Don't Blow It: Pneumoparotid Related to Overzealous Distension of the Oral Cavity During Puffed-Cheek CT Scans

Anil Y. Tumu, M.D. and Lawrence E. Ginsberg, M.D.

Abst rac t NO: EE-14

Disclosures

• None

Purpose

• Report the imaging and clinical features of two cases of pneumoparotid

• Review the potential mechanisms of iatrogenic pneumoparotid

• Review Puffed-cheek CT technique in evaluating oral cavity lesions

Background

• Mucosal lesions of the oral cavity, particularly buccal or lateral (buccal) gingival lesions, often are difficult to diagnosis radiographically due to adjacency of apposing mucosal surfaces

• The apposition of the mucosal surfaces (figure 1a) may obscure lesions that are clinically obvious when utilizing standard CT imaging techniques

• Puffed-cheek CT scans, obtained by insufflating the oral cavity with air, allow for better evaluation of the buccal and gingival mucosa by separating the apposed mucosal surfaces (figure 1b)

Figure 1a: Buccal lesion more difficult to identify on standard

sequences

Figure 1b: Buccal lesion easily seen with Puffed-cheek

Materials and Methods

• Two patients underwent routine puffed-cheek CT for evaluation of the oral cavity

• The first patient was a 71-year-old male with a new right gingivobuccal sulcus lesion suspicious for verrucous carcinoma (figure 3)

• The second patient was a 59-year-old male with history of oral cavity squamous cell carcinoma presenting for routine follow-up (figure 4)

Pneumoparotid

• Caused by various mechanisms that increase intraoral pressure and can be seen in wind musicians, glassblowers and divers

• Elevated intraoral pressure causes air to reflux into Stensen's duct (figure 2)

• Typically asymptomatic and self-limited

• Recurrent pneumoparotid can lead to infection and sialectasis Figure 2: 71-year-old male with

recurrent pneumoparotid which was seen on two consecutive CTs performed

with Puffed-cheek technique

Results

• Both patients were incidentally found to have pneumoparotid during routine head and neck CT exams and were asymptomatic

• Pneumoparotid likely was related to overzealous performance of the puffed-cheek technique during CT and possibly an underlying anatomic predilection

• One patient presented with recurrent pneumoparotid on subsequent routine follow imaging over 4 months later, further suggesting an underlying anatomic predilection

• No other causes of pneumoparotid or secondary inflammatory changes were identified radiographically in either patient

Anatomy

• Reflux of air into the salivary system typically is inhibited by the ostium of Stensen's duct, a slit-shaped orifice surrounded by redundant mucosal folds

• When intraoral pressures increase, these mucosal folds seal off the ostium and prevent retrograde flow into the duct

• Distension of the oral cavity also causes increased angulation of Stensen's duct, allowing for better compression of the duct by the adjacent buccinator muscle

• When these mechanisms break down due to anatomical abnormalities including patulous duct and weak buccinator muscle, or are overcome by oral hyperpressure, pneumoparotid can occur

Imaging Findings

• Radiographically pneumoparotid appears as air within Stensen's and may reflux into the intraparotid ducts.

• In extreme cases, air actually can rupture the parotid acini and capsule

• When capsular rupture occurs, air can disseminate within the soft tissues of the head and neck and mediastinum

• Confirmation of air in these locations is easily made utilizing lung windows

Figure 3: Air within Stensen's duct and intraparotid ducts sagittal (left) and axial (right) Puffed-cheek CT sequences

Figure 4: Refluxed air was noted within Stensen’s duct (left) which is shown to better advantage with the use of lung windows (right)

Conclusion

• Pneumoparotid related to Puffed-cheek CT is a rare but important iatrogenic complication to recognize

• Although typically asymptomatic and self-limited, recurrent pneumoparotid can lead to infection and sialectasis

• Iatrogenic pneumoparotid can be related to any combination of patulous Stensen's duct, weak buccinator muscle or oral hyperpressure

References

Goguen LA, April MM, Karmody CS, Carter BL. Self-induced pneumoparotitis. Arch Otolaryngol Head Neck Surg. 1995;121(12):1426-9.

Kyung SK, Heurtebise F, Godon A, Rivière MF, Coatrieux A. Head-neck and mediastinal emphysema caused by playing a wind instrument. Eur Ann Otorhinolaryngol Head Neck Dis. 2010;127(6):221-3.

Luaces R, Ferreras J, Patiño B, Garciarozado A, Vázquez I, Lópezcedrún JL. Pneumoparotid: a case report and review of the literature. J Oral Maxillofac Surg. 2008;66(2):362-5.

Weissman JL, Carrau RL. “Puffed-cheek” CT improves evaluation of the oral cavity. AJNR Am J Neuroradiol. 2001;22(4):741-4.