Any neurosurgical intervention involving the ventricles, especially the external ventriculostomy, requires strict aseptic precautions as meningitis and ventriculitis can develop if infection infiltrates the CSF.

Lumbar Puncture

An important clinical test that clinicians use to monitor the CSF is the lumbar puncture (spinal tap). In this procedure, a long, hollow needle is typically inserted into the subarachnoid space of the lumbar spine just below where the spinal cord ends (usually below L2). The needle can then be uncapped, and samples of CSF can be obtained. The first thing to note when doing a lumbar puncture is the opening CSF pressure. A high opening pressure can suggest various conditions, including hydrocephalus, intracranial mass, and idiopathic intracranial hypertension. When there is an elevated CSF pressure, there is a risk of damage to the brain by reducing the pressure too quickly.

For this reason, care is necessary to make sure that no masses are pressing on the brain before performing this procedure. A low CSF pressure can also be clinically significant. This situation can occur in conditions that allow for CSF to leak into surrounding tissues. CSF can leak due to physical trauma, previous lumbar punctures, or without an obvious physical cause (spontaneous cerebrospinal fluid leak).

Several analyses are possible on the contents of CSF obtained from a lumbar puncture. Since CSF should be transparent, the color is worth noting. A cloudy appearance can suggest an infectious cause, and red color can suggest the presence of blood. Cultures can be taken from this fluid to look for different infectious agents that can cause meningitis. Additionally, molecular analyses can help to look for protein abnormalities. These tests can help to diagnose a wide variety of diseases affecting the central nervous system.[7]

Hydrocephalus

Hydrocephalus is one important clinical disorder of cerebrospinal fluid. In this disorder, there is increased intracranial pressure due to an overabundance of CSF. This abundance is usually the outcome of an obstruction in the flow of CSF through the brain. In an adult, this can be the result of several different things. A few examples of possible culprits include neoplastic growths, infections (meningitis), traumatic brain injury, and hemorrhage. Hydrocephalus can also occur at birth, causing an acute enlargement of the child’s head, or it can occur later in life. Increased intracranial pressure is not as dangerous in an infant since the cranial bones fuse later in life. For this reason, an infant with hydrocephalus can present with an enlarged head. When a child is born with this condition, it is usually due to a defect in forming the neural tube or stenosis of the cerebral aqueduct.

The treatment of hydrocephalus involves removing whatever obstructs CSF flow. In cases where there is recurrence or difficulty in ensuring a non-obstructed flow of CSF, a shunt can help drain excess fluid from the intracranial cavity. These shunts most often drain the CSF into the peritoneal cavity, but they can also be placed in other locations such as the pleural cavity, gallbladder, and the right atrium of the heart.[8][9]

Idiopathic Intracranial Hypertension

Idiopathic intracranial hypertension is characterized by an increased intracranial pressure (usually detected through lumbar puncture) with no discernable cause. In other words, it is unclear what is causing the increased CSF pressures. Patients often experience headaches, vision changes, pulsatile tinnitus, weakness, nausea, vomiting, etc. The diagnosis is generally made based on the history and physical exam. However, neuroimaging investigations and lumbar puncture are often necessary to rule out other potential causes.

Chiari Malformations

Arnold-Chiari, also known as Chiari malformation, is the name given to a group of deformities of the hindbrain (cerebellum, pons, and medulla oblongata).[10] There are two types recognized:

• Chiari Type I Malformation
  • Occurs in 1 in 1,000 births; more common than type II malformations
  • Genetic syndromes or more commonly idiopathic reduced volume of the posterior fossa leads to a displacement of the cerebellar tonsils into the spinal canal.
• Chiari Type II Malformation
  • Invariably results in the setting of myelomeningocele. Leakage of cerebrospinal fluid (CSF) to the myelomeningocele follows herniation of the hindbrain into the spinal canal, disturbing the cerebrospinal fluid normal flow and potentially causing subarachnoid adhesions.