CHAPTER 34. Pain, anxiety, neurological and psychogenic disorders
within my private knowledge, two persons who had suffered alike from toothache and cancer, have pronounced the former to be on the scale of torture, by many degrees to be the worse’ Confessions of an English Opium Eater Thomas de Quincey 1821
Pain is the most common symptom for which patients seek help. Approximately 40% of the British population only visit a dentist for pain relief. Toothache can be so agonisingly severe that De Quincey, as well as quoting the opinions shown above, also claimed that it had made him dependent on opium. In the lay mind, dentistry and pain are inseparable and there is the persistent belief that dental treatment is necessarily painful. This belief emphasises the important point that pain has strong emotional associations which, in turn, may be determined to a varying degree by patients’ preconceptions. Emotional disturbance itself can also produce the symptom of physical pain.
There are many causes of oral or maxillofacial pain (Box 34.1). Pulpitis and periapical periodontitis as sequels of dental caries are by far the most common causes. The source of such pain is usually obvious on examination, but some sources of dental pain can be exceedingly difficult to identify (Box 34.2).
• Disease of teeth and/or supporting tissues
• Oral mucosal diseases
• Diseases of the jaw
• Pain in the edentulous patient
• Postoperative pain
• Pain triggered by mastication
• Referred pain
• Neurological diseases
• Psychogenic (atypical) facial pain
• Dentine hypersensitivity, cracked tooth or cracked cusp syndrome
• Periapical periodontitis
• Lateral (periodontal) abscess
• Acute necrotising ulcerative gingivitis
• HIV-associated periodontitis
These account for most causes of pain in this area. Disease of the teeth (usually the result of dental caries) and adjacent tissues must always be excluded in the investigation of pain.
Pulpitis is usually the cause when hot or cold food or drinks trigger the pain. It is also the main cause of spasmodic, poorly localised attacks of pain which may be mistaken for a variety of other possible causes. The pain of acute pulpitis is of a sharp lancinating character peculiar to itself, impossible to describe but unforgettable once experienced. Recurrent attacks of less severe, subacute or chronic pain, often apparently spontaneous, suggest a diseased or dying pulp.
Investigation of pulpitis has been discussed earlier (Ch. 4). The only non-dental condition that is indistinguishable from pulp pain by the patient is the pain of herpes zoster (Ch. 12). If no local cause can be found after the most careful search, it is important to look for early signs of the characteristic rash. Herpes zoster is an uncommon cause of toothache-like pain, but countless teeth have been extracted in patients with prodromal zoster under the mistaken impression that the pain was dental.
ACUTE PERIODONTITIS → Summary p. 448
Pain from acute periapical periodontitis should be readily identifiable as there is precisely localised tenderness of the tooth in its socket. Radiographs are of little value in the early stages but useful after sufficient destruction shows itself as loss of definition of the periapical lamina dura. In other cases, acute inflammation may supervene on chronic and a rounded area of radiolucency is seen.
Acute maxillary sinusitis can rarely cause similar tenderness of a group of teeth, particularly upper molars, as discussed later.
The tooth is tender in its socket, but is usually vital and there is deep localised pocketing (Ch. 6). Occasionally, both a periodontal and periapical abscess may form together on a non-vital tooth with severe periodontal disease, or a periodontal abscess may be precipitated by endodontic treatment when a reamer perforates the side of the root.
ACUTE NECROTISING ULCERATIVE GINGIVITIS AND HIV-ASSOCIATED NECROTISING PERIODONTITIS
Acute ulcerative gingivitis usually causes soreness, but when it extends deeply and rapidly, destroying the underlying bone, there may be severe aching pain. In such cases, the diagnosis is usually obvious clinically. HIV-associated periodontitis presents a somewhat similar picture and is acutely painful.
Pericoronitis usually produces a characteristic clinical picture (Ch. 6).
PAINFUL MUCOSAL LESIONS
Ulcers generally cause soreness rather than pain, but deep ulceration may cause severe aching pain. Carcinoma, in particular, causes severe pain once nerve fibres become involved. It is important to emphasise again that early carcinoma is painless; pain is a late symptom. By the time that pain becomes troublesome the tumour is usually easily seen unless it is far back in the mouth.
As mentioned above, Herpes zoster causes severe aching pain, sometimes indistinguishable from toothache, because of involvement of cervical ganglia (Ch. 12).
PAINFUL JAW DISEASES
The important feature of these conditions (Box 34.3) is that, as well as the history and clinical presentation, the provisional diagnosis depends on the radiographic findings. Fractures and osteomyelitis should be recognisable by such means. Other lesions of the jaws, by contrast, sometimes have less clear-cut clinical and radiographic features and the differentiation of (say) an infected cyst from a malignant tumour may be difficult.
