[Surgery of the spine in Duchenne's muscular dystrophy].

PURPOSE OF THE STUDY

The authors present a retrospective review of 27 patients presenting a Duchenne muscular dystrophy and who were operated for spinal deformity, with special reference to functional result and postoperative evolution of vital capacity.

MATERIAL AND METHODS

Age at surgery averaged 14. Mean scoliotic angulation was 42 degrees. A thoraco-lumbar kyphosis was present in 15 cases (kyphotic index less than 10 degrees). A pelvic obliquity averaging 17 degrees was associated in 19 cases. Mean pre-operative vital capacity was 56 per cent. Preoperative evolution of vital capacity was documented in 18 cases: annual rate of decrease was 4.3 per cent. Heart ejection fraction averaged 63 per cent in 23 cases, and was normal in 4 cases. Instrumentation was extended from D3, D4 or D5 to L5 (5 cases) or S1 (22 cases). Spinal fixation was done in all patients by subliminar wiring with Luque rods (5 cases) or Hartshill rectangle (22 cases). Sacral fixation was done with ilio-sacral screws linked to the rectangle by Cotrel Dubousset rods and dominos (15 cases).

RESULTS

Mean blood loss was 1750 cc. Postoperatively, 25 patients were extubated on the operative day, 1 patient at D + 1, and one patient underwent a tracheostomy after one month. Scoliosis was reduced to 10 degrees after surgery and 13 degrees after 30 months follow-up. Pelvic obliquity was reduced to 4 degrees after surgery and 7 degrees after 30 months. A good spinal balance was present after surgery in 20 patients; at follow-up, a coronal or sagittal imbalance averaging 40 mm was observed in 22 patients. Postoperative evolution of vital capacity was documented in 21 cases. The annual decrease rate was 6.4 per cent. Rate was higher in patients presenting a good preoperative vital capacity (over 70 per cent) and very low in patients presenting a preoperative vital capacity under 40 per cent. 10 patients were deceased at review after a mean 53 months survival, at a mean age of 19. 17 patients were alive with a 50 months follow-up.

DISCUSSION

Spinal surgery in Duchenne muscular dystrophy has a low morbidity. It allows to keep sitting position to the child and to preserve quality of life. Surgery should be considered as soon as frontal or sagittal collapse of the spine is observed. However surgery does not result in respiratory improvement nor in life duration lengthening.