This condition arises due to a fracture of more than one bony orbital walls of paranasal sinuses and tearing of adjacent sinus mucosa, and communication of a sinus with the orbit is established. This fracture usually involves the ethmoid, and sometimes involves frontal, sphenoid, and maxillary sinuses. The air usually enters the orbit when the pressure within the upper respiratory tract is increased due to expiratory efforts, nose blowing or sneezing. Orbitopalperbal emphysema
Orbitopalpebral emphysema refers to the trapping of air inside both the soft tissues of the orbit and the eyelid. It is usually a sequelae of a true orbital emphysema. When too much air accumulates inside the orbit, the orbital septum ruptures due to high intraorbital pressure. Air may then pass freely from the orbit into the eyelids through the break in the orbital septum. Stages
There are four stages of orbital emphysema. Stage I
Stage I orbital emphysema can only be diagnosed with radiological films. There is only a small amount of intraorbital air, and the patient does not show any clinical signs or symptoms. Stage II
Stage II orbital emphysema develops as the intraorbital air volume increases, causing the eyeball to displace horizontally or vertically (globe dystopia) or to protrude anteriorly (proptosis). The patient may experience diplopia as a result of the globe displacement. Stage III
Stage III orbital emphysema develops when the limits of spontaneous decompression are exceeded.
By reformatting these transverse images or taking coronal images, the examination of orbital floor and roof is permitted. Helical scanning is preferred as it has a lower imaging time and radiation dose comparing to conventional scanning, especially when reforming transverse helical scans into coronal images. The staging of orbital emphysema can then be determined with visual acuity examination and ophthalmoscopy. A disadvantage of using a CT scan is that when detecting air after orbital trauma, the presence of a wooden foreign object can give a false positive result of orbital emphysema. The wooden object can mimic the presence of orbital emphysema. Therefore, patients’ medical history is crucial in making the correct diagnosis. Other tests
Conventional radiography is commonly employed for imaging orbital injuries and identifying orbital fractures. It can be used to diagnose orbital emphysema because it shows the presence of air in the orbit best while the patient is standing upright. Skull films of posterior-anterior, lateral projections, and orbital rim views are recommended to show fractures in orbital rims and walls. However, CT scan is better than conventional radiography in the diagnosis of the condition, as it has a lower high false-negative rate and non-diagnostic rate.Orbital emphysema can also be diagnosed by magnetic resonance imaging (MRI). Although MRI has a low sensitivity for detecting orbital fractures, it can be used to evaluate rectus muscle pathology, optic nerve pathology, and brain pathology, as well as vascular injury. Treatment
Orbital emphysema on its own is a mild and self-limiting disease.