• Infected cysts
• Malignant neoplasms
• Sickle cell infarcts
With the exception of fractures and osteomyelitis, diagnosis depends on biopsy and histological examination.
PAIN IN EDENTULOUS PATIENTS
These conditions (Box 34.4) differ from most others because dental causes can be excluded. The chief difficulty is to decide whether the pain is due to the dentures themselves, or to some condition of the mucosa or jaws on which a denture is pressing.
Traumatic ulcers, usually the consequence of over-extension, often cause trouble with a new denture. After the denture has been relieved, these ulcers heal within 24–48 hours. Persistent ulceration after adequate relief of the denture is likely to be due to some more serious cause, particularly a neoplasm. Biopsy is then essential. Later, dentures cause traumatic pain when the bone has become severely resorbed, allowing the denture to bear on the mylohyoid ridge or genial tubercles. These result from the patients having worn the denture too long, and a well-designed replacement is necessary.
Lack of freeway space due to excessive vertical dimension of the dentures prevents the mandible and masticatory muscles from reaching their natural rest position. This causes the teeth to be held permanently in contact. Aching pain is usually felt in the fatigued masticatory muscles, but the excessive stress imposed on the denture-bearing area sometimes causes pain in this region. Very occasionally, patients seem unable to tolerate dentures however carefully they are constructed and complain of such symptoms as gripping, burning, or ‘drawing’ pain, particularly under the upper denture. These symptoms are not associated with any physical changes and are psychogenic.
It is usually straightforward to decide whether pain is caused by the dentures themselves or by some lesion under the dentures. Denture stomatitis is painless, but surprisingly few other mucosal diseases affect the denture-bearing area itself. Lichen planus can extend to the sulcus and impinge on the margin of the denture-bearing area. The most important condition to be excluded is carcinoma, either affecting the alveolar margin or in the labial or buccal sulcus, or floor of the mouth. Persistent lesions, whether ulcerated or not, developing beneath or at the margins of dentures, must be biopsied without hesitation, as it is in the edentulous age group that the incidence of carcinoma is highest. A carcinoma can persist for a long time with minimal symptoms and the patient may notice no more than the fact that the fit of the denture has deteriorated.
Jaw lesions causing pain in the edentulous patient may be associated with a swelling or an area of radiolucency and have been discussed above. A painful swelling of the jaw in the edentulous patient is probably most often due to an infected residual cyst. Malignant tumours are very much less common but must be considered, as they cannot be reliably distinguished from cysts and other benign conditions by radiography alone. Histological examination is therefore essential. Osteomyelitis of the jaws in edentulous patients must be considered virtually only in those who have had radiotherapy to this region. In such patients, denture ulceration can allow infection to penetrate and set up persistent painful chronic osteomyelitis of the ischaemic bone.
Retained roots or, rarely, late eruption of buried teeth beneath a denture become painful as they reach the surface, causing the mucosa to be pinched between them and the denture. This trouble will be obvious on clinical or radiographic examination, as are the late effects of a healed malaligned fracture.
Important causes are summarised in Box 34.5. By far the most common cause of pain after dental extractions is alveolar osteitis (dry socket), which can usually be recognised on clinical examination (Ch. 6). Fracture of the jaw following operative treatment is rare but can also be recognised from the history and by clinical and radiographic examination. Forcible opening of the mouth under general anaesthesia, particularly for removing wisdom teeth, can damage the temporomandibular joint and lead to persistent pain on opening or during mastication. Postoperative osteomyelitis should be a thing of the past, but could develop in an immunodeficient patient with, for example, unrecognised leukaemia.
• Alveolar osteitis (dry socket)
• Fracture of the jaw
• Damage to the temporomandibular joint
• Damage to the nerve trunks or involvement of nerves in scar tissue
Persistent postoperative pain is sometimes ascribed to damage to nerve fibres, either as a result of operative trauma or by involvement in scar tissue. However, if there is no objective evidence of disturbed sensation, there is little or nothing abnormal to be found. Operative intervention in the attempt to relieve such pain may do more harm than good. In some such cases, there is complaint of persistent pain unresponsive to treatment but without any organic cause.
Rarely, damaged nerve tissue may proliferate to form a traumatic neuroma which is tender to pressure. Its excision should lead to relief of the pain. However, meticulous investigation of postoperative pain is important as it is a major cause of medicolegal claims.
