Investigating Optic Nerve Sheath Diameter in Prone Position Spinal Surgery Patients: A Pilot Study

Area of Science:

• Neurosurgery
• Ophthalmology
• Anesthesiology

Background:

• Prone positioning during spinal surgery may affect intracranial pressure.
• Optic nerve sheath diameter (ONSD) is a non-invasive ultrasound marker for intracranial pressure changes.

Purpose of the Study:

• To assess the impact of intraoperative positioning and ocular immobility on cerebrospinal fluid (CSF) surrounding the optic nerve.
• To quantify changes in ONSD during prone spinal surgery using ultrasound.

Main Methods:

• Ultrasound measurements of ONSD were taken preoperatively, intraoperatively, and postoperatively.
• 15 patients undergoing prone spinal surgery were included.
• Measurements were correlated with surgery duration.

Main Results:

• A 21% average increase in ONSD was observed during surgery.
• A positive time-dependent relationship between ONSD and surgery length was found (P < 0.001).
• Postoperative ONSD returned to baseline levels, showing no significant difference from preoperative measurements.

Conclusions:

• Prone spinal surgery leads to temporary pooling and inadequate clearance of perioptic CSF.
• ONSD changes during surgery are reversible upon patient repositioning.
• Ultrasound measurement of ONSD can help monitor fluid dynamics around the optic nerve during prone surgery.