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NA PÁGINA PRINCIPAL NÃO DEIXE DE VER UMA REVISÃO SOBRE OS CUIDADOS PRÉ-OPERATÓRIOS NAS DOENÇAS NEUROMUSCULARES...........

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Cientistas descobrem causa da fadiga em pessoas com doenças neuromusculares (27/10/08)

USA - "A causa do esgotamento e da fadiga nas pessoas com doenças neuromusculares, como a distrofia muscular de Duchenne, é a falta de uma molécula na membrana celular dos músculos.Uma equipe de pesquisadores da Universidade de Iowa (EUA) explica hoje na revista científica britânica "Nature" que a falta do óxido nítrico sintase neuronal (nNOS) causa a fadiga muscular nesses pacientes.Nos músculos saudáveis, a nNOS dilata os vasos sanguíneos para que aqueles se recuperem mais rapidamente do exercício físico.Os pacientes com desordens neuromusculares têm um esgotamento físico extremo inclusive depois de esforço mais leve. Os cientistas detectaram a falta dessa molécula na membrana das células musculares de ratos de laboratório com doenças neuromusculares. A partir disso, analisaram amostras de tecido de pacientes que, com ampla categoria de desordens, sofriam com fadiga muscular, e também encontraram uma escassez desta molécula. A equipe de pesquisa, liderada por Kevin Campbell, forneceu aos ratos remédios que atuavam como a nNOS, o que permitiu que os animais recuperassem muito mais rapidamente a atividade depois do exercício. Os cientistas asseguram que sua descoberta poderá representar o primeiro passo para o desenvolvimento de tratamentos que melhorem a qualidade de vida desses pacientes"

O resumo em inglês do artigo pode ser lido abaixo:

(Nature, 2008) Sarcolemma-localized nNOS is required to maintain activity after mild exercise

Yvonne M. Kobayashi, Erik P. Rader, Robert W. Crawford, Nikhil K. Iyengar, Daniel R. Thedens, John A. Faulkner, Swapnesh V. Parikh, Robert M. Weiss, Jeffrey S. Chamberlain, Steven A. Moore & Kevin P. Campbell - USA

Many neuromuscular conditions are characterized by an exaggerated exercise-induced fatigue response that is disproportionate to activity level. This fatigue is not necessarily correlated with greater central or peripheral fatigue in patients, and some patients experience severe fatigue without any demonstrable somatic disease. Except in myopathies that are due to specific metabolic defects, the mechanism underlying this type of fatigue remains unknown. With no treatment available, this form of inactivity is a major determinant of disability3. Here we show, using mouse models, that this exaggerated fatigue response is distinct from a loss in specific force production by muscle, and that sarcolemmalocalized signalling by neuronal nitric oxide synthase (nNOS) in skeletal muscle is required to maintain activity after mild exercise. We show that nNOS-null mice do not have muscle pathology and have no loss of muscle-specific force after exercise but do display this exaggerated fatigue response to mild exercise. In mouse models of nNOS mislocalization from the sarcolemma, prolonged inactivity was only relieved by pharmacologically enhancing the cGMP signal that results from muscle nNOS activation during the nitric oxide signalling response to mild exercise. Our findings suggest that the mechanism underlying the exaggerated fatigue response to mild exercise is a lack of contraction-induced signalling from sarcolemma-localized nNOS, which decreases cGMP-mediated vasomodulation in the vessels that supply active muscle after mild exercise. Sarcolemmal nNOS staining was decreased in patient biopsies from a large number of distinct myopathies, suggesting a common mechanism of fatigue. Our results suggest that patients with an exaggerated fatigue response to mild exercise would show clinical improvement in response to treatment strategies aimed at improving exercise-induced signalling.

