Introduction Disorder of worsening neurologic dysfunction characterized by progressive muscle weakness caused by absent dystrophin protein Epidemiology demographics prevalence is 2-3/10,000 affects young males only age of onset is between 2-6 years of age Pathophysiology dystrophin absence leads to poor muscle fiber regeneration progressive replacement of muscle tissue with fibrous and fatty tissue skeletal and cardiac muscle lose elasticity and strength Genetics X-linked recessive Xp21.2 dystrophin gene defect due to point deletion and nonsense mutation one third of cases result from spontaneous mutations Associated conditions orthopaedic manifestations calf pseudohypertrophy scoliosis equinovarus foot deformity joint contractures nonorthopaedic conditions cardiomyopathy static encephalopathy Becker's Muscular Dystrophy similar to Duchenne's in that it is sex-linked recessive calf pseudohypertrophy is present CPK is elevated differs from Duchenne's in that dystrophin protein is decreased instead of absent later onset with slower progression and longer life expectancy (average diagnosis occurs at age 8 compared to 2 years of age with Duchenne's) more prone to cardiomyopathy Prognosis most are unable to ambulate independently by age 10 most are wheelchair dependent by age 15 most die of cardiorespiratory problems by age 20 Physical Exam Symptoms progressive weakness affecting proximal muscles first (begins with gluteal muscle weakness) gait abnormalities delayed walking toe walking clumsy, waddling gait difficulty climbing stairs, hopping, or jumping decreased motor skills Physical exam calf pseudohypertrophy (infiltration of normal muscle with connective tissue) deep tendon reflexes present (unlike spinal muscular atrophy) lumbar lordosis compensates for gluteal weakness Gower's sign rises by walking hands up legs to compensate for gluteus maximus and quadriceps weakness Trendelenburg sign Evaluation Labs markedly elevated CPK levels (10-200x normal) CPK leaks across defective cell membrane Muscle biopsy will show connective tissue infiltration and foci of necrosis will show absent dystrophin with staining DNA testing shows absent dystrophin protein EMG myopathic decreased amplitude, short duration, polyphasic motor Differential Diagnosis Similar traits to Duchenne's Distinguishing traits from Duchenne's Becker's • calf pseudohypertrophy• markedly elevated CPK• x-linked transmission • Becker's has slower progression of weakness with diagnosis made later (~8 yrs)• prone to cardiomyopathy Spinal muscular atrophy • proximal weakness • onset of weakness is earlier in childhood• absent deep tendon reflexes and fasciculations • CPK levels are normal• pseudohypertrophy is absent Emery-Dreifuss dystrophy • similar clinical picture • no calf pseudohypertrophy• CPK levels near normal • elbow and ankle contractures develop early Limb girdle dystrophy • progressive motor weakness • no calf pseudohypertrophy• CPK levels are only mildly elevated Guillain-Barre syndrome • acute onset of weakness • absent deep tendon reflexes• CPK levels are normal Treatment Nonoperative corticosteroid therapy (prednisone 0.75 mg/kg/day) indications 5 to 7-year-old child with progressive disease goals to maintain ambulatory capacity as long as possible outcomes significant positive effect on disease progression acutely improves strength, slows progressive weakening, prevents scoliosis formation, and prolongs ambulation delays deterioration of pulmonary function side effects osteonecrosis weight gain cushingoid appearance GI symptoms mood lability headaches short stature cataracts pulmonary care with nightly ventilation rehabilitation techniques physical therapy for range of motion exercises adaptive equipment power wheelchairs KAFO bracing (controversial) Operative soft tissue releases to prolong ambulation indications ambulatory child with Duchenne's techniques hip abduction contractures treated by release of iliotibial band Hip flexion contractures treated by release of sartorius, rectus femoris, and tensor fascia lata hamstring releases Achilles tendon and posterior tibialis lengthenings postoperative care early mobilization and ambulation to prevent deconditioning scoliosis surgery (see below) Scoliosis Introduction considered a neurogenic curve occurs in 95% of patients after becoming wheelchair dependent curve progresses rapidly from age 13 to 14 years begins with mild hyperlordosis progresses with general kyphosis and scoliosis with varying degrees of pelvic obliquity progresses 1° to 2° per month starting at age 8 to 10 years patients may become bedridden by age 16 treatment is complicated by restrictive pulmonary disease (significant decrease in forced vital capacity) cardiac and pulmonary function studies should be obtained pre-operatively as significant declines in function of both organ systems may make spinal fusion too high-risk Treatment nonoperative bracing is contraindicated may interfere with respiration operative early PSF with instrumentation indications curve 20-30° in nonambulatory patient treat early before pulmonary function declines can wait longer ~ 40° if responding well to corticosteroids FVC drops ≤ 35% rapidly progressive curve PSF with instrumentation to pelvis indications curves ≥ 40° pelvic obliquity ≥ 10° lumbar curve where apex is lower than L1 complications malignant hyperthermia is common intraoperatively pretreat with dantrolene intraoperative cardiac events anterior and posterior spinal fusion indications rarely for stiff curves Equinovarus Foot Introduction common foot deformity seen with Duchenne muscular dystrophy Pathoanatomy muscle imbalance secondary to muscle replacement with fibrofatty tissue Diagnosis made upon clinical exam Treatment nonoperative stretching, physical therapy, and night time AFO use operative Tendinoachilles lengthening with posterior tibialis tendon transfer, toe flexor tenotomies
