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Paper text:
orbital emphysema is usually caused by trauma and fracture of an orbital bone , allowing air to pass from the sinuses into the orbit .
we present a case of orbital emphysema with no history of trauma , sneezing , or surgery .
a 67-year - old - woman was admitted to our department complaining of left exophthalmos that had been present and started slowly worsening 1 month ago ( fig .
there was no history of trauma , sinus disease , sneezing , or sinus surgery .
the extent of forward displacement of the eyeball was 15 mm on the right and 22 mm on the left by hertel exophthalmometry .  
( a ) left exophthalmos , 15 mm on the right and 22 mm on the left by hertel exophthalmometry .
axial imaging of computed tomography ( b , c ) showing left frontal sinus pneumocele and orbital emphysema protruding the eye ball forward .
coronal imaging ( d ) showing that the left frontal sinus was remarkably enlarged and the orbital roof was partially absent .
the frontal sinus ostium was occluded with the mucocele that served a one - way valve between the frontal and the ethmoidal sinuses .
computed tomography scanning showed left orbital emphysema , which protruded the eyeball forward ( fig .
the left frontal sinus was remarkably enlarged associated with a partial defect of the orbital roof .
the frontal sinus ostium was tightly packed with mucus with consequent blockage of the communication with the nasal cavity ( fig .
the orbital roof constituting a part of the frontal sinus wall was thinned and partially lost .
after removal of mucus and the frontal sinus mucosa , the sinus ostium was enlarged by drilling the surrounding bone to fully open the blockage of the communication of the frontal sinus with the nasal cavity ( fig .
a series of follow - up computed tomography scans for 3 months after surgery showed no appearance of orbital emphysema ( fig .
3 ) .   surgical view showing that the periorbita was observed through the bony defect ( black arrow ) .
after removal of mucus as well as the frontal sinus mucosa , the sinus ostium was enlarged by drilling the surrounding bone to fully open a blockage of the communication of the frontal sinus with the nasal cavity ( white arrow ) .  
( a , b ) computed tomography scans and ( c ) picture after operation showing removal of orbital emphysema and improvement of left exophthalmos .
a rare cause of orbital emphysema is infection , complication of nasal surgery , sneezing , nose blowing , airplane travel , esophageal rupture , and frontal sinus pneumocele.1234 frontal sinus pneumocele is characterized by excessive pneumatization of frontal sinus extending beyond the margins of the frontal bone , with thinning and defect of the bony wall and extension of air into the surrounding soft tissue .
it is proposed that a redundant mucosa or mucocele may serve as a unidirectional valve at the sinus ostium , and that repeated air trapping due to sneezing or nose blowing may result in dilation of the sinus , pressure necrosis .
consequently , this may cause thinning and defect of the sinus wall.35 in the current case , the patient may originally have had frontal sinus pneumocele that has been proposed a cause of orbital emphysema.3 under such conditions , one can imagine that the patient have would have minor head trauma and light sneezing , triggering this orbital emphysema , even if the patient complained of no such experience .
the management of orbital emphysema associated with frontal sinus pneumocele depends on the clinical presentation and imaging .
if there is clinical manifestation of orbital compartment syndrome such as sudden orbital pain , visual disturbance , or restriction of ocular motion , emergent decomposition is necessary and can be made by canthotomy or needle aspiration of trapped air.3 other surgical managements have previously been reported , such as frontal sinusotomy with anterior orbitotomy through a subbrow incision3 and an endoscopic approach.6 on the other hand , muthiah et al reported that orbital emphysema associated with frontal sinus pneumocele resolved spontaneously as the air was absorbed.7 therefore , conservative management should be considered for nonemergent cases at first . in our case , we chose surgical intervention for orbital emphysema because the patient complained of exophthalmos on the affected side .
we selected a transcranial approach because frontal craniotomy can facilitate drilling of the bone surrounding the sinus ostium and radical removal of mucosa in sinuses .
because an endoscopic sinusotomy can merely remove mucus and thickened mucosa , there is a potential risk of recurrence .
we present a case of orbital emphysema associated with frontal sinus pneumocele that was treated by a transcranial approach . with a transcranial approach
, the sinus ostium can be fully enlarged by drilling the surrounding bone so as to prevent a recurrence of frontal sinus pneumocele .
orbital emphysema is usually caused by trauma and fracture of an orbital bone , allowing air to pass from the sinuses into the orbit . 
 orbital emphysema without any significant trauma is rare . 
 we present a case of a 67-year - old - woman who complained of left exophthalmos without any history of trauma , sneezing , or sinus surgery . 
 computed tomography scanning showed left orbital emphysema protruding the eyeball forward . 
 the left frontal sinus was remarkably enlarged associated with a partial defect of the orbital roof , allowing air entry into the orbit . 
 in addition , the frontal sinus ostium was occluded with the mucocele that served as a one - way valve between the frontal and the ethmoidal sinuses . 
 we performed frontal craniotomy and removed the mucocele and the inner table of frontal bone to communicate the frontal sinus with the nasal cavity . 
 after operation , her exophthalmos was improved .