The effect of cerebrospinal fluid pressure on the size of drainage pathways

The cerebrospinal fluid drainage pathways were studied using labeled molecules of different sizes. Following determination of the limiting size, the cerebrospinal fluid pressure was raised above the normal range and changes in transfer were measured. These data show that molecules smaller than the limiting size will transfer at an increased rate in response to elevated pressures. Larger molecules did not demonstrate an increased transfer with raised cerebrospinal fluid pressures, suggesting that the pathways did not enlarge.

Spontaneous rupture of the stomach in the newborn: clinical and experimental evaluation

Our study presents an experimental model for studying gastric rupture in the newborn. We showed that gastric rupture could be produced in eight newborn rodents and in three puppies less than 10 days old after injection of 120 ml air at 100 mm Hg pressure in the rodents and 175 ml air at 240 mm Hg pressure in the puppies. Gastric rupture occurred with animals supine and with approximately 20 ml barium injected into the stomach. Positioning of the animal in the supine position permitted the barium to pool in the antral-pyloric region of the stomach.

Communicating hydrocephalus. Cisternographic and neuropathologic studies

Chronic communicating hydrocephalus was produced in adult dogs by injection of silastic into the subarachnoid space. Electron microscopy was used to verify the sequence of pathologic changes in the ventricular wall. The pathologic findings were correlated with cisternographic images and measurements of cerebrospinal fluid (CSF) pressure. Early in hydrocephalus, the CSF pressure was increased and cisternograms showed ventricular entry and clearing; the ependyma was stretched and fluid accumulated in subependymal regions. In animals with chronic hydrocephalus, the CSF pressure was normal and cisternograms disclosed radioactivity persisting in the ventricles. At this time the ependyma was severely damaged, the subependymal white matter showed enlargement of the extracellular space, and degenerative changes were present in axons and myelin sheaths.

The use of diagnostic ultrasound in evaluation of the abdomen in primates with emphasis on the rhesus monkey (Macaca mulatta)

To characterize the sonographic appearance of the abdominal organs in primates, a program of routine imaging and diagnostic evaluation was undertaken. Compound B-mode methodology with bistable and grey scale machines was employed utilizing a 2.25- to 3.5-MHZ transducer focused at 7 cm. Visualization of the liver, gallbladder, spleen, kidney and of intraabdominal pathology are described. The stage, position, and condition of a pregnancy can be determined by this methodology.

Comparison of ventricular enlargement and radiopharmaceutical retention: a cisternographic-pneumoencephalographic comparison

The cisternograms and pneumoencephalograms of 58 patients with suspected "normal pressure" hydrocephalus were correlated and the relationship of ventricular radiopharmaceutical entry and stasis to ventricular size was analyzed. It was found that radiopharmaceutical entry relates directly to ventricular size, stasis occurring only in markedly enlarged ventricles. Cerebrospinal fluid imaging alone is a highly reliable diagnostic study only if patients exhibit the characteristic cisternographic patterns of normal pressure hydrocephalus. In those who do not, pneumoencephalography and cisternography are valuable complementary studies which can also be used to identify primary cortical atrophy.

In vitro measurement of respiration of choroid plexus cells in communicating hydrocephalus

Communicating hydrocephalus occurs as a result of inappropriate CSF production in the circumstance of diminished absorption. Ventricular enlargement does not progress as rapidly as the measured normal production of CSF would suggest. Thus, compensatory mechanisms must exist to respond in some manner to the altered pathophysiology. In this experiment the metabolic activity (O2 consumption) of the choroid plexus cells in animals with communicating hydrocephalus was compared with that of normals. The modified Cartesian diver technique of Zeuthen13 was employed. These preliminary measurements show that the metabolic activity of the choroid plexus cells was the same in hydrocephalic animals and normals. Response to experimentally induced increased CSF pressure also showed no difference.

The efficacy of the brain scan in diagnosis of brainstem gliomas

Nineteen cases of brainstem glioma were reviewed to evaluate lesion detection by brain imaging and other radiological methods. 99m-Tc-pertechnetate brain imaging was definitely abnormal in only one patient. Other techniques proved to be more sensitive and specific. Angiograms were abnormal in 10 of 18 cases while pneumoencephalography demonstrated the lesion in 16 of 19 cases. Brain imaging is not a sensitive diagnostic study in patients with suspected brainstem glioma. A normal brain scan is not useful in excluding this diagnosis and further radiological evaluation is necessary.

Barium or gastrografin: which contrast media for diagnosis of esophageal tears?

