OnabotulinumtoxinA for trigeminal neuralgia: a review of the available data

Abstract

Trigeminal neuralgia (TN) is a unilateral disorder characterized by brief electric-shock-like attacks of pain, abrupt in onset and termination and limited to the distribution of one or more divisions of the trigeminal nerve 1 . It is reported to have a prevalence of 0.1-0.2 per thousand and an incidence ranging from about 2 to 7.1/100 000/year and extending up to 20/100 000/year in individuals over 60 years of age. The condition is more common in women than in men (ratio 3:2) 2 . Treatment includes pharmacological therapy, usually with membrane stabilizers; invasive or minimally-invasive (mainly percutaneous procedures) surgical therapies; and radiosurgery 3 . In 2005, OnabotulinumtoxinA (BoNT/A) was reported to be effective for cases of TN that failed to respond to other therapies 4 . The therapeutic effect of BoNT/A in TN was first mentioned after a serendipitous finding by Wang and Jankovic 5. Reporting a case similar to the one that motivated a previous study by our group 4 , Jankovic described a patient who presented with hemifacial spasm and TN whose TN improved after treatment of the hemifacial spasm with BoNT/A. Since then, case reports and case series have been published in neurology, headache, pharmacology and pain medicine journals 6,7,8,9,10,11,12,13,14 . This literature, although suggesting the therapeutic effects of BoNT/A in TN, has been challenged 15 or even ignored by panels of experts 16,17 . The present review was undertaken to give readers an overview of the available evidence that BoNT/A has a therapeutic effect on TN. AbstrActTrigeminal neuralgia (TN) patients may develop side effects from centrally acting drugs, have contraindications for neurosurgical procedures, or experience relapse during conventional therapies. OnabotulinumtoxinA (BoNT/A) has been reported to be effective for TN, although this finding has been challenged. An overview of the available evidence based on a narrative/qualitative analysis of the literature is presented. About 90% of patients who receive BoNT/A show an improvement, a higher figure than that reported for the placebo effect of BoNT/A for other headaches. Tolerability of BoNT/A is good, and its few side-effects are transient. The articles reviewed were mainly case reports, case series and open-label trials; however, randomized controlled trials have endorsed the efficacy of BoNT/A for TN. This evidence, together with a better understanding of the analgesic mechanisms of BoNT/A and its proven efficacy in treating other pain syndromes, supports the use of this toxin as a therapeutic option for TN.Keywords: trigeminal neuralgia, botulinum neurotoxin type A, botulinum-A toxin, onabotulinumtoxinA, neuropathic pain. resumO Pacientes com neuralgia do trigêmeo (NT) podem apresentar efeitos colaterais decorrentes do uso de drogas psicoativas, contra-indicações a procedimentos neurocirúrgicos ou perda da eficácia destas terapias. A neurotoxina botulínica do tipo A (NTB/A) tem demonstrado ser eficaz no alívio da NT, ainda que este achado tenha sido contestado. Uma...

Intraoral administration of botulinum toxin for trigeminal neuropathic pain

“…A few small randomized clinical trials have been conducted and also suggested that botulinum toxin may be helpful in the treatment of neuropathic pain, namely painful peripheral diabetic neuropathy (20), CRPS (21), and trigeminal neuralgia (22). For the same reasons botulinum toxin has been used elsewhere in the body to help manage uncontrolled neuropathic pain, extraoral use in the orofacial region has been explored (23). While the exact mechanism for analgesic effect in such patients is not known, the adverse effects of botulinum toxin are generally minor and local to the injected tissues, such as dryness and muscle asymmetry.…”

Single-dose botulinum toxin type a compared with repeated-dose for treatment of trigeminal neuralgia: a pilot study

“…Since 2002, there have been many reports concerning BTX-A treatment for TN [ 9 – 19 ]. Several randomized clinical studies have focused on efficacy and safety issues [ 25 ]. These findings have triggered much interest in clarifying questions such as the optimal dose, duration of therapeutic efficacy, and common adverse reactions [ 26 ].…”

Two Doses of Botulinum Toxin Type A for the Treatment of Trigeminal Neuralgia: Observation of Therapeutic Effect from A Randomized, Placebo-Controlled Trial

“…The application of BTX-A to relieve TN was first reported in 2002, and its safety and effectiveness was later confirmed by series studies [3][4][5][6][7][8][9][10][11][12][13]. In 2012, our team conducted the first RCT study in this field, and obtained the prima facie evidence of BTX-A for TN.…”