Skip to main content
Advertisement

Main menu

  • Home
  • Content
    • Current Issue
    • Publication Preview--Ahead of Print
    • Past Issue Archive
    • Case of the Week Archive
    • Classic Case Archive
    • Case of the Month Archive
    • COVID-19 Content and Resources
  • For Authors
  • About Us
    • About AJNR
    • Editors
    • American Society of Neuroradiology
  • Submit a Manuscript
  • Podcasts
    • Subscribe on iTunes
    • Subscribe on Stitcher
  • More
    • Subscribers
    • Permissions
    • Advertisers
    • Alerts
    • Feedback
  • Other Publications
    • ajnr

User menu

  • Subscribe
  • Alerts
  • Log in

Search

  • Advanced search
American Journal of Neuroradiology
American Journal of Neuroradiology

American Journal of Neuroradiology

  • Subscribe
  • Alerts
  • Log in

Advanced Search

  • Home
  • Content
    • Current Issue
    • Publication Preview--Ahead of Print
    • Past Issue Archive
    • Case of the Week Archive
    • Classic Case Archive
    • Case of the Month Archive
    • COVID-19 Content and Resources
  • For Authors
  • About Us
    • About AJNR
    • Editors
    • American Society of Neuroradiology
  • Submit a Manuscript
  • Podcasts
    • Subscribe on iTunes
    • Subscribe on Stitcher
  • More
    • Subscribers
    • Permissions
    • Advertisers
    • Alerts
    • Feedback
  • Follow AJNR on Twitter
  • Visit AJNR on Facebook
  • Follow AJNR on Instagram
  • Join AJNR on LinkedIn
  • RSS Feeds
Research ArticleHEAD & NECK

Paratracheal Air Cysts: A Common Finding on Routine CT Examinations of the Cervical Spine and Neck That May Mimic Pneumomediastinum in Patients With Traumatic Injuries

J.E. Buterbaugh and W.K. Erly
American Journal of Neuroradiology June 2008, 29 (6) 1218-1221; DOI: https://doi.org/10.3174/ajnr.A1058
J.E. Buterbaugh
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
W.K. Erly
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
  • Article
  • Figures & Data
  • Info & Metrics
  • References
  • PDF
Loading

Abstract

BACKGROUND AND PURPOSE: Collections of extraluminal paratracheal gas may be present on CT images of the neck and cervical spine and the radiologist may question whether this is related to a pathologic process. This study is designed to demonstrate the appearance, clinical presentation, and prevalence of paratracheal air cysts, which, on CT examinations of the neck, can mimic abnormal extraluminal air.

MATERIALS AND METHODS: From January 1, 2005, through May 22, 2005, a total of 702 CT examinations of the cervical spine or soft tissue of the neck were reviewed. All examinations were at 2- to 5-mm thickness. Sagittal and coronal reconstructions were available for review, if necessary. Paratracheal air cysts were evaluated for size; the presence of visible communication with the trachea; association with pneumothorax, pneumomediastinum, or subcutaneous emphysema; and association with findings of emphysematous changes in the lung apices. Patient demographics of age, sex, and whether the patient had sustained a traumatic injury were also collected.

RESULTS: Of the 702 patients evaluated, 26 (3.7%) had paratracheal air cysts, all of which were found on the right, at the level of the thoracic inlet. Ages of the patients ranged from 15 to 74 years. In 9 (34.6%) of the patients, a direct communication with the trachea was seen. Sizes of the paratracheal air cysts ranged from 1 × 2 mm to 10 × 15 mm. No association was found with CT findings of emphysema in the lung apices, abnormal soft tissue air, or trauma.

CONCLUSION: Right paratracheal air cysts are a common CT finding that occur in a predictable location. In the setting of trauma, these characteristic structures can mimic pneumomediastinum and are seen in approximately 3% to 4% of the US population. The cause is unclear but may be either congenital or an acquired phenomenon, given that they are often seen in both children and adults. We found no association with either trauma or the presence of emphysematous changes in the lung apices.

A frequently occurring finding on CT examination of the neck is an air cyst or collection of air cysts to the right of the trachea at the level of the thoracic inlet (Fig 1). Paratracheal air cysts have been infrequently described in the radiologic literature. Previous reports suggested an association with obstructive lung disease and emphysema from weaknesses in the right posterior lateral wall of the trachea at the level of the thoracic inlet because of increased expiratory pressures in these patients.1 However, several case reports have described congenital right-sided tracheal diverticula in children with recurrent respiratory tract infections or with other congenital respiratory tract abnormalities such as bronchomalacia of the right upper lobe bronchus2 or with cystic adenomatoid malformation.3 It has also been reported that tracheal diverticula can be a rare cause of chronic cough.4,5 Other complications that have been reported include right-sided recurrent laryngeal nerve paralysis6 and difficult intubation.7

Fig 1.
  • Download figure
  • Open in new tab
  • Download powerpoint
Fig 1.

