Editorial
Copyright ©The Author(s) 2018. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Methodol. Nov 29, 2018; 8(3): 40-43
Published online Nov 29, 2018. doi: 10.5662/wjm.v8.i3.40
Microembolic signal detection by transcranial Doppler: Old method with a new indication
Sombat Muengtaweepongsa, Charturong Tantibundhit
Sombat Muengtaweepongsa, Charturong Tantibundhit, Department of Internal Medicine, Faculty of Medicine, Thammasat University, Pathum Thani 12120, Thailand
Author contributions: Muengtaweepongsa S contributed to conception and design of the work, data collection, drafting and critical revision of the article, and gave final approval; Tantibundhit C contributed to data collection and drafting of the article.
Conflict-of-interest statement: The authors declare they have no conflicts of interest.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Corresponding author to: Sombat Muengtaweepongsa, MD, MRCP, MSc, Associate Professor, Department of Internal Medicine, Faculty of Medicine, Thammasat University, Pathum Thani 12120, Thailand. musombat@staff.tu.ac.th
Telephone: +66-86-9994208 Fax: +66-29-269793
Received: August 4, 2018
Peer-review started: August 5, 2018
First decision: August 24, 2018
Revised: September 30, 2018
Accepted: October 17, 2018
Article in press: October 18, 2018
Published online: November 29, 2018
Processing time: 117 Days and 17.4 Hours
Abstract

Transcranial Doppler (TCD) is useful for investigation of intracranial arterial blood flow and can be used to detect a real-time embolic signal. Unfortunately, artefacts can mimic the embolic signal, complicating interpretation and necessitating expert-level opinion to distinguish the two. Resolving this situation is critical to achieve improved accuracy and utility of TCD for patients with disrupted intracranial arterial blood flow, such as stroke victims. A common type of stroke encountered in the clinic is cryptogenic stroke (or stroke with undetermined etiology), and patent foramen ovale (PFO) has been associated with the condition. An early clinical trial of PFO closure effect on secondary stroke prevention failed to demonstrate any benefit for the therapy, and research into the PFO therapy generally diminished. However, the recent publication of large randomized control trials with demonstrated benefit of PFO closure for recurrent stroke prevention has rekindled the interest in PFO in patients with cryptogenic stroke. To confirm that emboli across the PFO can reach the brain, TCD should be applied to detect the air embolic signal after injection of agitated saline bubbles at the antecubital vein. In addition, the automated embolic signal detection method should further facilitate use of TCD for air embolic signal detection after the agitated saline bubbles injection in patients with cryptogenic stroke and PFO.

Keywords: Cryptogenic stroke; Patent foramen ovale; Transcranial Doppler; Recurrent stroke; Patent foramen ovale closure; Brain ischemia; Real-time emboli

Core tip: Patent foramen ovale (PFO) is an emerging etiology of cryptogenic stroke, and PFO closure therapy has been shown to reduce the rate of recurrent stroke. Detection of the air embolic signal by transcranial Doppler (TCD) after injection of agitated saline bubbles at the antecubital vein will help to confirm the importance of PFO as the cause of a concurrent stroke. In addition, the automated embolic signal detection method should further facilitate use of TCD for air embolic signal detection after the agitated saline bubbles injection in patients with cryptogenic stroke and PFO.