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Muscular Dystrophies Neuromuscular Scoliosis. Dr. Donald W. Kucharzyk Clinical Assistant Professor University of Chicago Children’s Hospital. Muscular Dystrophies Neuromuscular Scoliosis. “Definition” Group of genetically determined progressive diseases of skeletal muscles
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Muscular DystrophiesNeuromuscular Scoliosis Dr. Donald W. Kucharzyk Clinical Assistant Professor University of Chicago Children’s Hospital
Muscular DystrophiesNeuromuscular Scoliosis “Definition” • Group of genetically determined progressive diseases of skeletal muscles • Not inflammatory in etiology • Classified as myopathies rather than as myositis
Muscular DystrophiesNeuromuscular Scoliosis “Definition” • Pathologic changes occur within the muscle fibers themselves • No abnormality seen in the innervation of the muscles • Peripheral nerves are normal
Muscular DystrophiesNeuromuscular Scoliosis “Historical Aspects” • Meryon in 1852 documented the first case of muscular dystrophy • Duchenne in 1868 published a treatise on muscular dystrophy • Duchenne described the entity as a muscle disease of childhood or adolescence
Muscular DystrophiesNeuromuscular Scoliosis “Historical Aspects” • Mostly seen in boys • Progressive weakness of the muscles • Begins in the lower limbs and spreads to the trunk and arms • Enlargement of the weakened muscles • Hyperplasia of connective tissues • Increase in fat cells in the affected muscles
Muscular DystrophiesNeuromuscular Scoliosis “Historical Aspects” • Gower in 1879 described the “Classic Clinical Sign” of the patient climbing up the legs • Later described another form of muscular dystrophy that primarily affected the distal musculature
Muscular DystrophiesNeuromuscular Scoliosis “Classification of Muscular Dystrophy” • X-Linked Recessive Duchenne’s muscular dystrophy Becker’s muscular dystrophy • Autosomal Recessive Limb Girdle Congenital muscular dystrophy
Muscular DystrophiesNeuromuscular Scoliosis “Classification of Muscular Dystrophy” • Autosomal Dominant Facioscapulohumeral Scapuloperoneal Late-onset proximal Distal (adult) Distal (infant) Ocular
Muscular DystrophiesNeuromuscular Scoliosis “Classification of Muscular Dystrophy” • Dystrophies with Myotonia Myotonia congenita Dystrophia myotonia Paramyotonia congenita
Muscular DystrophiesNeuromuscular Scoliosis “Etiology” • Gene responsible for Duchenne’s is located on the Xp21 region of the X chromosome • Spontaneous mutation occurs in one-third of the cases • Dystrophin is lacking in patients with muscular dystrophy (dystrophin necessary for cell membrane cytoskeleton)
Muscular DystrophiesNeuromuscular Scoliosis “Pathology” • Pathologic changes seen within the muscles are similar in all forms of muscular dystrophy • Most important histologic feature is loss of muscle fibers caused by segmental necrosis • Fiber necrosis with splitting, phagocytosis and fatty replacement are classic histopathologic findings
Muscular DystrophiesNeuromuscular Scoliosis “Pathology” • Muscle biopsy is the most effective test to distinguish the various types • General histological features include variation in fiber size, central location of muscle fibers, and degeneration of regional muscle fibers • Analysis for dystrophin in biopsy differentiates Duchenne’s from Limb-Girdle
Muscular DystrophiesNeuromuscular Scoliosis “Biochemical Considerations” • Creatine kinase is elevated although its not specific • Elevated to levels 20 to 200 times above normal levels • Highest in Duchenne’s than Becker’s • Aldolase is elevated and is classically highest early then declines as the disease progresses
Muscular DystrophiesNeuromuscular Scoliosis “Biochemical Considerations” • Dystrophin analysis reveals an absence or deficiency on the surface membrane of muscles cells • Assessment of dystrophin levels on muscle biopsy provides an index of prognosis for severity
Muscular DystrophiesNeuromuscular Scoliosis “Electromyography” • EMG can help differentiate myopathic and neuropathic processes • EMG in muscular dystrophies shows low amplitude, short duration, polyphasic motor unit potentials • NCV are normal in patients with muscular dystrophies
Muscular DystrophiesNeuromuscular Scoliosis “Duchenne’s Muscular Dystrophy” • Most common form • 1 per 3500 males • Males manifest the disease, females carry the gene • Must differentiate this process from Polymyositis early
Muscular DystrophiesNeuromuscular Scoliosis “Duchenne’s Muscular Dystrophy” • Clinically evident between three and six years of age • Onset of weakness insidious • Achieve developmental milestones at slightly older ages • Mild delay in walking seen • Gower’s sign may be seen as early as 15 months
