Atypical Odontalgia

Atypical Odontalgia

Atypical odontalgia (also known as persistent orodental pain syndrome) describes a heterogeneous group of pain syndromes that share in common the fact that the odontalgia cannot be classified as classic trigeminal neuralgia. The pain is continuous but may vary in intensity. It is almost always unilateral and may be characterized as aching or cramping rather than the shock-like neuritic pain typical of trigeminal neuralgia.

The vast majority of patients suffering from atypical odontalgia are female. Atypical odontalgia can occur at any age, but has a peak incidence in the fifth decade of life. The pain is felt in a single tooth or its surrounding area and occurs most commonly in the maxillary region.

Headache may occur with atypical odontalgia and is clinically indistinguishable from the tension type of headache. Stress is often the precipitating, or an exacerbating, factor in the development of atypical odontalgia.

Depression and sleep disturbance are also present in a significant number of patients. A history of dental or facial trauma, including dental extractions, root canal treatment, infection, or tumor of the head and neck may be elicited in some patients with atypical odontalgia, but in many cases no precipitating event can be identified.

What are the Symptoms of Atypical Odontalgia

The below table compares atypical odontalgia with trigeminal neuralgia. Unlike trigeminal neuralgia, which is characterized by sudden paroxysms of neuritic shock-like pain, atypical odontalgia is constant and has a dull, aching quality but may vary in intensity.

The pain of trigeminal neuralgia is almost always within the distribution of one division of the trigeminal nerve, whereas atypical odontalgia invariably involves just a single tooth, its surrounding gingival tissue, or underlying bone. The trigger areas characteristic of trigeminal neuralgia are absent in patients with atypical odontalgia. Most important, no findings of pathological condition of the painful tooth or adjacent gingival tissues are seen on physical examination.

Comparison of Trigeminal Neuralgia and Atypical Odontalgia

Pain Factor	Trigeminal Neuralgia	Atypical Odontalgia
Temporal pattern of pain	Sudden and intermittent	Constant
Character of pain	Shock-like and neuritic	Dull, aching, cramping
Pain-free interval	Usual	Rare
Distribution of pain	One division of the trigeminal nerve	One tooth and surrounding area
Trigger areas	Present	Uncommon
Underlying psychopathology	Rare	Common

How is Atypical Odontalgia diagnosed?

Radiographs of the head are usually within normal limits in patients suffering from atypical odontalgia, but they may be useful to identify a tumor or bony abnormality. Magnetic resonance imaging (MRI) of the brain and sinuses can help the clinician identify intracranial pathology such as tumor, sinus disease, and infection.

A complete blood count, erythrocyte sedimentation rate, and antinuclear antibody testing are indicated if inflammatory arthritis or temporal arteritis is suspected. Injection of the painful tooth with small amounts of local anesthetic can serve as a diagnostic maneuver to determine whether the tooth or adjacent structures are the source of the patient’s pain.

Differential neural blockade can help distinguish primary tooth pathology from atypical odontalgia and reflex sympathetic dystrophy of the face. Complete relief of pain after injection of the painful tooth with local anesthetic suggests a local pathological process, whereas incomplete pain relief suggests the pathological process is more central. Thus, the diagnosis of atypical odontalgia is a strong possibility of underlying pathological condition of the trigeminal nerve, adjacent bone, brain, or brainstem.

Complete relief of pain after ipsilateral stellate ganglion block is highly suggestive of reflex sympathetic dystrophy of the face. Psychological evaluation should be considered if significant coexistent depression or sleep disturbance is present.

Differential Nerve Block in the Diagnosis of Atypical Odontalgia

1. Record the patient’s pain level on a visual analogue scale of 0–10.

2. Isolate the painful area with cotton rolls and cheek retractor.

3. Dry the painful area with gauze.

4. Apply 20% topical benzocaine gel to the painful area.

5. Record the patient’s pain level on a visual analogue scale of 0–10 every 3 min for 15 min.

6. If the patient experiences incomplete pain relief, perform localized block of the painful tooth with 1% lidocaine 1.5 mL.

7. Record the patient’s pain level on a visual analogue scale of 0–10 every 3 min for 15 min.

8. If the patient experiences incomplete relief, perform ipsilateral stellate ganglion block with 0.5% preservative-free lidocaine 7–10 mL.

9. Record the patient’s pain level on a visual analogue scale of 0–10 every 3 min for 15 min.

10. Repeat this sequence on a separate visit to confirm the results.

Differential Diagnosis

The clinical symptoms of atypical odontalgia may be confused with pain of dental or sinus origin or may be erroneously characterized as trigeminal neuralgia. Careful questioning and physical examination usually allow the clinician to distinguish these overlapping pain syndromes.

Tumors of the zygoma, maxilla, and mandible, as well as posterior fossa and retropharyngeal tumors, may produce ill-defined pain that is attributed to atypical odontalgia. These potentially life-threatening diseases must be excluded in any patient with odontalgia.

Reflex sympathetic dystrophy of the face should also be considered in any patient with ill-defined odontalgia after trauma, infection, or central nervous system injury. As noted, atypical odontalgia is dull and aching, whereas reflex sympathetic dystrophy of the face causes burning pain and significant allodynia is often present.

Stellate ganglion block may help distinguish these two pain syndromes; the pain of reflex sympathetic dystrophy of the face readily responds to this sympathetic nerve block, whereas atypical odontalgia does not. Atypical odontalgia must also be distinguished from the pain of jaw claudication associated with temporal arteritis.

Treatment

The mainstay of therapy is a combination of drug treatment with tricyclic antidepressants and physical modalities such as oral orthotic devices and physical therapy. Trigeminal nerve block and intraarticular injection of the temporomandibular joint with small amounts of local anesthetic and steroid also may be of value.

Antidepressants such as nortriptyline at a single bedtime dose of 25 mg can help alleviate sleep disturbance and treat any underlying myofascial pain syndrome.

Orthotic devices help the patient avoid jaw clenching and bruxism, which may exacerbate the clinical syndrome. Management of underlying depression and anxiety is also mandatory.

Complications

The major pitfall in caring for patients thought to have atypical odontalgia is failure to diagnose underlying pathology that may be responsible for the patient’s pain.

Atypical odontalgia is essentially a diagnosis of exclusion. If trigeminal nerve block or intraarticular injection of the temporomandibular joint is being considered as part of the treatment plan, it must be remembered that the region’s vascularity and proximity to major blood vessels can lead to an increased incidence of postblock ecchymosis and hematoma formation, and the patient should be warned of this potential complication.

Clinical Pearls

Atypical odontalgia requires careful evaluation to design an appropriate treatment plan. Infection and inflammatory causes, including collagen-vascular diseases, must be ruled out. Stress and anxiety often accompany atypical odontalgia, and these factors must be addressed and treated.

The myofascial pain component of atypical odontalgia is best treated with tricyclic antidepressants such as amitriptyline. Dental malocclusion and nighttime bruxism should be treated with an acrylic bite appliance. Opioid analgesics and benzodiazepines should be avoided in patients with atypical odontalgia.