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.

Original Text by Clifford R. Wheeless, III, MD.

Last updated by Data Trace Staff on Monday, May 21, 2012 2:42 pm