Brain Tissue Displacement Research Articles

Assessment of human brain motion using CSPAMM

To quantify periodic displacement in the cranium using complementary spatial modulation of magnetization (CSPAMM) with harmonic phase (HARP) postprocessing. CSPAMM tagging sequence with separate tag-line preparation in two orthogonal directions was applied on 10 healthy volunteers in combination with HARP for tissue displacement mapping. Important features of brain dynamics, such as caudal displacement amplitude and the time-to-peak of the pulse wave were derived for six regions in the brain. Peak displacement values amounted to 0.18+/-0.02 mm, 0.10+/-0.01 mm, 0.09+/-0.02 mm, and 0.04+/-0.01 mm for regions in the pons, cerebellum, corpus callosum (splenium), and frontal lobe, respectively. Displacement values of the pons differed significantly from all other regions measured. With the additional information of the time-to-peak measure all six regions except the corpus callosum (splenium) and cerebellum can be distinguished. The values found suggest that the pulse wave travels from the brain stem first occipitally and then to the frontal lobe, where peak values appear later and are significantly attenuated. Direct quantification of periodic caudal brain tissue displacement is feasible with the proposed method, and several brain regions can be distinguished through peak displacement and time-to-peak values.

Pathophysiology of traumatic injury in the developing brain: an introduction and short update

Current understanding about the main peculiarities in pathophysiology of immature brain traumatic injury involves marked developmental discrepancy of biomechanical properties, aspects of altered features in water and electrolyte homeostasis as well as maturation dependent differences in structural and functional responses of major transmitter systems. Based on the fact that traumatic brain injury (TBI) is one of the major causes of morbidity and mortality in infants and children, the currently available epidemiological data are reviewed in order to gain insights about scope and dimension of health care engagement and derive the requirements for reinforced pathogenetic research. To this end, the main aspects of peculiarities in primary and secondary TBI mechanisms in the immature/developing brain are discussed, including structural and functional conditions resulting in a markedly diminished shear resistance of the immature brain tissue. As such, the immature brain tissue appears to be more susceptible to mechanical alterations, because similar mechanical load induces a more intense brain tissue displacement. Furthermore, available indications for increased incidence of brain swelling in the immature brain after TBI are reviewed, focusing on the interrelationship between the age-dependent differences in extracellular space and aquaporin-4 expression during brain maturation. The developmental differences of TBI induced cerebrovascular response as well as some relevant aspects of altered neurotransmission following TBI of the immature brain in regard to the glutamatergic and dopaminergic transmitter system are assessed. Thus, this mini-review highlights some progress but also an increased necessity for expanded pathogenetic research on a clinical scale in order to develop a solid foundation for adequate therapeutic strategies for the different life-threatening consequences of TBI in infancy and childhood, which mainly have failed up to now.

Critical Care Management of Increased Intracranial Pressure

Increased intracranial pressure (ICP) is a pathologic state common to a variety of serious neurologic conditions, all of which are characterized by the addition of volume to the intracranial vault. Hence all ICP therapies are directed toward reducing intracranial volume. Elevated ICP can lead to brain damage or death by two principle mechanisms: (1) global hypoxic-ischemic injury, which results from reduction of cerebral perfusion pressure (CPP) and cerebral blood flow, and (2) mechanical compression, displacement, and herniation of brain tissue, which results from mass effect associated with compartmentalized ICP gradients. In unmonitored patients with acute neurologic deterioration, head elevation (30 degrees), hyperventilation (pCO2 26-30 mmHg), and mannitol (1.0-1.5 g/kg) can lower ICP within minutes. Fluid-coupled ventricular catheters and intraparenchymal pressure transducers are the most accurate and reliable devices for measuring ICP in the intensive care unit (ICU) setting. In a monitored patient, treatment of critical ICP elevation (>20 mmHg) should proceed in the following steps: (1) consideration of repeat computed tomography (CT) scanning or consideration of definitive neurosurgical intervention, (2) intravenous sedation to attain a quiet, motionless state, (3) optimization of CPP to levels between 70 and 110 mmHg, (4) osmotherapy with mannitol or hypertonic saline, (5) hyperventilation (pCO2 26-30 mmHg), (6) high-dose pentobarbital therapy, and (7) systemic cooling to attain moderate hypothermia (32-33°C). Placement of an ICP monitor and use of a stepwise treatment algorithm are both essential for managing ICP effectively in the ICU setting.

