Sinus transillumination
What is transillumination?
Transillumination means projecting or reflecting the light through the tissues of the body part affected. For example, the light is shown against the paranasal sinuses to identify signs of inflammation that indicates sinusitis.
This method uses principles of refraction and reflection to assess fluid accumulation in the affected part.
Why and when is transillumination used?
Transillumination is used for diagnosing sinusitis when the sinuses are tender and infected.
How is transillumination performed?
The procedure involves the following steps:
- Arrange for a light source that generates a high-intensity light. For example, a flashlight or transilluminator.
- Take the patient in a dark room.
- Press a flashlight or transilluminator against the cheek, the side of the nose, or the eyebrow (or on the supraorbital ring), lighting the sinuses from the outside.
- Observe the light patterns.
- If the sinuses are normal i.e. filled with air, the light will reflect through the sinuses.
- In case of swollen sinuses clogged with the mucus, the light will not reflect or reflect less.
- The location of the resulting light patterns will depend on the place selected for projecting the light.
- If the light is applied against the eyebrow, the light reflects on the forehead / a red glow appears above the eyebrow.
- If the light is applied against the cheekbone below the median plane of the eye or on the side of the nose, look for the patterns on the roof of the mouth.
How are the results of sinus transillumination interpreted?
The infection reduces transillumination of the affected paranasal sinuses. The swollen sinuses reflect less light, so the red glow of the reflected light on the cheeks is absent or dim. Non-swollen sinuses reflect more light through the skin, therefore red glow on the cheeks is clear and bright.
The degree of transillumination is divided into the following three categories:
- Opaque: No transillumination
- Dull / Equivocal: Less transillumination
- Normal: Appropriate transillumination
The opaque and dull categories imply (1) presence of secretion in the sinus, or (2) absence of sinus development. However, interpreting the results correctly requires training and experience.
Is sinus transillumination a useful method for sinusitis diagnosis?
Sinus transillumination may or may not be useful in diagnosing sinusitis and / or sinus tumors. For instance, the procedure may facilitate identifying and assessing fluid accumulation in the frontal and maxillary sinuses. However, transilluminating the sinuses of the young patients aged less than 10 years is difficult because of poor or asymmetrical development of the sinuses.
Transillumination cannot be performed on the sphenoid and ethmoid sinuses. The procedure is also not very helpful in diagnosing chronic sinusitis owning to mucosal defects.