Dr. Fritz Wodarg, Senior Physician at the Clinic for Radiology and Neuroradiology at the University Medical Center Schleswig-Holstein in Kiel: The fundamental problem with bleeding in the brain is that space inside the skull is limited. If there is an increase in volume, for example in the form of bleeding, this leads to an increase in pressure inside the skull.

The only way to equalize the pressure is through the foramen magnum. This is a hole in the skull through which the brain and spinal cord are connected. This causes important brain structures to shift through this narrow, bony hole. However, the scope for this is limited: if the bleeding continues and the pressure continues to rise, the brain becomes stuck at this narrow point and blocks any further pressure equalization. Brain tissue is very sensitive to pressure and can be damaged very quickly. For this reason, many types of bleeding in the head are considered emergencies and require immediate medical intervention.

A basic distinction is made between different types of bleeding in the head: There are bleeds that press on the brain from the outside (epidural and subdural hemorrhages), which are often caused by trauma (e.g., traffic accidents). There are also hemorrhages in the brain tissue itself (intracerebral hemorrhages). These are often the result of high blood pressure or can also occur in connection with a brain tumor. And then there are subarachnoid hemorrhages, which in two-thirds of cases are caused by the rupture of an arterial aneurysm. These aneurysms are bulges in the blood vessels – weak spots in the vessel wall. They occur particularly in the basilar arteries, which form a circle below the brain in the subarachnoid space and are surrounded by cerebrospinal fluid (CSF).

If such an aneurysm ruptures, blood enters the subarachnoid space filled with CSF. This can lead to adhesions that impede the free circulation of cerebrospinal fluid. This is particularly dangerous because, in addition to the bleeding itself, the accumulated cerebrospinal fluid now also presses on the brain tissue. There is an acute risk to life and the affected patients must receive medical attention quickly. In the hospital, such bleeding is relieved. This is done by neurosurgeons removing part of the skull cap, creating a large artificial bone window through which the brain can expand outward. Alternatively, a small tube can be inserted into the ventricular system (fluid-filled spaces within the brain). This allows cerebrospinal fluid to drain away, leaving more space for the brain tissue.

However, even if this pressure relief is successful, the danger is not yet averted. If blood components come into contact with the outer wall of the blood vessels supplying the brain during bleeding, this can irritate the arteries and lead to vascular spasms. Vascular spasms are cramp-like constrictions of the arteries, which in extreme cases can restrict the blood supply to the brain to such an extent that the brain cells are not supplied with sufficient oxygen and the patient suffers an ischemic stroke in addition to the hemorrhage. To prevent this, patients are closely monitored and treated with medication if necessary. It is even possible to mechanically dilate the constricted vessel using a small balloon, which is advanced via a thin catheter through the leg artery to the affected cerebral vessel.

In summary, bleeding can have very different causes and, depending on the type of bleeding, can lead to life-threatening complications. If bleeding in the head is suspected, those affected should be taken to a hospital as quickly as possible!

Recorded by Johanna Rümenapp