Head and Neck Manifestations of Spontaneous Pneumomediastinum
Leh-Kiong Huon, MD1; Yen-Liang Chang, MD1,2; Pa-Chun Wang, MD, MSc1,2,3; Po-Yueh
Chen, MD1,4
Affiliations/Institution
1
Department of Otolaryngology, Head and Neck Surgery, Cathay General Hospital,
Taipei, Taiwan
2
School of Medicine, Fu Jen Catholic University, Taipei, Taiwan
3
School of Public Health, China Medical University, Taichung, Taiwan
4
Department of Otolaryngology, Head and Neck Surgery, Cathay General Hospital, Hsinchu
Branch, Taiwan
Manuscript classification: Article
Word count: 1,547
Financial support: None
Disclosure: No author has conflicts of interest
Correspondence
Po-Yueh Chen, MD
Department of Otolaryngology, Head and Neck Surgery
Cathay General Hospital, Hsinchu Branch, Taiwan
No. 280, Jen-Ai Road, Sec. 4, Taipei 10630, Taiwan (R.O.C.)
Tel: 8862-27082121 ext 5035
Fax: 8862-27082121
E-mail: anne215677@yahoo.com.tw
1
ABSTRACT
Objective: Spontaneous pneumomediastinum (SPM) is a rare disease entity that often
manifests localized signs in the head and neck region. The thoracic features of SPM have
been well described; however, there is a paucity of information on its otolaryngological
characteristics. We describe the clinical management among SPM patients having primarily
head and neck symptoms.
Study Design: A retrospective medical record review was performed among patients with
SPM over a 5-year period who were seen at ENT service. Patient’ clinical presentations were
recorded.
Setting: Cathay General Hospital, Taiwan.
Results: There were 13 men and 1 woman, with a mean age of 18.8 years (range, 14-29
years). The primary initial symptoms were neck swelling (11), neck pain (10), and
odynophagia (9). Neck soft tissue and chest radiography was diagnostic of SPM in all
patients. Conservative treatment consisted of bed rest and analgesics, which led to rapid
resolution of SPM.
Conclusions: SPM is a benign entity that responds well to conservative treatment. The results
of our investigation highlight the importance of an ENT clinical examination as a guide for
diagnosing SPM because of the high percentage of ENT manifestations in the initial clinical
profiles. Secondary causes of SPM must be ruled out to avoid an unfavorable outcome.
Key Words: cervical emphysema, mediastinal emphysema, spontaneous
pneumomediastinum, subcutaneous emphysema
2
INTRODUCTION
Pneumomediastinum denotes the presence of gas in the mediastinal space. It is most
common in children and is rare among adults, in whom it primarily appears as a complication
of thoracic injury, surgical operation, or pulmonary infection. It has been regarded as being
secondary to a respiratory disease. Spontaneous pneumomediastinum (SPM) is a separate
entity that occurs in previously healthy individuals without underlying respiratory diseases. It
is an unusual occurrence that may follow increases in intrathoracic pressure. Because the
management of pneumomediastinum involves the consideration of life-threatening conditions,
thoracic surgeons are routinely involved in the diagnosis and treatment of this condition.
Little is known about its otolaryngological features. However, otolaryngologists likely
become involved in the diagnosis of SPM when such patients are seen with head and neck
symptoms; hence, an awareness of this condition is important. The objective of this study was
to review the clinical experience of otolaryngologists with SPM at a single institution and to
detail the head and neck manifestations of this rare entity.
MATERIALS AND METHODS
We retrospectively reviewed the medical records of all patients with SPM who were
seen at our ENT emergency service and ENT outpatient department between January 2005
and December 2009. Excluded from the study were all trauma patients and patients with
intrathoracic malignant neoplasms, hemodynamic instability, or recent aerodigestive
instrumentation. Fourteen patients with SPM were identified.
For each patient, the following data were collected: demographics, likely etiology, initial
symptoms, radiography and axial computed tomography (CT) findings, results of any
3
contrast swallow study, use of antibiotics, dietary restrictions, length of hospitalization, and
condition at follow-up visits.
A systematic review of the English-language literature since 1990 was performed on the
clinical manifestations of SPM. The institutional review board of the Cathay General
Hospital approved this retrospective study.
RESULTS
Identified were 13 men and 1 woman with SPM. Their mean age was 18.8 years (age
range, 14-29 years). Predisposing and precipitating factors, symptoms, diagnostic methods,
and treatment and outcomes are given in Table 1. The etiology of SPM was unclear in 6
patients. Coughing was documented in 5 patients, vomiting in 2 patients, and asymptomatic
asthma in 1 patient. Neither cocaine use nor a history of pneumothorax was noted in any of
the patients.
