The obstruction can occur at the level of the fourth ventricle, foramen of Monro, or aqueduct of Sylvius.Įxcessive CSF production is seen in CSF-secreting choroid plexus papilloma. In obstructive hydrocephalus, anatomical obstruction of CSF flow leads to elevated pressure and subsequent dilatation of the ventricle proximal to the obstruction. Image: “Hydrocephalus in Comparison to a Healthy Infant’s Brain.” by CDC. The ventricles are enlarged but there is no increase in intracranial pressure due to shrinking of the brain matter. Normal-pressure hydrocephalus occurs mainly in adults. There is dilatation proximal to the obstruction, while the ventricular system distal to the region of obstruction is normal in size. Non-communicating (obstructive) hydrocephalus, in which the increased intracranial pressure is due to the anatomical obstruction of CSF flow in the ventricular system. There is no anatomical obstruction in normal CSF circulation instead, there is uniform dilatation of the ventricles. Classification of HydrocephalusĬommunicating hydrocephalus, in which the increased intracranial pressure is due to deficient absorption or increased production of the CSF in the subarachnoid space. Arachnoid villi are protrusions from the subarachnoid space into the sinuses that allow passive absorption of CSF into the sinuses depending on the pressure gradient.
The third ventricle connects with the fourth ventricle via the aqueduct of Sylvius, where the CSF circulates through two foramina of Luschka and the foramen of Magendie.Ībsorption of CSF occurs via the arachnoid villi, which drains into the systemic venous channels in the sagittal venous sinus. The CSF circulates through a pair of lateral ventricles that connect to the midline third ventricle via the foramen of Monro. The total amount of CSF is approximately 150 mL in adults and 50 mL in infants. A smaller amount of CSF is produced through diffusion from the cerebral tissue and acts as brain lymph. The choroid plexus consists of villous folds lined by epithelium with a central core of connective tissues.ĬSF is produced by a carbonic anhydrase– dependent active transport system and can be blocked by carbonic anhydrase inhibitors such as acetazolamide. Physiology of Cerebrospinal Fluid (CSF) and CirculationĬSF is produced mainly by the choroid plexus in the lateral ventricles.
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