Neuropathic Orofacial Pain Part 1‐Prevalence And Pathophysiology

Abstract

Neuropathic pain is defined as "pain initiated or caused by a primary lesion or dysfunction in the nervous system". Neuropathic orofacial pain has previously been known as "atypical odontalgia" (AO) and "phantom tooth pain". The patient afflicted with neuropathic oral/orofacial pain may present to the dentist with a persistent, severe pain, yet there are no clearly identifiable clinical or radiographic abnormalities. Accordingly, multiple endodontic procedures may be instigated to remove the likely anatomical source of the pain, yet the pain persists. There have been few studies and limited patient numbers investigating the condition. Two retrospective studies revealed the incidence of persistent pain following endodontic treatment to be 3-6% and 5% of patients; one author with wide experience in assessing the condition estimated its prevalence at 125,000 individuals in the USA alone. In one study, 50% of neuropathic orofacial pain patients reported persistent pain specifically following endodontic treatment. Patients predisposed to the condition may include those suffering from recurrent cluster or migraine headaches. Neuropathic pain states include postherpetic neuralgia (shingles) and phantom limb/stump pain. The aberrant developmental neurobiology leading to this pain state is complex. Neuropathic pain serves no protective function, in contrast to physiological pain that warns of noxious stimuli likely to result in tissue damage. The relevant clinical features of neuropathic pain include: (i) precipitating factors such as trauma or disease (infection), and often a delay in onset after initial injury (days-months), (ii) typical complaints such as dysaesthesias (abnormal unpleasant sensations), pain that may include burning, and paroxysmal, lancinating or sharp qualities, and pain in an area of sensory deficit, (iii) on physical examination there may be hyperalgesia, allodynia and sympathetic hyperfunction, and (iv) the pathophysiology includes deafferentation, nerve sprouting, neuroma formation and sympathetic efferent activity.

Orofacial pain: basic mechanisms and implication for successful management

“…Orofacial pain, like pain elsewhere in the body, is usually the result of tissue damage and the activation of nociceptors, which transmit a noxious stimulus to the brain 18 . However, due to the rich innervation of the head, face and oral structures, orofacial pain entities are often very complex and can be difficult to diagnose.…”

Trigeminal Neuropathic Pain Alters Responses in CNS Circuits to Mechanical (Brush) and Thermal (Cold and Heat) Stimuli

“…After a third molar tooth extraction (estimated to be Ͼ10 million/year in the United States, according to the American Dental Association), there is a 0.5-3% rate of phantom tooth pain (Marbach, 1993). Studies indicate that the incidence of persistent pain after endodontic treatment is ϳ5% (Vickers and Cousins, 2000). Other studies indicate that this surgery may produce acute (3.57%) or persistent (0.91%) dysesthesias, or outright injury of the lingual nerve (2.1%) (Gulicher and Gerlach, 2000).…”

Odontalgia atípica mandibular: relato de caso

“…Além da sensibilização central e plasticidade neuronal, uma deficiência nos mecanismos de modulação de dor contribui para a manutenção da dor neuropática 14,15 . O exame físico da odontalgia atípica deve buscar a análise do comprometimento da patologia, seja periférico ou mais central, podendo ser realizado através do uso anestésico, tópico ou por bloqueio, das fibras periféricas 16 . Caso esse procedimento reduza a intensidade da dor, podese entender que o comprometimento periférico é significativo e um tratamento tópico com pomadas compostas de anestésicos e capsaicina deve ser instituído 17 .…”

“…Os campos receptivos são então aumentados, o que leva à interpretação de estímulos tácteis como dolorosos 16,18,19 . É preciso que inicialmente se estabeleça o correto diagnóstico antes da instauração de procedimentos, a fim de evitar abordagens ineficazes, a exemplo da extração de elementos dentários do caso apresentado.…”