Muscular DystrophiesNeuromuscular Scoliosis “Duchenne’s Muscular Dystrophy” • Presenting signs range from a waddling gait to a difficulty climbing stairs • Toe walking seen in the early stages of the disease • Muscle weakness is symmetrical • Seen first in the proximal muscles with the hip extensors affected first
Muscular DystrophiesNeuromuscular Scoliosis “Duchenne’s Muscular Dystrophy” • Lower extremity involvement precedes upper involvement by 3 to 5 years • Ankle equinus is the first sign • Trendelenburg gait seen due to proximal muscle weakness • Gait reveals a slow cadence with altered stance
Muscular DystrophiesNeuromuscular Scoliosis “Duchenne’s Muscular Dystrophy” • Proximal shoulder girdle weakness produces the second clinical sign “Meryon’s Sign” • As disease progresses, contractures occur throughout the lower extremities • Reflexes in the upper and knee lost early with sparing of the ankle until the terminal phase • Equinus and cavus foot deformities seen
Muscular DystrophiesNeuromuscular Scoliosis “Duchenne’s Muscular Dystrophy” • Scoliosis develops in late childhood or early adolescence • Appears as a mild curve but rapidly progresses • Lumbar kyphosis develops later especially with wheelchair use • Dystrophin levels analysis abnormal
Muscular DystrophiesNeuromuscular Scoliosis “Duchenne’s Muscular Dystrophy” Muscle Biopsy • Progressive changes with time • Degeneration and regeneration • Variation fiber size, internal nuclei • Proliferation adipose and connective tissue
Muscular DystrophiesNeuromuscular Scoliosis “Duchenne’s Muscular Dystrophy” Cardinal Clinical Signs • Waddling gait • Lordotic posture • Abnormal run and inability to hop • Difficulty rising from floor • Proximal muscle weakness leg>arms • Prominence of calves
Muscular DystrophiesNeuromuscular Scoliosis “Becker’s Muscular Dystrophy” • Similar to Duchenne’s but later onset and slower rate of deterioration of muscles • Age at presentation usually after 7 years • Ambulate into early adult years • Pseudohypertrophy of the calves seen • Dilated cardiomyopathy seen in high percentage of the patients
Muscular DystrophiesNeuromuscular Scoliosis “Becker’s Muscular Dystrophy” Muscle Biopsy • Variable dystrophic changes • Degeneration and regeneration • Variable loss of fibers and proliferation of adipose and connective tissue • Foci of atrophic fibers resembling denervation
Muscular DystrophiesNeuromuscular Scoliosis “Becker’s Muscular Dystrophy” Cardinal Clinical Signs • Mild functional disability • Proximal muscle weakness • Prominence of calves • Waddling gait • Lumbar lordosis
Muscular DystrophiesNeuromuscular Scoliosis “Limb-Girdle Muscular Dystrophy” • Weakness of the proximal muscles of the limbs • Onset usually in the second or third decade at average age 17.2 years • More benign than Duchenne’s • Ambulatory ability persists for a longer period of time
Muscular DystrophiesNeuromuscular Scoliosis “Limb-Girdle Muscular Dystrophy” • Most common type pelvic-femoral • Affects iliopsoas, gluteus, and quadriceps initially with shoulder involvement later • Scapulo-humeral type affects shoulder first followed by pelvic muscle • Difficulty lifting arms, rising from floor and climbing stairs seen
Muscular DystrophiesNeuromuscular Scoliosis “Limb-Girdle Muscular Dystrophy” Muscle Biopsy • Dystrophic changes variable • Marked variability in fibre size and splitting of fibres • Degeneration and regeneration • Proliferation of adipose and connective tissue
Muscular DystrophiesNeuromuscular Scoliosis “Limb-Girdle Muscular Dystrophy” Cardinal Clinical Signs • Abnormal gait • Lordotic posture • Variable muscle weakness • Deformities after loss of ambulation • Functional disability with hopping and rising from floor
Muscular DystrophiesNeuromuscular Scoliosis “Congenital Muscular Dystrophy” • Evident at or shortly after birth as a floppy baby appearance • Hypotonia and motor weakness of the limbs, trunk and facial muscles seen • Difficulty in sucking and swallow seen • Static clinical course with mild progression of weakness seen
Muscular DystrophiesNeuromuscular Scoliosis “Congenital Muscular Dystrophy” • Ambulation develops around two years of age and continues into adulthood • Common orthopaedic conditions seen include DDH, equinus contractures, and clubfoot deformities • Scoliosis seen and is progressive and will require surgical stabilization
Muscular DystrophiesNeuromuscular Scoliosis “Congenital Muscular Dystrophy” Muscle Biopsy • Variable • Mild myopathic and dystrophic changes • Extensive dystrophic changes with marked replacement of muscle by adipose tissue and variable connective tissue
