Reticulocytes in untreated obstructive sleep apnoea.

BACKGROUND AND AIM: The short, repetitive hypoxaemic episodes observed in obstructive sleep apnoea (OSA) may determine small augmentations in mature red blood cells. It is unknown whether they affect reticulocyte release. This study explored whether the number and degree of maturation of circulating reticulocytes may be altered in OSA, possibly through the effect of erythropoietin. METHODS: Fifty male adult patients with suspected OSA, normoxic during wakefulness, were studied. After nocturnal polysomnography, a blood sample was withdrawn for blood cells count, erythropoietin, iron and transferrin determination. Reticulocyte concentration and degree of immaturity [high (H), medium (M), or low (L)] were also determined. Immature reticulocyte fraction (IRF) was calculated as (M+H) percentage of reticulocytes. RESULTS: A wide range of OSA severity was found [apnoea/hypopnoea index (AHI): 44.3 +/- 30.4, range 0.3-105; sleep time spent at oxyhaemoglobin saturation <90%: 18.1 +/- 22.2%, range 0-81%]. Both reticulocyte count and IRF slightly exceeded the normal range. Patients with a reticulocyte concentration > 2% had higher EPO levels (p < 0.05), but not worse nocturnal desaturations, than those with values < 2%. By contrast, subjects with IRF < 15% showed worse desaturations (p < 0.05), but similar EPO concentrations, when compared to subjects whose IRF was < 10%. At univariate analysis, reticulocyte count correlated to erythropoietin, while IRF to transferrin saturation, BMI and OSA severity. At multiple regression, only lowest nocturnal oxygen saturation remained a significant contributor to IRF (r2 0.223, p < 0.05). CONCLUSIONS: This data suggests that hypoxaemia due to OSA could influence the release of immature reticulocytes, but this effect is not mediated by erythropoietin.

Neuropsychological assessment in idiopathic REM sleep behavior disorder (RBD): does the idiopathic form of RBD really exist?

OBJECTIVE: To evaluate the cognitive performance of patients with idiopathic REM sleep behavior disorder (RBD). METHODS: The authors studied 17 consecutive patients with idiopathic RBD vs 17 age- and education-matched control subjects. Tests given to each patient and control included Mini-Mental State Examination, verbal and spatial short-term memory, visual selective attention, verbal fluency, prose memory, visuoconstructional abilities, spatial learning, and executive function tests. A self-administered depression rating scale was also used. RESULTS: RBD patients had significantly lower scores than control subjects in two tests: copy of Rey-Osterrieth Figure and Corsi Supraspan Learning. No correlation was found between the results of neuropsychological tests and RBD duration or with polysomnographic findings. CONCLUSIONS: Visuospatial constructional dysfunction and altered visuospatial learning may be present in idiopathic RBD. A neuropsychological assessment may be indicated in RBD patients.