Assistência ventilatória na distrofia muscular de Duchenne o uso da máquína de assistência da tosse em pacientes com doenças neuromusculares (25/10/08)

USA e Canadá - em dois resumos publicados nesta semana os benefícios da assistência ventilatória são demonstrados. A falência respiratória e a dificuldade em eliminar secreções são problemas muito frequentes em portadores de distrofia muscular e resultam em internações, complicações e morte. Um dos trabalhos demonstra que o uso da assistência ventilatória não invasiva permite adequada assistência ventilatória dos pacientes com Duchenne sem necessidade de traqueostomia. No segundo resumo o uso da máquina de assistência da tosse em casa se mostrou segura e reduziu as complicações de pacientes com doenças neuromusculares. Os resumos podem ser lido abaixo:

1) (CHEST, 2008) 24-HOUR NONINVASIVE VENTILATION IN DUCHENNE MUSCULAR DYSTROPHY

Nadia Griller, Carole LeBlanc, and Douglas A. McKim - Canada

PURPOSE:Duchenne patients eventually require 24 hour ventilatorysupport. Many centers recommend tracheostomy rather than noninvasiveventilation (NIV). We report the outcome of 19/23 adult DMD patients on nocturnal NIV plus daytime mouthpiece ventilation(MPV).

METHODS:16/23 patients used nocturnal bilevel NIV, avg. pressure17/6 cmH2O. 3/23 used volume-targeted ventilators, Vtavg 900ml, RRavg 13/min. Outpatient-initiated 24 hour NIV patients(12/23), used MPV, a chair-mounted ventilator and mouthpiece.Oximetry, downloads and clinical assessment assured adequateventilation. All patients used lung volume recruitment and 16/23had CoughAssistTM devices.

RESULTS:23 DMD patients were followed at the Ottawa HospitalRehabilitation Centre. Nocturnal NIV was used in 19/23 patients.Average values at initiation of nocturnal NIV were; FVC 1.08L (25%pred.), PaCO2 52mmHg, age 17.5 years. Duration on nocturnalNIV was 1 to 11.3 years with one death after 2 years on NIV.12 patients subsequently required 24 hour support, indications;dyspnea, tachypnea and hypercapnea despite adequate nocturnalNIV. Average values at initiation of 24 hour support were; FVC0.57L (13.2%pred.), PaCO2 53mmHg, age 19.3 years. PaCO2 wasreduced to 48mmHg with Nocturnal NIV and to 43mmHg with 24 hourNIV. Duration on 24 hour NIV/MPV is up to 12 years with twodeaths to date (after 3.75 and 4 years on NIV). No patient requireda permanent tracheostomy. In 81 patient-years on NIV there havebeen only 4 respiratory-related hospitalizations.

CONCLUSION:To date all of our patients with DMD have been managedlong beyond nocturnal NIV with MPV. No patient required a tracheostomyfor respiratory failure.

CLINICAL IMPLICATIONS:MPV should be considered as an alternativeto tracheostomy for 24 hour support in DMD.

2) (CHEST, 2008) HOME MECHANICAL IN-EXSUFFLATION: SAFETY AND EFFICACY IN NEUROMUSCULAR DISORDERS (NMD)

Joao A. Bento, Miguel Goncalves, Nuno Silva, RN, Tiago Pinto, Anabela Marinho and Joao C. Winck, Portugal

PURPOSE: NMD patients frequently have impaired cough. Inefficientbronchial clearance may cause ventilatory failure. Mechanicalin-exsufflation (MI-E) is effective to improve airway clearance,however limited data exist on its home long-term use. Our purposewas to determine safety and effectiveness of home MI-E treatment.

METHODS: Retrospective analysis of 17 NMD patients (12 males)with median age of 54.5 yrs-old. All patients were on continuoushome mechanical ventilation (3 under tracheostomy) and MI-Etreatment with oximetry feed-back. Data were recorded as functionof diagnosis, spirometry, respiratory muscle strength, unassistedpeak cough flow and level of ventilatory support. Safety andefficacy were assessed based on number of complications andhospitalizations related to secretion encumbrance. Side effects were also assessed.

