Tratamento farmacológico da dor musculoesquelética

Várias classes de fármacos são utilizadas com finalidade analgésica. A dor deve ser tratada segundo escala ascendente de potência analgésica. Os analgésicos antiinflamatórios e os psicotrópicos associados ou não aos opióides de baixa e/ou elevada potência e/ou aos miorrelaxantes são as classes medicamentosas mais utilizadas no tratamento da dor musculoesquelética. Oscorticosteróides, os anticonvulsivantes, os bloqueadores da atividade osteoclástica e os tranqüilizantes menores são indicados em casos especiais. A prescrição deve ser adequada às necessidades e respeitar a farmacodinâmica e a farmacocinética de cada agente e as contra-indicações peculiares a cada caso. As medicações devem ser preferencialmente de baixo custo e de fácil aquisição. Aadministração deve ser regular e não apenas quando necessário. A via enteral, preferentemente à oral, deve ser priorizada. Alguns efeitos colaterais são dependentes da dose dos agentes, outros de sua natureza; alguns desses efeitos podem ser minimizados com medidas medicamentosas ou físicas específicas. O tratamento antiálgico deve ser instituído imediatamente após as primeiras manifestações da condição dolorosa, pois não compromete o resultado da semiologia clínica ou armada e previne a cronificação da dor. A descoberta de analgésicos antiinflamatórios que inibem seletiva ou especificamante a COX-2, de antidepressivos que atuam seletivamente na recaptura de serotonina e noradrenalina de neurolépticos mais específicos, de miorrelaxantes de ação prolongada e o desenvolvimento de apresentações de derivados opióides de ação ou liberação prolongada são avanços que tornaram a analgesia mais eficaz e segura em doentes com afecções álgicas musculoesqueléticas

The contribution of concentric electrode-evoked potentials and nociceptive withdrawal reflex to the routine neurophysiological assessment of neuropathic pain:cross-sectional study

BACKGROUND AND OBJECTIVES:Conventional electrodiagnostic studies (EDX) are frequently used to support the diagnosis of peripheral neuropathic pain. However, routine EDX has poor diagnostic yield for identifying small fiber neuropathy, which may be cause of neuropathic pain in some patients. This study aimed to assess the gain in diagnostic yield brought by adding pain-related evoked potentials with concentric electrode (CN-PREP) and nociceptive withdrawal reflex (NWR) assessments to EDX.METHODS:Transversal observational accuracy study which included patients referred to routine EDX in a tertiary-care hospital who reported chronic neuropathic pain in their lower limbs. Besides routine EDX, subjects underwent CN-PREP and NWR assessments. Diagnostic yield and tolerability were examined and compared between test studies.RESULTS:The study enrolled 100 patients (54% female), with 57 ± 12 years. EDX was altered in 47% of all patients. The addition of CN-PREP alone, and NWR combined with CN-PREP increased diagnostic yield to 69% and 72%, respectively. CN-PREP proved to be well tolerable, while NWR was associated with higher test-related pain intensity and discontinuation rate (9% vs. 0%). Considering EDX as the reference test, CN-PREP sensitivity was 85.1% and specificity 58.5%.CONCLUSION:Combining CN-PREP with the routine EDX for patients with neuropathic pain is feasible and results in increased diagnostic yield. Conversely, the addition of NWR to the aforementioned tests provides little improvement to this yield and is less tolerable to the patient. Further studies are needed to determine the actual sensitivity and specificity of CN-PREP when compared to the gold-standard for small fiber neuropathy diagnosis, i.e. intraepidermal nerve fiber density assessment

Methadone in post-herpetic neuralgia: A pilot proof-of-concept study

OBJECTIVE: This research was designed as a pilot proof-of-concept study to evaluate the use of low-dose methadone in post-herpetic neuralgia patients who remained refractory after first and second line post-herpetic neuralgia treatments and had indications for adding an opioid agent to their current drug regimens. METHODS: This cross-over study was double blind and placebo controlled. Ten opioid naïve post-herpetic neuralgia patients received either methadone (5 mg bid) or placebo for three weeks, followed by a 15-day washout period and a second three-week treatment with either methadone or placebo, accordingly. Clinical evaluations were performed four times (before and after each three-week treatment period). The evaluations included the visual analogue scale, verbal category scale, daily activities scale, McGill pain questionnaire, adverse events profile, and evoked pain assessment. All patients provided written informed consent before being included in the study. ClinicalTrials.gov: NCT01752699 RESULTS: Methadone, when compared to placebo, did not significantly affect the intensity of spontaneous pain, as measured by the visual analogue scale. The intensity of spontaneous pain was significantly decreased after the methadone treatment compared to placebo on the category verbal scale (50% improved after the methadone treatment, none after the placebo, p = 0.031). Evoked pain was reduced under methadone compared to placebo (50% improved after the methadone treatment, none after the placebo, p = 0.031). Allodynia reduction correlated with sleep improvement (r = 0.67, p = 0.030) during the methadone treatment. The side effects profile was similar between both treatments. Conclusions: Methadone seems to be safe and efficacious in post-herpetic neuralgia. It should be tried as an adjunctive treatment for post-herpetic neuralgia in larger prospective studies

