Secondary Thoracic Insufficiency Syndrome in None Ambulatory Myelodisplastic Children

Authors  Norman Ramirez MD  Pablo Valentin BS  Frances M. Rodriguez BS/ RT  Francisco Jaume MD  Axel Velez MD  Ivan Iriarte MD  John Flynn MD ( Deceased)

Introduction  None ambulatory children with myelodysplasia develop progressive neuromuscular scoliosis at an early age.  This early onset scoliosis affect lung growth and normal respiration.  They develop Secondary Thoracic Insufficiency Syndrome due the diaphragms is forced cephalad by the collapsing spinal deformity and short trunk.  The natural history of Secondary TIS has never been described

Purpose  To evaluate the spine and chest anatomy of early onset scoliosis in myelodysplastic none ambulatory patients.  Determine how the chest wall mechanics and lung function are affected  Describe the natural history of Secondary TIS

Methods and Material  31 Myelodisplastic None Ambulatory patients were evaluated  Demographic  History and physical examination  Radiographs  CT scans  Pulmonary function test  Arterial blood gases  Echocardiogram

Results  15 male/ 16 female  Two patients currently deceased due to respiratory failures  Average age : 14.6 years ( range : 5 – 27 years)  Body Mass Index : 18 ( range : 8 to 33 )  Respiratory problems: Snoring : 17 pts Mouth breathing: 21 pts Cessant Breathing: 9 pts Insomnia : 7 pts Somnolence: 7 pts

Radiographs  Scoliosis Level : Mostly T8 to Pelvis  Cobb Angle: AP Supine: 30° Sitting : 40° Sitting push up: 29° Lateral : Kyphosis Lordosis Sitting : 35° 75°

Radiographs  Space available for the Lung (SAL) : 85%  Thoracic Spine Height : Sitting 18 cm Sitting Push up 19 cm Supine traction 20 cm  Lumbar Spine Height: Sitting 9 cm Sitting Push up 12 cm Supine traction 10 cm

Ct Scan  Thoracic Spine Height: 19 cm Expected: 28 cm  Lumbar Spine Height: 11 cm Expected: 18 cm  Lung Volume 1376 cm 3  Expected Lung Volume ( Age/Gender) 3195 cm 3  Lung Volume/ Expected Lung Volume: 43 %

Pulmonary Function Test  Forced Vital Capacity %: 56  Forced Expiratory Volume 1 %: 55  FEV1/ FVC Ratio: 112

Blood gases/ Echocardiogram Blood Gases : PO2 : 99 PCO2: 35 HCO3: 25 Echocardiogram: No evidence of pulmonary hypertension

Conclusions  This the first study to validate the entity named Secondary TIS  In none ambulatory myelodysplastic patients the progressive spine deformity causes Secondary TIS  At early age the respiratory dysfunction can be difficult to detect clinically  The most important factor was the sagittal spine deformity.