BREATHING ABNORMALITIES IN SLEEP IN ACHONDROPLASIA

Overnight sleep studies were performed in 20 subjects with achondropla sia to document further the respiratory abnormalities present in this group. Somatosensory evoked potentials (SEPs) were recorded in 19 of t he subjects to screen for the presence of brainstem abnormalities, whi ch are one of the potential aetiological mechanisms. Fifteen children aged 1 to 14 years, and five young adults, aged 20 to 31 years were in cluded. All had upper airway obstruction and 15 (75%) had a pathologic al apnoea index (greater than five per hour). Other sleep associated r espiratory abnormalities, including partial obstruction, central apnoe a, and abnormal electromyographic activity of accessory muscles of res piration, also showed a high prevalence. SEPs were abnormal in eight ( 42%), but there was no correlation between abnormal SEPs and apnoea du ring sleep, either qualitatively or quantitatively. A high prevalence of both sleep related respiratory abnormalities and abnormal SEPs in y oung subjects with achondroplasia was demonstrated. However, the sleep related respiratory abnormalities do not always result in significant blood gas disturbances or correlate with abnormal SEPs in this group.