Perioperative Evaluation of Respiratory Muscle Strength after Scoliosis Correction in Patients with Duchenne Muscular Dystrophy

Abstract

Study DesignRetrospective cohort study.PurposeTo investigate the effect of spinal correction on respiratory muscle strength in patients with Duchenne muscular dystrophy (DMD).Overview of LiteratureSeveral studies have reported that scoliosis correction in patients with DMD does not improve pulmonary function. In these studies, pulmonary function was evaluated using the traditional spirometric values of percent vital capacity (%VC) and percent forced vital capacity (%FVC). However, traditional spirometry may not be suitable for patients with DMD because the results can be influenced by patient fatigue or level of understanding. Therefore, we evaluated respiratory function focusing on respiratory muscle strength using maximal inspiratory pressure (MIP), maximal expiratory pressure (MEP), and sniff nasal inspiratory pressure (SNIP), in addition to %VC and %FVC.MethodsWe retrospectively reviewed 16 patients with DMD who underwent spinal correction surgery between 2006 and 2011 at Kitasato University Hospital. All patients were males, and the mean age was 13.5 years. Respiratory muscle strength was evaluated using MIP, MEP, and SNIP. Measurements were obtained preoperatively and at 1 and 6 months postoperatively, and %VC and %FVC were obtained preoperatively and within 6 months postoperatively.ResultsThe mean preoperative and postoperative %VC values were 54.0% and 51.7%, whereas the mean %FVC values were 53.9% and 53.2%, respectively. The mean MIP, MEP, and SNIP values obtained preoperatively and at 1 and 6 months postoperatively were as follows: MIP, 40.5, 42.7 and 47.2 cm H2O; MEP, 26.0, 28.0, and 29.0 cm H2O; and SNIP, 33.4, 33.0, and 33.0 cm H2O; respectively. The mean MIP and MEP values significantly improved postoperatively. There were no significant differences in SNIP, %VC, or %FVC preand postoperatively.ConclusionsBy focusing on respiratory muscle strength, our results suggest that scoliosis correction in patients with DMD might have a favorable effect on respiratory function.

Impact of scoliosis surgery on pulmonary function in patients with muscular dystrophies and spinal muscular atrophy

“…Accurate predicted values for nonambulatory patients with severe weakness and scoliosis are difficult due to error introduced by methods of height estimation when standing height cannot be measured. Our results are similar to the findings of Saito et al 5 in Duchenne muscular dystrophy who found no improvement in vital capacity postscoliosis surgery, with their data suggesting a trend (not statistically significant) toward decreased vital capacity. Our results contrast with Saito et al who suggested a small improvement in respiratory strength; we found no statistically significant nor clinically important change in respiratory strength measures comparing before and after scoliosis surgery.…”

“…4 A study of 16 patients with Duchenne muscular dystrophy found no improvement in forced vital capacity comparing pre-to postoperative values. 5 A study of 10 patients with spinal muscular atrophy found no significant differences in forced vital capacity comparing before and after scoliosis surgery, although 6 of 10 had a small improvement (mean, 0.2 L; SD, 0.1 L) in forced vital capacity atone to 4 years follow up. 6 A retrospective chart review study, published in 1995, of patients with spinal muscular atrophy found that among nine patients who had vital capacity measured before and after scoliosis surgery, eight (89%) had an increase in vital capacity, while one had a decrease in vital capacity on 5 to 76 months (mean, 39 months) follow up.…”

“…A study of patients with spinal muscular atrophy and Duchenne muscular dystrophy found the rate of decline in percent predicted forced vital capacity was decreased after scoliosis surgery 4 . A study of 16 patients with Duchenne muscular dystrophy found no improvement in forced vital capacity comparing pre‐ to postoperative values 5 …”

Short term effect and effect on rate of lung function decline after surgery for neuromuscular or syndromic scoliosis

“…Saito retrospectively reviewed lung function and respiratory muscle strength preoperatively, 1 month and 6 months postoperatively in 16 patients with DMD. Although no significant difference was observed in FVC and VC, mean values of PI max and PE max significantly improved postoperatively 16 .…”

“…The rate of decline in LFT results had broad confidence intervals due to small sample, which possible explains the non-significant mean change in progression rate. However, compared to other studies we included more patients 1,2,8,[11][12][13]16 . The follow up time of our study was limited.…”