What are the different types of hydrocephalus?

From the Guidelines

Hydrocephalus is classified into several distinct types, including communicating, non-communicating, normal pressure hydrocephalus (NPH), congenital, acquired, and ex-vacuo hydrocephalus, with treatment approaches varying based on the specific type and cause of the condition. The main types of hydrocephalus are:

• Communicating hydrocephalus, where CSF flow is blocked after exiting the ventricles
• Non-communicating (obstructive) hydrocephalus, where CSF flow is blocked within the ventricular system
• Normal pressure hydrocephalus (NPH), characterized by enlarged ventricles without increased intracranial pressure
• Congenital hydrocephalus, present at birth due to genetic factors or developmental issues
• Acquired hydrocephalus, developing after birth from injury, infection, or tumors
• Ex-vacuo hydrocephalus, where brain tissue shrinks and ventricles enlarge to fill the space Hydrocephalus can also be categorized as acute (rapid onset) or chronic (slow developing) 1. According to a recent study, the pooled proportion of postinfectious hydrocephalus was 28% (95% CI 22–36) with high heterogeneity (I²=97∙8% [95% CI 97·5–98·1]; p<0·0001) 1. Treatment typically involves surgical placement of a shunt system to divert excess CSF or endoscopic third ventriculostomy (ETV) to create an alternative CSF pathway 1. The specific type of hydrocephalus determines the most appropriate treatment approach, with some forms like NPH potentially improving with proper CSF diversion, while others may require ongoing management to prevent neurological damage from increased intracranial pressure 1.

Some key points to consider in the management of hydrocephalus include:

• The need for permanent CSF diversion, which has been associated with older age, early ventriculomegaly, intraventricular hemorrhage, poor clinical condition on presentation, and female sex 1
• The use of ventriculostomy, which may or may not be associated with rebleeding 1
• The importance of routine fenestration of the lamina terminalis, which may reduce the incidence of chronic hydrocephalus 1
• The role of clipping and coiling of ruptured and unruptured cerebral aneurysms, which were associated with similar incidences of ventricular shunt placement for hydrocephalus 1
• The potential for permanent CSF diversion to improve neurological outcome after aSAH 1.

Overall, the management of hydrocephalus requires a comprehensive approach that takes into account the specific type and cause of the condition, as well as the individual patient's needs and circumstances.

From the Research

Types of Hydrocephalus

• Communicating hydrocephalus: This type of hydrocephalus is characterized by the presence of cerebrospinal fluid (CSF) flow between the ventricles and the subarachnoid space, but with impaired CSF absorption 2, 3.
• Non-communicating hydrocephalus: This type of hydrocephalus is characterized by a blockage or obstruction in the flow of CSF between the ventricles and the subarachnoid space, resulting in the accumulation of CSF in the ventricles 2, 3.
• Obstructive hydrocephalus: This type of hydrocephalus is characterized by a physical blockage or obstruction in the ventricular system, which prevents the normal flow of CSF 4.
• Hydrocephalus can also be classified based on its cause, such as congenital or acquired, and based on its symptoms and treatment outcomes 5.

Classification of Hydrocephalus

• The classification of hydrocephalus into communicating and non-communicating types is almost 90 years old and has not been modified despite major advances in neuroimaging, neurosciences, and treatment outcomes 5.
• A more precise nomenclature is to divide hydrocephalus as either "communicating": with or without obstruction of CSF absorption, or as "noncommunicating": with definite obstruction to CSF absorption 3.
• The concept of the hydrodynamics of cerebrospinal fluid (CSF) as a hydraulic circuit can serve as a template for a contemporary classification scheme 5.

Diagnosis and Treatment of Hydrocephalus

• Imaging examinations, such as computed tomography (CT) and magnetic resonance (MR) images, are used to diagnose and assess the treatment of hydrocephalus 2, 3.
• The treatment of hydrocephalus depends on the type and cause of the condition, and may include surgical procedures such as ventriculoperitoneal shunt (VPS) or endoscopic third ventriculostomy (ETV) 6, 4.