Optic nerve sheath diameter measurement by ultrasound after moderate traumatic brain injury

Article information

Clin Exp Emerg Med. 2023;10(2):249-250

Publication date (electronic) : 2023 April 24

doi : https://doi.org/10.15441/ceem.23.017

Mario Graziano, Danilo Biondino, Isabella Fioretto, Andrea Valerio Marino

Department of Medicine Surgery and Dentistry, Faculty of Medicine, University of Salerno, Baronissi, Italy

Correspondence to: Danilo Biondino Department of Medicine, Surgery and Dentistry, University of Salerno, Via Salvador Allende, Baronissi 84081, Italy Email: danilojbiondino@libero.it

Received 2023 February 15; Revised 2023 March 13; Accepted 2023 March 20.

Dear Editor,

We recently reviewed an article by Torabi et al. [1] in your journal concerning evaluation of optic nerve sheath diameter (ONSD) by ultrasound after moderate traumatic brain injury [1]. The article is noteworthy for its intriguing idea, but we would like to raise several concerns.

In the study, the authors utilized a 7.5 MHz linear probe to perform ONSD measurements in axial and coronal sections, most likely using the ultrasound B-scan technique. The B scan is very sensitive in detecting small optic nerve calcifications as in cases of optic nerve drusen, but it is not very reliable for measurements. [2–6].

We are aware that measurement of ONSD by ultrasound B scan has largely been conducted as a noninvasive method to detect increased intracranial pressure, but the presence of artefacts hinders these measurements [7–10]. Moreover, measuring the ONSD in the primary position is essential because altering the eye position can affect the quantity of cerebrospinal fluid surrounding the optic nerve, resulting in inaccurate ONSD measurements.

The study mentions that the authors performed the examination with closed eye lids, making it challenging to determine the gaze direction and potentially decreasing the image quality due to sound attenuation from the lids, creating less reliable results [11–13]. For this reason, it is advised to perform the examination with open eye lids and in the primary position after administering anesthetic eye drops, using methylcellulose as a coupling agent between the probe and the eye [14–17].

Therefore, in order to eliminate these anomalies and allow more accurate outcomes, it is recommended that standardized A scan techniques be utilized in future studies [18–20].