Critical Care Management of Increased Intracranial Pressure

Increased intracranial pressure (ICP) is a pathologic state common to a variety of serious neurologic conditions, all of which are characterized by the addition of volume to the intracranial vault. Hence all ICP therapies are directed toward reducing intracranial volume. Elevated ICP can lead to brain damage or death by two principle mechanisms: (1) global hypoxic-ischemic injury, which results from reduction of cerebral perfusion pressure (CPP) and cerebral blood flow, and (2) mechanical compression, displacement, and herniation of brain tissue, which results from mass effect associated with compartmentalized ICP gradients. In unmonitored patients with acute neurologic deterioration, head elevation (30 degrees), hyperventilation (pCO2 26-30 mmHg), and mannitol (1.0-1.5 g/kg) can lower ICP within minutes. Fluid-coupled ventricular catheters and intraparenchymal pressure transducers are the most accurate and reliable devices for measuring ICP in the intensive care unit (ICU) setting. In a monitored patient...

The hydromechanics of hydrocephalus: Steady-state solutions for cylindrical geometry

Hydrocephalus is a state in which the circulation of cerebrospinal fluid is disturbed. This fluid, produced within the brain at a constant rate, moves through internal cavities in it (ventricles), then exits through passages so that it may be absorbed by the surrounding membranes (meninges). Failure of fluid to move properly through these passages results in the distention of the passages and the ventricles. Ultimately, this distention causes large displacements and distortion of brain tissue as well as an increase of fluid in the extracellular space of the brain (edema). We use a two-phase model of fluid-saturated material to simulate the steady state of the hydrocephalic brain. Analytic solutions for the displacement of brain tissue and the distribution of edema for the annular regions of an idealized cylindrical geometry and small-strain theory are found. The solutions are used for a large-deformation analysis by superposition of the responses obtained for incrementally increasing loading. The effects of structural and hydraulic differences of white and gray brain matter, and the ependymal lining surrounding the venticles, are examined. The results reproduce the characteristic steady-state distribution of edema seen in hydrocephalus, and are compared with experiment.

The hydromechanics of hydrocephalus: Steady-state solutions for cylindrical geometry

Hydrocephalus is a state in which the circulation of cerebrospinal fluid is disturbed. This fluid, produced within the brain at a constant rate, moves through internal cavities in it (ventricles), then exits through passages so that it may be absorbed by the surrounding membranes (meninges). Failure of fluid to move properly through these passages results in the distention of the passages and the ventricles. Ultimately, this distention causes large displacements and distortion of brain tissue as well as an increase of fluid in the extracellular space of the brain (edema). We use a two-phase model of fluid-saturated material to simulate the steady state of the hydrocephalic brain. Analytic solutions for the displacement of brain tissue and the distribution of edema for the annular regions of an idealized cylindrical geometry and small-strain theory are found. The solutions are used for a large-deformation analysis by superposition of the responses obtained for incrementally increasing loading. The effects of structural and hydraulic differences of white and gray brain matter, and the ependymal lining surrounding the ventricles, are examined. The results reproduce the characteristic steady-state distribution of edema seen in hydrocephalus, and are compared with experiment.

Tumor of the tongue containing heterotopic brain tissue

A polypoid tumor containing astrocytic glia and ependyma was excised from the base of the tongue of a 3-month-old infant. Neuroid elements were identified immunocytochemically and by means of electron microscopy. We attribute this rare anomaly to displacement of brain tissue in early embryogenesis before closure of the palate.

