Neuropathic Orofacial Pain

Key points

Trigeminal neuralgia

Trigeminal neuralgia (TN) is a paroxysmal, unilateral, short-lasting facial pain. Onset of TN may be abrupt or through a rarer preceding syndrome termed pre-TN.

Glossopharyngeal neuralgia

Glossopharyngeal neuralgia (GPN) is a severe, transient (fraction of a second to 2 minute), stabbing pain experienced in the ear, base of the tongue, tonsillar fossa, or beneath the angle of the jaw.³⁴ Pain is usually unilateral, but up to 25% of patients may experience bilateral pain.³⁵

The overall incidence is estimated to be between 0.2 and 0.7 per 100,000 individuals per year.³⁵ GPN occurs in adults, with a predilection for women and for patients over the age of 50.³⁶

GPN may be divided into

Nervus intermedius (facial nerve/geniculate neuralgia)

Nervus intermedius neuralgia is described as a severe, short-lasting pain in the auditory canal in the absence of other pathologic condition.³⁴ Nervus intermedius neuralgia is rare. Middle-aged adults seem to be predominantly affected, women more than men.⁴⁵

Superior laryngeal neuralgia

Superior laryngeal neuralgia is a rare disorder, with short-lasting pain, localized predominantly to one side of the laryngeal region and occasionally radiating to the lower lateral jaw or ear⁴⁹:

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  Paroxysmal pain

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  Lancinating pain

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  May be triggered by pressure to the skin above and lateral to the thyroid cartilage where the internal branch of the superior laryngeal nerve pierces the thyrohyoid membrane

Peripheral neuritis

Neuritis is a localized neural pathologic condition resulting from inflammation.

Herpes zoster and postherpetic neuralgia

Herpes zoster (HZ) results from the reactivation of the varicella zoster virus (VZV) within the cranial sensory ganglia. This viral reactivation leads to acute inflammatory changes within the ganglion of the affected dermatome but also extends peripherally along the length of the sensory nerve (neuritis), followed by neuronal destruction.⁶¹ These inflammatory changes and neural damage results in a painful vesicular rash in the associated unilateral dermatome.

HZ has a prodrome of less than a

Persistent idiopathic facial pain

Persistent idiopathic facial pain (PIFP) refers to persistent extraoral and/or intraoral pain along the territory of the trigeminal nerve that does not fit the classic presentation of other cranial neuralgias or another disorder.⁸⁰ PIFP is mainly seen in adult women with a prevalence of 0.03 to 1.0%.⁸⁰

Peripheral painful traumatic trigeminal neuropathy

Peripheral painful traumatic trigeminal neuropathy is defined as a spontaneous or stimulus-dependent pain or disturbed sensation, predominately affecting the receptive field of one or more divisions of the trigeminal nerve.

There is a combination of environmental (reduced social support),⁸⁹ psychosocial (anxious, introverted personalities),⁸⁹ and genetic factors (polymorphism in the gene encoding serotonin transporter),72, 89 which may vary an individual’s pain experience.

Summary

Further research is required to further the knowledge of neuropathic orofacial pain conditions as well as their management.

Newer therapies are currently being tested, such as novel cellular/molecular therapies, for neuropathic orofacial pain disorders, including local injection of autologous mesenchymal stem cells,⁹³ regulation of satellite glial cells,⁹⁴ and delivery of substance P,⁹⁵ endomorphin,⁹⁶ and cannabinoids.⁹⁷

Well-constructed trials are required to introduce more effective management