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Mar

CAUSES OF HEADACHES: SINUSITIS

The sinuses are large hollowed-out areas in the hones at the front of the skull. We need them for two reasons. Without sinuses the bones would be solid and heavy, so that our heads would tend to drop forward, especially as the bones concerned are at the front of the face, well away from the centre of gravity of the head, so the extra leverage the bone would create would be very great. The sinuses are small in children, and grow in size from the age of about six upwards, as the face enlarges towards the adult shape. The second reason why we need our sinuses is to give richness and reverberation to the voice.

There are four groups of sinuses – the frontal sinuses are in the bones of the forehead over the eyebrows; the maxillary sinus is underneath the eye, to each side of the nose; the ethmoid sinus is deeper in the facial bones, at the level of the eye, and the sphenoidal sinus is deep within the nasal cavity.

The sinuses are not closed spaces within the bones, but open – like little sacks, whose mouths open into the nasal cavity. This opening is called the antrum, Which is very important in sinusitis, as we’ll soon see.

The sinuses are lined with mucus-producing cells, together with cells with a covering of little hairs on top. These hairs are called cilia; they all move in unison and under the microscope the surface of the cells looks like waving fields of corn. St the cilia move, they propel any mucus that’s collected in the sinus out towards the antrum, from where the mucus enters the main nasal cavity, and thereafter can get lo the outside world, blown out on to the handkerchief or swallowed down the back of the throat. The mucus traps any dust, dirt or bacteria, and the cilia propel the accumulated rubbish out through the opening.

The weak point of the system is the small size of the antrum, which can all too easily become blocked. The cells lining the antrum can swell with inflammation (both allergic and infective), and the sinuses themselves can get infected, changing the thin mucus into thick infected pus, which is much harder for the cilia to waft out.

Once the antrum is blocked there’s a quick rise in pressure inside the sinuses as
more and more pus is produced. This pus is a mixture of bacteria, mucus, extra fluid from the inflamed cells lining the sinus, and white cells from the blood, which have migrated in to fight the infection.

Because the sinuses are carved out of bone, there is nowhere for this excess fluid to go, and consequently the pressure inside the sinuses rises very quickly. (It’s exactly the same as with a pimple on your nose. These are unbearably painful, simply because there is the same rise in pressure: when the pimple erupts to the outside surface and bursts there is an immediate reduction in pressure, and a corresponding immediate reduction in the amount of pain – even though the amount of pus released from that small spot may be little more than a pinhead.) It’s not the amount of pus that causes the pain, it’s the pressure it creates that causes the discomfort.

Sinusitis often follows a cold. The pain can be fiendish, with constant pain in the face or head, which gets worse on bending down, a stuffed-up sensation in the nose, and (often) infected green mucus coming down the nose. You may have a temperature. The sense of smell usually goes away (the sensitive organs of smell in the nose get liberally covered with sticky green pus, which delicate smells can’t penetrate), though sometimes when the infection is more or less localised to the sinus itself the patient can smell the pus.

You might think that infection in a small bony hole would be insignificant as far as the rest of the body is concerned – don’t you believe it. Sinusitis can make you feel dreadful, not just because it’s painful, but because a lot of pus is produced. The toxins that this pus liberates can enter the bloodstream and make you feel very rough.

An important diagnostic feature of sinusitis is that the pain is much worse when putting your head down. Often, there is local tenderness of the bone over the sinuses, and your doctor will press over these areas lo see if this increases the pain (pressing on the bone increases the pressure inside the sinuses even more, and it’s basically pressure that causes sinus pain).

In more difficult cases, or where there is long-continued sinus infection and Inflammation, it may be helpful for the doctor to arrange X-rays of the face and skull. It is easy lo see when the sinus is infected – normally sinuses have air inside them, which shows tip as dark shadows in the bone (X-rays penetrate air more easily than bone). II these air-filled sinuses get filled with pus or fluid, under X-ray they look more like the shading of the adjacent bone, so the radiologist can quickly spot which sinus is infected.

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