The cerebrospinal fluid space corresponds to a system of cavities in the central nervous system. In the so-called inner CSF space, the production of cerebrospinal fluid takes place, which is reabsorbed in the outer CSF space. Dilated CSF spaces give rise to pathological phenomena such as hydrocephalus.
What is the cerebrospinal fluid space?
Neurologists refer to the cerebrospinal fluid (CSF) space as a system of cavities that runs around the brain and spinal cord. This system of cavities is filled with a glassy fluid, also called cerebrospinal fluid or cerebrospinal fluid. The fluid in the cerebrospinal fluid spaces permanently washes around the brain and spinal cord. It plays an increased role in neurological diagnostics, since a CSF sample can be used, for example, to determine inflammation and bleeding in the brain. Medicine distinguishes between the inner and the outer CSF space. The inner CSF space is formed by the ventricular system of the brain. The outer CSF space is also known as the subarachnoid space. The aperturae laterales and apertura mediana are openings of the fourth ventricle of the brain. These openings connect the two CSF spaces. The individual spaces of the cavity system are in permanent communication. CSF circulates within them continuously.
Anatomy and structure
The inner CSF space is located in the central nervous system and results from the cavities of the four cerebral ventricles located one behind the other. The internal CSF space contains the choroid plexus. This structure is a nodular and ateriovenous vascular convulsion in the cerebral ventricles. The canalis centralis completes the internal cerebrospinal fluid space. This guiding canal extends down into the spinal cord. The internal CSF space is in additional communication with the spaces of the inner ear. This communication occurs through a fine canal called the aquaeductus cochleae, which contains the aqueous fluid of the inner ear. The inner ear fluid is also called perilymph. Its pressure depends on the pressure behavior of the CSF because of its connection to the inner CSF space. The outer CSF space, in turn, lies between the two meninges, pia mater and arachnoid mater. It is slit-shaped and communicates with the inner CSF space via the fourth cerebral ventricle. The arachnoid mater is provided with projections, also known as arachnoid villi.
Function and Tasks
The most important function of the cerebrospinal fluid space is the production of cerebrospinal fluid. The cerebrospinal fluid primarily performs cushioning functions in the central nervous system, thus protecting the brain and spinal cord. In addition, many scientists assume that the cerebrospinal fluid has a nutritional function. The fluid is produced in the choroid plexus of the inner CSF space. Ultrafiltration takes place there to collect CSF. This process filters the blood of large molecules. About 0.4 milliliters of CSF are formed per minute in the inner CSF space in this way. In total, about 120 to 200 milliliters of the cerebrospinal fluid formed in this way circulate in an adult human being. However, a total of 500 to 700 milliliters are formed each day. Around 500 milliliters of this fluid are therefore not retained in the cerebrospinal fluid space, but are reabsorbed. Without this reabsorption, the intracranial pressure would rise dangerously and cause phenomena such as hydrocephalus. The sodium ions of the ultrafiltrated fluid are therefore actively transported through the plasma membrane of the plexus epithelial cells in the inner CSF space. Finally, in the outer CSF space, resorption of the excess CSF takes place. In medicine, resorption is the absorption of certain substances by the body’s own cells or tissues. The protuberances of the arachnoid protrude intracranially into the vein of the dura mater in the outer CSF space. Through this draining position, they take over the reabsorption of excess cerebrospinal fluid.
Diseases
A dangerous event in the CSF space is the so-called subarachnoid hemorrhage. In this phenomenon, blood enters the cerebrospinal fluid space. In a consequence of this, the intracranial pressure increases because so much fluid circulates in the cavity system of the brain. In most cases, hemorrhage in the CSF space is due to a ruptured aneurysm. Subarachnoid hemorrhage can be life-threatening and manifests itself in early symptoms such as neck stiffness, impaired consciousness or fainting. Headaches and visual disturbances may also occur. Usually, when this occurs, the physician tries to identify the source of the bleeding. Ideally, the source can be closed surgically.Only one third of this phenomenon is said to be benign. An even better known disease of the cerebrospinal fluid spaces is hydrocephalus, also known as hydrocephalus. In this disease, the cerebrospinal fluid spaces are pathologically dilated. Such dilatation is usually related to an overproduction of cerebrospinal fluid, such as may occur in the course of meningitis. Congenital malformations of the brain can also cause hydrocephalus. On the other hand, a tumor can also result in an expansion of the CSF spaces. If such a tumor impedes the circulation of cerebrospinal fluid, then the CSF-carrying cavities may expand to allow the CSF to pass through. If only the internal CSF space is dilated, the neurologist refers to it as normal pressure hydrocephalus. The intracranial pressure increases significantly in this phenomenon. In contrast, the intracranial pressure remains normal. This clinical picture is most often characterized by gait disturbances, but can also lead to incontinence or dementia symptoms. Congenital dilatations of the cerebrospinal fluid spaces must be distinguished from these phenomena. They may occur in the setting of subcortical arteriosclerotic encephalopathy, also known as Binswanger’s disease, among other conditions.