Right-sided paratracheal air cyst (arrow) at the thoracic inlet. T indicates trachea; E, esophagus; cc, common carotid; SCA, subclavian artery; IJ, internal jugular vein; Thy, inferior portion of the right lobe of the thyroid gland.

Right-sided paratrachial air cysts at the thoracic inlet can be confused with other causes of extraluminal air collections in the same area such as in patients with apical hernia of the lung, which has been previously described.8 In the patient who has sustained traumatic injuries, right-sided paratracheal air cysts could misinterpreted as mediastinal air, which can also occupy the same location.

The purpose of our study was to determine the prevalence and other demographic associations of right-sided paratracheal air cysts in the general population by evaluating for the presence of this entity on CT examinations of the neck in patients with traumatic injuries and in patients undergoing a study for other indications. We also sought to determine if there is increased prevalence in the trauma population, which might indicate that the entity is related to increased tracheal pressures sustained during traumatic injury. In addition, because this entity has previously been reported to be related to, and possibly caused by, obstructive lung disease, we sought to corroborate this finding by evaluating our studies for evidence of emphysema in the lung apices.

Materials and Methods

From January 1, 2005, through May 22, 2005, a total of 702 consecutive patients had technically adequate CT examinations of the cervical spine or soft tissue of the neck at 2- to 5-mm intervals. These examinations were performed at the University of Arizona Health Sciences Center in Tucson, Arizona, and were reviewed. Additional or follow-up examinations were excluded. Indications for the examinations were for either emergent reasons such as a traumatic injury, with instructions from the emergency department, or for nonemergent reasons such as soft tissue neck studies. Indications for examination of a traumatic injury included pain, blunt trauma, flexion or extension injuries, or penetrating injuries. Sagittal and coronal CT reconstructions were available for review, if necessary. Paratracheal air cysts were evaluated for size; the presence of visible communication with the trachea; association with pneumothorax, pneumomediastinum, or subcutaneous emphysema; and association with findings of emphysematous changes in the lung apices. Patient demographics of age, sex, and whether the patient had sustained a traumatic incident were also collected.

We differentiated paratracheal air cysts from those conditions mimicking air cysts on the basis of several factors: a typical location in the right posterior paratracheal region at the thoracic inlet but located away from the lung pleura, communication with the trachea, and rounded margins that differentiate cysts from emphysematous changes with angular margins as they track along fascial planes.

Results

A total of 26 (3.7%) examinations demonstrated the presence of paratracheal air cysts that ranged in size from 1 × 2 mm to 10 × 15 mm. Ages of patients who had paratracheal air cysts were 15 to 74 years (average age, 34.6 years). Of these patients, 14 (53.9%) were male and 12 (46.1%) were female. Many of the larger air cysts were multiloculated (Fig. 2), and some cysts demonstrated multiple communicating necks with the trachea. Overall, 9 (34.6%) patients had 1 or more communications with the trachea (Fig 3). In the patients who had sustained a traumatic injury, 17 (65.4%) air cysts were found, and 9 were found in patients examined for nontraumatic indications. There were 2 (7.7%) patients who also had pneumothorax, but only 1 (3.9%), of these patients had subcutaneous emphysema (Fig 4). None of these patients had pneumomediastinum extending into the neck, and none had evidence of emphysematous changes in the lung apices.

Fig 2.
  • Download figure
  • Open in new tab
  • Download powerpoint
Fig 2.

An 18-year-old woman with typical multiloculated paratracheal air cyst seen in the axial plane (image A superior to B) and in the coronal (C) and sagittal (D) planes. Cyst is labeled with white arrows.

Fig 3.
  • Download figure
  • Open in new tab
  • Download powerpoint
Fig 3.

Sequential images through a right-sided paratracheal air cyst. Communication with the trachea via a narrow stalk (arrow) is seen on image A. The air cyst, which is at the level of the thyroid (t) gland, extends inferiorly.

Fig 4.
  • Download figure
  • Open in new tab
  • Download powerpoint
Fig 4.

A 63-year-old man involved in an automobile accident. There is a small right-sided paratracheal air cyst (arrow) in the typical location as well as abnormal soft tissue air in the right supraclavicular region (curved arrows). The paratracheal air cyst can be differentiated from the abnormal soft tissue gas in that it communicates with the trachea and is within the wall of the trachea and not adjacent to it.

