OnabotulinumtoxinA injections for atypical odontalgia: an open-label study on nine patients

Journal of Pain Research Dovepress open access to scientific and medical research ORIGINAL RESEARCH Open Access Full Text Article Journal of Pain Research downloaded from https://www.dovepress.com/ by 5.135.254.153 on 21-Dec-2018 For personal use only. OnabotulinumtoxinA injections for atypical odontalgia: an open-label study on nine patients This article was published in the following Dove Press journal: Journal of Pain Research Rafael García-Sáez 1 Álvaro Gutiérrez-Viedma 1,2 Nuria González-García 1 Víctor Gómez-Mayordomo 1 Jesús Porta-Etessam 1,2 María-Luz Cuadrado 1,2 1 Headache Unit, Department of Neurology, Instituto de Investigación Sanitaria del Hospital Clínico San Carlos (IdISSC), Madrid, Spain; 2 Department of Medicine, School of Medicine, Universidad Complutense de Madrid (UCM), Madrid, Spain Introduction Correspondence: María-Luz Cuadrado Department of Neurology, Hospital Clínico San Carlos, Calle Prof. Martín Lagos, S/N, 28040 Madrid, Spain Tel +34 91 330 3511 Fax +34 91 330 3512 Email Atypical odontalgia (AO) constitutes one of the multiple causes of orofacial pain, affecting up to 6% in patients following endodontic procedures.1,2 According to the literature, this condition is known under several names, such as persistent dentoalveolar pain3 or phantom tooth pain.4 According to the third edition of the International Classification of Headache Disorders (ICHD-3), currently this condition is considered to be a subtype of persistent idiopathic facial pain. However, seeing as on occasions there is a traumatic trigger, according to the ICHD-3, this condition may also be considered to be a subform of post-traumatic painful trigeminal neuropathy.5 Despite the heterogeneity in the classification and the diagnostic criteria proposed in the literature, the clinical characteristics are well defined. AO leads to a situation of continuous pain, located on one or several teeth or in the alveolus after a tooth extraction, in the absence of signs of dental illness upon examination or in the imaging tests. Within the temporal pattern of chronic pain, some patients experience acute worsening. The quality of pain is variable, and it can irradiate to the maxillary and jaw region and/or other orofacial regions. 1583 submit your manuscript | www.dovepress.com Journal of Pain Research 2018:11 1583–1588 Dovepress © 2018 García-Sáez et al. This work is published and licensed by Dove Medical Press Limited. The full terms of this license are available at https://www.dovepress.com/terms. php and incorporate the Creative Commons Attribution – Non Commercial (unported, v3.0) License (http://creativecommons.org/licenses/by-nc/3.0/). By accessing the work you hereby accept the Terms. Non-commercial uses of the work are permitted without any further permission from Dove Medical Press Limited, provided the work is properly attributed. For permission for commercial use of this work, please see paragraphs 4.2 and 5 of our Terms (https://www.dovepress.com/terms.php). http://dx.doi.org/10.2147/JPR.S169701 Powered by TCPDF (www.tcpdf.org) Background: Atypical odontalgia (AO) manifests as continuous pain in the region of one or several teeth, in the absence of signs of dental pathology. Currently, there is insufficient evidence to establish treatment guidelines for AO. The aim of this study was to describe the effectiveness and safety of treatment with OnabotulinumtoxinA (OnabotA) on a series of patients with AO. Methods: Nine patients with AO (four males and five females, aged between 31 and 77 years) received injections of OnabotA in the region of pain. The dosage used in each procedure ranged between 10 and 30 U, spread between 4 and 12 injection sites along the gums (n=9), the lips (n=3), and the hard palate (n=1). The median follow-up time was 27 months (interquartile range, IQR 20–40) and the median number of injection sessions per patient was seven (IQR 4.5–9). The assessment variables included the change in the maximal intensity of pain on a 0–10 numerical rating scale (NRS), the response latency, and the duration of the effect. Results: All patients experienced a significant improvement, with ≥50% of reduction in the intensity of the maximal pain. The median of reduction of maximal pain after treatment was six points on the NRS (IQR 5–8.5). The response latency was 2–15 days and the duration of the effect was 2–6 months. No significant adverse reactions were registered. Conclusion: OnabotA may be a safe and effective option for the treatment of AO. Keywords: neuropathic pain, orofacial pain, painful trigeminal neuropathy, persistent dentoalveolar pain, persistent idiopathic facial pain, phantom tooth pain Dovepress Journal of Pain Research downloaded from https://www.dovepress.com/ by 5.135.254.153 on 21-Dec-2018 For personal use only. García-Sáez et al On occasions, hypo- or hyperesthesia and/or allodynia may exist in the symptomatic area.1 The pathophysiology of AO is not fully known, and several hypotheses have been proposed. The most supported hypothesis suggests a neuropathic origin, considering that trauma to teeth and/or periodontal structures may alter the tissue continuity and, therefore, generate changes in the periodontal nerve plexus leading to the appearance of peripheral sensitization.6 This hypothesis is based on some studies of animal models of dental extraction that demonstrate that the loss of dental pulp in an inflammatory environment induces pathological changes in the periodontal plexus.7 Furthermore, the abnormalities found during neurophysiological tests, for example, a decreased response of the blink reflex,8 and in quantitative sensory testing9 in patients with AO suggest the existence of abnormalities in the processing of trigeminal nociceptive information. The treatment of this condition is based on the results of case series and recommendations by experts, most of which recommend the use of tricyclic antidepressants and antiepileptics.1,6,10 Nonetheless, their effect is usually insufficient and often there are tolerance problems that limit their use. Other therapeutic modalities, such as the local injection of anesthetics,11 have also demonstrated inconsistent results. A therapeutic alternative could be the local injection of botulinum toxin, considering this was found to be effective in a case series of four patients published in 2016 by our own research group,12 as well as one case report.13 Onabotulinumtoxin A (OnabotA) is a polypeptide that has an analgesic effect, on the peripheral level, as well as centrally.14 Although its mechanism of action is not completely known, it has demonstrated to be effective in the treatment of many types of neuropathic pain, such as trigeminal neuralgia (TN),15–18 post-herpetic neuralgia,19 and painful diabetic neuropathy.20 The aim of this study was to describe our experience with the local injection of OnabotA on a series of nine patients, extending the follow-up of the previously reported four (...truncated)