Sphenoid sinusitis is the least common sinus condition (only 3% of sinusitis cases).
The sphenoid sinus is at the very back part of the nose and sits just beneath the base of the brain (neurosurgeons will often go through the sphenoid sinus to get easier access the brain for pituitary gland operations called trans-sphenoidal hypophysectomy).
The big problem with this rare cause of sinusitis is that infection of the sinus may cause a bad, dull, non-descript, vague headache that will not go away.
Classic sinus symptoms like a runny nose are usually not present, so the diagnosis is often overlooked. The headache may be made worse by changes in posture, walking, stooping down or prolonged standing.
The pain of sphenoid infection is so severe that really strong painkillers like morphine do not work, and the pain will often prevent sleep.
The location of the headache can be almost anywhere. The nerve supplying sensation from the sphenoid sinus is the posterior ethmoid branch of the ophthalmic division of trigeminal nerve.
This could result in pain being felt in the eye, or forehead. Some people will have pain in the back of the head (about 25%), or pain on top of the head (about 33%).
No single pain location is diagnostic. The pain in these cases can disrupt sleep. (Remember that hypnic headache is also a cause of headache that disrupts sleep).
In my own practice, I have probably seen only 2 cases that would meet this criteria in the last 4-5 years.
One had facial pain, the other had pain in the top of the head.
In Northern Ireland, where I practice, 20-25% of all people referred to me have a headache disorder. I estimate that chronic infection of the sphenoid sinus causing chronic daily headache must either be rare or frequently overlooked.
Blurred vision can also occur, as the main nerve from the eye - the optic nerve, passes very close to the upper outer boundary of the sphenoid sinus.
In about 4% of people there is no bony covering at the back of the sphenoid sinus, just a tough membrane, making the brain and nerves there more vulnerable. Sphenoid sinus infection should always be considered when trying to determine the cause of meningitis.
One paper reviewed 354 cases of sphenoid sinus problems (not all were sinusitis, some were sphenoid sinus tumors). About 200 of these 354 cases had isolated sphenoid sinusitis.
Of those 200 cases, 87% had headache as a symptom. Cranial nerves such as the optic nerve can be affected in sphenoid sinusitis, so blurred vision can occur.
If you are not aware of this condition, or don't consider it, you are unlikely to be diagnosed.
On a CT Scan of Brain or MRI Brain Scan, sinus inflammation is extremely common, and is often dismissed as irrevelant.
It is always worth reviewing CT images in chronic daily headache cases to determine whether the amount of sinus inflammation is severe enough to warrant ENT opinion.
If Sphenoid Sinusitis is suspected as a cause of chronic daily headache, then a CT Brain Scan and/or paranasal sinuses CT is probably the best single test.
If a CT shows an empty sphenoid sinus, you do not have sphenoid sinus headaches.
If there is a small amount of inflammation, it is unlikely that headaches are due to sphenoid infection, or at the very least, surgery to the sphenoid sinuses is going to be an expensive mistake.
In my own practice, I would not be expecting an ENT surgeon to operate unless the sphenoid sinus was almost completely full of inflammatory material or was showing signs of erosion towards the brain.
The other reason for operation is if there is concern that the lesion in the sphenoid is not infection, but one of the other causes of congestion:
Here's the different things that can cause or mimic sphenoid sinusitis:
The entry to the sinus is via a small hole in the upper middle front wall of the sphenoid sinus called the ostium.
If the entry to the ostium is blocked by inflammation of nasal lining (rhinitis), then decongestants and anti-inflammatory nasal spray (like flixotide) may help the sinus to drain.
More often, by the time isolated sphenoid congestion has been diagnosed, these have been tried on several occasions. It is likely that some sort of surgery would be recommended by your ENT surgeon.
The usual surgery, in modern practice, is FESS - Functional Endoscopic Sinus Surgery.
I am not an ENT specialist, so will not make too much comment.
However, you should know that FESS involves passing a fine endoscope up the nose. The surgeon tries to get the fine tube into the sinus to drain it, and take samples for laboratory analysis.
Patient satisfaction with FESS is usually high. FESS requires a lot of skill, and when operating on the sphenoid sinus there are several critical structures just through the wall - internal carotid arteries, the cavernous venous sinus, abducens nerve, optic nerve and the pituitary gland.
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If there are no references listed, please notify me, as this box should contain a list of information sources, or a link to a 'Systematic Review' of the topic discussed on this page.
Here's the list of 79 references from my systematic review of the Medline database. If you want to be updated on new cases when they appear, please sign up to my monthly newsletter.
Here's the link to the Google Drive spreadsheet with sphenoid sinusitis references.