Humans have four sets of sinuses: a pair above the eyes (frontal), under the eyes (maxillary), between the nose and eyes (ethmoid), and posterior to the nose and eyes in the middle of the skull (sphenoid). Any of these can be blocked, inflamed or irritated, causing sinus pain with or without congestion.

Sinus Abnormalities

The nasal septum separates one side of the nose from the other. If not straight, this can cause bone spurs that project into the nasal lining. The more crooked (deviated) the septum is, the worse the pain can be. There are other nose structures, such as the middle turbinate (a bone that protrudes into the nasal passage), that, when oddly shaped or sized, can lead to sinus pain without congestion.

Inflammation

There are also nerves that send and receive impulses from inside the nose, and when these become irritated and swollen they cause tremendous pain in the sinus cavities. The cause of the inflammation could be a result of autoimmune disorders or hormones. In these cases inflammation usually occurs without congestion.

Hormones

During pregnancy and menstruation, women can experience swollen nasal passages caused by hormonal shifts. The swelling can lead to severe pain in any of the sinus cavities. Symptoms usually subside when the cycle or pregnancy is over.

Sinus Infection

It is possible to have an infection in your sinuses without congestion. This could happen after a respiratory illness or virus. The runny nose and sore throat might have cleared up, leaving just sinus pain. According to jacksonsinus.com, individuals can experience pain on one side only that worsens when they bend over, which can improve with medication.

Other Considerations

Sinus cavities can develop polyps, cysts or tumors that can obstruct nasal passages, causing breathing issues and pain that could be severe. Also, air pressure fluctuations or chemicals can irritate sinuses. Even seasonal allergies or asthma can cause sinus pain with no drainage.

Source:

Sinuscarecenter.com: When Sinus Pain Is the Only Nasal Symptom

Ghorayeb.com: Anatomy of the Sinuses

More Information:

Sinuses.com: Sinus CT Scans

Life Extension: Sinusitis