Discussion
This study is the first to report a patient with obstructive sleep apnea
syndrome accompanying pneumoparotid, who was treated effectively with an
oral appliance and was followed up for 10 years.
Pneumoparotid describes the presence of air within the duct system
and/or parenchyma of the parotid gland secondary to its reflux through
Stensen’s duct. Parotitis associated with pneumoparotide is referred to
as pneumoparotitis. The pneumoparotid has been observed in glass blowers
until the first half of the 20th century.2-4 In those
days, 6%–10% of glass blowers had symptoms of suspected
pneumoparotid.4 More pressure is required to produce
larger glassware than delicate works and is more likely to cause
pneumoparotid.3, 4 Fortunately, subsequent innovations
and mechanization have dramatically reduced the pneumoparotid as an
occupational disease in glass workers.
Previous studies indicated an association between playing wind
instruments, such as the trumpet,1, 40, 41horn,1, 8, 42 tuba,43clarinet,8 flute,44 or
recorder.45 The Stensen’s duct valve prevents reflux
into the parotid gland by the smaller diameter of the orifice, which is
covered by redundant mucosal layers. The duct is laterally compressed by
the masseter muscle and the buccinator muscle contraction with an
increase in oral pressure. If the intraoral pressure exceeds the
protective mechanism, pneumoparotid can occur. Hyrtl1stated that when pressure in the oral cavity increases when playing a
wind instrument, air can enter retrogradely from the orifice of
Stensen’s duct. He added that it is easier for beginners to pull in the
air when they blow with their cheeks full, and less likely to occur when
they learn the appropriate embouchure technique.
Gazia et al.46 reviewed 49 reports and analyzed 54
patients with pneumoparotid or pneumoparotitis. The most frequent
etiology is self-induction by blowing the cheeks, which mainly involves
children for conflicts with parents, excuses for not going to school,
and nervous tics.46 Treatment with antibiotics and
steroidal anti-inflammatory drugs is the most common treatment.
Behavioral therapy is applied to remove bad habits such as blowing
cheeks; in some cases, supportive psychotherapy is
necessary.7, 8, 10, 11, 41
The relationship between pneumoparotid and sleep apnea syndrome remains
to be elucidated. This patient played a traditional Japanese wind
instrument, hichiriki (Fig 4), for 20 years from the age of 7 years. The
hichiriki is made of bamboo and is small compared to other wind
instruments (Fig 3), but it requires considerably high pressure to play
and emits a very large sound. Kreuter et al.47reported intraoral pressure while playing various wind instruments;
however, hichiriki was not included. Although the patient had seldom
played hichiriki for 30 years after the age of 27, it might be a
predisposing factor for enlargement of the orifice of the Stensen’s
duct. It was suspected that air reflux occurred during sleep, as the
crepitus and swelling in the parotid region were prominent when waking
up. The patient noticed the first swelling of the right parotid region
when he boarded an airplane and slept, and the airplane landed. The
sleep test indicated that the patient had a mild obstructive sleep apnea
syndrome. Playing hichiriki could be a predisposing factor, and the
first occurrence of pneumoparotid was triggered by an increase in
barometric pressure on the board. Considering the fact that the patient
boarded only once and pneumoparotid recurred, an increase in intraoral
pressure could be a plausible cause of pneumoparotid. Cabello et
al.22 reported a case of pneumoparotid, who blew
severely overnight. The patient in this study did not snore. He might
have been blown during sleep. The oral appliance with anterior opening
might have helped prevent the oral cavity from increasing intraoral
pressure during sleep. Oxygen saturation was considerably reduced, and
during sleep apnea, the oral pressure can be increased, resulting in
pneumoparotid.
In 1995, the American Sleep Disorders Association issued guidelines
stating that oral appliances are indicated for snoring, mild obstructive
sleep apnea, and moderate to severe sleep apnea if continuous positive
airway pressure is not accepted or if surgery is not
appropriate.48 Various oral appliances have been
increasingly used in the treatment of sleep apnea syndrome. Many
randomized trials have confirmed the effects of oral
appliances.49-55 Recent guidelines have extended
indications to moderate and severe sleep apnea patients when a patient
refuses continuous positive airway pressure therapy after being informed
about the risks.56 All appliances for the treatment of
sleep apnea syndrome are constructed with the goal of advancing the
position of the mandible and tongue in order to enlarge the airway or
reduce its collapsibility. This may lead to an improvement in the upper
airway dimensions and possible effects on upper airway muscle
tone.57 It is indispensable to suppress events that
increase intraoral pressure for patients in this report. An oral
appliance to reduce intraoral pressure with anterior opening was
fabricated and inserted during sleep (Fig 4). Some researchers have
reported patients with pneumoparotid accompanied by obstructive sleep
apnea syndrome.22-24 Long-term use of oronasal
continuous positive airway pressure23, 24 or
mandibular advancement device22 can be a potential
cause of pneumoparotid. In a recent review46, 24.1%
of patients with pneumoparotid disease revealed an unknown etiology. The
average age of idiopathic cases was 28.6 years. In some patients, the
pneumoparotid gland can be related to sleep apnea syndrome. Further
studies confirmed by polysomnography in larger cases may be necessary to
clarify this hypothesis.