**1. Introduction**

Ventriculostomy is a neurosurgical procedure where a drainage hole (or stoma) is made inside the cerebral ventricle. It is usually carried out on people who have hydrocephalus [1]. The ventricular system of the brain is reached by surgically entering the skull, dura mater, and brain gaining access to the lateral ventricle, usually from the non-dominant lobe (the right frontal lobe in most individuals [2, 3]. An external ventricular drain (EVD) is a typical term used to describe temporary catheter drainage. This is going to be the focus of this chapter.

By diverting the CSF often kept in the ventricular system, a ventriculostomy decompresses the spaces and makes it easier for ICP to return to normal [3]. Many clinical situations could urgently call for the implantation of an EVD. In this regard, the rate of EVD installation in the general population has gradually increased, notably in the industrialized world [4, 5].

CSF draining has been attempted numerous times in the past. Its initial technical description has undergone numerous modifications, and new applications for it have emerged as a result of technological advancement. Congenital hydrocephalus was originally treated with external ventricular drainage in the 18th century [6]. Claude-Nicholas Le Cat (1700–1768) described his technique for performing a ventricular

puncture using a trocar and catheter modified for the treatment of ascites. Early attempts, however, were unsuccessful [6]. Later, Robert Whytt (1714–1766) concurred with Benjamin Hill that ventricular drainage should never be done, not even as a last resort, believing it to hasten death [6]. Midway through the 19th century, advancements in the ventricular drainage method were seen, proving its usefulness. Three different developments each helped to achieve this: The use of the aseptic approach, understanding of the effects of excessive ventricular drainage, and determination of the best locations for catheter insertion [7].

Brain trauma, cerebral hemorrhage, and brain tumors are only a few neuropathological diseases that frequently cause issues and changes in CSF dynamics in the pediatric population [5]. EVD insertion has been proposed as the most significant and often lifesaving emergency therapy in neurosurgery in this context. These circumstances may demand an urgent treatment of secondary hydrocephalus or to ICP monitoring. Due of this, residents acquire it as one of their initial surgical skills while undergoing training.

While planning to insert an EVD, it's crucial to take into account both the patient's age and the nature of their illness because different indications and technical considerations may apply.

The management of EVD in the pediatric population is reviewed in this chapter. The discussion of indications and technical factors will follow a quick overview of some ventricular anatomy. Finally, the most significant EVD-related consequences are discussed, along with several evidence-based recommendations for preventing or treating those issues.

#### **2. The ventricular system**

The brain's ventricular system is a network of compartments filled with cerebrospinal fluid (CSF), which cushions the brain [8]. The purpose of the cerebral ventricles was unknown, despite the fact that their existence has been recognized since antiquity. In the past, researchers thought that the ventricles were where memory, logic, and emotion were stored.

The walls of the brain's ventricular system (ependyma) are lined by a special kind of cell called an ependymocyte. This cuboidal or columnar epithelium was developed from the neuroepithelium. A collection of permeable capillaries in a connective tissue matrix makes up the choroid plexus, which generates CSF and is situated right underneath the ependymal layer. A layer of subependymal glial cells lies beneath the ependyma. These cells and the astrocyte processes work together to generate the blood-brain barrier, which is tightly connected [8].

The ventricular system consists of four ventricles, with two of them located in each cerebral hemisphere, one in the diencephalon, and the other in the hindbrain. It is connected inferiorly to the spinal cord's central canal.

Each cerebral hemisphere contains a C-shaped hollow known as the lateral ventricle. Ependyma lines the inside, which is filled with CSF with a capacity of 7 ml to 10 ml. The septum pellucidum, a narrow vertical layer of nerve tissue that divides the two lateral ventricles, is surrounded by ependyma on both sides. The interventricular foramen of Monroe serves as its conduit to the third ventricle. The foramen becomes more rounded as the ventricular size grows. The superior choroidal vein, septal vein, and medial posterior choroidal arteries all travel via this foramen [8–10].

A median slit-like hollow known as the third ventricle sits between the two thalami and a portion of the hypothalamus. Through the cerebral aqueduct of

#### **Figure 1.** *The ventricular system of the human brain.*

Sylvius, it communicates with the lateral ventricles on its anterosuperior aspect and the fourth ventricle on its posteroinferior aspect. Ependyma lines the third ventricle space, and a mass of gray matter known as the interthalamic adhesion or Massa intermedia, which is situated behind the foramen of Monroe and connects the two thalami, passes across it [8, 9].

The Sylvian aqueduct is the brain's ventricular system's thinnest section (as seen in **Figure 1**). It has a diameter of around 18 mm and is where interventricular blockage occurs most frequently. Due to the growth of the surrounding brain tissue, it has been found that the luminal thickness of the aqueduct lowers starting in the second foetal month [8, 9].

A large, tent-like cavity of the hindbrain filled with CSF is known as the fourth ventricle. The pons and cranial half of the medulla form its anterior border, and the cerebellum forms its posterior border. On a sagittal section, it appears triangular, and on a horizontal section, it appears rhomboidal. It connects to the cerebral aqueduct in the superior region and the spinal cord's central canal in the inferior region. The fourth ventricle interacts with the subarachnoid space by two lateral foramina of Lushka and one medial foramen of Magendie [9].

A solitary cavity, or hollow of the neural tube, is where the ventricular system originates. Around the fourth week of pregnancy, the neural tube begins to develop. The amniotic cavity and neural cavity are then segregated shortly after the spinal neurocele closes [8, 9].

Ventricles grow and expand to adult size in the early stages of development. After that, the brain tissue starts to grow in a different directions from the ventricles, from caudal to cephalic, and this difference in growth creates the adult ventricular shape. Any obstruction to the CSF's free passage through the ventricular system causes hydrocephalus [8, 9].
