engleski

Effect of body position on cerebrospinal fluid pressures in brain ventricle and cortical subarachnoid space in cats with acute aqueductal occlusion

It is not known how the changes of body position affect cerebrospinal fluid (CSF) pressures in lateral ventricle (LV) and cortical subarachnoid space (CSS) after accute occlusion of aqueduct. In our model (1) of aqueductal occlusion in cats we have investigated how body position changes affect CSF pressures in LV and CSS. In chloralose anaesthetized cats (n=4) the CSF pressures were measured via cannulas positioned in LV and CSS during horizontal, head-up, and head-down position of animal. The cannulas in LV and CSS were positioned at the same hydrostatic level during changes of body position. After control CSF pressures measurements the aqueduct was occluded by plastic cannula with tip covered by cyanoacrylate glue through a small tunnel in vermis of cerebellum. After hermetic reconstruction of skull the CSF pressures were recorded in horizontal, head-up and head-down positions of cat. When the cats were in horizontal position the CSF pressures in LV and CSS were equal (about 18 cm H2O) in control conditions and after occlusion of aqueduct during 30 min. In head-up position the CSF pressure in LV was subatmospheric (-3.9 ± 0.4 cm H2O) and not different from that in CSS (-3.4 ± 1.3 cm H2O)(p>0.05) during control period. However, when aqueduct was occluded the CSF pressure in LV (-1.2 ± 0.7 cm H2O) was different from that in CSS (-4.4 ± 0.5 cm H2O) (p<0.05) in head-up position, so that transmantle pressure gradient about 3 cm H2O was developed. In head-down position the CSF pressure in LV and CSS were about 40 cm H2O and did not differ in control period and after aqueductal occlusion (p>0.05). When aqueduct is occluded the transmantle pressure gradient developes when body is in head-up position. It appears that in head-up position the gravitational force of CSF does not affect in the same way isolated brain ventricles and CSS what can lead to development of hydrocephalus.

Body position ; CSF ; pressures ; brain ventricle ; acute aqueductal occlusion ; cats

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