Scientists have identified the underlying cause of hydrocephalus

The abnormally enlarged head and brain of newborns is due to abnormal activity of neuronal precursor cells, which, when dividing, block the channels for the outflow of cerebrospinal fluid from the brain.

Sometimes babies are born with complications such as cerebral hemorrhage and hydrocephalus. The first usually precedes the second: after the bleeding stops, hydrocephalus begins to develop. This strange disorder is associated with the improper functioning of the fluid circulation system in the brain. Cerebrospinal fluid is formed in the ventricular system of the brain, and as it is formed, it is absorbed by the blood and lymphatic vessels. If the transport of fluid to the place of absorption is difficult, it begins to press on the developing brain, which leads not only to an abnormal increase in the size of the head, but also to multiple neurophysiological disorders. According to statistics, one in 1,500 babies is born with hydrocephalus, which means that this disease cannot be called rare. There is no effective treatment for it, the only way to make life easier for the patient is surgical shunting of excess cerebrospinal fluid from the brain into the spinal canal. Over time, the shunt fails and the operation has to be repeated.

For a long time, it was believed that cerebral hemorrhage causes hydrocephalus due to clots of clotted blood. Blood, entering the cerebrospinal fluid circulation system, clots and closes the channels of its outflow from the cerebral ventricles. The theory of mechanical blockage existed for 100 years, until a group of researchers from the Scripps Institute (USA) came up with the idea to look for other mechanisms of the relationship between cerebral hemorrhage and hydrocephalus.

Neurophysiologists decided to find out whether there are any blood components that can cause blockage of the fluid circulation channels in the brain. In experiments on mice, injecting blood into the ventricles of the brain successfully recreated hydrocephalus. Then the researchers tried injecting red blood cells into the brain separately, and blood plasma separately. Red blood cells did not give the desired effect, but plasma worked. It was later discovered that the cause of hydrocephalus was a fat molecule - lysophosphatidylic acid, present in blood plasma. When this acid entered the ventricles of the brain, mice with hydrocephalus were born.

Lysophosphatidylic acid is an active regulator of the cell cycle: it stimulates cell division and takes part in the transformation of the cytoskeleton. Neuronal precursor cells are abundantly supplied with receptors to this acid; its excess or increased sensitivity of neuronal precursors to it leads to nerve cells appearing at the wrong time and in the wrong place, as required by normal brain development. In the case of hydrocephalus, the intensive formation of new cells can narrow the channel for cerebrospinal fluid. In the final experiment, the researchers injected the brain with a substance that blocked the binding of lysophosphatidylic acid to receptors on the surface of nerve cells, and the acid introduced after this treatment no longer led to disturbances in brain development. The scientists published the results of their research in the journal Science Translational Medicine.

Excess lysophosphatidylic acid can cause not only hydrocephalus, because disturbances in the dynamics of brain development change the architecture of neural circuits. Accordingly, the resulting neurophysiological defects can be very diverse. So a means of blocking lysophosphatidylic acid receptors will be in great demand among doctors. But first, the researchers need to confirm the applicability of the obtained results to human physiology, which is what they are going to do.

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