Of the 702 patients, 429 (61.1%) were male and 273 (38.9%) were female. Of the 542 (77.2%) patients who had sustained a traumatic injury, 25 (3.6%) had pneumothorax, 18 (2.6%) had either subcutaneous emphysema or pneumomediastinum extending into the neck, and 8 (1.1%) had both pneumothorax and soft tissue air. No patients were found to have CT evidence of emphysematous changes in the lung apices. The age range in the population was younger than 1 year to 103 years (average age, 39.6 years).

There were 676 patients without paratracheal air cysts. Of these, 415 (61.4%) were male and 261 (38.6%) were female. A total of 525 (77.7%) patients sustained a traumatic injury; of these, 23 (3.4%) had pneumothorax, 17 (2.5%) had either subcutaneous emphysema or pneumomediastinum extending into the neck, and 7 (1.0%) had both pneumothorax and soft tissue air. The age range in this population was younger than 1 year to 103 years (average age, 39.7 years).

Discussion

In this study, a right-sided paratracheal air cyst in the region of the thoracic outlet is relatively common, being present in approximately 3.7% of the population. Because of its predictable location and appearance, it should not be confused with pneumomediastinum or other causes of cystic lesions in the same region such as apical lung herniation on the right.

Right-sided paratracheal air cysts may be unilocular or multilocular and often can be seen to have communication with the trachea. In fact, some of these cysts have multiple narrow connections with the trachea. In our study, we found a communication with the trachea 35% of the time compared with the previously reported finding of a connection in 8%,1 probably because of the increased resolution in CT scanning that has occurred since the previous study. We believe that at least most, if not all, of these lesions are, in fact, tracheal diverticula. This conjecture is supported by a pathology series published, which demonstrated that these lesions were diverticula protruding through a weakened wall of the trachea in a characteristic location.9 It is interesting to note that although many of the patients with traumatic injuries were intubated, none of these lesions were seen in that population. This finding suggests that when there is compression of a cyst by an endotracheal balloon, the gas may be forced out of the cyst.

There does not seem to be an association between trauma and the prevalence of right-sided paratracheal air cysts. Of the total studied population, 77% were patients with traumatic injuries, but of the patients with right-sided paratracheal air cysts, only 64% had sustained traumatic injuries. There was also no association with the finding of soft tissue air or pneumothorax, as 5% of the total population had either 1 or the other, or both, compared with 8% who had a cyst. The difference was not statistically significant. Before our study, we had theorized that increased intratracheal pressures developed during trauma could lead to the development of tracheal diverticula. This does not seem to be the case.

Goo et al1 concluded in their study published in 1999 that there is an association between paratracheal air cysts and obstructive lung disease. We did not find any relationship in our study. None of the patients in our study had findings of emphysema in the lung apices. In addition, the average age of the patients with cysts was 37 years, which suggests that air cysts are unrelated to chronic obstructive pulmonary disease. Additionally given that five of the lesions were found in teenagers, this would also support that these could be congenital or developmental lesions rather than acquired through a disease process such as obstructive lung disease.

We observed a prevalence of air cysts of 3.7%, whereas Goo et al1 reported a prevalence of 2%. They also reported a size range of 5 to 20 mm compared with a range of 2 to 15 mm in our study. The differences are likely because of the increased ability to detect smaller cysts with the advent of thinner cuts and higher spatial resolution.

In summary, right-sided paratracheal air cysts at the level of the thoracic inlet are common and should not be confused with pneumomediastinum on CT of the cervical spine in the patient who has sustained a traumatic injury.

References

  1. ↵
    Goo JM, Im JG, Ahn JM, et al. Right paratracheal air cysts in the thoracic inlet: clinical and radiologic significance. AJR Am J Roentgenol 1999;173:65–70
    CrossRefPubMed
  2. ↵
    Early EK, Bothwell MR. Congenital tracheal diverticulum. Otolaryngol Head Neck Surg 2002;127:119–21
    CrossRefPubMed
  3. ↵
    Restrepo S, Villamil MA, Rojas IC, et al. Association of two respiratory congenital anomalies: tracheal diverticulum and cystic adenomatoid malformation of the lung. Pediatr Radiol 2004;34:263–66
    CrossRefPubMed
  4. ↵
    Infante M, Mattavelli F, Valente M, et al. Tracheal diverticulum: a rare cause and consequence of chronic cough. Eur J Surg 1994;160:315–16
    PubMed
  5. ↵
    Tanaka H, Mori Y, Kurokawa K, et al. Paratracheal air cysts communicating with the trachea: CT findings. J Thoracic Imag 1997;12:38–40
    PubMed
  6. ↵
    Caversaccio MD, Becker M, Zbaren P. Tracheal diverticulum presenting with recurrent laryngeal nerve paralysis. Ann Otol Rhinol Laryngol 1998;107:362–64
    FREE Full Text
  7. ↵
    Davies R. Difficult tracheal intubation secondary to a tracheal diverticulum and a 90 degree deviation in the trachea.[see comment]. Anaesthesia 2000;55:923–25
    PubMed
  8. ↵
    McAdams HP, Gordon DS, White CS. Apical lung hernia: radiologic findings in six cases. AJR Am J Roentgenol 1996;167:927–30
    PubMed
  9. ↵
    MacKinnon D. Tracheal Diverticula. J Pathol Bacteriol 1953;65:513–17
    CrossRefPubMed
  • Received October 16, 2007.
  • Accepted after revision January 27, 2008.
  • Copyright © American Society of Neuroradiology
View Abstract
PreviousNext
Back to top