Muscular DystrophiesNeuromuscular Scoliosis “Congenital Muscular Dystrophy” Cardinal Clinical Signs • General hypotonia • Weakness • Fixed deformities in relation to intrauterine posture • Variable weakness or contractures in later presenting cases
Muscular DystrophiesNeuromuscular Scoliosis “Spinal Muscular Atrophy” • Group of genetically determined disorders of the anterior horn cells of the spinal cord • Associated muscle weakness which is symmetrical affecting legs more than arms and proximal more than distal • Classified into severe, intermediate and mild based upon ability to sit, stand and walk
Muscular DystrophiesNeuromuscular Scoliosis “Spinal Muscular Atrophy” Severe • Werdnig-Hoffmann Disease • Age of onset: in utero or first few months • Hypotonia and weakness • Sucking and swallowing difficulty • Respiratory problems
Muscular DystrophiesNeuromuscular Scoliosis “Spinal Muscular Atrophy” Muscle Biopsy • Large group atrophy • Isolated or clusters of large fibres
Muscular DystrophiesNeuromuscular Scoliosis “Spinal Muscular Atrophy” Cardinal Clinical Signs • Severe limb and axial weakness • Frog posture • Marked hypotonia • Poor head control • Diaphragmatic breathing • Costal recession
Muscular DystrophiesNeuromuscular Scoliosis “Spinal Muscular Atrophy” Cardinal Clinical Signs • Bell shaped chest • Internal rotation of arms: jug handle posture • Normal facial movements • Absent tendon reflexes • Weak cry
Muscular DystrophiesNeuromuscular Scoliosis “Spinal Muscular Atrophy” Intermediate • Age of onset: between 6 and 12 months • Weakness of legs • Inability to stand or walk • Scoliosis • Excessive joint laxity • Respiratory problems
Muscular DystrophiesNeuromuscular Scoliosis “Spinal Muscular Atrophy” Muscle Biopsy • Characteristic patterns of large group atrophy • Variable clusters of enlarged fibres • Uniformly or predominantly type 1
Muscular DystrophiesNeuromuscular Scoliosis “Spinal Muscular Atrophy” Cardinal Clinical Signs • Symmetrical weakness of legs, predominantly proximal • Able to sit but unable to stand or put full weight on legs • Fasciculations of tongue, facial muscles spared • Tremors of hands • Absent reflexes
Muscular DystrophiesNeuromuscular Scoliosis “Spinal Muscular Atrophy” Mild • Age of onset from second year of life through childhood and adolescence into adulthood • Difficulty with activities such as running, climbing, steps, or jumping • Limitation in walking ability: quality and quantity
Muscular DystrophiesNeuromuscular Scoliosis “Spinal Muscular Atrophy” Muscle Biopsy • Characteristic pattern of large group atrophy • Variable groups of normal or enlarged fibres • Retention of normal bundle architecture with fibre type grouping • Focal small group atrophy
Muscular DystrophiesNeuromuscular Scoliosis “Spinal Muscular Atrophy” Cardinal Clinical Signs • Abnormal gait: waddling, flat-footed, wide based • Difficulty rising from floor • Proximal weakness legs>arms • Hand tremor • Tongue fasciculations
Muscular DystrophiesNeuromuscular Scoliosis “Treatment” • Orthopaedic management focuses on maximizing the child’s function whenever possible • The primary goal is to maintain functional ambulation as long as possible • Treatment involves PT, Orthotics, Steroid Therapy, and Surgical correction of contractures and deformities
Muscular DystrophiesNeuromuscular Scoliosis “Physical Therapy” • Prolongation of functional muscle strength • Prevention and correction of contractures • Gait training and assistance in maintaining ambulation • Maximum resistance exercises • Prevent adaptive posturing due to contractures of musculature
Muscular DystrophiesNeuromuscular Scoliosis “Steroid Therapy” • Prednisone therapy has shown to delay the loss of muscle strength for up to 3 years • Griggs et al 1991: prednisone use increases strength as early as 10 days into treatment • Response is dose related with higher muscle strength’s noted at 0.75mg/kg versus 0.3 mg/kg
Muscular DystrophiesNeuromuscular Scoliosis “Steroid Therapy” • Prednisone therapy does produce side effects including weight gain, cushingoid appearance and osteopenia • Side effects are dose related and duration related • Role still remains controversal
Muscular DystrophiesNeuromuscular Scoliosis “Orthotics” • AFO’s and KAFO’s are used when gait becomes precarious • KAFO’s are supplemented with a walker to prevent incidents of falling • Ishial weightbearing support, posterior thigh cuff and spring loaded drop lock knee joint with fixed ankle joint are key components to brace use • Extend ambulation up to three years