Management of Persistent Idiopathic Facial Pain

Persistent Idiopathic Facial Pain

Constant, unremitting pain (often perceived within deep tissues) presenting extraorally and/or intraorally with variable and fluctuating intensity. Also known as continuous neuropathic orofacial pain (formerly known as atypical odontalgia, atypical facial pain or phantom tooth pain).

Presentation

Population

• Generally thought to be uncommon. Epidemiological studies are difficult to perform and interpret due to a lack of consensus on the nomenclature and definition of this disorder and the variation in study methodologies.
• The following prevalence rates have been reported:
  • In the general population: 0.03%–1.0%
  • In a tertiary orofacial pain centre: 2.1%–10.6%
  • In patients who have undergone endodontic procedures (nonsurgical and/or surgical root canal treatments): 3.0%–12.0%
• More frequently reported by females in their 40s and 50s.

Signs

• Usually presents unilaterally.
• Trigeminal sensory abnormalities affect sensitivity to pain through either heightened (i.e., hyperalgesia, hyperesthesia, paresthesia, dysesthesia, and allodynia) or reduced sensitivity (i.e., hypoalgesia, hypoesthesia, and anesthesia) or a combination of both.
• Clinical examination, including dental and radiographic findings, does not find abnormalities or other reasons for the pain.
• Pain cannot be attributed to any other disorder.
• Patients have often visited multiple dental and medical practitioners to resolve their pain and have unsuccessfully undergone multiple interventions.

Symptoms

• Patients present with a complaint of pain, usually moderate to severe in intensity.
• A distinguishing feature is constancy of pain.
• Pain is disproportionate to various stimuli (e.g., thermal testing, percussion, palpation) and clinical characteristics usually remain unchanged for weeks, months or years.
• Pain may have started spontaneously (idiopathic) or due to an event, such as a traumatic injury, minor or major surgical procedure, or dental intervention (may be referred to as peripheral painful traumatic trigeminal neuropathy or chronic continuous dentoalveolar pain).
• Patients are convincingly able to identify the exact location of pain either extraorally and/or in the dentoalveolar complex (pain is localized in a tooth, teeth or edentulous mucosa).

Investigation

• Obtain thorough medical and dental patient history, including pain-related details.
• Perform extraoral (head and neck) and intraoral (teeth, gingival and oral soft tissue) examinations to rule out local pathology or other sources of pain.
• Complete a cranial nerve screening to determine abnormalities that require further investigation.
• Use diagnostic imaging. Dental imaging, such as bitewings, periapical and panoramic radiographs, is required to rule out dental causes of pain. Medical imaging, such as CT and MRI scans, is required to rule out central nervous system and hard/soft tissue pathosis.
• Consider performing neurosensory testing (e.g., cotton swab, pin prick, hot/cold stimuli) to determine if trigeminal sensory abnormalities are present. Mapping affected areas with sketches or photos provides additional information about dermatomal distribution.

Non-specific Tests

• Apply topical anesthetic (e.g., benzocaine 20%) to help determine if pain is peripherally generated.
• Use local anesthetic injections (short-acting without vasoconstrictor) to help with the diagnosis. If profound anesthesia is established but patient continues to experience pain, pain may be centrally generated.

Note: To date, there are no validated guidelines for testing orofacial somatosensory sensitivity.

Diagnosis

• Diagnosis of persistent idiopathic facial pain is mainly a diagnosis of exclusion based on information gathered through patient history, clinical examination, radiographs and adjunctive testing.

Differential Diagnosis

• Dental
  • Dental caries
  • Tooth fracture
  • Dentin hypersensitivity
  • Periapical/periodontal/osseous pathosis
• Musculoskeletal
  • Temporomandibular disorders
• Neurovascular
  • Primary headache, such as migraine, trigeminal autonomic cephalalgias and tension-type headaches, may be reported by patient as “toothache”
• Respiratory
  • Sinusitis and nasal cavity pathosis
• Cardiovascular
  • Cardiovascular disease, such as cardiac ischemia or acute myocardial infarction, may be reported by patient as “toothache”
• Endocrine
  • Diabetes
  • Hypothyroidism
• Dermatologic
  • Systemic lupus erythematosus
  • Rheumatoid arthritis
  • Sjögren syndrome 
  • Mixed connective tissue disease
• Neurologic
  • Central nervous system lesions
  • Neuralgias/pretrigeminal neuralgia
  • Herpes zoster/postherpetic neuralgia
• Other
  • Neoplasm due to primary tumours, metastatic disease, systemic cancer, distant nonmetastasized cancers, or cancer treatment

Treatment

Common Initial Treatments

• Diagnose and treat diseases and disorders that are most likely to be contributing factors to the patient’s chief complaint of pain, including peripapical/periodontal specific pathology as well as TMD.
• Use caution about performing multiple dental procedures when these situations arise. Repeated invasive dental interventions in the region of pain will not only fail to produce relief, but may also exacerbate the pain.
• If peripapical/periodontal specific pathology as well as TMD are not present then the dentist needs to unequivocally state these findings to the patient and refer to the appropriate clinician(s).

Alternate Treatments

Consider managing the patient with individual or combination therapies involving:

• Behavioural medicine approaches to assist with cognitive-behavioural therapy, coping strategies, relaxation techniques, biofeedback or psychotherapy.
• Pharmacologic approaches involving topical formulations (topical anesthetic or compounded medications) and/or systemic medications (antidepressants, anticonvulsants, anxiolytics, analgesics, antiarrhythmics). Guidelines for pharmacologic management of neuropathic pain, but not specific for trigeminal pain, have been established by the Canadian Pain Society, European Federation of Neurological Societies and the Neuropathic Pain Special Interest Group of the International Association for the Study of Pain.

Advice

• Refer to the appropriate clinician(s), such as an oral medicine specialist and/or a multidisciplinary team including a neurologist, anesthesiologist, pain physician and pain psychologist, who are capable and ideally interested in working the patient through the diagnostic process.

THE AUTHORS

	Dr. Klasser is associate professor, Louisiana State University School of Dentistry, division of diagnostic sciences, New Orleans, LA, USA.

Correspondence to: Dr. Gary D. Klasser, Louisiana State University School of Dentistry, Division of Diagnostic Sciences, 1100 Florida Ave., New Orleans, LA 70119, USA. Email: gklass@lsuhsc.edu

The authors have no declared financial interests.

This article has been peer reviewed.

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