- 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.