Children with thoracic insufficiency syndrome (TIS) have spine and chest wall disorders that produce restrictive lung disease and sleep-related breathing abnormalities. Children with early onset scoliosis due to neuromuscular weakness, known as secondary TIS, may have worse sleep-related breathing due to added impact of respiratory muscle weakness. Comparison of breathing patterns and gas exchange during sleep between children with primary and secondary TIS has not been previously reported.
Overnight polysomnograms obtained for clinical indications were reviewed in 15 children with TIS (11 Primary TIS vs. 4 Secondary TIS) prior to surgical intervention when well. Differences between groups were assessed by univariate analyses. Predictors of apnea hypopnea index (AHI) and nadir oxyhemoglobin saturation were assessed using multiple linear regression.
Median AHI in patients with secondary TIS was significantly higher (26.8 events/hr, IQR 8.4–48.8), than in patients with primary TIS (4.3 events/hr, IQR 2.3–1, p=0.005). Obstructive hypopneas constituted the majority of sleep-related breathing abnormalites, and occurred more often in REM sleep. Median nadir oxyhemoglobin saturation was significantly lower in the secondary TIS group (83%, IQR 80–89%) than those with primary TIS (92%, IQR 88–93%, p=0.03). Neither group had hypoventilation. Mean Cobb angle was similar between the 2 groups (67 vs. 69 degrees, p=0.86), though body mass index (BMI) was significantly higher in patients with neuromuscular weakness (19.5 vs. 15.4, p=0.03). The association of neuromuscular weakness with AHI and nadir oxyhemoglobin saturation remained significant when adjusted for severity of scoliosis by measured Cobb angle and BMI.
All children with TIS are at risk for sleep disordered breathing due to restrictive pulmonary mechanics and low lung volumes; however, in those with secondary TIS, neuromuscular weakness incurs an additional risk that may require earlier intervention, such as BIPAP, CPAP or surgical correction in the face of progressive scoliosis.
Children with TIS and neuromuscular weekness warrant early assessment for sleep disordered breathing.
Amanda Striegl, No Financial Disclosure Information; No Product/Research Disclosure Information