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World J Radiol. Nov 28, 2014; 6(11): 850-854
Published online Nov 28, 2014. doi: 10.4329/wjr.v6.i11.850
Spontaneous pneumomediastinum and Macklin effect: Overview and appearance on computed tomography
Sadayuki Murayama, Shinji Gibo
Sadayuki Murayama, Department of Radiology, Graduate School of Medical Science, University of the Ryukyus, Okinawa 903-0215, Japan
Shinji Gibo, Department of Radiology, Urasoe General Hospital, Okinawa 901-2132, Japan
Author contributions: Murayama S designed and wrote the paper; Gibo S provided case examples for this article.
Correspondence to: Sadayuki Murayama, MD, PhD, Department of Radiology, Graduate School of Medical Science, University of the Ryukyus, 207 Uehara, Nishihara-cho, Okinawa 903-0215, Japan. sadayuki@med.u-ryukyu.ac.jp
Telephone: +81-98-8951160 Fax: +81-98-8951420
Received: April 23, 2014
Revised: June 16, 2014
Accepted: September 23, 2014
Published online: November 28, 2014
Abstract

Spontaneous pneumomediastinum (SPM) is described as free air or gas located within the mediastinum that is not associated with any noticeable cause such as chest trauma. SPM has been associated with many conditions and triggers, including bronchial asthma, diabetic ketoacidosis, forceful straining during exercise, inhalation of drugs, as well as other activities associated with the Valsalva maneuver. The Macklin effect appears on thoracic computed tomography (CT) as linear collections of air contiguous to the bronchovascular sheaths. With the recent availability of multidetector-row CT, the Macklin effect has been seen in the clinical setting more frequently than expected. The aim of this review article is to describe the CT imaging spectrum of the Macklin effect in patients with SPM, focusing on the common appearance of the Macklin effect, pneumorrhachis, and persistent SPM with pneumatocele.

Keywords: Pneumomediastinum, Spontaneous pneumomediastinum, Computed tomography, Macklin effect, Interstitial emphysema

Core tip: The Macklin effect can be frequently seen on imaging by multidetector-row computed tomography (CT) of patients who are found to have spontaneous pneumomediastinum from respiratory causes other than chest trauma. The collections of air dissect along the bronchovascular sheaths to the hilum and into the mediastinum. The Macklin effect as seen on CT may help differentiate respiratory from other etiologies of pneumomediastinum.