Polysomnographic values in adolescents with ataxia telangiectasia.

Most adolescents with ataxia telangiectasia (A-T) develop progressive bulbar muscle weakness and decreased pulmonary reserve. The purpose of this study was to define the patterns of sleep and respiration during sleep, and to identify sleep-related breathing problems in subjects with A-T. To address these issues, overnight polysomnography was performed on 12 adolescents with A-T. Eleven of the 12 subjects completed overnight polysomnography. The median age was 16 years (range, 13-20 years). All subjects in the study were wheelchair-bound and the median forced vital capacity (% predicted of normal) was 44% (range, 16-82%). The mean sleep efficiency was 72.6% with a mean apnea hypopnea index (AHI) of 0.7 events/hr (range, 0-2.2). The majority of apnea/hypopneas were REM related. The mean central apnea index was 0.1 events/hr (range, 0-0.2). The mean oxygen saturation nadir was 92.7% (range, 87-96) and the mean peak end-tidal carbon dioxide ET(CO(2) ) value was 53.8 mm Hg (range, 49-60). Two of 11 subjects had ET(CO(2) ) values >or=50 mm Hg for more than 50% of total sleep time. In this study, the majority of A-T adolescents had infrequent partial or complete upper airway obstructions during sleep and minimal nighttime hypoxemia. They did, however, have decreased sleep efficiency most likely, due in part, to their underlying neurological condition. This decrease in total sleep time may underestimate hypoventilation. Based on these findings, overnight polysomnography should be considered in adolescents with A-T, particularly in those in which there is a clinical suspicion of sleep related breathing abnormalities.

Pulmonary function in adolescents with ataxia telangiectasia.

INTRODUCTION: Pulmonary complications are common in adolescents with ataxia telangiectasia (A-T), however objective measurements of lung function may be difficult to obtain because of underlying bulbar weakness, tremors, and difficulty coordinating voluntary respiratory maneuvers. To increase the reliability of pulmonary testing, minor adjustments were made to stabilize the head and to minimize leaks in the system. Fifteen A-T adolescents completed lung volume measurements by helium dilution. To assess for reproducibility of spirometry testing, 10 A-T adolescents performed spirometry on three separate occasions. RESULTS: Total lung capacity (TLC) was normal or just mildly decreased in 12/15 adolescents tested. TLC correlated positively with functional residual capacity (FRC), a measurement independent of patient effort (R2=0.71). The majority of individuals had residual volumes (RV) greater than 120% predicted (10/15) and slow vital capacities (VC) less than 70% predicted (9/15). By spirometry, force vital capacity (FVC) and forced expiratory volume in 1 sec (FEV1) values were reproducible in the 10 individuals who underwent testing on three separate occasions (R=0.97 and 0.96 respectively). Seven of the 10 adolescents had FEV1/FVC ratios>90%. CONCLUSION: Lung volume measurements from A-T adolescents revealed near normal TLC values with increased RV and decreased VC values. These findings indicate a decreased ability to expire to residual volume rather then a restrictive defect. Spirometry was also found to be reproducible in A-T adolescents suggesting that spirometry testing may be useful for tracking changes in pulmonary function over time in this population.