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Michael J. Rosner and Donald P. Becker

intracranial pressure (ICP) after fluid-percussion injury. Materials and Methods All experiments were conducted using conditioned cats of either sex, each weighing 2.5 to 3.5 kg. Anesthesia was induced using intravenous methohexital sodium titrated to the absence of the lid reflex; the cats were then intubated using a 5-mm cuffed endotracheal tube. Animals were placed on small-animal ventilators adjusted to deliver a tidal volume of 15 cc/kg at an initial rate of 12 respirations/min. The respiratory gas mixture, N 2 O 70% and O 2 30%, was bubbled through sterile

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Origin and evolution of plateau waves

Experimental observations and a theoretical model

Michael J. Rosner and Donald P. Becker

. They usually abort in a manner as sudden and spontaneous as they began. During the ICP plateau wave, patients have been known to complain of additional headache, drowsiness, disorientation, vomiting, and diplopia, but overall these pressure phenomena have been well tolerated. Lundberg concluded that these spontaneous A-waves reflected vasodilatation with subsequent increases in cerebral blood volume (CBV). It was recognized that vascular phenomena were the only mechanisms that might reasonably explain events that came on so quickly and aborted so suddenly, yet

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Stanley J. Goodman and Donald P. Becker

subjected to mass expansion producing supratentorial pressures in excess of 1100 mm H 2 O ( Table 1 , Group 1). There was no particular relation between the degree of gross brain stem deformation and the volume of hemorrhage. The transtentorial gradients were 400, 450, 380, and 1025 mm H 2 O. Vascular stasis was quite prominent in the pons and midbrain in this group. The animals subjected to extreme intracranial hypertension became deeply comatose and unresponsive to painful stimuli during the mass expansion, and died soon after. Cardiorespiratory collapse and death

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Steven K. Gudeman, Humbert G. Sullivan, Michael J. Rosner and Donald P. Becker

Neurol 35: 527–529, 1978 36. Welch K : The principles of physiology of the cerebrospinal fluid in relation to hydrocephalus including normal pressure hydrocephalus , in Friedlander WJ (ed): Advances in Neurology, Volume 7. Current Reviews of Higher Nervous System Dysfunction. New York : Raven Press , 1975 , pp 232 – 247 Welch K: The principles of physiology of the cerebrospinal fluid in relation to hydrocephalus including normal pressure hydrocephalus, in Friedlander WJ (ed): Advances in Neurology, Volume 7. Current

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Yoichi Katayama, Toru Nakamura, Donald P. Becker and Ronald L. Hayes

Microinjection Procedures Injection cannulas were constructed from No. 33 tubes (200 µ in outer diameter, 100 µ in inner diameter), and connected to lengths of PE 20 polyethylene tubing which were fitted to needles of microsyringes. † Injection cannulas were then placed through previously implanted guide tubes. Solutions of the cholinergic agonist, carbachol, or an equal volume of saline were microinjected bilaterally through the left and right cannulas sequentially. In an effort to minimize the mass of neural tissue affected by the microinjections, a small unilateral

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J. Paul Muizelaar, Enoch P. Wei, Hermes A. Kontos and Donald P. Becker

, whereas maximum decrease in ICP occurred at 10 to 15 minutes and was at only approximately 50% of maximum at 60 minutes; furthermore, a slight increase in ICP was found at 120 minutes. If brain water content, and thus tissue mass, remains unchanged after mannitol administration, or does not correlate with ICP changes after urea administration, then, according to the Monro-Kellie doctrine, either the amount of CSF or the amount of intracranial intravascular blood (cerebrovascular blood volume, CBV) must decrease in order to effect a drop in ICP. In the present study

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Steven K. Gudeman, J. Douglas Miller and Donald P. Becker

of heart rate, blood pressure, and ICP, and frequent intermittent neurological evaluations. This consisted of assessment using the Glasgow Coma Scale (eye opening, motor response, verbal response), measurement of oculocephalic or oculovestibular response, pupillary size, and light response and limb power. 1, 15 After a stable recording of ICP had been obtained, three to five measurements of the volume-pressure response (VPR) were made. This was done by injecting 1 ml of normal saline into the ventricular catheter in 1 second and measuring the resultant rise in

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J. Paul Muizelaar, Harry A. Lutz III and Donald P. Becker

concentration changes in response to changes in oxygen delivery 29, 31 or demands. 30 There is, however, still the possibility that the so-called “Bayliss effect” is operative with higher intravascular pressure or volume expansion: the smooth muscle of the vessel wall is stretched, which results in vessel-wall contraction. 2 Mannitol administration undoubtedly leads to intravascular volume expansion. Thus, when Bayliss autoregulation is intact, the vessels constrict, CBV decreases, and this enhances the ICP reduction due to extraction of water from the brain or CSF. It

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Ronald L. Hayes, Brian J. Galinat, Pramod Kulkarne and Donald P. Becker

. These fluid volumes are introduced extradurally by an impact-driven pistol which forces a fixed volume of isotonic saline through a hollow plastic tube (17.5 mm in diameter) into the skull cavity. Increasing fluid loading produces greater magnitudes of injury. The biomechanical events present at injury are inferred by measuring pressure transients. Magnitudes of pressure changes are positively correlated with the volumes of fluid introduced intracranially. With the animal in a stereotaxic frame, the scalp and temporal muscle were reflected and the hollow tube

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injury by early evacuation of the lesion. Information concerning attempts to analyze this preadmission period would be of interest. The significance of “midline brain shift” is also difficult to evaluate. It is well known that an expansive lesion in the temporal lobe, frontal pole, or bilaterally may give very little shift in spite of a dangerous volume or site (temporal lobe). This may partly explain the lack of graded relationship to intracranial pressure. The outcome of the 23 patients with slight “shift” and with “diffuse brain injury” showed perhaps a different