In order to study the effects of the commonly employed contrast media alone and in combination with bacteria in the mediastinum, various mixtures of barium and meglamine diatrizoate (Gastrografin) with and without flora were instilled in the mediastinum of 29 domestic cats. The animals were killed for pathological studies at serial time intervals following mediastina injection. These data demonstrate that water-soluble contrast media cause no significant histological reaction. Barium causes granuloma formation but has no additional deleterious effects when mixed with flora. Barium has superior physical properties of mucosal coating and radiographic density. It should be employed as the contrast agent of choice in difficult clinical problems with regard to esophageal tears. A water-soluble contrast study of the esophagus may be utilized as the initial diagnostic procedure, but if this is normal a follow-up barium esophagram is recommended.

Results and complications in 55 shunted patients with normal pressure hydrocephalus

This retrospective study of 55 shunted patients with "normal pressure" hydrocephalus evaluates the surgical results. Sixty percent of these patients had objective improvement following cerebrospinal fluid diversion but 44% had shunt-related complications of which 9% were fatal. Those patients who received a single theco-peritoneal shunt had a higher improvement rate and a lower incidence of postoperative complications. Successfully treated complications did not preclude postoperative improvement.

Patterns of excretion of radioactive chelates in obstructive uropathy

Radioactive chelates such as 99mTc-DTPA are advantageous in ranal imaging, particularly in defining functional and morphological abnormalities of the excretory tract. In a review of more than 200 studies, 19 cases of lower-tract disease were diagnosed by the gamma camera image alone. In 16 of them, the diagnosis was confirmed by excretory urography. Normal radionuclide patterns are described and compared with the characteristic findings in caliectasis, hydronephrosis, and hydroureter. By facilitating evaluation of renal perfusion, renal glomerular function, and gross renal structure as well as good difinition of excretory function, radioactive chelate imaging is ideally suited for use as general screening test.

Pathophysiology of chronic communicating hydrocephalus in dogs (Canis familiaris). Experimental studies

A model designed to produce chronic communicating hydrocephalus in dogs has been developed in our laboratory. The animals tolerate the procedure well and the yield of animals with communicating hydrocephalus is high. Serial cisternograms show ventricular entry first with "clearing" and later with "stasis". CSF pressures are initially increased, but when the ventricles become enlarged the pressure falls into the normal range. Grossly there is generalized ventricular enlargement and, on histological studies, the ependyma is flattened and denuded. Periventricular edema occurs in the white matter. Autoradiographs show transependymal movement of protein. CSF production appears to be normal despite obstruction to flow of CSF to areas where resorption is greatest. Diversionary shunting probably produces relief of many of the neurological symptoms by providing an efficient pathway for the removal of CSF and thus by lessening edema and ventricular enlargement. A more appropriate treatment would appear to be a noninvasive method of decreasing CSF production. Only when the basic pathophysiological alterations of CSF production and absorption are understood will this be possible. We believe that this animal model affords us the opportunity of studying these mechanisms.

Radionuclide and angiographic studies of placental circulation in man and rhesus monkey

Imaging maternal and fetal circulation during perfusion of isolated human placental lobules was performed. Radionuclide and contrast angiograms, specimen scans, and histologic preparations obtained on human material during in vitro investigations were compared to the results obtained in vivo on pregnant rhesus monkeys. The distribution of maternal blood flow within the placenta appeared similar in both human and rhesus studies. The 'spurts' of radiopaque medium shown on the contrast angiograms correlated with the appearance of areas of increased radioactivity. These 'hot spots' are located where the uteroplacental spiral arteries open into the intervillous space or where the perfusion cannulae irrigate the maternal side of the placenta. Time-radioactivity curves reached an early peak and remained the same as did their distribution on delayed scans. The 15 to 30 micron microspheres injected into the intervillous spaces are not removed onto the venous side by maternal flow through arteriovenous communications (or 'shunts') but are retained in localized areas of the intervillous space adjacent to the spiral arteries. Many of these microspheres adhere to the 'brush border' of the chorionic villi syncytiotrophoblast. These comparative studies confirm that rhesus monkeys and perfused human placental lobules are relevant models to investigate uteroplacental hemodynamics.

Positive contrast peritoneography and herniography in primate animals. With special referENCE TO INDIRECT INQUINAL HERNIAS

In a number of primate animals contrast medium was injected intraperitoneally to diagnose hernias as well as evaluate the normal anatomical relationships. The technical considerations are discussed. Contrast herniography and peritoneography appear useful under certain clinical circumstances.

An experimental model for chronic communicating hydrocephalus

✓ A reliable technique is described for producing chronic communicating hydrocephalus in experimental animals. This involves the injection of Silastic into the basilar cisterns by way of a cisterna magna puncture. This model proves to be very useful in studying the physiology of chronic communicating hydrocephalus and allows the evaluation of the condition by isotope cisternography.