Muscular Dystrophies Neuromuscular Scoliosis Dr. Donald W. Kucharzyk Clinical Assistant Professor University of Chicago Children’s Hospital.
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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 Not inflammatory in etiology Classified as myopathies rather than as myositis Muscular Dystrophies Neuromuscular Scoliosis “Definition” Pathologic changes occur within the muscle fibers themselves No abnormality seen in the innervation of the muscles Peripheral nerves are normal Muscular Dystrophies Neuromuscular 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 Dystrophies Neuromuscular 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 Dystrophies Neuromuscular 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 Dystrophies Neuromuscular Scoliosis “Classification of Muscular Dystrophy” X-Linked Recessive Duchenne’s muscular dystrophy Becker’s muscular dystrophy Autosomal Recessive Limb Girdle Congenital muscular dystrophy Muscular Dystrophies Neuromuscular Scoliosis “Classification of Muscular Dystrophy” Autosomal Dominant Facioscapulohumeral Scapuloperoneal Late-onset proximal Distal (adult) Distal (infant) Ocular Muscular Dystrophies Neuromuscular Scoliosis “Classification of Muscular Dystrophy” Dystrophies with Myotonia Myotonia congenita Dystrophia myotonia Paramyotonia congenita Muscular Dystrophies Neuromuscular 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 Dystrophies Neuromuscular 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 Dystrophies Neuromuscular 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 Dystrophies Neuromuscular 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 Dystrophies Neuromuscular 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 Dystrophies Neuromuscular 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 Dystrophies Neuromuscular 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 Dystrophies Neuromuscular 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 Dystrophies Neuromuscular 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 Dystrophies Neuromuscular 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 Dystrophies Neuromuscular 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 Dystrophies Neuromuscular 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 Dystrophies Neuromuscular 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 Dystrophies Neuromuscular 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 Dystrophies Neuromuscular 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 Dystrophies Neuromuscular 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 Dystrophies Neuromuscular Scoliosis “Becker’s Muscular Dystrophy” Cardinal Clinical Signs Mild functional disability Proximal muscle weakness Prominence of calves Waddling gait Lumbar lordosis Muscular Dystrophies Neuromuscular 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 Dystrophies Neuromuscular 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 Dystrophies Neuromuscular 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 Dystrophies Neuromuscular 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 Dystrophies Neuromuscular 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 Dystrophies Neuromuscular 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 Dystrophies Neuromuscular 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 Dystrophies Neuromuscular 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 Dystrophies Neuromuscular 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 Dystrophies Neuromuscular 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 Dystrophies Neuromuscular Scoliosis “Spinal Muscular Atrophy” Muscle Biopsy Large group atrophy Isolated or clusters of large fibres Muscular Dystrophies Neuromuscular Scoliosis “Spinal Muscular Atrophy” Cardinal Clinical Signs Severe limb and axial weakness Frog posture Marked hypotonia Poor head control Diaphragmatic breathing Costal recession Muscular Dystrophies Neuromuscular 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 Dystrophies Neuromuscular 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 Dystrophies Neuromuscular Scoliosis “Spinal Muscular Atrophy” Muscle Biopsy Characteristic patterns of large group atrophy Variable clusters of enlarged fibres Uniformly or predominantly type 1 Muscular Dystrophies Neuromuscular 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 Dystrophies Neuromuscular 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 Dystrophies Neuromuscular 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 Dystrophies Neuromuscular 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 Dystrophies Neuromuscular 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 Dystrophies Neuromuscular 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 Dystrophies Neuromuscular 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 Dystrophies Neuromuscular 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 Dystrophies Neuromuscular 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 Muscular Dystrophies Neuromuscular Scoliosis “Lower Limb Surgery” As muscles weakness worsens, contractures develop and walking becomes labored and unstable Soft tissue surgery can improve gait and prolong the time during which the child is able to ambulate Shapiro and Specht et al JBJS 1993 classified surgical type based upon ambulatory approach Muscular Dystrophies Neuromuscular Scoliosis “Lower Limb Surgery” Early-Extensive Ambulatory: release hip, hamstring, heel cords, and PT transfer before contracture Moderate Ambulatory: rarely includes the