Bedside Ultrasound to Measure Optic Nerve Sheath Diameter in Pediatric CSF Shunts

Using Bedside Ultrasound to Measure the Optic Nerve Sheath Diameter in the Evaluation of Pediatric Patients With CSF Shunts

Bedside ultrasound in the emergency department is useful for quick assessments of patients. One growing use is to measure the optic nerve sheath diameter of patients for whom increased pressure in the head is a concern. This study will look at the optic nerve sheath diameters of a specific population of pediatric patients with shunts that drain extra fluid from their heads.

The particular interest of this study is the use of ultrasound to evaluate a child's optic nerve sheath diameter (ONSD), or the size of the covering around the nerve behind the eye. This covering expands when there is a higher than normal pressure inside the head. The group of interest on which this study focuses is the children with cerebrospinal shunts that drain extra fluid from their heads to other parts of the body (abdomen, heart, lungs) because the brain cannot drain all of the fluid like normal. When these shunts malfunction or fail, this can cause a backup of fluid in the brain, and raise the intracranial pressure (ICP) inside the skull. Depending on the degree of pressure buildup, this can be a surgical emergency due to pressure on the brain. Currently, computed tomography (CT) scans or magnetic resonance imaging (MRI) scans are used to diagnose the condition, but a quick screening tool, such as use of ultrasound to screen for elevated ICP in the emergency department, would be of great benefit to the patients to expedite care. Previous studies have explored the use of bedside ultrasound to evaluate the optic nerve sheath diameter in children with shunts. However, to date, there have been no reported prospective observational studies that compared before and after ultrasound measurements of the ONSD in patients in whom shunt failure is diagnosed and treated. Of note, this study is observational and the measurements taken with the ultrasound machine will not be used for clinical decision making. The measurements in this study will have no clinical impact on patient care. The use of ultrasound to measure the ONSD is an already accepted application of ultrasound.

Inclusion Criteria:

• Children and adolescents, ages 6 months through 17 years who have a shunt and who present to the children's emergency department for evaluation and treatment.
• Children and adolescents, ages 6 months through 17 years who have a shunt and are directly admitted to the inpatient children's hospital from an outside facility.

Exclusion Criteria:

• Patients for whom the parents or guardians do not agree to participate in the study.
• Patients with any acute trauma to the eyes, face, or head.
• Severe anaphylactic allergy to ultrasound gel or Tegaderm