6.4Etiology of Xerostomia

Many patients complain of a dry mouth but yet lack objective evidence of hyposalivation (hyposialia). The feeling of oral dryness is associated with a lack of saliva, yet many patients with hyposalivation do not complain of dry mouth. Because oral dryness is a subjective complaint, it is not surprising that there is a huge variation in the patient’s threshold of discomfort or other symptoms. Xerostomia is also impacted by tolerance and adaptation over time.

Older patients in particular often complain of a dry mouth; indeed, in the older age groups, up to 25% of patients have this complaint. Medications are usually responsible for this symptom in such cases [6, 7], but 10% of healthy young adults also complain of persistent xerostomia and note that it influences their overall quality of life [8].

A 15-year longitudinal study of xerostomia in people between 50 and 65 years of age showed an almost linear increase with age in the prevalence of xerostomia [9]. Dry mouth is also a common periand postmenopausal symptom [10].

In general, however, in HEALTHY men and women, there are NO age-associated differences in parotid and submandibular salivary flow rates, either at rest and with 2% citrate stimulation [11].

Xerostomia can stem from many causes other than SS (Table 6.2). The cause of xerostomia is sometimes simple such as smoking or mouth-breathing [12]. Smokers often complain of daytime xerostomia [9]. Medications are the most common cause. Medications with anticholinergic or sympathomimetic activity are the most frequent offenders. Irradiation of the major salivary glands as part of cancer therapy and bone marrow transplants often lead to xerostomia.

The main other causes of hyposalivation to be considered in the proper circumstances are dehydration, HIV disease, hepatitis C virus infection, and sarcoidosis (Algorithm 6.1).

6.5Orofacial Manifestations in SS

Diminished salivary gland function and parotid gland enlargement are among the most prevalent manifestations in SS [13] but there are others, as shown in Table 6.3.

SS may affect not only the salivary glands but may also result in neurological manifestations.

6.5.1Salivary Involvement

Hyposalivation has been recognized as a prominent feature of SS since the first descriptions of the syndrome. Because saliva is essential to oral health, patients who have hyposalivation have difficulty with functions such as swallowing and speech, and may develop oral or salivary gland infections. Some complain of a burning sensation within the mouth [14].

Table 6.2 Causes of xerostomia

•Interference with neural rransmission:

–Medications/drugs

Anticholinergic drugs: e.g., atropine, scopolamine Sympathomimetic drugs; e.g., ephedrine

Anti-neoplastic agents that directly damage salivary glands Antireflux agents, e.g., proton-pump inhibitors Antidepressants

Selective serotonin reuptake inhibitors Tricyclic antidepressants

Other psychoactive drugs Antihistamines Benzodiazepines Nicotine

Opioids Phenothiazines

Antihypertensives

Alpha-1 antagonists (e.g., terazosin and prazosin) Alpha-2 agonists (e.g., clonidine)

Beta blockers (e.g., atenolol, propanolol) Drugs that deplete fluid: diuretics

•Autonomic dysfunction

–Cholinergic dysautonomia

–Dysautonomia

–Endocrine (diabetes, hypothyroidism)

–Ganglionic neuropathy

•Central nervous system conditions

–Alzheimer disease

–Anxiety or stress

–Bulimia nervosa

–Hypochondriasis

–Psychogenic disorders

•Dehydration

–Diabetes mellitus

–Diabetes insipidus

–Diarrhea and vomiting

–Hypercalcemia

–Renal disease

–Severe hemorrhage

•Starvation

•Cancer therapy

–Chemotherapy

–Chemoradiotherapy

–Hematopoietic stem cell transplantation/bone marrow transplantation/chronic graft-versus-host disease

–Irradiation (radiotherapy or radioactive iodine)