[The effects of spinal fusion on respiratory function and quality of life in Duchenne muscular dystrophy].

We studied the functional outcome of spinal fusion for the surgical treatment of scoliosis in 8 patients with Duchenne muscular dystrophy (DMD). The mean age of DMD patients at the time of the surgery and the mean follow-up duration was 13.8 (12.3 to 15.4) and 3.9 (1.5 to 6.8) years, respectively. The average spinal angle (Cobb angle) was corrected from 58.8 to 28.6 degrees with the mean corrective rate of 51.3% by the surgical intervention. The correction rate was higher and the corrected Cobb angle remained unchanged during follow-up period in mildly scoliotic patients. Forced vital capacity (FVC) increased post-operatively in 3 patients with moderate scoliosis (Cobb angle: 50 to 80 degrees), indicating that the correction of spinal alignment is effective for the treatment of decreased thoracic volume in DMD. On the other hand, two cases with low % FVC (16.9% and 30.4%, respectively) had poor prognosis in respiratory status. Namely, one died of pneumonia at 17 months after the surgery and the other required mechanical ventilation via nasal mask at 3 years post surgery. Sitting balance improved in all patients, which resulted in more functional use of their upper extremities. During the follow-up period, all patients except one patient who died of pneumonia could maintain sitting balance without support. Moreover these included 2 patients over 20 year old. No complications related to spinal deformities have been found in these patients. Previous study in our hospital showed that 7 of 48 (14.6%) of DMD patients spent all their lives without apparent scoliosis (Cobb angle less than 30 degrees). These suggest that spinal fusion could be recommended for patients with Cobb angle more than 30 degrees and with % FVC more than 35%. Although the impact of spinal fusion upon the life expectancy remains unclear, favorable effect on respiratory function and quality of life can be expected for carefully selected patients with DMD.