Sinusitis

Definitions & Key takeaways

Sinusitis is a common condition in which the paranasal sinuses become inflamed, which makes it more difficult for them to drain. The condition can be caused by a viral, bacterial, or fungal infection, or by other factors such as allergies. Symptoms of sinusitis include facial pain, headaches, fevers, congestion, nasal discharge, and a cough that's typically worse at night. Treatment may include antibiotics, decongestants, and pain relievers. In some cases, sinus surgery may be necessary to open up the wall of the infected sinus to allow it to drain more easily into the nasal cavity.

Watch video only
Sinusitis is inflammation of the paranasal sinuses - which are pairs of air spaces that surround the nose in the front of the face.
Usually, acute sinusitis can last up to four weeks, subacute sinusitis lasts between 1 to 3 months, and chronic sinusitis lasts more than 3 months.
When you breathe in, air flows through the nostrils and enters the nasal cavity, which is lined by goblet cells that release mucus.
That mucus is salty, sticky, and contains lysozymes, which are enzymes that help kill bacteria. Nose hairs at the entrance of the nasal cavity get coated with that mucus and are able to trap large particles of dust and pollen as well as bacteria, forming tiny clumps of boogers.
The nasal cavity is connected to four paired paranasal sinuses, named according to the bones in which they lie. The largest are the maxillary sinuses, found right below the eyes.
Then we have the ethmoidal and sphenoidal sinuses behind the eyes. Finally, the frontal sinuses are in the forehead, right above the eyes.
The paranasal sinuses act like tiny echo-chambers that help amplify the sound of your voice, which is why you sound so different when they’re clogged with mucus during a cold!
They also allow the inspired air to circulate for a bit so it has time to get warm and moist. Like the rest of the respiratory tract, the walls of the paranasal sinuses are made up of a mucosal epithelium.
The mucosal epithelium contains goblet cells, which produce mucus to trap small foreign particles, as well as columnar cells, which have cilia, which are tiny little hair like projections that move mucus, draining into the nasal passages.
One of these passages is also called a nasal meatus, and there are three; the superior, middle, and inferior meatus which help drain mucus.
The sphenoidal sinus drains to the spheno-ethmoidal recess, which is a small space in the nasal cavity right above the superior meatus.
The ethmoid sinus can be divided into posterior, which drains to the superior meatus, middle and anterior, both draining into the middle meatus.
And finally the maxillary and frontal sinuses drain into the middle meatus. Most cases of sinusitis are acute; and are the result of a viral infection.
The most common viruses include rhinovirus and parainfluenza virus which cause the common cold, and influenza virus which causes the flu.
Bacterial infections are another cause of acute sinusitis, and the most common bacterial strains are Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis.
Sometimes, bacterial sinusitis develops during or after a viral infection, other times it may develop due to a blockage of the normal flow out of the sinuses like a like a deviated septum.
In acute sinusitis, an invading pathogen often causes an inflammatory response to the invading pathogen. This causes the goblet cells to over secrete mucus which also leads to congestion.
At the same time, immune cells try to fight off these pathogens, and it can create pus - a mixture of pathogens, immune cells, and dead tissue.
If acute sinusitis doesn’t resolve quickly, then it’s considered subacute or chronic sinusitis. Now, in addition to infections, another cause of subacute or chronic sinusitis are environmental allergies, like to dust, pollution, or even fungi like Aspergillus in some immunocompromised people.
Finally, in response to allergies, some individuals develop chronic hyperplastic sinusitis, which is where the connective tissue of the sinuses undergoes hyperplasia, meaning it starts proliferating faster than usual.
This can give rise to nasal polyps, which are noncancerous outgrowths of inflamed tissue in the nose or sinuses. Symptoms of sinusitis are mainly associated with mucus build-up, which can cause facial pain, and a feeling of pressure in the face or even a headache.
When the cause is an infection, particularly a bacterial infection, it can cause fevers. There can also be changes in voice, and a change in a sense of smell and taste, or a cough that’s often worse at night because lying down causes mucus to pool.
Diagnosis of acute sinusitis is mainly based on symptoms, but in subacute or chronic sinusitis it can be helpful to get a CT scan or rhinoscopy, which is a tube containing a camera that is inserted into the nose to directly see the nasal passages and sinuses.
These would show evidence of clogged up sinuses that may be filled with mucus or pus. The main treatment for acute sinusitis due to a bacterial infection is antibiotics.
In addition, it can be helpful to use decongestants to help reduce swelling and promote better drainage. If there’s an underlying allergy or if there are nasal polyps, steroids or allergy medications can be helpful as well.
Finally, in cases of chronic or recurrent sinusitis, sinus surgery can be used to open up the wall of the infected sinus to allow it to drain more easily into the nasal cavity.
Alright, as a quick recap, sinusitis is a common condition in which the paranasal sinuses become inflamed, which makes it more difficult for them to drain.
It can lead to facial pain, headaches, fevers, and a cough that’s typically worse at night. Typically it’s caused by infections or allergies, and can be managed with medications, but in chronic or recurrent cases sinus surgery may be needed.