Short term effect and effect on rate of lung function decline after surgery for neuromuscular or syndromic scoliosis.
Esther S. Veldhoen, MRCPCH 1, Anneloes de Vries, Msc1 , Tom P.C. Schlosser, PhD2, Moyo C. Kruyt, PhD2 , Ruben P.A. van Eijk, PhD3,4, Joyce M. Tersmette, Msc5, Erik H. Hulzebos, PhD6, Ludo W. van der Pol, PhD3, Roelie M. Wösten-van Asperen, PhD1 , Cornelis K. van der Ent, PhD5.
1 Pediatric Intensive Care Unit, Wilhelmina Children’s Hospital, University Medical Center Utrecht,The Netherlands.
2Department of Orthopedic surgery, University Medical Center Utrecht,The Netherlands.
3 Department of Neurology, Brain Centre Rudolf Magnus, University Medical Center Utrecht, The Netherlands.
4Biostatistics & Research Support, Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
5Department of Pediatric Pulmonology, Wilhelmina Children’s Hospital, University Medical Center Utrecht, The Netherlands.
6Child Development and Exercise Center, Wilhelmina Children’s Hospital, University Medical Center Utrecht, The Netherlands.
Corresponding Author: E.S. Veldhoen Wilhelmina Children’s Hospital, University Medical Center Utrecht, PO box 85090, 3508 AB Utrecht The Netherlands Tel +31 887554702 E.S.Veldhoen@umcutrecht.nl
No financial support or grants.
Keywords: Lung function; Neuromuscular disease; Scoliosis,
Abbreviated title: Lung function after scoliosis surgery.
Abstract
Introduction
Understanding the impact of scoliosis surgery on lung function is important for counseling patients about risks and benefits of surgery. We prospectively compared the trends in lung function test (LFT) results prior to and after scoliosis surgery in children with neuromuscular diseases, or dysmorphic syndromes. We hypothesized a stabilization.
Methods
We prospectively included children with neuromuscular or syndromic scoliosis able to perform LFTs. We studied (Forced) Vital Capacity ((F)VC), the ratio of Forced Expiratory Volume in 1 second (FEV1) and FVC, and Peak Expiratory Flow (PEF). Preoperative LFT results were compared with results 3-4 months after surgery. The mean monthly change in LFT results up to 2 years after surgery was compared with the preoperative natural history using linear mixed effects models.
Results
We included 43 patients. No significant change was observed in absolute values of (F)VC, FEV1/FVC and PEF prior to and after surgery. Median standardized VC, FVC and PEF decreased significantly after surgery from 59 to 58%, 60 to 51% and 61 to 53% respectively. The monthly rate of change in FVC was -0.13 % (95% CI -0.42 to 0.17) prior to surgery and -0.20% (95% CI -0.42 to 0.03) after surgery, mean difference -0.07 (95% CI -0.46 to 0.31; p=0.36).
Conclusion
No stabilization of lung function 3-4 months after scoliosis surgery was observed in children with neuromuscular and syndromic scoliosis with restrictive lung function disease. The effect of surgery on the rate of lung function decline remains inconclusive.
Introduction
Scoliosis is a common complication in patients with neuromuscular diseases (NMDs) and genetic syndromes and scoliosis surgery may be necessary for a number of reasons. It improves ease of nursing care, reduces back pain and allows the patient a much better sitting posture and balance, thereby improving the patient’s overall quality of life and self-image 1,2. One of the more significant factors causing morbidity and mortality in patients with neuromuscular scoliosis is the deterioration in pulmonary function to which scoliosis progression may contribute1. By distorting thoracic anatomy and rib alignment, severe scoliosis decreases the compliance of the chest wall, thereby restricting vital capacity (VC) 2, while lordotic deformation of the thoracic spine may cause bronchial kinking or compression and bronchial obstruction 3. Straightening the spine has the potential to improve the ability to elevate the ribs and thus expand the chest on inspiration 2. On the other hand, children with preexisting respiratory compromise have an increased risk of developing postoperative complications4. Understanding the impact of neuromuscular or syndromic scoliosis surgery on lung function is important for counseling patients about risks and longer term benefits of scoliosis surgery on respiratory function 2.
Research on the impact of scoliosis surgery on lung function has yielded conflicting results.
In this prospective cohort study, we compared lung function test (LFT) results of children with probable restrictive lung function due to neuromuscular disease (NMD) or syndromic syndromes prior to and after scoliosis surgery in a single center.
We aimed to study the short term improvement of lung function after surgery and determine the mean change in post-operative compared to pre-operative progression rate in lung function. We hypothesized that scoliosis surgery slows the rate of lung function decline.
Materials and methods
Eligibility was checked in pediatric patients planned for surgery for a neuromuscular or syndromic scoliosis at the preoperative clinic of the Pediatric Intensive Care Unit (PICU) of the Wilhelmina Children’s Hospital Utrecht, the Netherlands in 2018 or 2019. Patients were included if they were able to perform lung function tests (LFTs). Only reproducible LFT results were included. We excluded patients with hereditary proximal spinal muscular atrophy (SMA) who had started treatment with genetic therapies during follow up, as this might provide an alternative explanation for improvement of LFT results. This study was approved by the local Medical Ethics Committee. Written informed consent was obtained from all participants and/or their parents. The reporting of this study conforms to the STROBE statement5.
Spirometry data (Geratherm Spirostick®) were collected at the department of pulmonology prior to and 3 months after surgery. We included results of (Forced) Vital Capacity ((F)VC), the ratio of Forced Expiratory Volume in 1 second (FEV1) and FVC, and Peak Expiratory Flow (PEF). All LFTs were measured in sitting position, without corsets or braces by a small team of professionals experienced in conducting these tests in children with NMDs and other comorbidities. All LFTs were measured and reported according to the European Respiratory Society guideline 6. If patients were unable to stand to measure height, arm span was used as a surrogate measure. We reported absolute and standardized LFT values, according to the Global Lung Initiative 7.
We compared values 0-3 months before and 3-4 months after scoliosis surgery. In patients with more than three months between the PICU clinic visit and surgery, LFTs were repeated on the day of admission. We chose this timing of 3-4 months after surgery, to combine it with regular orthopedic follow up and consequently minimize the burden for the patient .
To study the progression rate of LFT results before and after surgery, we used LFT results obtained during regular follow up in the 2 years before and after surgery whenever available.