Salivary gland stones form when the salts within the saliva crystallise and then they
can gradually build and the crystal gets bigger and bigger until it forms a blockage within
one of the salivary gland ducts.
We all form salivary gland stones. We form
microcalculi which are really tiny microscopic stones. Usually, they flush out of the gland
with the saliva. But at times of dehydration or infection, we think that these microcalculi
get lodged within the natural kinks and curves and bends of the salivary gland duct. They
can get lodged there and can then grow as salts within the saliva crystallise on these
microcalculi and they can get bigger. Again, once they’re large enough, they can block
the salivary gland duct. The salivary gland duct on average is about
2mm in diameter, so when a stone gets to 2mm or larger, you’re likely to start to get
symptoms of a salivary gland stone.
You can tell if you have a salivary gland
stone as you’ll start to get symptoms when it’s large enough to block one of the ducts.
It tends to be at times when you have something really tasty to eat that your saliva flow
increases and then a stone can block the duct and the saliva backs up behind it. This gives
symptoms of increasing pain and swelling of the glands that can really ruin your meals.
The swelling can take about 20 minutes or sometimes up to an hour or a bit more to gradually
subside and go down. There might be a salty taste that you notice in your mouth as
the saliva starts to come out. Symptoms can go on for several months to years
until at some point, it’s often that you’ll start to get infections within the glands
and at these times, the pain and the swelling will last much longer. Characteristically,
the pain and swelling won’t settle until antibiotics are given.
Salivary gland stones aren’t particularly common and it will be approximately 60 people
per million per year who have a symptomatic salivary gland stone. But because of this,
many doctors haven’t seen patients with salivary gland stones and so it might take
some time before the condition is realised and then an appropriate referral is made.
There are several different ways of removing salivary gland stones. The treatment of choice
depends on both the sight of the stone within the salivary gland and also the size of the stone.
If stones are really tiny, it might well be amenable to basket retrieval of the stone.
At this point, you could use an endoscope which is a thin tube and a camera at one end
and a light source at the other and put that directly into one of the salivary gland ducts.
Through this, you can see directly into the duct and you can see the stone. Once you can
see the stone, you can introduce small wire baskets through the endoscope and into the
duct system of the gland to grasp the basket and then on the camera system, you can see
that the stone is removed through the endoscope. If stones are a little bit larger, then there
are several different ways of breaking them into smaller pieces and so those smaller pieces
can either flush through the ducts spontaneously or make them small enough to be amenable to
basket retrieval. The site of the stone within the gland is
also really important because if they’re near the exit point into the mouth, you can
often feel them and they’re very amenable to maybe just a small incision to remove them.
However, if they’re much deeper back into the gland, that’s more challenging and often
for small stones isn't possible then the use of these endoscopes is really essential.
Much larger stones might be resistant to fragmentation or it may just be impractical
to try to keep breaking a really large stone down into small pieces because it might just
take too much time. If this is the case, then a surgical approach to remove them is possible
such as making a cut directly where the stone is if you can feel it and removing it directly
and then putting some dissolving stitches through the duct wall to close it and to aid
healing. This technique has reduced the need to remove
salivary glands to approximately 3% and in many centres, salivary gland removal is still
the treatment of choice but with salivary gland removal comes several risks. These risks
are a scar but also nerve damage. The particular nerves at risk if you’re removing an entire
salivary gland include a nerve that supplies movement to the side of the face so you can
have paralysis as a consequence of surgery. You could have weakness of the tongue and you
can also have altered taste sensation or sensation generally to the side of the tongue.
These minimally invasive techniques to remove the salivary gland stone but retain the gland
avoid many of the nerve complications of gland removing surgery. That’s why they’re so useful.