A The salivary glands include the parotid (lying along the jawline beneath the ear), submandibular (under the jaw) and sublingual (under the tongue) pairs of glands, along with a large number of minor salivary glands. The parotid and submandibular glands drain into a single duct each, but the sublingual glands drain into eight to 20 ducts, so obstruction by a stone is rare.
Salivary duct stones - called 'calculi' - are generally made up of calcium carbonate and calcium phosphate. Symptoms include swelling of the face or neck, pain in the face or mouth and a dry mouth. These symptoms are usually most noticeable while eating or drinking.
In 80-90 per cent of cases, 'sialolithiasis' - medicalese for salivary stones - most often affects the submandibular glands and, rarely, the salivary glands under the tongue. They are usually solitary, although multiple stones are found.
Some stones sit within the gland and cause no symptoms. In other cases, the stone may block the glandular duct either partially or completely. When this happens, the gland typically becomes painful and swollen, and usually infected, and saliva flow is partially or completely blocked.
Although the exact cause(s) of such stones is unknown, some stones may be related to dehydration, which thickens the saliva - but not likely in your case, given the amount of water you say you drink every day.
Sj"ogren's syndrome, which causes dryness of the mouth and of other mucous membranes, can increase the risk of stone development and, in some autoimmune disorders, the body attacks its own salivary glands, causing saliva to thicken and form stones.
Stones form when salivary flow is poor, so they can form when you don't eat enough and so have less of a demand for saliva; a poor flow allows debris to become a place where minerals can attach and accumulate.
Some medications - certain antihistamines, blood-pressure drugs such as diuretics and psychiatric medications such as antidepressants - can also decrease saliva production. So, if you're taking any of these types of drugs, it may well be contributing to your stone formation.
Finally, it's the chemicals in saliva that crystallise into stones, so the pH (alkaline-to-acid balance) of saliva may affect their formation. Saliva is more alkaline (and contains more of the precipitating chemicals) in the submandibular glands and is more acidic in the parotids, the second most commonly affected site for stones.
You may help to prevent future salivary duct stones by:
* drinking six to eight glasses of water a day
* massaging the salivary gland after meals to break up thickened saliva
* seeking effective treatment for autoimmune disorders
* using only prescription antihistamines instead of over-the-counter versions. You could also try herbal help in the form of 'bitters' - chamomile flowers, chicory root, dandelion root and leaf, Calendula flower, gentian, horehound, motherwort, mugwort and vervain - all of which increase the flow of saliva
* stopping smoking
* eating a healthy diet
* practising good oral hygiene, with regular toothbrushing and flossing.
If a stone does return, the usual treatment is for your doctor to push the stone out of the duct or, failing that, to make a small incision to remove them.
However, sometimes the location or size of the stone will require more invasive surgery - the possible side-effects of which can be more serious. Surgical removal of the stone may lead to scarring of the duct opening, which will then prevent the gland from draining properly. The subsequent buildup of saliva and precipitation of chemicals could, in turn, lead to problems such as further stone formation and infections.
And, as your doctors suggest, where salivary-stone formation appears to be chronic, it may be safer to remove the whole of the salivary gland rather than risk the constant need for surgery and its attendant risks. But you are right to prefer not to undergo such a procedure. One possible complication of such an operation is damage to the nearby nerves - something which you have already suffered with your tongue. Sometimes, the nerves cut during surgery grow back abnormally and become connected to sweat glands of the face, causing flushing and sweating when you chew. This condition then requires yet further medications or additional surgery to correct.
Furthermore, if the stones are in the parotid gland, this will impact on the facial nerve, which controls movement on that side of the face, and passes through the parotid. Removal of or damage to this nerve can result in paralysis and loss of sensation in the tongue or face on that side.
But these invasive forms of surgery are not always necessary. Salivary duct endoscopy and shockwave lithotripsy - using ultrasound waves to break up stones in situ - have been found to be an effective, yet minimally invasive, non-surgical treatment for salivary stones (Lancet, 1992; 339: 1333-6; Curr Opin Otolaryngol Head Neck Surg, 2003; 11: 173-8; Laryngoscope, 2004; 114: 1069-73). Stone-clearance rates are higher among patients who: are under age 46; have stones located in ducts or in the parotids rather than in the submandibular glands; have stones that are less than 7 mm in diameter; and have undergone six or fewer treatment sessions. Complete clearance of stones may take from 10 to 58 months after lithotripsy to occur. Side-effects are minor, often involving petechiae - pinpoint-sized haemorrhages of the tiny blood vessels (capillaries) in the skin.
Finally, you may wish to consider alternative treatments such as the homoeopathic remedy Calculus renalis. This - as the name suggests - is derived from kidney stones but, nevertheless, is reported to also work on salivary stones, which respond by growing smaller and being reabsorbed. Also, traditional Chinese herbal medicine uses various herbs in combination to treat and prevent salivary stones. As these medicines work holistically, you may wish to see a Chinese herbalist to get the combination that best suits you.