engleski

The effect of body position on cerebrospinal fluid (CSF) movement and pressure

Change of body position, from horizontal to vertical, is followed by transient fall of intracranial pressure presumably due to CSF and blood shift from cranium to lower parts of body. We hypothesized that these effects are not related to the cranial fluid volume changes, but depend on laws of fluid mecahnics and cervico-lumbar redistribution of fluids To test this, we compared changes in anaesthetized cats (n=5) and in the new artificial model of the CSF system with dimensions similar to the CSF system in cats, consisting of non-distensible cranial and distensible spinal part. The measuring cannulae were introduced into lateral ventricle (4 cm from foramen magnum) and lumbar subarahnoid space (L3 ; 31 cm from formen magnum). In horizontal position the pressures were similar in cranial and lumbar regions in both animal and artificial model (about +16 cm H2O). In vertical position the CSF pressure in cranium (-3.80± 1.39 cm H2O) and lumbar region (+31.00± 3.12 cm H2O) of cats was almost the same as in "cranial" (-4.06± 0.11 cm H2O) and "lumbar" (+30.92± 0.16 cm H2O) region of model. Changes in pressure on the model were not followed by the changes of fluid volume in the non-distensible cranial part of model. Thus, similarity of results between cat and the model implicates that CSF pressure in cranium in upright position is determined by laws of fluid mechanics but not by changes of CSF and blood in cranium. In each body position the cranial volume of CSF and blood remains constant, which enables a good blood brain perfusion.

body position ; cerebrospinal fluid (CSF) ; movement ; pressure

nije evidentirano