Sleep-disordered breathing in patients with Chiari malformation type II: a case-control study and review of the literature

The main aim was to evaluate the prevalence of sleep-disordered breathing (SDB) in patients with Chiari II malformation (CM-II). The secondary objectives were to evaluate the association between SDB, morphological abnormalities and neurological symptoms and to review the literature of patients with SDB and CM-II. The study has a cross-sectional, case-control design. Patients with CM-II (cases) were compared to subjects (controls) referred for clinical polysomnography in the Sleep Medicine Unit, matched for age and sex. All cases underwent brain and spinal cord MRI, and a polysomnography (PSG) was performed to all participants. A review of the literature about SDB in patients with CM-II was performed. Forty patients were included (20 cases vs 20 controls). SDB was identified in 45% of cases, a significantly higher prevalence compared to controls. Three patients presented a purely obstructive SDB, three patients a purely central SDB, and three patients a both obstructive and central SDB. Compared with controls, patients with CM-II showed higher Oxygen Desaturation Index (ODI) (median ODI: CM-II: 3.7, IQR: 1.6-19.5; Controls: 1.1, IQR: 0.3-3.2) and Obstructive-Apnea Hypopnea Index (O-AHI) (median O-AHI: CM-II: 1.5, IQR: 0.5-5.1; Controls: 0.1, IQR: 0.0-0.7). A logistic regression showed that the risk to develop SDB in patients affected by CM-II was 14.7 times higher than in control population. Our study and literature review showed a high prevalence of SDB in patients with CM-II. These patients are often asymptomatic at diagnosis suggesting that PSG should be routinely provided in this population.