Intraoperative measurement of intraventricular pressure in dogs with communicating internal hydrocephalus

Surgical management of primary and idiopathic internal hydrocephalus in dogs and cats

Ventriculoperitoneal shunt placement is an effective method to treat internal hydrocephalus in dogs and cats. Although it has a long history in veterinary medicine, the technique continues to evolve. Despite continuing attempts to reduce the incidence of associated complications, shunt failure remains a major problem, and often leads to multiple hospital admissions. This review gives an overview about current knowledge of ventriculoperitoneal shunting techniques in animals, applicable shunt hardware as well as shunt-associated complications and their prevention and treatment.

Risk factors, treatment, and outcome in dogs and cats with subdural hematoma and hemispheric collapse after ventriculoperitoneal shunting of congenital internal hydrocephalus

BACKGROUND

Overshunting and hemispheric collapse are well-known complications after ventriculoperitoneal shunt (VPS) implantation. Risk factors that predispose to overshunting, treatment options, and prognosis after therapeutic intervention have not been described.

HYPOTHESIS/OBJECTIVES

To identify preoperative risk factors for overshunting, the effect of surgical decompression, and their outcomes.

ANIMALS

Seventy-five dogs and 7 cats.

METHODS

Retrospective case cohort study. Age, breed, sex, body weight, number of dilated ventricles, ventricle brain ratio, intraventricular pressure, and implanted pressure valve systems were evaluated as possible risk factors.

RESULTS

Overshunting had a prevalence of 18% (Cl 95% 9.9-26.66). An increase of 0.05 in VBR increased the risk of overshunting by OR 2.23 (Cl 95% 1.4-3.5; P = .001). Biventricular hydrocephalus had the highest risk for overshunting compared to a tri- (OR 2.48 with Cl 95% 0.5-11.1) or tetraventricular hydrocephalus (OR 11.6 with Cl 95% 1.7-81.1; P = .05). There was no influence regarding the use of gravitational vs differential pressure valves (P > .78). Overshunting resulted in hemispheric collapse, subdural hemorrhage, and peracute deterioration of neurological status in 15 animals. Subdural hematoma was removed in 8 dogs and 2 cats with prompt postoperative improvement of clinical signs.

CONCLUSIONS AND CLINICAL IMPORTANCE

Biventricular hydrocephalus and increased VBR indicate a higher risk for overshunting. The use of differential valves with gravitational units has no influence on occurrence of overshunting related complications and outcomes. Decompressive surgery provides a favorable treatment option for hemispheric collapse and has a good outcome.

Evaluation of Overshunting between Low and Medium Pressure Ventriculoperitoneal Shunts in Dogs with Severe Hydrocephalus Using Frameless Stereotactic Ventricular Shunt Placement

Hydrocephalus is a neurological disorder characterized by an abnormal accumulation of cerebrospinal fluid (CSF) within the ventricular system of the brain, leading to cerebral ventricular dilation, brain parenchyma compression, and neuronal cell loss. Surgery is an effective method of draining excessive amounts of CSF. Ventriculoperitoneal shunt (VPS) allows excess CSF to divert into the abdomen; this device is the most commonly used in the treatment of hydrocephalus both in veterinary and human patients. This study aims to describe the application of two types of VPS, low-pressure valve and medium-pressure valve, using a frameless stereotactic neuronavigational system in eight severe hydrocephalus in dogs and, in particular, analyze the prevalence of postoperative overshunting. Non-communicating hydrocephalus was found in seven dogs, whereas the rest of them had communicating hydrocephalus caused by traumatic brain injury with a skull fracture. The criteria for pressure valve selection depended on the intraoperative intraventricular pressure (IVP) that was determined by the adaptive manometer, according to the human protocol. Low-pressure valve placement was performed in five dogs, and the others received medium-pressure valve placement. The follow-up period was 2 weeks, 4-12 weeks, and 12 weeks to 12 months. Pre- and postoperative information including neurological signs, CT-Scan or MRI, medical treatment, complications, and ventricular volume were compared in all dogs. Seven dogs showed neurological improvement within 2 weeks after surgery. Overshunting was seen in four dogs who received low-pressure valve placement. Three of them had shunt infections within 4 to 6 weeks after surgery. One dog underwent shunt revision from a low-pressure valve to a medium-pressure valve caused by severe overshunting and progressive neurological signs. In addition, cognitive and learning improvements were evaluated based on the owners' feedback, and neurological signs were examined during the follow-up period in two dogs that received low-pressure valve placement. We conclude that a medium-pressure valve is recommended for overshunting prevention. However, low-pressure valve placement seems to improve cognitive function and learning ability, which is related to an increase in the brain parenchyma observed during long-term monitoring. Moreover, we also report our experience and surgical procedure for frameless stereotactic ventricular shunt placement (FSVSP) in VPS surgery in dogs affected by hydrocephalus.

