Experimental approach for monitoring surface brain pressure

Abstract

✓ A method for monitoring brain surface pressure through the intact dura has been designed based upon the concept of a coplanar, non-sensitive ring transducer. The transducer detects the underlying brain pressure while the stretching forces of the dural membrane are dissipated at the outer ring. The strain gauge consists of a piezo-resistive silicon-chip sensing element and a dummy element that provides temperature compensation. Cisternal cerebrospinal fluid (CSF) and brain surface pressures were monitored simultaneously in dogs under general anesthesia, both before and after increased intracranial pressure was produced experimentally. A difference was found between CSF and brain surface pressures. Possible explanations for this observation are discussed.

Effect of supratentorial space-occupying lesions on regional intracranial pressure and local cerebral blood flow: an experimental study in baboons

“…Several groups have presented data Majors et al, 1972;Sundbarg and Nornes, 1972;Tindall et al, 1972) to show that in conditions of low and moderate intracranial pressure, extradural pressure and central CSF space pressure (cisternal or ventricular) yield identical recordings, but that in circumstances of high intracranial pressure extradural recording with a coplanar device will yield consistently higher pressures, indicating that it is at this stage measuring a component of actual tissue pressure transmitted from the brain held under tension by the elastic pia mater itself. To discuss the potential of coplanar measurements for dynamic deformation analysis in the brain would be outside the scope of this paper, but has been initiated in the work of Schettini et al (1971), who were the first to point out the extreme importance of coplanarity in such pressure recordings. The extradural transducer made and used in our laboratory enables recordings to be made with ease at four points in the baboon skull; further miniaturization of the transducer might enable more recordings to be made, but in the present study a four-point placement was sufficient to demonstrate beyond equivocation the development of differential pressures between the supratentorial compartments with a posterior parieto-occipital extradural expanding lesion.…”

Measurement of extradural pressure and its relationship to other intracranial pressures: An experimental and clinical study

“…However, this technique has serious disadvantages-namely, the difficulty of locating a displaced or compressed ventricle, alteration in intracranial hydrodynamics with possible disastrous effects when cerebrospinal fluid is withdrawn or inadvertently lost (Schettini, McKay, Majors, Mahig, and Nevis, 1971;Nornes, personal communication) the possibility of introducing infection directly into the ventricular system, and difficulty in maintaining an unobstructed catheter/manometer tube system over a prolonged period (Lundberg, 1960;Lundberg et al, 1965;Jacobson and Rothballer, 1967). In our own series of 25 patients, the ventricle could not be located in one, and obstruction or displacement of the catheter occurred in two.…”

“…In the subdural space, fluid-filled latex balloons (Hoppenstein, 1965), pneumatic switches (Numoto, Slater, and Donaghy, 1966) and electronic transducers (Hulme and Cooper, 1966;Coe et al, 1967;Richardson, Hide, and Eversden, 1970) have been used. This approach, however, involves breaching the integrity of the dura mater, and therefore miniature transducers of varying design (Nornes and Serck-Hanssen, 1970;Schettini, McKay, Majors, Mahig, and Nevis, 1971) have been designed for implanting in the extradural space. These have not been widely accepted for clinical monitoring because of technical difficulties concerning zero drift, calibration, and hysteresis.…”

Intracranial Pressure Gradients Caused by Experimental Cerebral Ischemia and Edema

“…4 However, despite these features the pressures recorded after epidural implantation were dependent on the amounts of PSS used to fill the chambers of the balloon devices. Although epidural pressures were recorded by filling the balloon devices with the same amount of fluid each time, the relatively dense dura affected and distorted the transmission of intradural pressures to the extradural space.…”