kaolinite and Dilatation--Pathologic

Object Experimental data about the evolution of intracranial volume and pressure in cases of hydrocephalus are limited due to the lack of available monitoring techniques. In this study, the authors validate intracranial CSF volume measurements within the lateral ventricle, while simultaneously using impedance sensors and pressure transducers in hydrocephalic animals. Methods A volume sensor was fabricated and connected to a catheter that was used as a shunt to withdraw CSF. In vitro bench-top calibration experiments were created to provide data for the animal experiments and to validate the sensors. To validate the measurement technique in a physiological system, hydrocephalus was induced in weanling rats by kaolin injection into the cisterna magna. At 28 days after induction, the sensor was implanted into the lateral ventricles. After sealing the skull using dental cement, an acute CSF drainage/infusion protocol consisting of 4 sequential phases was performed with a pump. Implant location was confirmed via radiography using intraventricular iohexol contrast administration. Results Controlled CSF shunting in vivo with hydrocephalic rats resulted in precise and accurate sensor measurements (r = 0.98). Shunting resulted in a 17.3% maximum measurement error between measured volume and actual volume as assessed by a Bland-Altman plot. A secondary outcome confirmed that both ventricular volume and intracranial pressure decreased during CSF shunting and increased during infusion. Ventricular enlargement consistent with successful hydrocephalus induction was confirmed using imaging, as well as postmortem. These results indicate that volume monitoring is feasible for clinical cases of hydrocephalus. Conclusions This work marks a departure from traditional shunting systems currently used to treat hydrocephalus. The overall clinical application is to provide alternative monitoring and treatment options for patients. Future work includes development and testing of a chronic (long-term) volume monitoring system.

Topics: Animals; Calibration; Catheters; Cerebrospinal Fluid; Cisterna Magna; Dilatation, Pathologic; Disease Models, Animal; Electric Impedance; Equipment Design; Gels; Hydrocephalus; In Vitro Techniques; Injections; Intracranial Pressure; Kaolin; Lateral Ventricles; Monitoring, Physiologic; Rats; Reproducibility of Results; Sepharose

In communicating hydrocephalus (CH), explanations for the symptoms and clear-cut effective treatments remain elusive. Pulsatile flow through the cerebral aqueduct is often significantly elevated, but a clear link between abnormal pulsations and ventriculomegaly has yet to be identified. We sought to demonstrate measurement of pulsatile aqueductal flow of CSF in the rat, and to characterize the temporal changes in CSF pulsations in a new model of CH. Hydrocephalus was induced by injection of kaolin into the basal cisterns of adult rats (n = 18). Ventricular volume and aqueductal pulsations were measured on a 9.4 T MRI over a one month period. Half of the animals developed ventricular dilation, with increased ventricular volume and pulsations as early as one day post-induction, and marked chronic elevations compared to intact controls (volume: 130.15 +/- 83.21 microl vs. 15.52 +/- 2.00 microl; pulsations: 114.51 nl +/- 106.29 vs. 0.72 +/- 0.13 nl). Similar to the clinical presentation, the relationship between ventricular size and pulsations was quite variable. However, the pulsation time-course revealed two distinct sub-types of hydrocephalic animals: those with markedly elevated pulsations which persisted over time, and those with mildly elevated pulsations which returned to near normal levels after one week. These groups were associated with severe and mild ventriculomegaly respectively. Thus, aqueductal flow can be measured in the rat using high-field MRI and basal cistern-induced CH is associated with an immediate change in CSF pulsatility. At the same time, our results highlight the complex nature of aqueductal pulsation and its relationship to ventricular dilation.