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

A 14-year-old male neutered domestic short-hair cat was presented for a history of behavioral changes and episodes of urinary retention. Neurological examination was consistent with a multifocal intracranial neuroanatomical localization, with suspected right sided lateralisation and suspected raised intracranial pressure (ICP). Brain magnetic resonance imaging (MRI) revealed an intraventricular multilobulated well-defined T2W-hyperintense and T1W-isointense, markedly contrast enhancing mass lesion within the dorsal aspect of the III ventricle extending into the left lateral ventricle, causing hypertensive obstructive hydrocephalus. A ventriculoperitoneal shunt (VPS) was placed within the left lateral ventricle, followed by a radiation therapy (RT) course of 45 Gy total dose in 18 daily fractions. Six-months post-RT, computed tomography revealed mild reduction in mass size and resolution of the hydrocephalus. The patient was neurologically normal with no medical treatment. Raised ICP causes severe clinical signs, can lead to brain ischaemia and herniation, and significantly increases anesthetic risk during RT. Placement of a VPS in cats with hypertensive obstructive hydrocephalus may allow improvement of neurological signs due to raised ICP, and therefore making the patient a more stable candidate for anesthesia and radiation therapy.

Preliminary evaluation of a non-invasive device for monitoring intracranial pressure waveforms in dogs

OBJECTIVES

The objective of this study was to compare waveforms obtained with a new device for the non-invasive monitoring of intracranial pressure (ICP) in dogs with and without neurological disease.

MATERIALS AND METHODS

This prospective study was conducted on both neurologically normal dogs and dogs with neurological diseases. First, non-invasive ICP waveforms were recorded in normal dogs using the Braincare® BcMM 2000 monitor while the dogs were under general anaesthesia induced for procedures unrelated to this study. The dogs were positioned in lateral recumbency, and the sensor was placed over the skin of the parietal region. Secondly, non-invasive ICP waveforms were monitored in dogs with brain and spinal disease until waveforms with characteristic peaks were acquired. All the recorded signals were amplified, filtered and digitalized, by the device, and then transferred to a computer for analysis.

RESULTS

Normal pulse waveforms indicating normal brain complacency were observed in eight neurologically normal dogs. In six dogs with brain disease, abnormal pulse waveforms were observed suggesting increased ICP and decreased brain complacency. Four dogs with spinal disease undergoing myelography, had normal waveforms before contrast medium injection and abnormal pulse waveforms during contrast medium injection, indicating a potential increase in ICP.

CLINICAL SIGNIFICANCE

Based on these preliminary observations, this method was capable of detecting abnormal pulse waveforms that suggested increased ICP.

