Optic nerve ultrasound for the detection of elevated intracranial pressure in the hypertensive patient.

PURPOSE: We sought to determine whether dilation of the optic nerve sheath diameter (ONSD), as detected at the bedside by emergency ultrasound (US), could reliably correlate with patient blood pressure and whether there was a blood pressure cutoff point where you would start to see abnormal dilation in the ONSD.

METHODS: This was a single-blinded, prospective, observational trial from September 2010 to April 2011. One hundred fifty patients presenting to the emergency department were enrolled. There were 3 arms to the study with 50 patients in each arm: (1) ONSD in normotensive/asymptomatic patients; (2) ONSD in hypertensive/asymptomatic patients; and (3) ONSD in hypertensive/symptomatic patients. Ocular US was conducted on all subjects.

RESULTS: Neither the number of symptoms nor the type of symptom present in the hypertensive/symptomatic group was able to significantly predict the average ONSD before treatment (P = .818 and .288, respectively). There was a significant correlation between both systolic blood pressure (SBP) and diastolic blood pressure (DBP) with the ONSD in all hypertensive patients. The best SBP and DBP cutoff point for abnormal ONSD was 166/82 mm Hg. Decrease in ONSD observed after blood pressure treatment was not statistically significant (P = .073).

CONCLUSIONS: In conclusion, our study shows that practitioners can use bedside ocular US and a blood pressure cutoff point to help predict whether patients require more aggressive management of their symptomatic hypertension. Knowing the SBP and DBP readings that lead to increased ONSD and increased intracranial pressure can help guide management and treatment decisions at the bedside.