The saw-tooth sign as a clinical clue for intrathoracic central airway obstruction

Akira Nakajima,Hidefumi Takei,Yoko Nakazato,Hajime Takizawa,Saori Takata,Takeshi Saraya,Haruyuki Ishii,Hajime Goto

doi:10.1186/1756-0500-5-388

Abstract

BackgroundThe saw-tooth sign was first described by Sanders et al in patients with obstructive sleep apnea syndrome as one cause of extrathoracic central airway obstruction. The mechanism of the saw-tooth sign has not been conclusively clarified. The sign has also been described in various extrathoracic central airway diseases, such as in burn victims with thermal injury to the upper airways, Parkinson’s disease, tracheobronchomalacia, laryngeal dyskinesia, and pedunculated tumors of the upper airway.Case presentationA 61-year-old man was referred to our hospital with a two-month history of persistent dry cough and dyspnea. He was diagnosed with lung cancer located in an intrathoracic central airway, which was accompanied by the saw-tooth sign on flow-volume loops. This peculiar sign repeatedly improved and deteriorated, in accordance with the waxing and waning of central airway stenosis by anti-cancer treatments.ConclusionThis report suggests that the so-called saw-tooth sign may be found even in intrathoracic central airway obstruction due to lung cancer.

Highlights

The saw-tooth sign was first described by Sanders et al in patients with obstructive sleep apnea syndrome as one cause of extrathoracic central airway obstruction
This report suggests that the so-called saw-tooth sign may be found even in intrathoracic central airway obstruction due to lung cancer
We described here the first case of the saw-tooth sign in a patient with lung cancer, which showing the sign could be seen even in an intrathoracic central airway stenosis, depending on its severity during the phase of anti-cancer treatment

Summary

Conclusion

This report highlights the saw-tooth sign, which tell us that we should consider the possibility of structural and/ or functional upper airway obstruction, either extrathoracic (i.e., OSAS) or involving an intrathoracic central airway when it is evident. Consent Written informed consent was obtained from the patient for publication of this case report and any accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of the journal. Competing interests The authors declare that they have no competing interests. Authors’ contributions AN, TS, ST, and HI managed the patient as primary physicians. AN and TS were primarily responsible for preparing the manuscript. HT and HG had responsibility for all aspects of management as chiefs of our respiratory department. All authors read and approved the final manuscript. Author details 1Departments of Respiratory Medicine, Kyorin University School of Medicine, 6-20-2 Shinkawa, Mitaka City, Tokyo 181-8611, Japan. Author details 1Departments of Respiratory Medicine, Kyorin University School of Medicine, 6-20-2 Shinkawa, Mitaka City, Tokyo 181-8611, Japan. 2Departments of General Surgery, Kyorin University School of Medicine, Tokyo 181-8611, Japan

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