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DMD: Scoliosis

- See:
       - Duchenne Muscular Dystrophy
       - Scoliosis - Discussion:

- Discussion:
    - scoliosis is almost universal in pts who have DMD, and it usually develops after they lose the ability to walk (after age 10 yrs);
            - early scoliosis develops in 25% of pts while they are still able to walk;
    - scoliosis that has progressed to 35-40 degrees, will most likely continue to worsen as a  collapsing neuromuscular scoliosis;
    - scoliosis is generally centered in the lower thoracic or lumbar region and almost always curves into a pelvic obliquity;
            - there is a high prevalence of thoracolumbar kyphosis;
    - as the deformity becomes more severe, there will be increased difficulty w/ sitting and increasing pain;
    - surgery prolongs pulmonary f(X) & life of patient;
    - dorsal instrumentation & fusion does arrest progression of curvature, & it enables pt to sit for longer periods, and promotes comfort;

- Bracing:
    - orthotic management apparently has not changed the natural history of this condition and are poorly tolerated in these patients;
    - use of braces or wheelchair seating systems has not controlled progression of scoliosis in pts who have DMD;
    - as deformity increases, the brace must be modified frequently;
    - to further assist w/ sitting, patients should be provided w/ a narrow wheelchair w/ firm seat and back, lateral chest-wall supports, and dual seat belts;

- Surgical Indications:
    - non ambulating patients;
          - these patients always have a decreased forced vital capacity, which becomes manifest in late childhood due to weakness of the thoracic muscles;
          - patients who have DMD generally have a forced vital capacity of 50 to 70 percent of normal when they begin to use a wheelchair full-time;
                 - w/ time, there is further prgressive loss of pulmonary function;
                 - forced vital capacity decreases will decrease w/ spinal curve progression;
          - due to the poor prognosis of DMD scoliosis, spinal fusion should be considered w/ curves even as small as 10-20 deg and no pelvic obliquity;
          - patients w/ curves greater than 40 deg are at higher risk for pulmonary complications due to loss of forced vital capacity;

- Anesthesia Workup:
    - see malignant hyperthermia:
    - safe anesthetic agents include: nitrous oxide, intravenous narcotics, sedative hypnotics, and non-depolarizing muscle relaxants;
    - dangerous agents include: succinylcholine & vapor anesthetics;
    - subclinical cardiomyopathy: worked up w/ electrocardiograms, echocardiograms, and Holter monitoring;

- Surgery:
    - curves in patients who have Duchenne muscular dystrophy tend to remain flexible for extended periods of time;
    - anterior instrumentation & fusion is not appropriate for patients w/ decreased pulmonary function;
    - in absence of pelvic obliquity, instrumentation and fusion can be stopped at L-5;
    - expect high rates of failure of instrumentation, loss of correction, and discomfort in patients who do not have an arthrodesis;

- Contraindications to Surgery:
    - forced vital capacity is less than 30 per cent of normal, because of increased risk of pulmonary problems postoperatively;
           - patients who undergo fusion should be aware of the risk of ventilator dependency after surgery

Progression of scoliosis in Duchenne muscular dystrophy.

Spinal stabilisation in Duchenne muscular dystrophy.