The most common initial symptoms of SPM were neck swelling (11 patients) and neck
pain (10 patients). Nine patients were initially seen with odynophagia, and 7 patients had
chest pain (usually retrosternal). Less common symptoms included dyspnea (5 patients),
cough (5 patients), voice change (2 patients), and dysphagia (1 patient). On palpation
examination, 13 patients had cervical subcutaneous emphysema and crepitation. Table 2
summarizes the major literature published since 1990 on SPM.1-19
Among our cohort, pneumomediastinum was visible on radiography in all patients, but
no effusions were noted on any radiographs. Pneumomediastinum resolution was apparent on
chest radiography within 2 to 7 days (mean, 3.5 days). Axial CT of the chest was performed
4
in all patients. The finding of pneumomediastinum on axial CT was associated with comorbid
subcutaneous emphysema in all patients and with pneumoperitoneum in none. A contrast
swallow study was performed in 3 patients, who vomited, resulting in negative findings.
These 3 patients received limited oral intake, and prophylactic antibiotics were administered
for 2 to 3 days. The remaining patients were allowed a regular diet.
Eleven patients were initially admitted to the ward for observation, with lengths of stay
ranging from 3 to 7 days (mean, 3.3 days). There are no specific interventions for the
treatment of SPM; only rest and adjunctive treatment, such as analgesics, were indicated.
Within 3 to 7 days, clinical manifestations of SPM resolved in all patients, and radiographic
signs of the condition diminished.
DISCUSSION
Pneumomediastinum was first described by pathologist Laënnec in 1819 as a
consequence of traumatic injury.20 It is defined as free air or gas contained within the
mediastinum, which almost invariably originates from the alveolar space or the conducting
airways. The etiology of pneumomediastinum is multifactorial. Many authors distinguish
primary SPM as a form of pneumomediastinum that is not associated with blunt force or
penetrating chest trauma, endobronchial or esophageal procedures, neonatal lung disease,
mechanical ventilation, or chest surgery or other invasive procedures. The pathogenesis of
this disorder was described by Macklin and Macklin.21 The most frequent underlying factor is
alveolar rupture caused by overdistension or increased alveolar pressure. Alveolar rupture
allows bubbles of gas to disseminate along the pulmonary vasculature toward the hilum and
mediastinum and subsequently to the soft tissue of the cervical region through fascial planes
connecting these areas. Pneumomediastinum differs from pneumothorax in that there is a
disruption of parietal pleura with collection of air in the pleural space in pneumothorax; in
5
pure pneumomediastinum, the parietal pleura remain intact.
Spontaneous pneumomediastinum is rare among adults, observed in 1 of 44 511
emergency department visits.22 Children have increased frequency of SPM, seen in 1 of 800
to 1 of 15 150 emergency department visits.23 Our case series findings suggest that this
condition is seen predominantly in healthy thin young men, consistent with other published
studies.1-19 It is most common in the second and third decades of life. Associations of SPM
with a possible underlying elastic tissue disorder have been postulated.10 Other related
conditions include smoking and asthma.8,10
Precipitating and predisposing factors of SPM have been described in the literature.
Precipitating factors include those that provoke a Valsalva maneuver, including coughing,
sneezing, defecating, giving birth, and vomiting, in which straining against a closed glottis
may cause pneumomediastinum. Up to 32% to 66% of SPM cases have no identified
precipitating factors.23 In our series of 14 patients with SPM, coughing (in 5 patients) was the
most frequent predisposing factor.
According to previously published series of patients with SPM1-19, chest pain and
dyspnea are the most common initial symptoms. Head and neck manifestations are always
secondary to pneumomediastinum but represent the first warning of mediastinal emphysema
due to air accumulation, subsequently disseminating along the fascia to the cervical region.
According to data from case series, neck swelling, neck pain, and odynophagia are the most
common initial symptoms of SPM. Neck swelling (in 4%-86% of patients), neck pain (in
4%-70%), and odynophagia (in 4%-100%) were also frequently reported symptoms in the
literature review on SPM (Table 2). Otolaryngologists often saw patients with sudden onset
6
of neck swelling and neck discomfort or pain. The symptoms usually occur after events
associated with a Valsalva maneuver, such as coughing or vomiting. The primary symptom
among patients with SPM in the literature review was visible neck swelling with dull pain but
no inflammation, such as redness, erythema, or local heat. Otolaryngologists often found no
inflammatory infectious process in the neck or pharyngeal region. During the palpation
examination, observation of crepitation over the neck that was consistent with subcutaneous
emphysema was noted in almost every patient in our case series. Other frequently reported
symptoms were cough, voice change, and dysphagia. Voice change and dysphagia are
secondary to displacement (usually anterior) of the larynx and esophagus by air present
between the fascial planes (Figure 1). Less common findings on physical examination in
patients with SPM are crepitations occurring with reduced heart sounds (Hamman sign) on
pericardial auscultation.
