Effectiveness of the association between carbamazepine and peripheral analgesic block with ropivacaine for the treatment of trigeminal neuralgia

Journal of Pain Research Dovepress open access to scientific and medical research O r i g i n al R e s e ar c h Journal of Pain Research downloaded from https://www.dovepress.com/ by 71.90.6.221 on 16-Jul-2020 For personal use only. Open Access Full Text Article Effectiveness of the association between carbamazepine and peripheral analgesic block with ropivacaine for the treatment of trigeminal neuralgia This article was published in the following Dove Press journal: Journal of Pain Research 23 October 2010 Number of times this article has been viewed Laurinda Lemos 1,2 Ramalho Fontes 3 Sara Flores 2 Pedro Oliveira 4 Armando Almeida 1 Life and Health Sciences Research Institute (ICVS), School of Health Sciences, Campus de Gualtar, University of Minho, Braga, Portugal; 2 Hospital Center of Alto Ave, Unit of Fafe, Fafe, Portugal; 3Department of Neurology, Hospital São Marcos, Braga, Portugal; 4Products and Systems Engineering, Campus de Azurém, University of Minho, Guimarães, Portugal 1 Abstract: Treatment of trigeminal neuralgia (TN) is achieved by using adjuvant analgesics like antiepileptics, with carbamazepine (CBZ) being the first-line approach for TN patients, although side effects may be present. Other approaches using gabapentin, namely when associated with peripheral analgesic block of TN trigger points with the local anesthetic ropivacaine (ROP), resulted in decreased pain and daily drug intake (reduced side effects). This study evaluates if the association between CBZ and the peripheral block with ROP reinforces the clinical value of CBZ. In this parallel, double-blinded study, idiopathic TN patients were randomized to receive during 4 weeks either CBZ (CBZ; n = 21) or CBZ associated with the peripheral analgesic block using ROP (CBZ + ROP; n = 24). The primary outcome measures were the following: i) pain intensity, evaluated by the numerical rating scale; ii) number of pain crises; and iii) number needed to treat. Evaluation points were at the beginning (day 1) and end (day 29) of treatment and after a follow-up of 5 months (month 6). Both protocols resulted in a decrease of pain intensity and number of pain crises, but only the association CBZ + ROP showed i) a significant stronger reduction in pain intensity at month 6 and ii) a significant decrease in the daily dose of CBZ given to patients (both at day 29 and month 6). In contrast, the daily dose in CBZ-only patients remained constant or even increased. The number needed to treat for the association CBZ + ROP over the CBZ protocol reduced from 5 at the end of the 4-week treatment to 3 after the 5-month follow-up. Data reinforce the use of CBZ as a primary tool to control pain in TN patients, as the association CBZ + ROP i) improves the clinical qualities of CBZ, ii) strongly reduces the daily dose of CBZ, and iii) reduces the potential side effects attributed to high doses of CBZ. Keywords: trigeminal neuralgia, carbamazepine, ropivacaine, therapeutical association, pain intensity, daily dose Introduction Correspondence: Armando Almeida Life and Health Sciences Research Institute (ICVS), School of Health Sciences, Campus de Gualtar, University of Minho, 4710-057 Braga, Portugal Tel +351 253 604808 Fax +351 253 604809 Email submit your manuscript | www.dovepress.com Dovepress DOI: 10.2147/JPR.S13154 Powered by TCPDF (www.tcpdf.org) Neuropathic pain is a form of pain caused by a lesion or disease of the peripheral or central nervous system.1,2 It is a challenging condition to treat because of the following reasons: i) the heterogeneity of etiologies, symptoms, and underlying mechanisms; ii) poor response to conventional analgesics; and iii) the tendency for treatment being performed in a uniform fashion across the patient population.3 Trigeminal neuralgia (TN) (annual incidence of 4–5/100,000)4 is a type of neuropathy characterized by periods of intense paroxystic pain, usually of short duration and triggered by innocuous stimuli, although resulting in excruciating pain.5,6 A large number of cases of TN are idiopathic (primary or asymptomatic TN), usually with no detectable structural nerve Journal of Pain Research 2010:3 201–212 201 © 2010 Lemos et al, publisher and licensee Dove Medical Press Ltd. This is an Open Access article which permits unrestricted noncommercial use, provided the original work is properly cited. Journal of Pain Research downloaded from https://www.dovepress.com/ by 71.90.6.221 on 16-Jul-2020 For personal use only. Lemos et al lesion (includes the potential vascular compression of the fifth nerve in 15% of these patients) and a normal neurological evaluation.7,8 Like in other neuropathies, classic analgesics most frequently have no beneficial effects in controlling TN pain, even in secondary (symptomatic) TN, when it is associated with identifiable structural lesions, like a tumor or multiple sclerosis. Treatment is achieved by using adjuvant analgesics like antiepileptics (AE) and antidepressives.6,8 Contrary to other neuropathies, which use gabapentin as first-line treatment,1,9,10 the AE carbamazepine (CBZ) has for a long time been and still is considered the first-line pharmacological approach for TN patients.5–8,11,12 Several drawbacks are associated with CBZ intake. It produces a toxic epoxide metabolite and regular blood tests are thus recommended; it is also associated with 10% incidence of rashes, has a negative effect on bone density, may induce abnormal liver function, may result in interstitial pneumonitis, and presents significant interactions with other drug classes.3,6,8,12,13 Oxcarbazepine may be used in TN patients unresponsive to CBZ6,14 and, as second-line drugs, baclofen, lamotrigine,8 and pregabalin15/ gabapentin12,16–21 are at front line. In cases of CBZ intolerance, hypersensitivity, drug interactions or a narrower therapeutic index, and a higher degree of adverse side effects, gabapentin can be used as a second-line treatment.12,16–21 Recently, a combination of different drugs have been used to treat TN.7 When gabapentin is associated with the peripheral analgesic block of TN trigger points with the local anesthetic ropivacaine (ROP), the result is a significant decrease of pain intensity scores, number of paroxystic pain crises, and daily drug intake.21 As a consequence of smaller gabapentin doses during the combination gabapentin + ROP, a reduction of adverse side effects is obtained when compared with gabapentin in monotherapy, the latter presenting already a much lighter pattern of side effects than CBZ in monotherapy.12 Finally, one main objective of the clinical approach to TN, the functional capacity for the patients, was shown to be significantly improved when associating the oral intake of gabapentin with the peripheral block of TN trigger points with ROP.21 Following these data,21 the objective of the present study is to evaluate if a similar association between CBZ and the peripheral analgesia of TN trigger points with ROP reinfor (...truncated)