Duchenne’s Muscular Dystrophy: A Multidisciplinary Approach By: Brittany Annis, Student PT Ithaca College 2010 Objectives Introduce background information on Duchenne’s Muscular Dystrophy Identify associated pathologies Identify and explain the benefits of the multidisciplinary team members Describe the goals and interventions of physical therapy for DMD Describe current evidence and recommendations for exercise and DMD Intro to DMD Most prevalent childhood muscular dystrophy, every 1 in 3000-6000 male births X-linked recessive disorder- gene deletion Deficiency of the muscle protein Dystrophin Progressive muscle weakness in skeletal, smooth, and cardiac muscle It has been observed that there is a greater number of Type II muscle fibers with degeneration compared to Type I. Dystrophin Provides mechanical reinforcement to the sarcolemmal membrane of muscle fibers; protects muscle fibers from being damaged while stressed during muscle contraction. Lifespan of DMD Shortened lifespan due to progressive muscle weakness and complications- mean age is 19 without intervention, mid-to-late twenties with proper care. Now, studies and research are showing that if properly diagnosed, individuals with DMD can have possible lifespan into their forties Signs and Symptoms Early signs between ages 3 and 5, when most commonly diagnosed Delayed walking Inability to run, jump, keep up with peers Difficulty climbing stairs Gower’s Sign Frequent falls Occasionally (30%) global developmental delay and delayed speech Associated Pathologies: Weakness Progressive weakness of hip and shoulder girdle musculature Weakness in paraspinals make walking difficult Leads to: – Waddling gait – Lumbar lordosis – Forward thrusting of the abdomen – Scapular winging – Anteroposterior scoliotic curve – Joint contractures – Respiratory impairment – Weight gain Associated Pathologies: Joint Contractures Mainly found at hips, Equinovarus: knees, ankles – Ankle plantarflexion and supination – Tight gastrocnemius mm/Achilles tendon Contractured Tensor – Associated weakness of Fascia Latae: tibialis anterior and – Waddling gait peroneal mms – Tightened IT Band Complications include: – Resultant hip and Difficulty wearing shoes knee Foot pain pain/deformities Hypersensitivity Concern about foot’s appearance Associated Pathologies: Scoliosis Most commonly seen when non- ambulatory, due to increased amount of time spend seated in a wheelchair May require spinal fusion to promote better sitting and comfort, to prevent further deformity, avoid respiratory compromise The Multidisciplinary Team Can alter the natural – Rehabilitation progression of the – Orthopedics disease and improve function and quality of – Pharmocologics life. – Psychosocial Comprehensive set of – Respiratory care recommendations to manage the wide – Cardiovascular care spectrum of – Pain complications – Gastroenterology/ Includes: Nutrition Corticosteroids Currently the best treatment option available Improve muscle strength and function Significantly slow the progression of muscle weakness Prolong ambulation to mid-teens or later Delay the onset of respiratory and/or cardiac dysfunction [Use caution: complications include weight gain, vertebral fractures, failure to gain height, irritability] Respiratory Management Patients with DMD are at increased risk of respiratory complications Because of progressive loss of muscle strength: – Cough may be ineffective – Nocturnal hypoventilation – Sleep-disordered breathing PT can assist with respiratory management by having patient breathe against a resistive load (water in pool), breath-holding, bubble-blowing, to improve ventilatory strength and endurance. Important to note signs and symptoms of hypoventilation to refer patient to respiratory physician. – Fatigue, dyspnea, tachycardia, morning/continuous headaches, sleep dysfunction, nightmares, difficulty concentrating Cardiac Management Cardiomyopathy and/or cardiac arrhythmia are major sources of mortality in DMD The heart/myocardium have areas of hypertrophy, atrophy, and fibrosis Failure to see a cardiac specialist early in the disease process have led to late treatment and poor outcomes Higher levels of fitness are associated with better cardiac health Potential Surgeries Heelcord lengthening Hamstring lengthening ITB lengthening Cannot perform hip flexor lengthening (responds poorly, weakens muscles and cannot properly brace) – Hip deformities often correct themselves once knee and ankle malalignments have been altered. Surgery in the late ambulatory phase or after is usually not effective. Other Important Teams: Nutritional, swallowing, gastrointestinal, speech and language, pain management, psychosocial, pharmacological All fields are continuously changing as the stages of the disease change Goals of Physical Therapy Prolong independent ambulation Maximize functional ability Prevent complications of inactivity Improve emotional well- being Physical Therapy Interventions Stretching/Positionin Objective measures g and testing to Management of monitor progression contractures Assistive devices Exercise Objective Measures Strength testing- MMT to ROM: goniometry to identify monitor disease progression hypomobility, jt contractures and predict functional losses, that may contribute to assess responses to functional deterioration or to musculoskeletal/integumenta treatment and monitor ry complications, or to note muscle imbalances need of splinting/orthotics. – Test LEs every 6 months – In ambulatory phase, when ambulatory; test measure hips, knees, UE and LE every 6 ankles (ITB, H/S, months when non- heelcords). In non- ambulatory ambulatory phase, measure UE as well as LE (elbows, wrists, finger flexors) Objective Measures, Con’t Timed Testing: ADLs: Assessment Standardized tests are of impairment in responsive to change, home, school, easy to administer, relevant to function community settings (when ambulatory only) – Frequency of falls, – Timed 10 meter walk, self-care skills timed Gower’s manuever, time to climb 4 stairs, 6 min walk test Stretching Heelcords: