ABSTRACT
Abstract Nociceptive and inflammatory orofacial pain is highly prevalent in the population, which justifies the search for safer analgesics. There is increasing evidence of the analgesic and anxiolytic potential of Lavandula angustifolia essential oil (LAV EO), which may represent, when administered through inhalation, may represent a safer alternative for pain treatment. Objective to evaluate whether LAV EO has antinociceptive effect in the formalin test, and anti-hyperalgesic and anxiolytic-like effects in rats subjected to a model of orofacial postoperative pain. Methodology Female Wistar rats were exposed to LAV EO (5%) by inhalation for 30 minutes. After exposure, animals were injected with formalin (2.5%, 50 μL) or saline into the hind paw or upper lip and the number of flinches or facial grooming time, respectively, were evaluated. Likewise, on day 3 after intraoral mucosa incision, the animals were exposed to LAV EO and facial mechanical, and heat hyperalgesia were assessed. The influence of LAV EO inhalation on anxiety-like behavior was assessed in operated rats by testing them on the open field (OF) and elevated plus maze (EPM). Results LAV EO reduced the phase II of the paw formalin test and both phases of the orofacial formalin test. On day three post-incision, LAV EO reduced heat and mechanical hyperalgesia, from 30 minutes up to three hours, and reduced the anxiety-like behavior in operated rats without causing locomotor deficit. Conclusion LAV EO inhalation results in antinociceptive and anxiolytic-like effects in orofacial pain models, which encourages further studies on LAV EO indications and effectiveness on orofacial pain conditions.
ABSTRACT
Introduction: Trigeminal neuralgia (TN) is defined as sudden, usually unilateral, severe and brief pain episodes within the distribution of one or more branches of the trigeminal nerve. In some patients a constant background pain may persist, additionally to pain attacks, which can make difficult to differentiate the trigeminal neuralgia from other orofacial pain types. Objective: To review the classification, physiopathological aspects, epidemiologic data and pharmacological options to control pain related to trigeminal neuralgia. Literature review: One of the proposed etiologies for this condition is a localcircumscribed demyelination of the trigeminal nerve resulting in neuronal hyperexcitability and generation of ephaptic coupling, which would be responsible for the pain paroxysms. Initially, the treatment of patients with these pain characteristics is based on the use of anticonvulsants, in order to attenuate the ectopic-generated pain impulses. Carbamazepine is the first-line drug, but other anticonvulsants may be employed and have shown variable efficacy in the treatment of trigeminal neuralgia. Conclusion: According to the new classification of the International Headache Society, classic trigeminal neuralgia is divided in purely paroxysmal and with concomitant persistent facial pain. The pathophysiology is unclear, but trigeminal neuralgia seems to be the consequence of vascular compression of the trigeminal nerve near the brain stem. Although TN presents a low prevalence in general population (i.e. 5-30 new patients per 100,000), trigeminal neuralgia is an important clinical concern both by pain severity and difficulty of its satisfactory control. Anticonvulsants are the medication of choice in the treatment of trigeminal neuralgia; however, their use is associated with several adverse effects and possibility of treatment refractoriness.