Identification of the cerebrospinal compensatory mechanisms via computer-controlled drainage of the cerebrospinal fluid

Abstract

The constant rate infusion test is still widely used for the diagnosis of hydrocephalus in children. The increased resistance to reabsorption of the cerebrospinal fluid (CSF) is considered the most important factor in the improvement seen after shunting. However, the classic infusion test has some disadvantages: the compensatory model is identified in the conditions of raised intracranial pressure, which may provoke some uncontrolled changes in cerebral blood volume in the mechanism of vasomotor response; also non-linear effects in reabsorption mechanisms may have a significant influence. The controlled drainage of CSF can be considered as a form of pressure-volume testing if the volume of the drained fluid is precisely measured. The main advantage of the method is the possibility of estimating unknown parameters in practically physiological conditions (with only slightly decreased pressure). This paper presents a new method for the identification of an electrical model of cerebrospinal volume compensation. The method has been described theoretically, verified on the simulator and introduced into clinical practice at the Medical Academy in Warsaw and the Children's Health Center in Miedzylesie.