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

A 3-month-old male cross-breed dog presented with signs of progressive diffuse brain disease. Noncommunicating congenital hydrocephalus concurrent with cervical syringomyelia was diagnosed on magnetic resonance images. On time-spatial labeling inversion pulse (Time-SLIP) images CSF flow through the mesencephalic aqueduct was poorly defined and there was flow into the syrinx across the craniocervical junction. After percutaneous ventricular drainage and ventriculoperitoneal shunting, CSF flow through the aqueduct was clearly detected and flow into the syrinx disappeared. In addition, CSF flow in the subarachnoid space at the pons and ventral aspect of the cervical subarachnoid space was restored. Signs of neurological dysfunction improved after ventriculoperitoneal shunting and the cerebral parenchyma was increased in thickness on 2-year follow-up computed tomography images. Patterns of CSF flow on Time-SLIP images before and after CSF drainage or ventriculoperitoneal shunting aid in clarifying disease pathogenesis and confirm effects of CSF drainage.

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

BACKGROUND

Seizures are considered a clinical sign in dogs with internal hydrocephalus but are not found in recent studies. Seizure prevalence due to ventricular enlargement and the prevalence of postoperative seizures in animals is not known.

OBJECTIVES

To determine seizure prevalence in dogs and cats with idiopathic internal hydrocephalus, to identify risk factors for seizure development, and to determine seizure prevalence in a 2-year period after ventriculo-peritoneal shunting (VPS).

ANIMALS

Records and MRIs of 197 animals from 2001 to December 2019 were investigated. A total of 121 animals (98 dogs and 23 cats) were included in the study.

METHODS

A retrospective multicenter case cohort study was conducted. Databases were searched for dogs and cats with internal hydrocephalus. MRI and CSF examinations were evaluated for signs of additional underlying disorders. Prevalence of seizures was estimated for animals showing only hydrocephalus internus. Risk factors were evaluated according to age, morphometric and morphological findings in the brain. All animals that underwent surgery were reexamined 2 years after surgery.

RESULTS

One hundred twenty-one animals (98 dogs and 23 cats) with internal hydrocephalus met the inclusion criteria. Seizure prevalence in dogs and cats with internal hydrocephalus was low (1.7%; <5.8% CI 95%). Seizures were not observed in the 2-year period after surgery.

CONCLUSION AND CLINICAL IMPORTANCE

Seizure prevalence in dogs and cats diagnosed with hydrocephalus internus is low. Seizures in association with VPS do not seem to be a complication of the procedure.

Palliative ventriculoperitoneal shunting in dogs with obstructive hydrocephalus caused by tumors affecting the third ventricle

BACKGROUND

Hypertensive or obstructive hydrocephalus is a common complication in dogs with tumors affecting the third ventricle for which few therapeutic options are available.

OBJECTIVES

To describe signalment, neurological status, and pre- and postsurgical findings, complications and survival time in 4 dogs with obstructive hydrocephalus caused by third ventricle tumors that were palliatively treated using ventriculoperitoneal shunting (VPS).

ANIMALS

Four client-owned dogs with obstructive hydrocephalus caused by tumors affecting the third ventricle.

METHODS

Medical records were reviewed for dogs diagnosed with third ventricular tumors. Inclusion criteria were complete medical record, advanced diagnostic imaging for review, and VPS as sole surgical treatment.

RESULTS

At the time of diagnosis, all patients displayed acute onset and rapidly progressive diffuse intracranial clinical signs. On advanced imaging, all dogs had a homogeneously enhancing mass occupying or collapsing the third ventricle as well as obstructive hydrocephalus. All of the dogs underwent VPS of the most dilated lateral ventricle. In 2 of the patients, intracranial hypertension followed by normotension after VPS placement was confirmed intraoperatively by means of direct intracranial pressure monitoring. Excellent clinical improvement was observed in all dogs immediately after surgery. Three patients required a second VPS in the contralateral lateral ventricle 3, 7 and 11 months after the first surgery, all of them with renewed improvement in clinical signs.

CONCLUSION AND CLINICAL IMPORTANCE

Ventriculoperitoneal shunting is a rapid and effective treatment for patients with obstructive (hypertensive) hydrocephalus caused by tumors located within the third ventricle.