Optic nerve sheath diameter (ONSD) in sovratentorial brain tumor surgery: an option for non invasive raised ICP detection and management. Preliminary results and feasibility assessment (06AP04-9)

Background and Goal of Study: Increase in optic nerve sheath diameter (ONSD) in transorbital sonography has been proven to be able to non-invasively detect elevated intracranial pressure in different clinical scenarios. The aim of this study is to assess the feasibility of ONSD sonography method detecting changes in intracranial pressure in patients with sovratentorial brain tumors. Materials and Methods: After a learning curve of 25 cases, for two intensivists, high-frequency linear probes 7 Mhz are used to measure ONSD (ophthalmic artery - optic nerve cross point) in a patients population with sovratentorial brain solid tumors scheduled to elective neurosurgery. A convenience small sample of patients’ cohort with sovratentorial brain tumors scheduled to elective neurosurgery was analyzed. ONSD was measured, also, in preoperative RMN and/or CT scan and compared with postoperative CT scan in another small cohort of patients. Results and Discussion: A total of 25 encounters were completed. ONSD was enlarged in 94.3% of patients bilaterally (cut off > 5.5 mm). The mean ultrasound ONSD before surgery was 6,64 +/- 0,33 mm preoperatively and 5,31 +/- 0,10 mm postoperatively. Mean ONSD on CT/MRI scan was respectively 5,62 +/- 0,51 mm preoperatively and 5,42 +/- 0,46 mm postoperatively. We also found a good correlation between the side of lesion and rasied ONSD. Conclusion(s): ONSD ultrasound measurement in sovratentorial tumors patient population could be an optional non invasive method, beside CT or MRI to detect changes in intracranial pressure even if the paucity of the sample can’t allow us to make a precise assessment. References: Moretti R, Pizzi B Ultrasonography of the optic nerve in neurocritically ill patients, Acta Anaesthesiol Scand 2011; 55: 644-652. Bekerman I, Sigal T, Kimiagar I, Almer ZE, Vaiman M., Diagnostic value of the optic nerve sheath diameter in pseudotumor cerebri. J Clin Neurosci. 2016 Aug;30:106-9. Frederick A. Zeiler, Markus T.Ziesmann, Patrick Goeres, Bertram Unger, Jason Park1, Dimitrios Karakitsos, Michael Blaivas, Ashley Vergis and Lawrence M. Gillman - A unique method for estimating the reliability learning curve of optic nerve sheath diameter ultrasound measurement - Crit Ultrasound J (2016) 8:9