hip and is performed while child is still able to walk but is getting worse Minimum Ambulatory: corrects only the equinus contractures Muscular Dystrophies Neuromuscular Scoliosis “Lower Limb Surgery” Rehabilitative Approach: operative intervention after the child ceases walking but with goal of reestablishing ambulation Palliative Approach: surgical correction of equinovarus after full-time wheelchair use has begun with goal of pain relief and better shoe/orthotic use Muscular Dystrophies Neuromuscular Scoliosis “Lower Limb Surgery” Proponents of surgery site that operating before contractures develop improve the quality of ambulation without braces and wheelchair dependence is delayed ‘Rideau et al’ On average, operative approaches prolong walking time by 2 to 3.5 years Muscular Dystrophies Neuromuscular Scoliosis “Lower Limb Surgery” If surgery is delayed until after the child loses the ability to walk, it must be performed in a timely manner to reestablish ambulation This small window is only three to six months after the child stops ambulating Operations after this time will not help regain the patients ability to walk Muscular Dystrophies Neuromuscular Scoliosis “Lower Limb Surgery” Foot and Ankle Equinus is managed by percutaneous TendoAchilles lengthening Varus is treated by anterior transfer of the posterior tibilais tendon through the interosseous membrane This addresses hindfoot varus and augments dorsiflexion of the ankle Muscular Dystrophies Neuromuscular Scoliosis “Lower Limb Surgery” Knee Consists of lengthening or tenotomy of the hamstrings Yount procedure helpful KAFO bracing essential postop Muscular Dystrophies Neuromuscular Scoliosis “Lower Limb Surgery” Hip Abduction contractures of the hips are treated by resection of the iliotibial band ‘Ober Release” Hip flexion contractures can be improved by release of the sartorius, rectus femoris, and tensor fascia lata Muscular Dystrophies Neuromuscular Scoliosis “Lower Limb Surgery” Postoperative care Postoperative care should allow for early weightbearing and ambulation Standing position encouraged on the first postoperative day Casting should be limited Bracing instituted as soon as possible after casting and or surgery Muscular Dystrophies Neuromuscular Scoliosis “Spinal Deformities” Prevalence is higher than that of idiopathic scoliosis Greater the neuromuscular involvement the greater the likelihood and severity of the scoliosis Curves tend to become increasingly pronounced after the child is nonambulatory Muscular Dystrophies Neuromuscular Scoliosis “Spinal Deformities” Curve patterns are different from idiopathic scoliosis Long and sweeping thoracoclumbar curves extending to the pelvis with pelvic obliquity commonly seen Thoracolumbar kyphosis common and sometimes lumbar hyperlordosis can be seen Muscular Dystrophies Neuromuscular Scoliosis “Spinal Deformities” Scoliosis develops in 25% of the patients while they are still able to walk Curves that progress to 35 to 40 degree’s will continue to worsen If left untreated, most curves will progress beyond 90 degree’s As curves increase,increased difficulty with sitting, increasing pain, and respiratory problems develop Muscular Dystrophies Neuromuscular Scoliosis “Spinal Deformities” Treatment Options Observation Bracing Surgical Stabilization Muscular Dystrophies Neuromuscular Scoliosis “Spinal Deformities” Bracing Has been tried but not recommended Used only to improve sitting wheelchair posture Bracing Premise: prevents progression but all these curves progress despite bracing Progression duration longer in neuromuscular’s due to prolonged muscle weakness Bracing will effect pulmonary status Muscular Dystrophies Neuromuscular Scoliosis “Spinal Deformities” Surgery Surgical principles are different from those of idiopathic scoliosis Performed younger Fusion’s are longer Commonly extends to the sacrum Anterior/Posterior fusion’s are common Muscular Dystrophies Neuromuscular Scoliosis “Spinal Deformities” Surgery Important concept to understand is the centering of the head over the pelvis in both the coronal and sagittal planes Maintains sitting balance Improves head control Allows more independent upper extremity control Muscular Dystrophies Neuromuscular Scoliosis “Spinal Deformities” Surgery Surgery should be performed once a curve reaches 30 degree’s in a nonambulator Mubarak et al recommend surgery for curves greater than 20 degree’s and when FVC is greater than 40 percent of normal Surgery tolerated if FVC is less than 35% of normal Muscular Dystrophies Neuromuscular Scoliosis “Spinal Deformities” Surgery Fusion consists of segmental fixation with sublaminar wires Extension of the fusion to the pelvis dependent on the presence of pelvic obliquity Mubarak et al: mild curve without preexisting pelvic obliquity, fuse to L5 only Muscular Dystrophies Neuromuscular Scoliosis “Spinal Deformities” Surgery Because the primary goals are to ensure a level pelvis for seating, fusion ‘s are extended to the pelvis via Galveston technique Pelvic obliquity must be controlled and therefore caudal fusion is necessary Muscular Dystrophies Neuromuscular Scoliosis “Spinal Deformities” Complications Ramirez et al: reported a 27% major complication rate Substantial blood loss due to osteopenic bone Postoperative infection Hardware failure Curve progression Muscular Dystrophies Neuromuscular Scoliosis “Spinal Deformities” Complications Miller et al: pneumonia occurred in 17% of the patients Prolonged mechanical ventilator dependency Malignant Hyperthermia Sudden Death Muscular Dystrophies Neuromuscular Scoliosis THANK YOU Dr. Donald W. Kucharzyk