-Activation of the trigemino-cervical system constitutes one of the first steps in the genesis of migraine. The objective of this study was to confirm the presence of trigemino-cervical convergence mechanisms and to establish whether such mechanisms may also be of inhibitory origin. We describe a case of a 39-years-old woman suffering from episodic migraine who showed a significant improvement in her frontal headache during migraine attacks if the greater occipital nerve territory was massaged after the appearance of static mechanical allodynia (cortical sensitization). We review trigemino-cervical convergence and diffuse nociceptive inhibitory control (DNIC) mechanisms and suggest that the convergence mechanisms are not only excitatory but also inhibitory.KEy WoRDS: DNIC, inhibitory control of pain, migraine.Massagem sobre o nervo occipital maior reduz a intensidade dos ataques de migrânea: evidên-cia de mecanismos de convergência inibitórios trigemino-cervical RESUMo -Ativação do sistema trigemino-cervical constitui um dos primeiros passos na gênese da crise de migrânea. o objetivo do estudo foi descrever um caso clínico que sugere a existência de mecanismos de convergência trigemino-cervical (CTC) e que esses possam ser do tipo inibitórios. Nós descrevemos o caso de mulher de 39 anos com migrânea episódica que mostrou significante melhora em sua cefaléia frontal durante suas crises quando realizava massagem sobre o território do nervo occipital maior ipsilateral a dor. A melhora clínica só ocorria quando a paciente apresentava alodinia mecânica estática (sensibilização cortical). Neste estudo nós revisamos os conceitos de CTC e de mecanismos de controle inibitório nociceptivo difuso (MCIN), sugerindo que este último é um elemento comprobatório da presença de CTC do tipo inibitório durante as crises de migrânea.PAlAvRAS-ChAvE: controle de dor, MCIN, enxaqueca.
The purpose of this study was to investigate if botulinum neurotoxin type-A (BoNT/A) had a preemptive antinociceptive effect in a formalin-induced orofacial pain model (FT). To test this hypothesis, male Rattus norvegicus were injected with isotonic saline solution 0.9% or BoNT/A administered as a 40 µl bolus, lateral to their nose, at 24 hours, 8, 15, 22, 29 or 36 days pre-FT. The procedures were repeated 42 days later. Influence on motor activity was assessed through the open-field test. Pain scores corresponded to the time spent rubbing and flicking the injected area. Animals pre-treated with BoNT/A at the first protocol (8 days subgroup) showed reduced inflammatory scores (p=0.011). For the other groups no significant results were observed at any phase. Motor activity was similar in both groups. BoNT/A showed to be effective preventing inflammatory pain up to eight days after the first treatment, an effect not reproduced on the second dose administration. Key words: antinociceptive effect, orofacial pain, preemptive treatment, botulinum neurotoxin type-A.Toxina botulínica do tipo-A no tratamento preemptivo da dor trigeminal aguda: estudo pré-clínico duplo cego placebo controlado RESUMO O objetivo deste estudo foi investigar o efeito preemptivo da neurotoxina botulínica do tipo/A (NTBo/A) através de um modelo de dor orofacial induzida pelo teste da formalina (TF). Rattus norvegicus machos foram injetados no lábio superior com solução salina isotônica 0,9% (SSI) ou NTBo/A (subgrupos 24 horas, 8, 15, 22, 29 ou 36 dias) antes do TF, em dois tratamentos farmacológicos e respectivas avaliações intercalados por 42 dias. Os escores da dor corresponderam ao tempo de fricção da região injetada. Após o primeiro pré-tratamento com NTBo/A no subgrupo 8 dias os escores da fase inflamatória foram menores do que no grupo SSI (p=0,011). Todas as outras comparações não foram significativas. Nos testes de atividade motora não ocorreram diferenças entre SSI e NTBo/A. A NTBo/A pode ser considerada como tratamento preemptivo das dores orofaciais quando utilizada até oito dias antes do estímulo álgico, não havendo consistência terapêutica após um segundo tratamento. Palavras-chave: dor orofacial, efeito antinociceptivo, toxina botulínica do tipo-A, tratamento preemptivo.
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...
This paper achieved its goals of addressing and condensing information on the pathophysiology of the visual aspects of migraine and its clinical aspects, especially with regards to therapy, making it useful not only for those unfamiliar to the theme but to experienced physicians as well.
The clinical diagnosis of Parkinson's disease (PD) is susceptible to misdiagnosis, especially in the earlier stages of the disease. Recently, in vivo imaging techniques assessing the presynaptic dopamine transporter (DAT) have emerged as a useful tool in PD diagnosis, improving its accuracy. OBJECTIVE: It was to illustrate the clinical usefulness of a brain single-photon emission computed tomography (SPECT) DAT ligand, and highlight relevant aspects of scans without evidence of dopaminergic deficit (SWEDDs) in this context. CASES: We described four representative patients with clinically unclear parkinsonian syndromes who underwent [99mTc]-TRODAT-1 SPECT and reviewed the clinical implications. CONCLUSION: DAT-SPECT is an important, cost-effective, technique for the differential diagnosis of parkinsonian syndromes. Additionally, SWEDD cases present clinical and paraclinical peculiarities that may retrospectively identify them as essential/dystonic tremor. The lack of histopathological data limits further conclusions.
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