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Biomedical subjects

G M Hochwald

Publications and source records attributed to G M Hochwald.

At least 55 records · Page 3Linked to original sources
PubMed1976

Evaluation of pediatric hydrocephalus by computed tomography.

Computed tomography (CT) is a safe and reliable technique for the study of children with increased head circumference. Hydrocephalic children requiring drainage of cerebrospinal fluid may be shunted on the basis of the CT scan alone and their postsurgical course followed by serial CT scans thereafter. Any additional pneumographic studies required may be performed via the existing shunt tube, eliminating transcerebral catheterization and its attendant complications.

Brain Edema↗
PubMed1976

On the movement of fluid through the brain of hydrocephalic cats.

The effects of changes in serum osmolality on the volume flow of fluid into the cerebral ventricles and on brain water content was examined in cats with kaolin-induced hydrocephalus. Slopes of the regression lines relating volume flow and serum osmolality for both normal and hydrocephalic cats are the same. The constant difference in flow rates between the two lines, 7 mul per minute, is probably due to impaired choroid plexuow rates between the two lines, 7 mul per minute, is probably due to impaired choroid plexus function of the hydrocephalic cats. The osmotic pressure gradient that causes the flow of fluid is therefore probably between blood and brain. Under these conditions changes in brain water content of hydrocephalic cats were smaller than in normals and can be related to the edema present in this disorder. Despite the inflammatory response to kaolin, the blood-brain barrier remains intact. From the calculated filtration coefficient, it can be inferred that the flow of water from serum through brain and into cerebrospinal fluid is limited by the resistance of fluid flow through the brain.

Animals↗
PubMed1976

Hydrocephalus: I. Histological and ultrastructural changes in the pre-shunted cortical mantle.

Hydrocephalus results in a reduction in the thickness of the cerebral cortical mantle which seemingly is restored by ventricular shunting. In order to determine the effect of hydrocephalus and its potential reversibility, experimental hydrocephalus was produced in adult cats by the introduction of kaolin or silicone into the basal cisterns followed by bilateral craniectomies. Microscopic and fine structural studies of these animals suggest the occurrence of significant focal axonal destruction. These studies suggest a sequence of events consisting of ventriculomegaly, disruption of the periventricular ependyma, periventricular edema, axonal destruction, secondary myelin disintegration and finally reactive astrocytosis. The damage to axons and meylin and resulting gliosis is irreversible.

Animals↗
PubMed1976

Hydrocephalus: II. Cell number and size, and myelin content of the pre-shunted cerebral cortical mantle.

The number of cells in the brain and their size can be calculated by determining the total brain DNA, RNA and protein. Myelin can be determined biochemically. This analysis was applied to brains of a group of adult cats with craniectomies that were made severely hydrocephalilc by the introduction of kaolin or silicone into the basal cisterns. In severely hydrocephalic brains sectioned rostral to the area of kaolin inflammation there was no loss of dry weight. Wet weight increased slightly reflecting periventricular edema. There was a slight increase in total DNA, RNA and protein, presumably reflecting the increase in small inflammatory cells. There was a significant reduction in galactolipids reflecting myelin loss.

Animals↗
PubMed1976

Hydrocephalus: III. Reconstitution of the cerebral cortical mantle following ventricular shunting.

Adult cats with hydrocephalus were sacrificed at varying times following valveless ventricular shunting. This shunting resulted in a prompt reduction of ventricular size and rapid gross reconstitution of cortical mantle. Ultrastructurally it was evident that white matter edema persisted for many weeks, even in the presence of normal size ventricles. The areas most severely affected by the hydrocephalus such as the corpus callosum showed a paucity of myelinated fibers and their replacement by numerous reactive astrocytes. Reconstitution of the cortical mantle consists predominantly of a diminution of white matter edema and reactive astrocytosis. Clinical improvement undoubtly results from the functional improvement of remaining elements rather than from the replacement of lost elements. This scheme of hydrocephalus suggests that if hydrocephalus is relieved when only ependymal disruption and periventricular water accumulation have occurred, it may be reversible. The subsequent sequence of events consisting of axonal degeneration, myelin disruption and reactive astrocytosis may be less, if at all reversible.

