventricular shunt is a surgically implanted thin, plastic tube that drains extra fluid and relieves pressure on the brain. Children receive ventricular shunts for hydrocephalus, a condition where brain fluid doesn’t drain or reabsorb properly from brain bleeds, tumors, or other causes. Nearly 30% of shunts break, are displaced, or become blocked within two years of placement, and another 5% fail each year after that, experts say.
When a patient visits the emergency department for potential shunt failure, their symptoms are often nonspecific, including headache, vomiting, and fatigue, according to researchers. Shunt failure is life threatening, and children with shunts typically undergo multiple computed tomography and magnetic resonance imaging scans per year, exposing them to excessive radiation and sedation. A backup of fluid causes the optic nerve sheath to swell, which researchers can measure with eye ultrasound.
The study found that comparing the diameter of the optic nerve when a patient is symptomatic to the diameter when they are well can help determine if a shunt is blocked.
“The research team is interested in finding ways to lessen radiation exposure and expedite diagnosing shunt failure in the emergency department,” said Adrienne L. Davis, MD, MSc, FRCPC, pediatric emergency medicine research director at The Hospital for Sick Children (SickKids) and presenting author. “The study uses patients as their own controls by measuring the optic nerve when well and sick—a strategy that individualizes this test for every patient and recognizes that every patient with a shunt has a unique degree of shunt dependence and ability to tolerate high brain pressures.”
The researchers studied 76 pairs of eye ultrasounds of nearly 60 children presenting to the Toronto hospital’s emergency department with potential shunt failure. Researchers note that while findings are promising, results require further confirmation in a larger population of children with shunts across North America.
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EDITOR:
Dr. Adrienne Davis will present “CHange in Optic nerve sheath diameter (ONSD) and Optic disc elevation (ODE) in predicting Shunt failure in the Emergency department (CHOOSE study)” on Sunday, May 5 from 9:15-9:30 AM E.T.
Reporters interested in an interview with Dr. Davis should contact Amber Fraley at amber.fraley@pasmeeting.org.
SickKids contact: Sarah.warr@sickkids.ca
The PAS Meeting connects thousands of pediatricians and other health care providers worldwide. For more information, please visit www.pas-meeting.org.
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Abstract: CHange in Optic nerve sheath diameter (ONSD) and Optic disc elevation (ODE) in predicting Shunt failure in the Emergency department (CHOOSE study)
Presenting Author: Adrienne L. Davis, MD, MSc, FRCPC
Organization: The Hospital for Sick Children (SickKids)
Topic
Emergency Medicine: All Areas
Background
Thirty percent of ventricular shunts malfunction within the first 2 years of placement and 5% per year subsequently. Patients present to the Emergency Department (ED) with nonspecific symptoms and commonly undergo multiple CTs/MRIs per year. The CSF-filled, optic nerve sheath (ONS) swells with increased intracranial pressure and can be measured with ocular point-of-care ultrasound (POCUS). Prior studies using age-based ONS diameter (ONSD) upper limits found poor sensitivity for shunt malfunction, possibly due to larger ONSD ranges in children with shunts.
Objective
Determine if change in ONSD (∆ONSD) and change in optic disc elevation (∆ODE) from prior asymptomatic baseline measurements are predictive of shunt failure in children < 19 years presenting to the ED with query shunt failure.
Design/Methods
Prospective cohort study in an urban, tertiary care children’s hospital. Baseline ocular POCUS, by trained ED and neurosurgery staff were performed on asymptomatic shunted children attending neurosurgery clinic for routine care. Patients with comorbid eye pathology were excluded. A 2nd POCUS was performed if presenting to the ED with 1+ symptoms of shunt failure. Shunt failure (primary outcome, yes/no) was defined as complete/partial obstruction of 1+ components of the shunt, fracture or migration, determined intraoperatively. A sample size of 73 paired scans achieves 80% power to detect a mean of paired differences of 0.5mm (σ of 1.5, 2-sided α of 5%). Logistic regression was used to examine the association between ∆ONSD (ONSDsymptomatic–ONSDasymptomatic) and shunt failure, adjusted for age, time from baseline, obstruction type, tolerance of US, image quality, and # prior shunt revisions; the same regression was repeated for ∆ODE.
Results
76 pairs of scans were completed on 58 patients. Mean age was 7.6 years (SD 4.6) and 65.8% male. 53% congenital hydrocephalus, 21% tumor; 53% were admitted to hospital and 21% went to the OR. ∆ONSD was significantly associated with shunt malfunction: OR 11.0 (95%CI 2.5-47.8), p=0.001, while ∆ODE was not: OR 5 (95%CI 0.291-89), p=0.265. ∆ONSD AUROC was 0.83. △ONSD was also associated with +CT/MRI (increased ventricle size, periventricular interstitial edema, or effacement of cortical sulci): OR 8.3 (95%CI 2.3-29.8), p=0.001.
Conclusion(s)
∆ONSD is associated with shunt failure in our sample of children with ventricular shunts, while ∆ODE is not. Lack of ODE in shunted patients should not give false reassurance. Further research is needed to determine if ∆ONSD positively contributes to clinical prediction rules for shunt failure.
Article Title
CHange in Optic nerve sheath diameter (ONSD) and Optic disc elevation (ODE) in predicting Shunt failure in the Emergency department (CHOOSE study)