In this issue

American Journal of Neuroradiology: 29 (6)
American Journal of Neuroradiology
Vol. 29, Issue 6
June 2008
  • Table of Contents
  • Index by author
Advertisement
Print
Download PDF
Email Article

Thank you for your interest in spreading the word on American Journal of Neuroradiology.

NOTE: We only request your email address so that the person you are recommending the page to knows that you wanted them to see it, and that it is not junk mail. We do not capture any email address.

Enter multiple addresses on separate lines or separate them with commas.
Paratracheal Air Cysts: A Common Finding on Routine CT Examinations of the Cervical Spine and Neck That May Mimic Pneumomediastinum in Patients With Traumatic Injuries
(Your Name) has sent you a message from American Journal of Neuroradiology
(Your Name) thought you would like to see the American Journal of Neuroradiology web site.
CAPTCHA
This question is for testing whether or not you are a human visitor and to prevent automated spam submissions.
Citation Tools
Paratracheal Air Cysts: A Common Finding on Routine CT Examinations of the Cervical Spine and Neck That May Mimic Pneumomediastinum in Patients With Traumatic Injuries
J.E. Buterbaugh, W.K. Erly
American Journal of Neuroradiology Jun 2008, 29 (6) 1218-1221; DOI: 10.3174/ajnr.A1058

Citation Manager Formats

  • BibTeX
  • Bookends
  • EasyBib
  • EndNote (tagged)
  • EndNote 8 (xml)
  • Medlars
  • Mendeley
  • Papers
  • RefWorks Tagged
  • Ref Manager
  • RIS
  • Zotero
Share
Paratracheal Air Cysts: A Common Finding on Routine CT Examinations of the Cervical Spine and Neck That May Mimic Pneumomediastinum in Patients With Traumatic Injuries
J.E. Buterbaugh, W.K. Erly
American Journal of Neuroradiology Jun 2008, 29 (6) 1218-1221; DOI: 10.3174/ajnr.A1058
Reddit logo Twitter logo Facebook logo Mendeley logo
  • Tweet Widget
  • Facebook Like
  • Google Plus One
Purchase

Jump to section

  • Article
    • Abstract
    • Materials and Methods
    • Results
    • Discussion
    • References
  • Figures & Data
  • Info & Metrics
  • References
  • PDF

Related Articles

  • No related articles found.
  • PubMed
  • Google Scholar

Cited By...

  • Case of a tracheal diverticulum causing airway obstruction
  • Paratracheal air cysts on thoracic multidetector CT: incidence, morphological characteristics and relevance to pulmonary emphysema
  • Crossref
  • Google Scholar

This article has not yet been cited by articles in journals that are participating in Crossref Cited-by Linking.

More in this TOC Section

  • CT and MR Imaging Appearance of the Pedicled Submandibular Gland Flap: A Potential Imaging Pitfall in the Posttreatment Head and Neck
  • Increased Labyrinthine T1 Postgadolinium Signal Intensity Is Associated with the Degree of Ipsilateral Sensorineural Hearing Loss in Patients with Sporadic Vestibular Schwannoma
  • MRI for Cushing Disease: A Systematic Review
Show more HEAD & NECK

Similar Articles

Advertisement

News and Updates

  • Lucien Levy Best Research Article Award
  • Thanks to our 2022 Distinguished Reviewers
  • Press Releases

Resources

  • Evidence-Based Medicine Level Guide
  • How to Participate in a Tweet Chat
  • AJNR Podcast Archive
  • Ideas for Publicizing Your Research
  • Librarian Resources
  • Terms and Conditions

Opportunities

  • Share Your Art in Perspectives
  • Get Peer Review Credit from Publons
  • Moderate a Tweet Chat

American Society of Neuroradiology

  • Neurographics
  • ASNR Annual Meeting
  • Fellowship Portal
  • Position Statements

© 2023 by the American Society of Neuroradiology | Print ISSN: 0195-6108 Online ISSN: 1936-959X

Powered by HighWire