Gastrocnemius/ Combination of Achilles Tendon lengthening AROM, AAROM, into dorsiflexion PROM, prolonged Tensor Fascia Latae/Iliotibial Band: stretch hip into elongation (splinting, adduction, internal rotation, and extension. positioning) Other muscles throughout Minimum of 4-6 the hips, knees and ankles days per week, at In non-ambulatory phase, also focus on upper home/school and in extremities: finger flexors, wrist flexors, elbow and the clinic shoulder joints Assistive Devices: AFOs Custom-molded and comfortable for optimum foot and ankle alignment Throughout life: AFO’s are appropriate at night to prevent or minimize the progression of equinus contractures Late stages: – KAFOs for non-ambulatory boys to prevent contracture and deformity (not for use at night) – Resting hand splints for finger flexors Assistive Devices Con’t Wheelchair: Need Standing Frames: A few appropriate postural hours per day, even positioning to prevent with minimal weight scoliosis and back bearing, to prevent and pain/aches reduce the severity of – Powered for more contractures, decubitis involved patients. ulcers, and scoliosis. – Manual Lightweight for Also improves bone less involved patients so can self propel and mineral density, increase independence, circulation, and GI and as well as provide arm respiratory functions. exercise Exercise There is a high level of controversy concerning whether exercise is beneficial or harmful to patients with DMD Normal, dystrophic muscle (those without muscular dystrophy) can withstand mechanical forces during contraction. Those with muscular dystrophy are compromised due to weakened muscles, joints, tendons, and bones during muscle contractions and weight-bearing. But exercise is very important to avoid disuse atrophy and other secondary complications of inactivity Type I vs Type II Fibers Type I muscle fibers are It is possible to switch Type slow twitch for slower II muscle fibers to Type I with contractions, and fatigue- exercise training, so with an resistant, so good for increased number of Type I continuous contractions fibers, the muscles are more (postural muscles) durable and more resistant Type II muscle fibers are fast to degeneration. twitch for quick contractions, But the form of exercise and are easily fatigued needed to switch Type II (“sprinter” muscles). They fibers to Type I is very are also less resistant to specific mechanical stresses (more easily injured) Current Evidence Regarding Exercise In a mouse study, a It has been observed greater percentage of that Type II muscle Type I muscle fibers fibers are subject to were observed after low greater degeneration, intensity, long-term and the majority of exercise research using animal Sedentary mice with models and some DMD had a higher human studies suggest percentage of Type I that increasing activity fibers than sedentary may actually slow the mice without DMD degeneration in dystrophic muscle. Current Evidence, Con’t Further studies and information are needed for each subtype of muscular dystrophy to create subtype-specific recommendations, including specifics such as age, severity, rate of progression, and level of motivation. Recommended Exercise for DMD Low resistive and Long term, low- aerobic exercise are intensity, preferably no justified to: load (or low-load) – Prevent deconditioning, decreased fitness, disuse weight-bearing activity atrophy and joint to reduce mechanical contractures stress on the muscle – Counteract secondary – Increased Type I fibers, complications of inactivity which are less vulnerable such as obesity, to degeneration Diabetes, osteoporosis and cardiovascular – Will not promote diseases hypertrophy Recommended Exercise for DMD, Con’t Use caution to ensure Aquatic Therapy! that cardiovascular or Excellent for improving/ muscular complications maintaining mobility, do not develop strength, flexibility, and High-resistance and aerobic conditioning eccentric exercise is and cardiopulmonary NOT recommended, although it has not fitness actually been proven harmful for a DMD patient Current Evidence Research and studies are being done with continuous advances and milestones in DMD research The severity of DMD can be determined by a positive correlation to the amount of dystrophin present in the muscle (the more dystrophin, the less severe the symptoms and progression) Corticosteroid prednisone was found effective in slowing the progression of DMD, and it also stimulates utrophin production ( a mm protein similar to dystrophin) Gene therapy clinical trials are underway and dystrophin gene injections are judged safe in clinical trial including 6 boys with DMD; studies are being continued Works Cited Ansved, Tor. "Muscular Dystrophies: Influence of Physical Conditioning on Disease Evolution." Current Opinion in Clinical Nutrition and Metabolic Care 6 (2003): 435-39. Print. Bushby, Katharine, Richard Finkel, and David Birnkrant. "Diagnosis and Management of Duchenne Muscular Dystrophy, Part 1: diagnosis, and pharmacological and psychosocial management." 30 Nov. 2009. Web. 1 Dec. 2009. <http://quest.mda.org/files/pdfs/Part_1- newDMD.pdf>. Bushby, Katharine, Richard Finkel, and David Birnkrant. "Diagnosis and Management of Duchenne Muscular Dystrophy, Part 2: implementation of multidisciplinary care." 30 Nov. 2009. Web. 1 Dec. 2009. <http://http://quest.mda.org/files/pdfs/Part_2-newDMD.pdf>. Ciafaloni, MD, Emma, and Richard T. Moxley, MD. "Treatment Options for Duchenne Muscular Dystrophy." Current Treatment Options in Neurology 10.2 (2008): 86-93. Print. Milestones in Duchenne's Muscular Dystrophy Research. MDA.org, Feb. 2009. Web. 1 Dec. 2009. <http://www.mda.org/publications/milestones/dmd.html>. Palmieri, B., V. Sblendorio, A. Ferrari, and A. Pietrobelli. "Duchenne Muscle Activity Evaluation and Muscle Function Preservation." Obesity Reviews 9 (2008): 121-39. Print. Sayers, Stephen P. "The Role of Exercise as a Therapy for Children with Duchenne Muscular Dystrophy." Pediatric Exercise Science 12 (2000): 23-33. Print.
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