Definition
Since the sphenoid sinuses (Sinus sphenoidales) are two interconnected, air-filled cavities in the sphenoid bone of the skull and lined with nasal mucosa, they belong, like the frontal and maxillary sinuses and the ethmoid cells, to the so-called paranasal sinuses. Like all paranasal sinuses, they serve to reduce the weight of the skull bone system and as a resonance chamber during voice and sound formation. Only the ethmoidal cells are already created at birth, all other paranasal sinuses only develop with advancing childhood: the sphenoidal sinuses are in the second place of development and form – after the frontal sinuses and before the maxillary sinuses – around the age of 3-6 years.
Cause
The causes for the development of a sphenoid sinusitis coincide with those of all other sinusitis: in the vast majority of cases, it is a secondary infection of the paranasal sinus mucosa caused by viruses or, more rarely, bacteria, which spread from a pre-existing respiratory disease (nasal/pharyngeal inflammation such as a cold) via the nasal passages into the sinus system. The causative pathogens are usually transmitted by a droplet infection. In 70-80% of cases, these are cold viruses such as rhinoviruses or adenoviruses.
An infection caused solely by bacteria is rather rare, mostly it is a kind of “additional infection”, since the paranasal sinus mucosa, which is attacked and swollen by the viral infection, forms an optimal breeding ground for bacteria (e.g. for haemophilus influenza or streptococcus pneumoniae). More rarely, an inflammation of the paranasal sinuses can also occur on its own, without a preceding respiratory disease, as a primary infection, whereby diseased tooth roots (dentogenic sinusitis), pathogens in the bath water (bath sinusitis) or extreme pressure fluctuations when diving or flying (barosinusitis) are considered the causes. But also in the context of allergies, paranasal sinus involvement can certainly occur.
Various anatomical peculiarities can thereby favour the development of a nasal sinus inflammation (sphenoidal bone inflammation) and are therefore considered to be risk factors. On the one hand, a crooked nasal septum (congenital or acquired) and on the other hand, so-called nasal mucosa polyps can impede the removal of the mucus formed in the sinuses via the nasal passages into the nasal cavity. This leads to a build-up of mucus in the sinus system, causing it to become narrower and less well ventilated. All of these factors together favour the settlement, survival and reproduction of viruses and bacteria and can lead to the development of an initially acute, but later also chronic sinusitis if the risk factors are not eliminated.
