Intraoperative measurement of intraventricular pressure in dogs with communicating internal hydrocephalus

Abstract

Collapse of the lateral cerebral ventricles after ventriculo-peritoneal drainage is a fatal complication in dogs with internal hydrocephalus. It occurs due to excessive outflow of cerebrospinal fluid into the peritoneal cavity (overshunting). In most shunt systems, one-way valves with different pressure settings regulate flow into the distal catheter to avoid overshunting. The rationale for the choice of an appropriate opening pressure is a setting at the upper limit of normal intracranial pressure in dogs. However, physiological intraventricular pressure in normal dogs vary between 5 and 12 mm Hg. Furthermore, we hypothesise that intraventricular pressure in hydrocephalic dogs might differ from pressure in normal dogs and we also consider that normotensive hydrocephalus exists in dogs, as in humans. In order to evaluate intraventricular pressure in hydrocephalic dogs, twenty-three client owned dogs with newly diagnosed communicating internal hydrocephalus were examined before implantation of a ventriculo-peritoneal shunt using a single use piezo-resistive strain-gauge sensor (MicroSensor ICP probe). Ventricular volume and brain volume were measured before surgery, based on magnetic resonance images. Total ventricular volume was calculated and expressed in relation to the total volume of the brain, including the cerebrum, cerebellum, and brainstem (ventricle-brain index). Multiple logistic regression analysis was performed to assess the influence of the covariates “age”, “gender”, “duration of clinical signs”, “body weight”, and “ventricle-brain index” on intraventricular pressure. The mean cerebrospinal fluid pressure in the hydrocephalic dogs was 8.8 mm Hg (standard deviation 4.22), ranging from 3–18 mm Hg. The covariates “age”, (P = 0.782), “gender” (P = 0.162), “body weight”, (P = 0.065), or ventricle-brain index (P = 0.27)” were not correlated with intraventricular pressure. The duration of clinical signs before surgery, however, was correlated with intraventricular pressure (P< 0.0001). Dogs with internal hydrocephalus do not necessarily have increased intraventricular pressure. Normotensive communicating hydrocephalus exists in dogs.

Prevalence of seizures in dogs and cats with idiopathic internal hydrocephalus and seizure prevalence after implantation of a ventriculo‐peritoneal shunt

“…Although the development of ventricular dilatation in this form of hydrocephalus is very progressive leading to an increase of IVP to 4‐fold the normal level, seizures were never documented in these animals 33,34 . On the other hand, it was shown that dogs with internal hydrocephalus must not have increased IVP 35 . It must therefore be questioned whether increased IVP, ventricular distention and associated parenchymal damage alone can really evoke seizures in affected animals.…”

Case Report: Ventriculoperitoneal Shunting and Radiation Therapy Treatment in a Cat With a Suspected Choroid Plexus Tumor and Hypertensive Hydrocephalus

“…A comparison between dogs with congenital hydrocephalus treated with VPS or medical management showed similar outcomes, although the median follow up time was only 9 months for medical and 15 months for surgical management ( 31 ). However, a case series with dogs with hydrocephalus secondary to tumors of the third ventricle found that the ICP measured considerably higher (28 mmHg and 31 mmHg) than the intracranial pressures found in dogs with communicating internal hydrocephalus (mean 8.8 mmHg, range from 3 to 18 mmHg) ( 2 , 32 ). In these dogs with hydrocephalus secondary to III ventricle tumors, their clinical signs were not improved by medical management but significantly improved after being treated with VPS placement ( 2 ).…”

Cerebrospinal fluid flow on time‐spatial labeling inversion pulse images before and after treatment of congenital hydrocephalus in a dog

“…(the ability to accommodate increased volume without increase in pressure) is also considered to influence CSF dynamics and abnormal compliance may constitute a cause of hydrocephalus, especially in brachycephalic dogs. [33][34][35] In normal dogs, expansion of the intracranial arteries during systole compresses the intracranial CSF cistern and ventricles and also promotes flow of blood, CSF, or both, into the draining veins. In some dogs with communicating hydrocephalus, persistent high pressure cannot be detected within the ventricular system, [33][34][35] suggesting that CSF accumulation in the ventricles might Time-SLIP images obtained after CSF drainage by CSF-TT or VPS suggested that the driving forces generated by respiratory movement and heartbeat were restored, allowing normal cranial and caudal CSF flow in the aqueduct and prepontine cistern, similar to that occurring in human patients.…”

“…[33][34][35] In normal dogs, expansion of the intracranial arteries during systole compresses the intracranial CSF cistern and ventricles and also promotes flow of blood, CSF, or both, into the draining veins. In some dogs with communicating hydrocephalus, persistent high pressure cannot be detected within the ventricular system, [33][34][35] suggesting that CSF accumulation in the ventricles might Time-SLIP images obtained after CSF drainage by CSF-TT or VPS suggested that the driving forces generated by respiratory movement and heartbeat were restored, allowing normal cranial and caudal CSF flow in the aqueduct and prepontine cistern, similar to that occurring in human patients. 19 There was also impedance of flow in the cranial cervical epidural space, perhaps because of local occlusion associated with foramen magnum herniation (secondary to raised pressure in the lateral ventricles) and reduced craniospinal compliance.…”