Hidrocefalia crónica del adulto (hidrocefalia “normotensiva”) y macrocefalia

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.

Head circumference: the forgotten tool for hydrocephalus management. A reference interval study in the Spanish population

INTRODUCTION

In children, deviations from the normal range of head circumference (HC) have traditionally been related with CSF dynamics abnormalities. In adults, this neglected parameter is helpful in the diagnosis and understanding of the pathophysiology of some CSF abnormalities. It has been demonstrated that HC is related to height. Because humans have increased in stature dramatically during the last 50 years, pediatric charts for head growth physiology and normal HC values in adults should be reevaluated.

OBJECTIVES

The main aim of the present study was to assess HC in a series of 270 normal healthy Spanish adults and to determine any differences between sexes and age groups. A secondary aim was to discuss the relevance of this parameter in the management of hydrocephalus in adult people.

METHODS

HC measurements were taken using a measuring tape placed over the greatest frontal and occipital protuberances. The reference interval and the upper and lower thresholds for HC were calculated by 3 different methods: normal distribution, the non-parametrical percentile method, and the "robust method".

RESULTS

The results were consistent and showed that Spanish adult men with a HC greater than 60 cm, and Spanish adult women with a HC greater than 58 cm should be considered macrocephalic. Microcephaly should be considered when HC is 53.6 cm in men and 51.3 cm in women. Adult age groups of either sex do not present any statistically significant differences in HC.

CONCLUSIONS

HC obtained in Spanish adult people are greater than those reported in the classical Nellhaus graphs in both men and women aged 18. These findings should be considered in the management of hydrocephalus in adults today.