QUESTIONS 1 of 19 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 Previous Next This is an AAOS Self assessment question. Orthobullets was not involved into the editorial process, and does not have the ability to alter. If you prefer to hide SAE questions on topics simply turn them off in your Content Settings (SAE13BS.10) A 5-year-old boy has a history of delayed walking and difficulty climbing stairs. Physical examination shows a positive Gower sign and scoliosis. Laboratory tests show elevated serum creatine phosphokinase. A mutation of what protein results in this disorder? Review Topic QID: 8242 1 Dystrophin 95% (99/104) 2 Collagen type I 1% (1/104) 3 Neurofibromin 1% (1/104) 4 Runt-related transcription factor 2 (Runx2) 2% (2/104) ML 1 Select Answer to see Preferred Response PREFERRED RESPONSE 1 (OBQ13.199) Which of the following is most commonly inherited as a X-linked recessive disorder? Review Topic QID: 4834 1 Charcot-Marie-Tooth disease 6% (191/3338) 2 Marfan's syndrome 2% (71/3338) 3 Larsen's syndrome 2% (68/3338) 4 Duchenne's muscular dystrophy 84% (2791/3338) 5 Turner's syndrome 6% (202/3338) ML 2 Select Answer to see Preferred Response PREFERRED RESPONSE 4 This is an AAOS Self assessment question. Orthobullets was not involved into the editorial process, and does not have the ability to alter. If you prefer to hide SAE questions on topics simply turn them off in your Content Settings (SAE07PE.60) Figure 24 shows the sitting AP and lateral spinal radiographs of a nonambulatory 12½-year-old boy with Duchenne muscular dystrophy who is being evaluated for scoliosis. The lumbar curve from T12 to L5 measures 36 degrees, and the thoracic curve from T3 to T12 measures 24 degrees on the AP radiograph. He has 5 degrees of pelvic obliquity. His forced vital capacity is 45% of predicted for height and weight. What is the most appropriate treatment for the spinal deformity? Review Topic QID: 6120 FIGURES: A 1 Posterior spinal fusion from T2 to L5 with segmental instrumentation 48% (22/46) 2 Anterior spinal fusion from L1 to L4, followed by posterior spinal fusion from T2 to the sacrum with segmental instrumentation including iliac fixation 15% (7/46) 3 Custom-molded spinal orthosis worn 23 hours per day until skeletal maturity 20% (9/46) 4 A spinal orthosis until age 14 years, followed by posterior spinal fusion with segmental instrumentation 7% (3/46) 5 Adapted wheelchair seating with a custom-molded back support to correct scoliosis and kyphosis 11% (5/46) ML 4 Select Answer to see Preferred Response PREFERRED RESPONSE 1 This is an AAOS Self assessment question. Orthobullets was not involved into the editorial process, and does not have the ability to alter. If you prefer to hide SAE questions on topics simply turn them off in your Content Settings (SAE07PE.43) Duchenne’s muscular dystrophy is a genetic disorder that is transmitted by which of the following modes of inheritance? Review Topic QID: 6103 1 X-linked 87% (48/55) 2 Autosomal-dominant 7% (4/55) 3 Autosomal-recessive 5% (3/55) 4 Chromosomal duplication 0% (0/55) 5 Chromosomal deletion 0% (0/55) ML 1 Select Answer to see Preferred Response PREFERRED RESPONSE 1 Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK (SBQ04PE.47) An 11-year-old boy is evaluated after reporting progressive difficulty walking. After extensive workup, he is diagnosed with Becker muscular dystrophy. Which of the following best describes the characteristic findings associated with this diagnosis? Review Topic QID: 2232 1 Pseudohypertrophy of the calves, markedly increased creatine kinase levels, and abnormal dystrophin 79% (1510/1918) 2 Proximal muscle weakness occuring early in childhood, absent deep tendon reflexes and fasciculations 7% (143/1918) 3 Mildly elevated creatine kinase levels, severe limb contractures present at an early age 3% (61/1918) 4 Acute onset of weakness, hypotonia, and arefelxia resulting from postinfectious demyelination of the peripheral nerves 1% (26/1918) 5 X-linked transmission, absence of dystrophin, and significantly increased creatine kinase levels 8% (163/1918) ML 2 Select Answer to see Preferred Response PREFERRED RESPONSE 1 (OBQ10.49) A 9-year-old boy with Duchenne muscular dystrophy has increasing difficulty with ambulation. He denies back pain, difficulty sitting in a chair, or shortness of breath. Annual screening spine radiographs demonstrate a 20 degree thoracolumbar curve. Which of the following statements best describes the appropriate treatment plan for his scoliosis? Review Topic QID: 3137 1 Given the poor prognosis, surgical treatment is not appropriate 2% (44/2405) 2 Posterior spinal fusion should be performed before curve progresses beyond 30 degrees 70% (1689/2405) 3 Posterior spinal fusion should be performed if the curve progresses to greater than 55 degrees 12% (289/2405) 4 Posterior spinal fusion should be performed if FVC drops below 60% 10% (232/2405) 5 With appropriate bracing, curve progression and surgical treatment will most likely be unnecessary 6% (141/2405) ML 2 Select Answer to see Preferred Response PREFERRED RESPONSE 2 (OBQ09.131) What is the inheritance pattern for Duchenne's muscular dystrophy? Review Topic QID: 2944 1 autosomal recessive 4% (44/1109) 2 autosomal dominant 6% (68/1109) 3 X-linked recessive 77% (854/1109) 4 X-linked dominant 13% (141/1109) 5 random 0% (2/1109) ML 2 Select Answer to see Preferred Response PREFERRED RESPONSE 3 Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK
Upgrade to View Premium Videos Upgrade to View Premium Videos Gower's Sign Derek Moore Pediatrics - Duchenne Muscular Dystrophy 10/24/2011 2385 views
Pediatric Gait Abnormality - Unknown Diagnosis (C1523) Derek Moore Pediatrics - Duchenne Muscular Dystrophy 6/4/2013 261 1 21