Performance characteristics of upper airway critical collapsing pressure measurements during sleep

Objective: The critical pressure (PCRIT), a measurement of upper airway collapsibility, is a determinant of the severity of upper airway obstruction during sleep. We examined the performance characteristics of the passive and active PCRIT by examining both within-night and between-night variability in the measurements. Methods: We studied 54 sleep apnea patients (39 men, 15 women) and 34 normal subjects (20 men, 14 women) on either 1 or 2 nights during sleep. The PCRIT was measured during relative hypotonia ( passive state) or during periods of sustained upper airway obstruction used to recruit upper airway neuromuscular responses ( active state) within- and between-nights. In a subgroup of 10 normal subjects, we performed repeated measurements during hypnotic-induced sleep. Bland-Altman analyses were used to determine the within-night and between-night reliability of the PCRIT measurements. Results: There were no significant within-night or between-night differences for the mean passive PCRIT. The active PCRIT was ∼1 cm H 2O more collapsible on the second night than on the first night. The limits of agreement, which bound the passive and active PCRIT, was ∼ ± 3 cm H2O and was reduced to ∼ ± 1 cm H 2O for the passive PCRIT with hypnotic-induced sleep. Conclusion: Passive and active PCRIT measurements are reasonably reliable within and between nights. An approximately 3 cm H2O change in passive or active PCRIT appears to represent the minimally significant change in PCRIT necessary to assess the effect of an intervention (e.g., positional therapy, surgical interventions, oral appliance effects, and pharmacotherapy) on upper airway mechanical loads or neuromuscular responses

Performance Characteristics of Upper Airway Critical Collapsing Pressure Measurements during Sleep

Objective: The critical pressure (PCRIT), a measurement of upper airway collapsibility, is a determinant of the severity of upper airway obstruction during sleep. We examined the performance characteristics of the passive and active PCRIT by examining both within-night and between-night variability in the measurements. Methods: We studied 54 sleep apnea patients (39 men, 15 women) and 34 normal subjects (20 men, 14 women) on either 1 or 2 nights during sleep. The PCRIT was measured during relative hypotonia ( passive state) or during periods of sustained upper airway obstruction used to recruit upper airway neuromuscular responses ( active state) within- and between-nights. In a subgroup of 10 normal subjects, we performed repeated measurements during hypnotic-induced sleep. Bland-Altman analyses were used to determine the within-night and between-night reliability of the PCRIT measurements. Results: There were no significant within-night or between-night differences for the mean passive PCRIT. The active PCRIT was ∼1 cm H 2O more collapsible on the second night than on the first night. The limits of agreement, which bound the passive and active PCRIT, was ∼ ± 3 cm H2O and was reduced to ∼ ± 1 cm H 2O for the passive PCRIT with hypnotic-induced sleep. Conclusion: Passive and active PCRIT measurements are reasonably reliable within and between nights. An approximately 3 cm H2O change in passive or active PCRIT appears to represent the minimally significant change in PCRIT necessary to assess the effect of an intervention (e.g., positional therapy, surgical interventions, oral appliance effects, and pharmacotherapy) on upper airway mechanical loads or neuromuscular responses

Peritrigonal and temporo-occipital heterotopia with corpus callosum and cerebellar dysgenesis

ObjectiveTo describe a homogeneous subtype of periventricular nodular heterotopia (PNH) as part of a newly defined malformation complex.MethodsObservational study including review of brain MRI and clinical findings of a cohort of 50 patients with PNH in the temporo-occipital horns and trigones, mutation analysis of the FLNA gene, and anatomopathologic study of a fetal brain.ResultsThere were 28 females and 22 males. All were sporadic with the exception of an affected mother and son. Epilepsy occurred in 62%, cerebellar signs in 56%, cognitive impairment in 56%, and autism in 12%. Seventy percent were referred within the 3rd year of life. Imaging revealed a normal cerebral cortex in 76% and abnormal cortical folding in 24%. In all patients the hippocampi were under-rotated and in 10% they merged with the heterotopia. Cerebellar dysgenesis was observed in 84% and a hypoplastic corpus callosum in 60%. There was no gender bias or uneven gender distribution of clinical and anatomic severity. No mutations of FLNA occurred in 33 individuals examined. Heterotopia in the fetal brain revealed cytoarchitectonic characteristics similar to those associated with FLNA mutations; cortical pathology was not typical of polymicrogyria. Cerebellar involvement was more severe and the hippocampi appeared simple and under-rotated.ConclusionsThis series delineates a malformation complex in which PNH in the trigones and occipito-temporal horns is associated with hippocampal, corpus callosum, and cerebellar dysgenesis. This subtype of PNH is distinct from classic PNH caused by FLNA mutations