Cerebral Contusion

Cerebral contusions occur as a result of traumatic head injury. These lesions may consist of tissue necrosis, hemorrhage, and edema. The patient with a cerebral contusion is at risk to develop increased ICP and brain tissue displacement that may cause a rapid deterioration in his clinical condition.

Abnormalities of the spinal meninges in anencephalic fetuses.

The spinal cord and meninges were examined, at all levels, in seven anencephalic fetuses of between 19 and 24 weeks of gestation. Four of the seven anencephalics showed dense collections of cells resembling immature neural tissue throughout the spinal subarachnoid space. The leptomeninges were excessively vascular and contained many active macrophages and small round cells in all the anencephalics and the cord was more slender than normal. Control fetuses did not show these features, although inactive macrophages were seen occasionally. It is concluded that the abnormal collections are made up of heterotopic neural tissue which may have been dislodged downwards from the skull during earlier development and that the spinal leptomeninges show an inflammatory response. The significance of both the heterotopia and the phagocytic activity in these anencephalic fetuses is discussed. In particular, the findings are compared with those in patients with the "respirator brain" syndrome, in whom displacement of brain tissue is associated with raised intracranial pressure.

Irradiation of meningioma: A prototype circumscribed tumor for planning high-dose irradiation of the brain

The purpose of this report is to provide specific data concerning the radiation dose required to destroy meningioma, and to demonstrate that radiation doses much greater than the alleged tolerance dose, can be administered to the brain in some patients. Most meningiomas are not responsive to irradiation, but, some surgically incurable lesions benefit from irradiation with radically high doses to small volumes of tissue. The arrest of 7 of 12 consecutive meningiomas in adults for periods of 2–17 years following maximum tumor doses up to 8800 R in 40 days is reported in this paper. All patients, when irradiated, had active tumor in the form of inoperable primary tumor, recurrence or known postoperative residual tumor. Three of the successful results were achieved with orthovoltage radiation. The incidence of brain damage may be acceptable to the patient when it is related to arrest of tumor growth but he must be forewarned of possible brain damage. The factors influencing the radioresponsiveness of meningioma are: the required tumor lethal dose, histology and vascularity of the tumor, anatomical site in the brain, treatment technique for each tumor site, small size of the treated volume, growth rate of the tumor, displacement of normal brain tissue by tumor, inherent individual variations of tumor and normal tissues, quality of the radiation, and tolerance of normal brain tissues. The role of these factors is discussed in the light of modern radiobiological concepts.

Movements evoked from the region of the caudate nucleus in cats.

AbstractMosfeldt Laursen, A. Movements evoked from the region of the caudate nucleus in cats. Acta physiol. scand. 1962. 54. 175–184. – The caudate nucleus and adjacent structures were stimulated in alert cats with implanted electrodes. With a 14 lead multielectrode assembly thresholds could be determined successively in points known distances apart without intervening displacement of brain tissue. Contraversive head turning and circling were the only motor responses of caudate origin: they were eliminated by lesions in the caudate whereas degeneration of the internal capsule left them unaffected. Flexion of contralateral extremities previously attributed to the caudate was elicited with the lowest threshold when stimuli were applied to the internal capsule. It remained unaffected by lesions in the caudate whereas it was eliminated by degeneration of the internal capsule. Thus when flexion of contralateral extremities was obtained from lead pairs of the multilead electrode situated in the caudate the response must be assumed to be due to stimulation of the internal capsule by current spread. It is consistent with this interpretation that contraversive head turning‐circling and contralateral flexion had their lowest thresholds at different frequencies of stimulation. Lip‐smacking, salivation and other responses with vegetative components were elicited from lead pairs of the multilead electrode in the septum or by current spread from electrodes in the caudate to the septum. The results were confirmed using bipolar electrodes of conventional design.