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15 Articles in Volume 18, Issue #5
Chronic Pelvic Pain: The Need for Earlier Diagnosis and Diverse Treatment
Cross-Linked Hyaluronic Acid for the Management of Neuropathic Pelvic Pain
Fentanyl: Separating Fact from Fiction
Gender Bias and the Ongoing Need to Acknowledge Women’s Pain
Letters to the Editor: 90 MME/day Ceiling; Ehlers-Danlos; Redefining Pain
Post-Menopausal MSK Pain and Quality of Life
PPM Welcomes Dr. Fudin and Dr. Gudin as New Co-Editors
Practitioner as Patient: Understanding Disparities in CRPS
States Take Action to Manage Opioid Addiction
Step-by-Step Injection Technique to Target Endometriosis-Related Neuropathic Pelvic Pain
The Many Gender Gaps in Pain Medicine
The Need for Better Responses to Vulvar Pain
Topical Analgesics for Common, Chronic Pain Conditions
Topical Medications for Common Orofacial Pain Conditions
What’s the safest, effective way to taper a patient off of opioid therapy?

Topical Medications for Common Orofacial Pain Conditions

Topical applications for trigeminal neuralgia, painful post-traumatic trigeminal neuropathy, burning mouth syndrome, myofascial pain, and TMJ arthralgia. Plus, cannabinoid spray and traumeel in orofacial treatment.
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Orofacial pain disorders comprise those painful conditions that affect the masticatory and cervical musculature, temporomandibular joints, intraoral structures, and the occipital, temporal, orbital, and frontal regions of the head. The diversity of pain complaints in this region often requires multidisciplinary management. As a result, patients may seek out practitioners from several specialties within medicine and dentistry for assessment and treatment. Having a basic understanding of these conditions may help patients avoid unnecessary office visits or diagnostic tests, as well as inappropriate treatments.

Orofacial pain disorders may be categorized as neuropathic, neurovascular, and temporomandibular joint (TMJ). Some of the most commonly treated conditions in a typical orofacial pain clinic may include: myofascial pain, trigeminal neuropathy, migraine, tension-type headache, chronic daily headache, TMJ arthritis and internal derangements, and burning mouth syndrome. Topical medications offer one modality with the following potential benefits compared to systemic approaches: topicals bypass first-pass metabolism; reduce systemic adverse effects; reduce potential for drug-drug interactions; provide direct, local analgesia; and improve patient compliance. This article provides a review of the topical medications currently used to treat orofacial pain, including their mechanisms of action and evidence supporting them, and provides insight into two emerging approaches: cannibinoids and traumeel.

Neuropathic Pain

Defined as “pain caused by a lesion or dysfunction of the somatosensory nervous system,”1 neuropathic pain is a chronic pain disorder resulting from injury to the nervous system. The injury may be to any site in the central nervous system (CNS) or the peripheral nervous system (PNS), and pain may vary in intensity. However, in many patients, the pain may be so severe that it impacts their quality of life and daily function.

Within the orofacial region, there are several diagnoses for neuropathic pain, including: trigeminal neuralgia, painful post-traumatic trigeminal neuropathy, burning mouth syndrome, post-herpetic neuralgia, trigeminal neuroma, and other neuropathies related to systemic diseases (eg, diabetes mellitus, cancer, drug-induced, HIV/AIDS-related).2 Described below, trigeminal neuralgia, painful post-traumatic trigeminal neuropathy, and burning mouth syndrome are the more common types of neuropathies seen in orofacial pain and dental practices according to the authors' practice and the literature.

Trigeminal Neuralgia

Trigeminal neuralgia is defined as a sudden, short-lived stabbing or electric shock-like pain affecting one or more of the branches of the trigeminal nerve (cranial nerve V). The characteristics of this disorder are so specific that the diagnosis is made by history alone, although brain imaging is sometimes necessary. Pain is paroxysmal, lasting from seconds to a few minutes.3 Trigeminal neuralgia may mimic tooth pain, and some patients report an intraoral trigger zone. While first-line treatment involves oral, medical management with carbamazepine, topical medications may also be effective. Specifically, topicals, such as 20% benzocaine, capsaicin, or a compounded formula of anticonvulsants, tricyclic antidepressants, serotonin and norepinephrine reuptake inhibitors, may be applied over an intraoral trigger zone (see below for more detail).

Painful post-Traumatic Trigeminal Neuropathy

Painful post-Traumatic Trigeminal Neuropathy (PTTN) is the term coined by the International Headache Society to describe neuropathic pain resulting from trauma to the trigeminal nerve.4 Historically, this type of pain has also been described as deafferentation pain, traumatic neuropathy, phantom tooth pain, and atypical odontalgia.4 PTTN affects approximately 2 to 3% of patients.5 Occurring intraorally, PTTN can be complex to diagnose and to treat. Usually, the pain is localized to the site of trauma, but the pain may move around the area as well.

The pathophysiology of PTTN involves both the peripheral and central nervous systems. Alterations to a damaged nerve may lead to the sprouting of neural fibers, causing increased nociception. These changes may be localized to the peripheral nerve and termed "peripherally sensitized." However, if central nerves become affected, then the nerves may be considered "centrally sensitized." PTTN results in normal sensory signals being perceived as painful. In a peripheral injury, there is upregulation of voltage-gated sodium (Nav1.3 and Nav1.8) and calcium (α2γ subunit) channels. In addition, there is often a down-regulation of potassium channels and a reduction in the threshold of heat sensitive channels. These changes may cause ectopic discharge, leading to increased release of glutamate and activation of the N-methyl-D-aspartate (NMDA) receptors located in the CNS. Furthermore, there is increased excitatory neurotransmitter release and decreased inhibitory neurotransmitter release, which facilitate the nociceptive response centrally. Sympathetic nervous system involvement may also be seen in neuropathic pain.6,7 All of these can serve as potential targets for pain management.

Topical Options for Trigeminal Neuralgia & PTTN

Treatment for trigeminal neuropathic pain conditions such as PTTN or neuralgia may involve both topical and systemic medications. When the injury only involves the peripheral branches of the nerve, topical medications such as those described below may be effective. However, when there is central sensitization, systemic medications are required. These include the usual classes prescribed for other neuropathies, such as anticonvulsants, tricyclic anti-depressants, serotonin, and norepinephrine reuptake inhibitors, or opioids.4,8

When there is an intraoral trigger zone for PPTN or trigeminal neuralgia, topical medications may be more effective due to their enhanced absorption via the oral mucosa versus the skin. Topical medications that have demonstrated significant pain relief in orofacial neuralgias and neuropathies include anesthetics, capsaicin, anticonvulsants, anti-inflammatories, α2-adrenergic agonists, and NMDA-receptor antagonists.9,10 In some cases, a compounded formula including some or all of these agents may be beneficial, but these formulations require the expertise of a pharmacist.

Last updated on: August 2, 2018
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Topical Analgesics for Common, Chronic Pain Conditions
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