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Muscular Dystrophies Neuromuscular Scoliosis

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 Dystrophies Neuromuscular Scoliosis

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  1. Muscular DystrophiesNeuromuscular Scoliosis Dr. Donald W. Kucharzyk Clinical Assistant Professor University of Chicago Children’s Hospital

  2. Muscular DystrophiesNeuromuscular Scoliosis “Definition” • Group of genetically determined progressive diseases of skeletal muscles • Not inflammatory in etiology • Classified as myopathies rather than as myositis

  3. 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

  4. 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

  5. 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

  6. 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

  7. 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

  8. Muscular DystrophiesNeuromuscular Scoliosis “Classification of Muscular Dystrophy” • Autosomal Dominant Facioscapulohumeral Scapuloperoneal Late-onset proximal Distal (adult) Distal (infant) Ocular

  9. Muscular DystrophiesNeuromuscular Scoliosis “Classification of Muscular Dystrophy” • Dystrophies with Myotonia Myotonia congenita Dystrophia myotonia Paramyotonia congenita

  10. 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)

  11. 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

  12. 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

  13. 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

  14. 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

  15. 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

  16. 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

  17. 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

  18. 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

  19. 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

  20. 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

  21. 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

  22. 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

  23. 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

  24. 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

  25. 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

  26. Muscular DystrophiesNeuromuscular Scoliosis “Becker’s Muscular Dystrophy” Cardinal Clinical Signs • Mild functional disability • Proximal muscle weakness • Prominence of calves • Waddling gait • Lumbar lordosis

  27. 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

  28. 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

  29. 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

  30. 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

  31. 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

  32. 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

  33. 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

  34. 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

  35. 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

  36. 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

  37. Muscular DystrophiesNeuromuscular Scoliosis “Spinal Muscular Atrophy” Muscle Biopsy • Large group atrophy • Isolated or clusters of large fibres

  38. 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

  39. 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

  40. 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

  41. Muscular DystrophiesNeuromuscular Scoliosis “Spinal Muscular Atrophy” Muscle Biopsy • Characteristic patterns of large group atrophy • Variable clusters of enlarged fibres • Uniformly or predominantly type 1

  42. 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

  43. 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

  44. 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

  45. 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

  46. 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

  47. 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

  48. 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

  49. 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

  50. 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

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