The diagnosis of SPM is made based on radiologic findings. Chest radiography was
diagnostic among all patients in our case series (Figure 2). Chest CT was also performed in
all patients. We believe that chest radiography may not always be sufficient to make the
diagnosis of SPM. Computed tomography provides confirmation of the diagnosis, as well as
assessment of any associated causes or abnormalities. Chest CT was necessary to obtain a
definitive diagnosis and to exclude life-threatening differential diagnoses, as secondary
pneumo-mediastinum can be associated with a poor outcome. Neck soft tissue radiographs
were obtained in most of our patients because of neck pain and swelling. Neck soft tissue
symptoms are caused by air leaking from the mediastinum and extending subsequently to the
soft tissue of the cervical region through fascial planes connecting these areas (Figure 1). A
gastrointestinal (GI) workup (eg, esophagography) should be reserved for patients with
significant GI symptoms, such as those of Boerhaave syndrome, which is associated with
7
high mortality and morbidity. Diagnostic challenges include differentiating
pneumomediastinum from medial pneumothorax and pneumopericardium.
As reported previously1-19 and as seen among our case series, SPM generally follows a
benign and self-limiting course, and the usual treatment is bed rest, analgesics, and oxygen
therapy. Patients in our study responded well to treatment, with clinical manifestations
resolving and radiographic signs of SPM diminishing within 3 to 7 days. No complications,
such as pneumothorax or tension pneumomediastinum, were observed in our case series,
similar to the other recent studies in the literature review. In the absence of any primary cause
of pneumomediastinum, such as infection, instrumentation, esophageal rupture, or trauma,
the prognosis for recovery is excellent, and recurrence is unlikely.
In conclusion, SPM is a rare benign entity. Despite that it primarily affects the chest,
symptoms in the neck or throat are common manifestations of SPM. Patients may be seen
with symptoms predominantly in the head and neck region; awareness of this among
otolaryngologists is important because of the variable presentation and clinical course of
SPM. Important and potentially life-threatening differential diagnoses must be excluded
using appropriate investigations.
8
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9
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11
Figure 1. Lateral radiograph of neck soft tissue shows subcutaneous emphysema with a large
amount of air in the tissues of the neck. Air separates the esophagus from the spine (small
arrows).
Figure 2. Anteroposterior radiograph shows the continuous diaphragm sign (small arrows),
pneumomediastinum parallel to the cardiac shadow (large arrow), and subcutaneous
emphysema.
12
Table 1. Characteristics of 14 patients with spontaneous pneumomediastinum
Variable
Value
Male sex (No.)
13
Female sex (No.)
1
Age, mean (yr)
18.8
Predisposing and precipitating factors (No.)
Vomiting
2
Coughing
5
Asymptomatic asthma
1
Idiopathic
6
Symptoms (No.)
Neck swelling
11
Neck pain
10
Odynophagia
9
Chest pain
7
Dyspnea
5
Cough
5
Voice change
2
Dysphagia
1
Diagnostic methods (No.)
Neck soft tissue radiography
Chest radiography
Chest computed tomography
Esophagography
Treatment
Admission (No.)
Length of stay (day)
Outpatient (No.)
Prophylactic antibiotics (No.)
Limitation of oral intake (No.)
Observation alone (No.)
11
14
14
3
11
3.3
4
3
3
11
13
Table 2. Summary of recent literature on spontaneous pneumomediastinum
Chest
manifestation
Head and neck manifestation (%)
Age, Male
(%)
Source (date)
mean sex Chest
(yr)
(%)
Neck
Neck Odynoph
Voice
Dyspnea
Cough
Dysphagia
swelling pain
agia
change
pain
Kelly et al (2010)
19
[1]
Iyer et al (2009) [2]
30
Perna et al (2010)
27.3
[3]
Gunluoglu et al
27
(2009) [4]
Al-Mufarrej et al
25.5
(2008) [5]
Caceres et al (2008)
27
[6]
Takada et al (2008)
20.1
[7]
Macia et al (2007)
21.3
[8]
Mondello et al
25
(2007) [9]
Newcomb and
20
Clark (2005) [10]
Freixinet et al
21
(2005) [11]
Koullias et al
17.5
(2004) [12]
Weissberg and
Weissberg (2004)
15-37
[13]
Jougon et al (2003)
25
[14]
Miura et al (2003)
17.5
[15]
Gerazounis et al
12-32
(2003) [16]
Kaneki et al (2000)
17.6
[17]
Panacek et al (1992)
25
[18]
Abolnik et al (1991)
18.8
[19]
82
77
29
82
24
0
…
…
0
66
63
44
…
18
…
45
5
5
70
60
26
…
…
…
33
…
38
87
26
43
86
4
4
26
65
0
65
58
41
…
11.8
17.8
…
…
0
57
54
39
14
…
4
32
…
…
72
68
44
…
20
52
…
…
8
83
85
49
…
44
37
24
12
12
56
100
88
10
44
100
77
66
22
78
89
67
6
11
…
…
6
3
75
78
40
78
…
…
9
…
6
75
66
8
50
33
25
41
…
8
55
81
45
54
…
…
36
…
36
92
50
…
8
25
…
…
16
8
88
25
62
…
…
12
…
…
…
82
72
59
22
…
…
27
22
…
79
100
58
79
70
…
…
…
39
76
47
18
65
0
17
…
…
…
84
88
60
4
48
…
…
…
40
14
Figure 1
Figure 2
15