RESULTS: Patients fell into 5 different NMD: Amyotrophic LateralSclerosis (ALS) (10), Duchenne Muscular Dystrophy (DMD) (3),other Muscular Dystrophy (MD) (2), Multiple Sclerosis (MS) (1)and Transverse Myelitis (TM) (1). Pulmonary function previousto initiation of MI-E revealed: median FVC=0.78L (29%), median FEV1=0.68L (33%), median MIP=28cmH2O, median MEP=22cmH2O andmedian PCF=90L/min. Median follow-up under home MI-E was 9 months(1–35 months). Seven patients (6 with ALS, 1 with DMD)used MI-E daily, while 10 patients used it intermittently, duringexacerbations. All patients with tracheostomy used MI-E everyday and more times a day than patients under NIV, but none ofthose patients needed antibiotherapy. MI-E was well-tolerated.There were no complications related to the treatment. In general,MI-E was considered effective by caregivers. Timely initiationof MI-E (guided by oximetry feed-back) avoided hospitalizationin 6 patients. Only 2 patients (in 3 occasions) had to be hospitalizeddue to difficulty in handling secretions.Four patients havedied (all ALS), 3 of them related to disease progression and1 from unknown reason.

CONCLUSION: Home MI-E was well tolerated and effective. We considerit safe if used adequately by well prepared caregivers.

CLINICAL IMPLICATIONS: Increased MI-E use during respiratoryinfections avoided hospitalization in non-tracheostomized patients.Daily home MI-E use decreased frequency of tracheobronchialinfections in tracheostomized patients.

Efeitos benéficos do uso de órteses tornozelo-pé na distrofia muscular de Duchenne (25/10/08)

Brasil - Neste estudo feito na ABDIM os autores demonstram que o uso de órteses tornozelo-pé por 4 horas melhora a dorsiflexão e a flexão plantar do pé após 6 meses e persistência da melhora da dorsiflexão do pé após 12 meses. O resumo em inglês do trabalho pode ser lido abaixo:

(Archives of Physical Medicine and Rehabilitation, Volume 89, Issue 10, October 2008, Page e48) The Effects of Ankle-Foot Orthoses in the Treatment on the Evolution of Plantarflexion Contracture in Muscular Dystrophy.

Denise Troise (Muscular Dystrophy Association of Brazil, San Paulo, Brazil), Maria Fornari, Michele Hukuda, Maria Hayashi.

Objective: To evaluate the effect of ankle-foot orthoses (AFOs) on the evolution of plantarflexion contractures in patients with muscular dystrophy. Design: Prospective study. Setting: Patients from Muscular Dystrophy Association of Brazil. Participants: 29 patients diagnosed with muscular dystrophy, both male and female, between 6 and 42 years of age. They were divided in 2 groups: the adherent group (n=25) and no adherent group (n=14). Interventions: Use of an AFO for 4 hours a day. Main Outcome Measures: Passive range of motion (ROM) of ankle dorsiflexion and plantarflexion measured with a goniometer. Patients were followed for 12 months and evaluated initially and at 6-month intervals. Results: Significant improvement in ankle dorsiflexion and plantarflexion was related in the adherent group after 6 months as compared with the no adherent group. After 12 months, the adherent group maintained improvements in ankle dorsiflexion. Conclusions: AFOs improved the ROM of ankle in patients with muscular dystrophy.

Quantificação das alterações musculares no seguimento de pacientes com Duchenne utilizando a ressonância magnética e a espectroscopía (25/10/08)

USA - quando se realizam pesquisam ou mesmo no acompanhamento a longo prazo dos pacientes com Duchenne não há métodos não invasivos confiáveis que demonstrem o estado do músculo como se pode ver com a bíopsia (que é um exame invasivo). Nesta pesquisa os autores demostram os benefícios da utilização da ressonância magnética e da espectroscopia no acompanhamento de pacientes com distrofia muscular de Duchenne. O resumo em inglês do trabalho pode ser lido abaixo:

(Archives of Physical Medicine and Rehabilitation, Volume 89, Issue 10, October 2008, Page e8) Quantification of Longitudinal Changes in Muscle Pathology in Boys With Duchenne’s Muscular Dystrophy Using Magnetic Resonance Imaging and Spectroscopy

Sunita Mathur (University of Florida, Gainesville, FL), D. Lott, C. Senesac, S. Germain, G. Walter, K. Vandenborne.