PAIN INDUCED BY MASTICATION
The common dental cause for pain on mastication is apical periodontitis, but any condition which causes the tooth to be tender in its socket, whether it be a lateral periodontal abscess or, occasionally, maxillary sinusitis, can cause this symptom (Box 34.6).
• Disease of teeth and supporting tissues
• Pain dysfunction syndrome
• Diseases of the temporomandibular joint
• Temporal arteritis
• Trigeminal neuralgia (rarely)
• Salivary calculi
The least common cause of pain during eating is organic disease of the temporomandibular joint. Pain during eating comes much more frequently from the many other structures involved. Fractures and dislocations of the temporomandibular joint are usually obvious from the history, their effects on the occlusion and the radiographic changes (Ch. 11).
Pain dysfunction syndrome
Dull, aching pain, often associated with clicking sounds from the joint, episodes of locking and some limitation of opening, in varying combinations are characteristic. Young women are predominantly affected and there is typically a strong neurotic element (Ch. 11).
Cranial arteritis → Summary p. 448
The typical manifestation of cranial (giant-cell) arteritis is headache, but though uncommon, is a particularly important cause of masticatory pain because of the high risk of blindness. It should be considered particularly in patients over middle age with this symptom. The pain is due to ischaemia of the masticatory muscles, caused by the arteritis and is comparable to intermittent claudication (Ch. 11). Corticosteroids are effective in controlling the disease and relieving symptoms. They should be given when there is headache or masticatory pain associated with a tender scalp vessel and a high ESR.
The characteristic pain is very occasionally triggered by mastication. Trigeminal neuralgia may then be misdiagnosed as dental or due to pain dysfunction syndrome. However, the quality of these types of pain is quite different, as discussed later.
Particularly when obstructing the parotid duct, these can cause pain when salivation is triggered by eating. Hence, the history of the relationship of the pain to stimulation of salivation rather than to mastication itself is distinctive.
PAIN FROM EXTRAORAL DISEASE
Extraoral causes of pain are summarised in Box 34.7. Antral disease can cause pain felt in the upper teeth, but a sinus radiograph should provide the diagnosis. Salivary gland and ear diseases typically cause preauricular pain. They may simulate temporomandibular joint symptoms, but are rarely mistaken for dental problems.
Diseases of the maxillary antrum
• Acute sinusitis
• Carcinoma, particularly when it involves the antral floor
Diseases of the salivary glands
• Acute parotitis
• Salivary calculi (see above)
• Sjögren’s syndrome
• Malignant neoplasms
Disease of the ears
• Otitis media
• Neoplasms in this region
Acute sinusitis is the most common paranasal disease that causes facial pain but antral carcinoma is rare (Ch. 28).
Mumps is a common cause of pain from, and swelling of, the parotid glands. In children, the diagnosis is usually quickly made on clinical grounds. In adults, the diagnosis may not be immediately suspected and, occasionally, these patients think they have dental disease.
Suppurative parotitis is uncommon but can be a complication of dry mouth. Acute parotitis may therefore be seen as a complication of Sjögren’s syndrome or irradiation damage to the glands. Sjögren’s syndrome itself can occasionally cause parotid pain and swelling of the glands (Ch. 18).
Swelling rather than pain is usually the first symptom of malignant tumours of salivary glands. Parotid gland tumours can also cause facial palsy and, finally, ulceration and fungation.
Myocardial infarction usually causes constricting or crushing pain substernally, but pain may radiate down the inside of the left arm or up into the neck or jaw. Rarely, cardiac pain is felt in the jaw alone. There is even a case on record where a dentist recognised the cardiac cause of jaw pain to the dismay of his patient, who was a cardiologist. This pain can come on at any time, at rest or during exercise. The clinical picture is variable but, in typical cases, the patient is obviously anxious, pale and sweating with a rapid pulse and low blood pressure.
INTRACRANIAL AND PSYCHOLOGICAL DISORDERS
Trigeminal neuralgia is one of the most important of these conditions (Box 34.8).
• Trigeminal neuralgia
• Multiple sclerosis
• Herpes zoster
• Postherpetic neuralgia
• Migrainous neuralgia
• Intracranial tumours
• Bell’s palsy
• Psychogenic pain (atypical facial pain)
Trigeminal neuralgia → Summary p. 448
Typical features are summarised in Box 34.9. Elderly patients are affected, and though the pain is excruciatingly severe, there is complete, or almost complete, relief between spasms. During an attack the patient’s face is often distorted with anguish, while between attacks the patient may appear apprehensive at the thought of recurrence. The severity of the pain may also make the patient depressed.