Animals↗
PubMed1975

Effects of changes in serum osmolarity on bulk flow of fluid into cerebral ventricles and on brain water content.

The effects of changes in serum osmolarity on the rate and osmolarity of bulk flow of fluid into the cerebral ventricles and on cortical white and grey matter water content were studied in cats. Bulk flow rates and osmolarities were measured during ventriculocisternal perfusion both before and after intravenous infusion of glucose solutions. Infusions of glucose in concentrations greater than 6% decreased fluid bulk flow rate and its osmolarity. Glucose in concentrations less than 6 percent increased fluid bulk flow rate and decreased its osmolarity. Bulk flow rate and serum osmolarity were found to be linearly related with a coefficient of osmotic flow of minus 0.835 mul/min per mOsm/l. At the extremes of induced serum osmolarities, (290 and 360 mOsm/l) bulk flow rate was either increased by 120 percent or completely inhibited. Effluent osmolarity also increased proportionately to serum osmolarity (0.338 mOsm/l per mOsm/l). When compared to controls, cortical grey and white matter water content increased by 1.9 percent and 2.9 percent, respectively, when the infused glucose concentration was 2.5 percent or less, and decreased by 1.8 percent and 2.9 percent when the concentration was 10 percent or more. The results of these experiments suggest that the increased bulk flow comes from the brain, rather then directly from the blood.

Animals↗
PubMed1975

Changes in regional blood-flow and water content of brain and spinal cord in acute and chronic experimental hydrocephalus.

The effects of kaolin-induced hydrocephalus on regional blood-flow and water content of cat brain and spinal cord were measured. The role of the central canal of the spinal cord as an alternative pathway for cerebrospinal fluid in experimental hydrocephalus was also studied by positive contrast ventriculography. In comparison with normal cats, blood-flow in the cerebrum, cerebellum and brain stem of cats with acute hydrocephalus was reduced by more than 20 per cent: in those with chronic hydrocephalus it was reduced by only 12 per cent. There was an absolute increase of 1-5 per cent in water content of the brain in cats with acute hydrocephalus. Water content in the spinal cord was increased by 6 per cent in cats with acute hydrocephalus and by 8 per cent in those with chronic hydrocephalus. When the increased water-content was taken into account, hydrocephalus caused no significant change in blood-flow in the cervical, thoracic or lumbar spinal cord. Contrast material perfused through the ventricles of hydrocephalic cats flowed directly into the enlarged central canal of the spinal cord. Kaolin-induced arachnoiditis completely obstructed communication between the ventricles and the cranial subarachnoid space. The contrast material in the central canal communicated both with the cavities extending into the dorsal columns and with the spinal subarachnoid space. When kaolin was injected directly into the spinal subarachnoid space there was an increase in spinal water-content, without an enlarged central canal. These results suggest that in addition to kaolin-induced arachnoiditis, increased intraluminal pressure is necessary to enlarge the central canal.

Acute Disease↗
PubMed1975

Avoidance of shunt dependency in hydrocephalus.

An approach to the treatment of neonatal hydrocephalus is proposed which is intended to reduce or eliminate shunt dependency by increasing the effectiveness of remaining pathways of absorption of cerebrospinal fluid. In suitable cases, intermittent cranial compression by means of an elastic bandage or a helmet with an inflatable inner-lining may be effective. Hydrocephalus was arrested in nine of 14 children treated with this method, eight of whom have developed normally. When cranial compression is contra-indicated or not successful, the preferred method of treatment is an 'on-off' type of valve which is used intermittently to drain a fixed volume of cerebrospinal fluid. Of 18 children who had such shunts inserted, 10 have become totally independent of their shunts and their hydrocephalus has become compensated. All are of normal intelligence. Subtemporal craniectomy was performed on seven shunt-dependent children with recurrent catheter obstruction. Four have been followed for six months and three for two years and in no case has there been further malfunction of the proximal catheter.

Cerebrospinal Fluid Shunts↗