Central sleep apnoea in Arnold-Chiari malformation: evidence of pathophysiological heterogeneity

We report on the case of two young patients with type I Arnold-Chiari malfo rmation (ACM), as revealed IF a central sleep apnoea (CSA) syndrome without any other neurological defect. Case 1 was a 14-yr-old male patient, who developed severe alveolar hypovent ilation and needed long-term mechanical ventilation via,a tracheostomy. Case 2 was a 39-yr-old male patient, who developed features suggestive of s leep apnoea and responded to nasal continuous positive airway pressure vent ilation despite the central type of apnoeas. Those two cases illustrate the different pathophysiological mechanisms invo lved in CSA, namely a blunted chemical drive (in hypercapnic patients) and an increased chemical drive, which destabilizes the breathing pattern durin g sleep (in normo/hypocapnic patients), Central sleep apnoea can be the initial manifestation of Arnold-Chiari malf ormation and can lead to a life-threatening condition.