The hydrokinetic parameters of shunts for hydrocephalus might be inadequate

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.

Computational Modeling and Simulation to Quantify the Effects of Obstructions on the Performance of Ventricular Catheters Used in Hydrocephalus Treatment

Pediatric hydrocephalus is a debilitating condition that affects an estimated 1-2 in 1000 newborns, and there is no cure. A traditional treatment is surgical insertion of a shunt system which was designed 50 years ago, and minimal ensuing progress has been made in improving the failure rate of these devices resulting in the need for multiple brain surgeries during an affected child's lifetime for shunt replacement. A first step toward decreasing the failure rate is to optimize the ventricular catheter component of the shunt to minimize its propensity for obstruction. Given the many geometric properties and patient specific in vivo conditions needed to characterize the fluid dynamics affecting ventricular catheter performance, validated computational simulation is an efficient method to rapidly explore and evaluate the effects of this large parameter space to inform improved design and to investigate patient specific shunt performance. This chapter provides the details on how to build a computational model of a ventricle and implanted catheter, analyze the fluid dynamics through an obstructed catheter, and postprocess the results to predict catheter performance for varying geometry and in vivo conditions.

Slit ventricle syndrome: Historical considerations, diagnosis, pathophysiology, and treatment review

After the introduction of shunt treatment for the management of childhood hydrocephalus, a wide variety of complications related to this treatment modality have been recognized. The entity of slit ventricle syndrome (alternatively, symptomatic ventricular coaptation) is one of them, is frequently encountered in the pediatric population and its symptom complex resembles that of shunt failure. We conducted research on PubMed^®, MEDLINE^®, and Web of Science^®, using the keywords: “slit ventricles,” “slit ventricle syndrome,” “SVS” and “ventricular coaptation.” The aim of our review was to trace the advances made through the past decades, concerning our knowledge about the clinical characteristics, pathophysiology, and treatment options of this entity. The discrepancy among researchers about the offending etiology and the optimum treatment algorithm of this entity, as well as the necessity of an updated concept regarding shunt over drainage is analyzed. The multiple treatment modalities proposed and pathophysiologic mechanisms implicated for the treatment of slit ventricle syndrome illustrate the complexity of this entity. Consequently, the issue requires more detailed evaluation. In this review, we comment on all the main facets related to shunt over drainage and the resultant slit ventricle syndrome.

Shunt Overdrainage: Reappraisal of the Syndrome and Proposal for an Integrative Model

Although shunt overdrainage is a well-known complication in hydrocephalus management, the problem has been underestimated. Current literature suggests that the topic requires more examination. An insight into this condition is limited by a lack of universally agreed-upon diagnostic criteria, heterogeneity of published series, the multitude of different management options and misunderstanding of relationships among pathophysiological mechanisms involved. We carried out a review of the literature on clinical, radiological, intracranial pressure (ICP), pathophysiological and treatment concepts to finally propose an integrative model. Active prophylaxis and management are proposed according to this model based on determination of pathophysiological mechanisms and predisposing factors behind each individual case. As pathophysiology is progressively multifactorial, prevention of siphoning with gravitational valves or antisiphon devices is mandatory to avoid or minimize further complications. Shunt optimization or transferal and neuroendoscopy may be recommended when ventricular collapse and cerebrospinal fluid isolation appear. Cranial expansion may be useful in congenital or acquired craniocerebral disproportion and shunting the subarachnoid space in communicating venous hydrocephalus and idiopathic intracranial hypertension.

A computational fluid dynamics simulation framework for ventricular catheter design optimization

In this research an optimization methodology and 3D computational fluid dynamics algorithm were coupled to reach an important design objective for ventricular catheters: uniform inlet flow distribution. The optimized catheter design presented significantly improves on previous designs explored in the literature and on standard catheter designs used clinically. The automated, iterative fluid simulation framework described in this work can be used to rapidly explore design parameter influence on other flow-related objectives in the future.

The truth and coherence behind the concept of overdrainage of cerebrospinal fluid in hydrocephalic patients

INTRODUCTION

Overdrainage, siphoning, and slit-ventricle syndrome are well-documented complications of shunting in hydrocephalic patients. Despite the prevalence of these conditions, their mechanisms are still not fully understood. In this paper, the authors trace the concept of overdrainage and the related phenomena of siphoning and slit-ventricle syndrome.

PURPOSE

To provide a historical overview of overdrainage and to reignite discussion of a topic that has been settled.

METHODS AND RESULTS

A medical literature search and review were performed via Google Scholar. Of 565 publications, 3 primary papers were identified and a timeline was developed demonstrating the convergence of the aforementioned concepts. From the primary papers, 25 relevant publications were selected and further analyzed searching for hypothesis, evidence, and conclusions.

CONCLUSION

Overdrainage, siphoning, and slit-ventricle syndrome are associated concepts that have converged into a pathophysiological theory where siphoning of CSF leads to overdrainage, which is then hypothesized to cause slit-ventricle syndrome in a small subset of patients. Our data suggests that while there have been numerous reports regarding overdrainage and its consequences, the evidence is not as robust as currently presumed and this subject requires prospective exploration.