Epidemiologia clínica da dor músculo-esquelética

Pain is more frequent in females. The studies about thoracic and lumbar pains are inconclusives. Artralgias and fibromyalgia have increasing frequency with the progression of the ages in both sexes and but are more common in females.Temporomandibular pain conditions are more common in women. The differences in the prevalence of pain related with gender are based in constitutional, hormonal, cognitive and cultural aspects. The increasing of occurrence of certain pain conditions in older people is due to degenerative conditions and accumulation of diseases during in younger ages and the reduction may be due to the improvement of the causal conditions, increasing of incapacities or deaths.Vários estudos demonstram que as mulheres apresentam mais dor do que os homens. Entretanto, os estudos sobrelombalgia e dor torácica não são conclusivos. Em casos de dores articulares e fibromialgia existe aumento da prevalência com o progredir das idades em ambos os sexos, apesar de haver predominio nas mulheres. As síndromes dolorosas decorrentes das disfunções têmporo-mandibulares são mais comuns nas mulheres que nos homens e apresentam pico de ocorrência nas fases reprodutivas. A diferença na ocorrência da dor nos homens e nas mulheres pode ser devida a vários fatores incluindo os constitucionais, os hormonais, os cognitivos e os culturais, entre outros. O aumento da freqüência da dor com o avanço da idade, especialmente das dores articulares e da fibromialgia, sugere haver associação entre as afecções degenerativas ou acúmulo de casos de dor com o progredir da idade. A redução da freqüência de alguns casos de dor nos idosos pode ser devida à melhora das condições causais com o passar do tempo ou ao aumento da incapacidade ou da mortalidade que remove tais indivíduos das comunidades

Dissecting central post-stroke pain:a controlled symptom-psychophysical characterization

Central post-stroke pain affects up to 12% of stroke survivors and is notoriously refractory to treatment. However, stroke patients often suffer from other types of pain of non-neuropathic nature (musculoskeletal, inflammatory, complex regional) and no head-to-head comparison of their respective clinical and somatosensory profiles has been performed so far. We compared 39 patients with definite central neuropathic post-stroke pain with two matched control groups: 32 patients with exclusively non-neuropathic pain developed after stroke and 31 stroke patients not complaining of pain. Patients underwent deep phenotyping via a comprehensive assessment including clinical exam, questionnaires and quantitative sensory testing to dissect central post-stroke pain from chronic pain in general and stroke. While central post-stroke pain was mostly located in the face and limbs, non-neuropathic pain was predominantly axial and located in neck, shoulders and knees (P < 0.05). Neuropathic Pain Symptom Inventory clusters burning (82.1%, n = 32, P < 0.001), tingling (66.7%, n = 26, P < 0.001) and evoked by cold (64.1%, n = 25, P < 0.001) occurred more frequently in central post-stroke pain. Hyperpathia, thermal and mechanical allodynia also occurred more commonly in this group (P < 0.001), which also presented higher levels of deafferentation (P < 0.012) with more asymmetric cold and warm detection thresholds compared with controls. In particular, cold hypoesthesia (considered when the threshold of the affected side was <41% of the contralateral threshold) odds ratio (OR) was 12 (95% CI: 3.8–41.6) for neuropathic pain. Additionally, cold detection threshold/warm detection threshold ratio correlated with the presence of neuropathic pain (ρ = −0.4, P < 0.001). Correlations were found between specific neuropathic pain symptom clusters and quantitative sensory testing: paroxysmal pain with cold (ρ = −0.4; P = 0.008) and heat pain thresholds (ρ = 0.5; P = 0.003), burning pain with mechanical detection (ρ = −0.4; P = 0.015) and mechanical pain thresholds (ρ = −0.4, P < 0.013), evoked pain with mechanical pain threshold (ρ = −0.3; P = 0.047). Logistic regression showed that the combination of cold hypoesthesia on quantitative sensory testing, the Neuropathic Pain Symptom Inventory, and the allodynia intensity on bedside examination explained 77% of the occurrence of neuropathic pain. These findings provide insights into the clinical-psychophysics relationships in central post-stroke pain and may assist more precise distinction of neuropathic from non-neuropathic post-stroke pain in clinical practice and in future trials