Erratum: Transcranial optical monitoring for detecting intracranial pressure alterations in children with benign external hydrocephalus: a proof-of-concept study.

[This corrects the article DOI: 10.1117/1.NPh.9.4.045005.].

Transcranial optical monitoring for detecting intracranial pressure alterations in children with benign external hydrocephalus: a proof-of-concept study.

Significance: Benign external hydrocephalus (BEH) is considered a self-limiting pathology with a good prognosis. However, some children present a pathological intracranial pressure (ICP) characterized by quantitative and qualitative alterations (the so-called B-waves) that can lead to neurological sequelae. Aim: Our purpose was to evaluate whether there were cerebral hemodynamic changes associated with ICP B-waves that could be evaluated with noninvasive neuromonitoring. Approach: We recruited eleven patients (median age 16 months, range 7 to 55 months) with BEH and an unfavorable evolution requiring ICP monitoring. Bedside, nocturnal monitoring using near-infrared time-resolved and diffuse correlation spectroscopies synchronized to the clinical monitoring was performed. Results: By focusing on the timing of different ICP patterns that were identified manually by clinicians, we detected significant tissue oxygen saturation ( StO 2 ) changes ( p = 0.002 ) and blood flow index (BFI) variability ( p = 0.005 ) between regular and high-amplitude B-wave patterns. A blinded analysis looking for analogs of ICP patterns in BFI time traces achieved 90% sensitivity in identifying B-waves and 76% specificity in detecting the regular patterns. Conclusions: We revealed the presence of StO 2 and BFI variations-detectable with optical techniques-during ICP B-waves in BEH children. Finally, the feasibility of detecting ICP B-waves in hemodynamic time traces obtained noninvasively was shown.

Neurodevelopmental profile in children with benign external hydrocephalus syndrome. A pilot cohort study.

PURPOSE: The management of children with benign external hydrocephalus (BEH) remains controversial. Most BEH children do well in the long-term, but a substantial number have temporary or permanent psychomotor delays. The study aims to assess the prevalence and pattern of neurodevelopmental delay in a cohort of children with BEH. METHODS: We conducted a cohort study of 42 BEH children (30 boys and 12 girls, aged 6 to 38 months). A pediatric neurosurgeon performed a first clinical evaluation to confirm/reject the diagnosis according to the clinical features and neuroimaging studies. Two trained evaluators assessed the child's psychomotor development using the third edition of the Bayley Scales of Infant and Toddler Development (Bayley-III). Developmental delay was defined as a scaled score < 7 according to the simple scale and/or a composite score < 85. RESULTS: Eighteen children (43%) presented statistically lower scores in the gross motor and composite motor of the Bayley-III scales compared to their healthy peers. CONCLUSION: In BEH, it is important to establish a diagnostic algorithm that helps to discriminate BEH patients that have self-limiting delays from those at risk of a persistent delay that should be referred for additional studies and/or interventions that might improve the natural evolution of a disease with high impact on the children and adult's quality of life.

How to Choose a Shunt for Patients with Normal Pressure Hydrocephalus: A Short Guide to Selecting the Best Shunt Assembly.

Most patients with hydrocephalus are still managed with the implantation of a cerebrospinal fluid (CSF) shunt in which the CSF flow is regulated by a differential-pressure valve (DPV). Our aim in this review is to discuss some basic concepts in fluid mechanics that are frequently ignored but that should be understood by neurosurgeons to enable them to choose the most adequate shunt for each patient. We will present data, some of which is not provided by manufacturers, which may help neurosurgeons in selecting the most appropriate shunt. To do so, we focused on the management of patients with idiopathic "normal-pressure hydrocephalus" (iNPH), as one of the most challenging scenarios, in which the combination of optimal technology, patient characteristics, and knowledge of fluid mechanics can significantly modify the surgical results. For a better understanding of the available hardware and its evolution over time, we will have a second look at the design of the first DPV and the reasons why additional devices were incorporated to control for shunt overdrainage and its related complications. We try to persuade the reader that a clear understanding of the physical concepts of the CSF and shunt dynamics is key to understand the pathophysiology of iNPH and to improve its treatment.