Objectives: To examine longitudinal changes in muscle size, damage, lipid content, and function in boys with Duchenne’s muscular dystrophy (DMD) and to compare this with controls. Design: Cohort study, with 6- to 12-month follow-up. Setting: Research lab. Participants: Volunteer sample, boys with DMD (n6; age range, 6-13y); age- and sex-matched controls (n6). Interventions: Not applicable. Main Outcome Measures: Magnetic resonance imaging (MRI) and spectroscopy (MRS) (at 1.5T or 3.0T) were used to quantify muscle cross-sectional area (CSA), T2 relaxation time (muscle damage), and lipid content of the lower leg. Functional tests included timed 30-foot walk and isometric muscle strength. Results: Increases of 2% to 32% in lipid and 2% to 11% in T2 of the soleus were observed in boys with DMD. These values were higher than in controls (P<.05). Time to walk 30ft increased an average of 30% over time in boys with DMD and was longer than for controls (P<.01). CSA of the plantar- and dorsiflexors was 15% to 143% higher, whereas strength was 49% to 74% lower in boys with DMD compared with controls (P<.01). Conclusions: MRI and MRS provide unique, noninvasive quantification of progressive muscle pathology in boys with DMD and may be applicable in clinical trials examining new therapies for DMD.

Efeito benéfico dos betabloqueadores e dos inibidores da ECA na distrofia muscular de Duchenne (25/10/08)

Japão - pacientes com distrofia muscular de Duchenne frequentemente apresentam insuficiência cardíaca severa com alta mortalidade. Os sintomas se iniciam na adolescência com piora progressiva em 2 a 2 anos. O uso da associação entre betabloqueadores e inibidores da ECA tem demonstrado efeito benéfico. O estudo atual foi feito a partir da analise retrospectiva da evolução de 52 pacientes com Duchenne, todos cadeirantes no período de 1992 a 2005; doze apresentavam sintomas e os demais 40 casos eram assintomáticos apesar do ecocardiograma alterado. A sobrevida de 5 anos foi de 93% e de 7 anos 84%. Os pacientes que tinham sintomas tiveram uma sobrevida de 81% em 5 anos e 71% em 7 anos, com sobrevida de zero após 10,9 anos. Nos pacientes assintomáticos a sobrevida foi maior: 97% em 5 anos e 84% em 10 anos e com 10 anos a sobrevida era de 72%. Nove pacientes deste grupo permanecem sem complicações após mais de 10 anos. O resumo em inglês do trabalho pode ser lido abaixo:

(Journal of Cardiology, 2008) Beneficial effects of beta-blockers and angiotensin-converting enzyme inhibitors in Duchenne muscular dystrophy

Hitoko Ogata (MD, FJCC), Yuka Ishikawa (MD), Yukitoshi Ishikawa (MD), Ryoji Minami (MD) - Japan

Background: Patients with Duchenne muscular dystrophy (DMD) often have severe heart failure with a high mortality rate. Most DMD patients with cardiomyopathy became symptomatic in their early to middle teens and usually die of congestive heart failure within 2—3 years from the onset of symptoms. It has been reported that the combination of an angiotensin-converting enzyme (ACE) inhibitor and a betablocker has additive benefits in patients with heart failure. The aim of this study was to assess whether the combination of an ACE inhibitor and a beta-blocker is associated with long-term survival of DMD patients with left ventricular (LV) dysfunction. Methods: We retrospectively analyzed the outcomes of 52 DMD patients who had begun treatment for heart failure with an ACE inhibitor and a beta-blocker at National Yakumo Hospital during the period from 1992 to 2005. All patients used wheelchairs in their daily lives. Patients were classified as symptomatic or asymptomatic at the initiation of treatment with these two drugs. Twelve patients who had already had apparent symptoms due to heart failure were enrolled in a treatment group. Forty patients who had no symptoms with reduced LV ejection fraction (≤45% in echocardiography) were enrolled in a prevention group. Results: Five-year and 7-year survival rates of all patients were 93 and 84%, respectively. In the treatment group, 5-year and 7-year survival rate were 81 and 71%, respectively. Survival rate became zero at 10.9 years. In the prevention group, 5-year and 7-year survival rates were 97 and 84%, respectively, and 10-year survival rate was 72%. Nine patients in the prevention group remained event-free over 10 years.