Topics: Analysis of Variance; Animals; Cerebral Aqueduct; Cerebral Ventricles; Dilatation, Pathologic; Disease Models, Animal; Female; Hydrocephalus; Imaging, Three-Dimensional; Kaolin; Magnetic Resonance Imaging; Pulsatile Flow; Rats; Rats, Sprague-Dawley; Time Factors

Hydrocephalus is a pathological enlargement of the cerebral ventricle that results from an obstruction of the space containing cerebrospinal fluid (CSF) in the brain. Motor abnormalities, such as abnormal gait and posture, are frequently seen in patients with hydrocephalus. The present study was designed to investigate locomotor activity in the elevated plus maze behaviorally. Hydrocephalus was induced in Sprague-Dawley rats by injection of 0.1 ml of 20% kaolin solution into the cisterna magna (n=14). Control rats received the same volume of saline (n=12). The rats were sacrificed at 3 days and 4 weeks after the elevated plus maze test. Tyrosine hydroxlyase (TH) immunoreactivity in the substantia nigra was evaluated by immunohistological staining. Hydrocephalic rats showed decreased motor activity for entries of arms when compared to control rats (p<0.05). Compared to control rats, the number of TH immunoreactive neurons was significantly decreased in hydrocephalic rats. These results suggest that decreased motor responses due to ventricle enlargement in hydrocephalic rats are associated with the functional impairment of the central dopamine system.

Topics: Animals; Cerebral Ventricles; Dilatation, Pathologic; Dopamine; Hydrocephalus; Kaolin; Male; Maze Learning; Motor Activity; Neurons; Rats; Rats, Sprague-Dawley; Substantia Nigra; Tyrosine 3-Monooxygenase

Much has been written about the relationship between the pulse pressure (PP) of the intracranial pressure pulse wave (ICPPW) and ventricle dilatation. Some data suggest that high PP is the cause of ventricle dilatation, and other authors have reported that high PP results from decreased intracranial compliance. In order to clarify these points, the amplitude of PP and pressure-volume response (PVR: an indicator of intracranial compliance) were measured in bilateral ventricles using Hochwald's hydrocephalic model (right-left difference in ventricle size is clear due to hemicraniectomy). Hydrocephalus was induced by means of intracisternal injection of a kaolin powder solution to dogs. The mean ICP, amplitude of the PP, PVR and ventricle size (estimated by MR imaging) were evaluated in pathologic conditions induced by the following procedures. Group A, control: kaolin-induced hydrocephalus without craniectomy; group B: kaolin-induced hydrocephalus with right-sided craniectomy; group C: kaolin-induced hydrocephalus with right-sided craniectomy and dural resection; group D: kaolin-induced hydrocephalus with right-sided craniectomy, dura resection and temporal muscle resection. Using MR imaging, the same degree of symmetrical ventricle dilatation was identified in all groups except group D. Group D alone demonstrated a difference in ventricular size (craniectomy side > non-craniectomy side). There was no appreciable difference in mean ICP between any two groups. However, the amplitude of PP and the PVR decreased stepwise from group A to group D. The difference in the amplitude of the PP and PVR between the right and left ventricles was not significant in any group.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Animals; Cerebral Ventricles; Craniotomy; Dilatation, Pathologic; Disease Models, Animal; Dogs; Hydrocephalus; Intracranial Pressure; Kaolin; Magnetic Resonance Imaging

Topics: Animals; Cerebral Ventricles; Dilatation, Pathologic; Hydrocephalus; Kaolin; Rabbits

Adult craniectomized cats, rendered hydrocephalic by intracisternal kaolin injection, were repeatedly studied as to parameters pertaining to cerebrospinal fluid (CSF) dynamics and ventricular size. Intraventricular pressure was up to 8-fold of normal (mean 17.1 cm H2O) initially after induction of hydrocephalus and then went gradually down after 1 month. Ventricular volumes attained their maximum volume of approximately 4.5 ml at the very earliest study. The absorptive reserve (excess of absorption over formation rate of CSF) increased with time, thereby theoretically enabling the 'arrest' of the hydrocephalic process. Ventricular distensibility also increased with time, thus even the low ventricular pressure maintains the larger ventricular volume.

Topics: Animals; Cats; Cerebral Ventricles; Cerebrospinal Fluid; Dilatation, Pathologic; Disease Models, Animal; Hydrocephalus; Intracranial Pressure; Kaolin