POCUS OBTAINED OPTIC NERVE SHEATH DIAMETER IN PATIENTS PRESENTING WITH INTRACEREBRAL HEMORRHAGE

Abstract

TOPIC: Critical Care TYPE: Original Investigations PURPOSE: Intracerebral hemorrhage (ICH) results in spontaneous bleeding into the brain. This accounts for 10-15% of all strokes in the United States and has poor outcomes due to death or disability. An ICH can result in increased intracranial pressure due to blood occupying extra space. Optic nerve ultrasonography has emerged as a quick noninvasive procedure to detect increased intracranial pressure. A question that has not been answered is whether there is a specific correlation between the size of hematoma in the brain and the optic nerve sheath diameter (ONSD). The optic nerve is wrapped by a sheath derived from the meninges. Cerebrospinal fluid (CSF) can transfer freely between the intracranial and intraorbital spaces. METHODS: 23 patients were recruited into this study. Each of these patient’s received the diagnosis of ICH and admitted to the neuro intensive care unit (NICU). Ultrasound of the optic nerve was performed using a Sonosite machine and the high frequency probe. The exam was performed upon admission to the NICU. Both eyes were scanned in two planes, longitudinal and transverse. Once the ONSD measurements were recorded, the volume of the ICH was noted on initial head CT. RESULTS: The average ICH score was 1.35 and the average APACHE IV score was 27.35. In addition, the average GCS on admission was 13. The most common cause of ICH was hypertension. The most common location for the ICH was lobar hemorrhage. 8 out of 23 patients had midline shift on their initial head CT. 4 out of 23 patients underwent some sort of surgical intervention. The smallest average combined ONSD was 4.43cm. The longest average combined ONSD was 8.03cm. The minimum hemorrhage volume was 0.20cm3. The maximum was 60.0cm3. A moderate, positive correlation was detected between average optic nerve size and hemorrhage volume (correlation=0.5262; p-value=0.0099). A weak positive correlation was detected between APACHE IV and average ONSD (correlation=0.2052; p-value=0.3476). A weak-moderate positive correlation was detected between ICH score and average ONSD. (correlation=0.3622; p-value=0.0895). Those who experienced a midline shift had significantly higher averaged ONSD compared to those who did not. CONCLUSIONS: This study determined there was a moderate positive correlation between the ONSD and volume of hematoma. From a pathophysiological standpoint, conditions like ICH lead to cerebral parenchyma swelling which is transmitted to the optic nerves through the meninges. Additionally, our study revealed a significant difference in average ONSD and midline shift observed on CT scan. In settings where no invasive monitoring is available, ONSD enlargement may be a useful technique for monitoring midline shift. CLINICAL IMPLICATIONS: There are already established prognostic indicators for ICH including an ICH volume of 60cm3or greater on initial CT along with a GCS of 9 or less which predict a 30 day mortality of 19%. ONSD has a role in prognostication. Growth of the hematoma in the first 24 hours is an independent predictor of mortality and poor outcome. Serial exams of a patients ONSD can be applied to indirectly monitor any expanding hematoma. Given the positive correlation between ONSD and hematoma volume, I would be interested in ONSD and the degree of disability scores such as the modified rankin scale. DISCLOSURES: No relevant relationships by Braden Anderson, source=Web Response No relevant relationships by Shekhar Ghamande, source=Web Response No relevant relationships by Sarita Kambhampati, source=Web Response No relevant relationships by Matthew Lohse, source=Web Response No relevant relationships by Alireza Nathani, source=Web Response