In vitro performance of six combinations of adjustable differential pressure valves and fixed anti-siphon devices with and without vertical motion

Cerebrospinal fluid hydrocephalus shunting: cisterna magna, ventricular frontal, ventricular occipital

Despite advances in cerebrospinal fluid shunting technology, complications remain a significant concern. There are some contradictions about the effectiveness of proximal catheter entry sites that decrease shunt failures. We aim to compare efficiency of shunts with ventricular frontal, ventricular occipital, and cisterna magna entry sites. The systemic search was conducted in the database from conception to February 16, 2022 following guidelines of PRISMA. Between 2860 identified articles, 24 articles including 6094 patients were used for data synthesis. The aggregated results of all patients showed that "overall shunt failure rate per year" in mixed hydrocephalus with ventricular frontal and occipital shunts, and cisterna magna shunt (CMS) were 9.0%, 12.6%, and 30.7%, respectively. The corresponding values for "shunt failure rate" due to obstruction were 15.3%, 31.5%, and 10.2%, respectively. The similar results for "shunt failure rate" due to infection were 11.3%, 9.1%, and 27.2%, respectively. The related values for "shunt failure rate" due to overdrainage were 2.9%, 3.9%, and 13.6%, respectively. CMS was successful in the immediate resolution of clinical symptoms. Shunting through an occipital entry site had a greater likelihood of inaccurate catheter placement and location. Contrary to possible shunt failure due to overdrainage, the failure likelihood due to obstruction and infection in pediatric patients was higher than that of mixed hydrocephalus patients. In both mixed and pediatric hydrocephalus, obstruction and overdrainage were the most and least common complications of ventricular frontal and occipital shunts, respectively. The most and least common complications of mixed CMS were infection and obstruction, respectively.

Shunt technology for infants and a lifetime

The use of cerebrospinal fluid (CSF) shunts remains a fundamental therapeutic modality in the management of hydrocephalus. Nowadays, neurosurgeons have an arsenal of different shunt technologies on their hands, with several companies producing many different configurations of them. The greatest difficulty of treating a child with hydrocephalus is to deal with a brain that will enormously change its size and hydrodynamic conditions and a body that will multiply its height and weight in a short time. Detailed knowledge of the hydrodynamic properties of shunts is mandatory for any neurosurgeon and much more for those taking care of pediatric patients. It is necessary to know that these properties of the valve may influence the evolution of the patient after shunting and it is recognized that a patient physiology-specific valve selection may yield better outcomes and decrease complications. This article provides a summary of the most common available CSF valves and overdrainage control devices, their technology, and possible combinations. The objective is to offer a quick overview of the armamentarium to facilitate the recognition of the implanted device and improve the selection of the most suitable valve for each patient.

In vitro testing of explanted shunt valves in hydrocephalic patients with suspected valve malfunction

Diagnosis of symptomatic valve malfunction in hydrocephalic patients treated with VP-Shunt (VPS) might be difficult. Clinical symptoms such as headache or nausea are nonspecific, hence cerebrospinal fluid (CSF) over- or underdrainage can only be suspected but not proven. Knowledge concerning valve malfunction is still limited. We aim to provide data on the flow characteristics of explanted shunt valves in patients with suspected valve malfunction. An in vitro shunt laboratory setup was used to analyze the explanted valves under conditions similar to those in an implanted VPS. The differential pressure (DP) of the valve was adjusted stepwise to 20, 10, 6, and 4 cmH₂O. The flow rate of the explanted and the regular flow rate of an identical reference valve were evaluated at the respective DPs. Twelve valves of different types (Codman CertasPlus valve n = 3, Miethke Shuntassistant valve n = 4, Codman Hakim programmable valve n = 3, DP component of Miethke proGAV 2.0 valve n = 2) from eight hydrocephalic patients (four male), in whom valve malfunction was assumed between 2016 and 2017, were replaced with a new valve. Four patients suffered from idiopathic normal pressure (iNPH), three patients from malresorptive and one patient from obstructive hydrocephalus. Post-hoc analysis revealed a significant difference (p < 0.001) of the flow rate between each explanted valve and their corresponding reference valve, at each DP. In all patients, significant alterations of flow rates were demonstrated, verifying a valve malfunction, which could not be objectified by the diagnostic tools used in the clinical routine. In cases with obscure clinical VPS insufficiency, valve deficiency should be considered.