Considerations in the Use of Gravitational Valves in the Management of Hydrocephalus. Some Lessons Learned with the Dual-Switch Valve.

In the past decade, there has been a clear trend towards better outcomes in patients with hydrocephalus, especially those with normal pressure hydrocephalus (NPH). This is partly due to the availability of more sophisticated hardware and a better understanding of implants. However, there is little evidence to show the superiority of a specific type of valve over another. The most commonly reported consequence of hydrodynamic mismatch is shunt over-drainage. Simple differential pressure valves, with a fixed opening pressure or even adjustable valves, lead to non-physiologic intraventricular pressure (IVP) as soon as the patient moves into an upright posture. These valves fail to maintain IVP within physiological limits due to the changes in hydrostatic pressure in the drainage system. To solve this problem more complex third-generation hydrostatic valves have been designed. These gravitational devices aim to reduce flow through a shunt system when the patient is upright but there are important technical differences between them. Here we review the main characteristics of the Miethke® Dual-Switch valve, which includes two valve chambers arranged in parallel: a low-opening pressure valve, designed for working in the supine position, and a second high-opening pressure valve, which starts working when the patient assumes the upright position. This paper specifies the main advantages and drawbacks of this device and provide a series of recommendations for its use. The discussion of this specific gravitational valve allows us to emphasize the importance of using gravitational control in implanted shunts and some the caveats neurosurgeons should take into consideration when using gravitational devices in patients with hydrocephalus. The correct function of any gravitational device depends on adequate device implantation along the vertical body axis. Misalignment from the vertical axis equal to or more than 45° might eliminate the beneficial effect of these devices.

Distal catheter lengthening in pediatric patients with hydrocephalus using a guidewire-assisted technique.

PURPOSE: The aim of this study was to evaluate the lengthening or replacement of the peritoneal catheter in a ventriculoperitoneal shunt by using a simple guidewire-assisted technique. Here we report on our experience with this methodology, its indications, caveats, and contraindications. METHODS: A prospective study was performed in 59 consecutively shunted children who required elective lengthening of the peritoneal catheter (25 females and 34 males, mean 10.5 + 4.2 years). The procedure required an incision of only 1 cm over the distal catheter. The catheter was sectioned, and a soft hydrophilic guidewire was inserted into the exposed end of it, which serves as a route for the guidewire to reach the intraperitoneal space. The procedure was followed by the replacement of the patient's catheter with one with additional length as considered appropriate, prior to putting additional slots in the last 5 to 8 cm of the new catheter. RESULTS: The technique was used in 62 CSF shunts (3 patients had a double derivative system). Fifty-five of the 62 (89%) procedures performed were effective. A conventional peritoneal opening technique was used in the 7 unsuccessful attempts. One patient presented a migration of the abdominal catheter during the first days after surgery. No incident of peritoneal perforation was associated with this technique, nor were any infections or other early or late complications associated with this surgical procedure. CONCLUSION: The technique we propose permits the peritoneal catheter of a derivative system to be lengthened or replaced in a manner that is simple, fast, and safe.

Spatial recognition memory in a virtual reality task is altered in refractory temporal lobe epilepsy.

Temporal lobe epilepsy is often resistant to medical management. Patients experience seizures for years until they receive surgical interventions. During that time, they can exhibit an altered cognition that can be assessed using virtual reality-based neuropsychological tasks. In this study, we coupled a recognition task with a spatial learning task to assess spatial learning and spatial recognition in patients with pharmacoresistant epilepsy. We tested spatial learning and spatial recognition in 8 subjects with epilepsy and 8 control subjects. Tests were based on virtual reality technologies. Data collected showed that groups did not differ in spatial learning, but recognition was better in the control group. They showed a shorter reaction time and fewer errors. This supports the hippocampal role in managing an allothetic environment representation and suggests that the spatial recognition task can be very sensitive to hippocampal disturbances.