Efeito da gentamicina sobre os camundongos com distrofia muscular e os benefícios da expressão da distrofina sobre as alterações dos músculos (18/10/08)

Itália - os aminoglicosídeos são antibióticos que administrados nos camundongos conseguem corrigir a mutação de ponto e melhorar as alterações musculares da distrofia. Com este tratamento (32mg/Kg/dia por 8 a 12 semana) os animais passam a expressar a distrofina e neste estudo os autores foram estudar as funções que melhoram com a expressão da distrofina tentando deduzir o que poderá melhorar com a terapia gênica quando ela estiver disponível. Os resultados demonstraram que a gentamicina melhora as alterações patológicas dos músculos, a redução da necrose muscular e a redução de fatores inflamatórios. As funções da membrana celular se recuperam e os níveis de CK se reduzem no sangue. No entanto o equilíbrio nos níveis do cálcio na célula muscular não se normalizou e a permeabilidade do cálcio na membrana não se reduziu. Os autores concluiram que uma expressão maior de distrofina é necessária para a total correção das funções musculares. O resumo em inglês pode ser lido abaixo:

(Neurobiology of Disease, Volume 32, Issue 2, November 2008, Pages 243-253) Gentamicin treatment in exercised mdx mice: Identification of dystrophin-sensitive pathways and evaluation of efficacy in work-loaded dystrophic muscle

Annamaria De Luca, Beatrice Nico, Jean-François Rolland, Anna Cozzoli, Rosa Burdi , Domenica Mangieri, Viviana Giannuzzi, Antonella Liantonio, Valentina Cippone, Michela De Bellis, Grazia Paola Nicchia, Giulia Maria Camerino, Antonio Frigeri, Maria Svelto and Diana Conte Camerino - Italy

Aminoglycosides force read through of premature stop codon mutations and introduce new mutation-specific gene-corrective strategies in Duchenne muscular dystrophy. A chronic treatment with gentamicin (32 mg/kg/daily i.p., 8–12 weeks) was performed in exercised mdx mice with the dual aim to clarify the dependence on dystrophin of the functional, biochemical and histological alterations present in dystrophic muscle and to verify the long term efficiency of small molecule gene-corrective strategies in work-loaded dystrophic muscle. The treatment counteracted the exercise-induced impairment of in vivo forelimb strength after 6–8 weeks. We observed an increase in dystrophin expression level in all the fibers, although lower than that observed in normal fibers, and found a concomitant recovery of aquaporin-4 at sarcolemma. A significant reduction in centronucleated fibers, in the area of necrosis and in the percentage of nuclear factor-kB-positive nuclei was observed in gastrocnemious muscle of treated animals. Plasma creatine kinase was reduced by 70%. Ex vivo, gentamicin restored membrane ionic conductance in mdx diaphragm and limb muscle fibers. No effects were observed on the altered calcium homeostasis and sarcolemmal calcium permeability, detected by electrophysiological and microspectrofluorimetric approaches. Thus, the maintenance of a partial level of dystrophin is sufficient to reinforce sarcolemmal stability, reducing leakiness, inflammation and fiber damage, while correction of altered calcium homeostasis needs greater expression of dystrophin or direct interventions on the channels involved.

Antagonistas do cálcio para tratamento da distrofia muscular de Duchenne (11/10/08)

Reino Unido - os autores fizeram uma revisão da literatura médica a procura de artigos que descrevessem os efeitos dos antagonistas do cálcio na tratamento da distrofia muscular de Duchenne. As drogas já testadas são: verapamil, diltiazem, nifedipina e flunarizina. Apesar de poucos estudos e de poucos pacientes tratados em cada estudo não há evidências que este grupo de drogas auxilie no tratamento da distrofia muscular de Duchenne.

Distrofia Muscular de Duchenne: uma cardiomiopatia que pode ser prevenida? (04/10/08)

Holanda - neste editorial os autores comentam as recentes pesquisas sobre o uso da ressonância nuclear magnética em distrofia muscular de Duchenne. Este exame é considerado muito importante para avaliar com fidelidade a anatomia e a função cardíaca. Também em estudos recentes a ressonância nuclear magnética permitiu em Duchenne o diagnóstico da fibrose muscular e a detecção de alterações precoces da doença. Os pacientes com Duchenne tratados com corticóides apresentam melhora da função cardíaca e retardo no aparecimento da disfunção ventricular podendo indicar um efeito preventivo na função cardíaca da doença.

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