What is a brain biopsy?
A biopsy is a tissue sample taken from a specific area of the body. Consequently, one speaks of a brain biopsy when sample material is obtained from the brain. You have to choose between the different parts of the brain. Samples can be taken particularly well from the superficial areas of the brain (especially the cerebral cortex). But the cerebellum and the diencephalon can also be biopsied. In contrast, deeper brain sections such as the so-called thalamus or the brain stem are more difficult to reach.
Read more on the subject at: biopsy
A brain biopsy is seldom done, as the direct intervention on the brain always involves risks. It is therefore particularly important to weigh the risks against the benefits of the brain biopsy. Common indications for a brain biopsy are masses in the brain. These can be triggered by both benign and malignant processes and must therefore be clarified as soon as possible so that a sensible therapy strategy can be developed. The brain biopsy therefore plays an important role in tumor diagnosis.
A biopsy can also be performed in the case of degenerative diseases in which the brain substance is increasingly disappearing in order to identify the cause of the symptoms. Brain biopsy is rarely used in infectious diseases. Here one usually resorts to a CSF examination (examination of the brain water).
What is a stereotactic brain biopsy?
In medicine, procedures that are carried out from several directions are called stereotactic. A brain biopsy to be performed on a very small area in the brain is best done stereotactically. To do this, three-dimensional imaging of the brain is required first. With the help of computer simulations, the exact location of the brain region to be examined can then be determined. A ring is then placed on the head, to which the biopsy instruments are attached at various points. The instruments enter the brain through small holes that are drilled in the skull. The place where the instruments meet is where the brain biopsy should be taken.Due to its precision, the stereotactic brain biopsy is particularly gentle on tissue compared to other procedures.
When preparing for a brain biopsy, the indication initially plays an important role. Due to some serious complications, the benefits of the biopsy should be carefully considered. However, if preliminary examinations indicate that a malignant disease is suspected, the biopsy must be carried out for a meaningful therapy planning. Precise three-dimensional imaging of the brain (usually an MRI of the brain) is also necessary before the biopsy, as this is the only way to determine the exact location of the sample. As a rule, the perfect biopsy locations are then determined using computer simulations. The biopsy itself takes place under anesthesia (often also under general anesthesia), so that the anesthetists (anesthetists) must prepare for it.
The process of the brain biopsy differs slightly, depending on where and how many biopsies are to be taken. First of all, it is important to plan the exact positions using three-dimensional images and computer animations. It is then decided whether the brain biopsy will be taken under general anesthesia. Usually the biopsy is done using very thin instruments. These are stretched on a ring that can be placed on the head. This ensures that the brain biopsy is localized in advance by the computer. Before the actual biopsy, small holes must be drilled in the skull, through which the instruments can be inserted into the skull. The biopsy instruments are then brought precisely to the desired location (s). One or more biopsies are taken there.
The tissue samples are then usually immediately preserved and sent to a pathology department, where the biopsies can be examined for abnormalities under the microscope. The instruments are removed from the skull, then the holes are closed again. If the procedure was performed under general anesthesia, the wake-up phase follows, during which organ functions (breathing, heartbeat, etc.) are monitored.
How painful is it afterwards?
Since the brain biopsy can usually be performed through small holes in the skull, the procedure is not particularly painful. The brain itself does not have a distinct system of pain-conducting nerve fibers, so no pain stimuli can be felt there. The pain, on the other hand, can be felt in the meninges (those surrounding the brain within the skull) as well as the skull bones and the scalp. Due to the additional local anesthesia of the skin and the periosteum of the skull, pain usually only occurs a few hours after the operation. As a rule, they can be treated well with mild pain relievers such as ibuprofen and subside after a few days.
The results of the brain biopsy differ very significantly depending on the underlying disease. In the case of spatial claims, a distinction should first be made between benign and malicious processes. It then needs to be determined more precisely which brain tissue the lesion originates from. In addition to the individual large parts of the brain (cerebrum, cerebellum, diencephalon, etc.), a decision can also be made between different cells in the brain. The masses can, for example, originate from the nerve cells themselves. But also cells that only serve to isolate the nerve tracts can degenerate or multiply unintentionally. In addition, cells in the meninges (meninges) can also change.
A precise distinction between the underlying mechanisms is usually made under the microscope. In addition, various staining methods are used that can examine certain biological properties of the affected cells. In the case of neurodegenerative diseases (decline in brain tissue), the results of the biopsy should also be able to explain which brain cells are responsible for the processes. If necessary, brain biopsies can also find deposits of toxic substances in the brain, which explain certain symptoms. Occasionally one also comes across pathogens (fungi, bacteria) that can trigger an infectious disease of the brain.
Duration until the results
Depending on the urgency, the rough results can usually be expected after a day after a brain biopsy (depending on whether the hospital carrying out the procedure has its own pathology department or has to send the samples to a suitable facility). A detailed examination of the diseased cells and their biological profile, on the other hand, can take a few days to weeks. Often individual results arrive on several consecutive days.
Risks - How Dangerous Can That Be?
The risks of a brain biopsy can be divided into different categories. This can lead to general complications such as bleeding, secondary bleeding, swelling and damage to structures on the skin or the skull. This can subsequently lead to pain in the affected area. An allergic reaction to the local anesthetic and possibly to the anesthetic is also possible.
Complications immediately caused by the biopsy are particularly noticeable in the brain. There, too, individual structures can be damaged, which can lead to functional failures in the brain. Usually only small structures are replaced, so that more temporary phenomena occur. In addition, short-term confusion after the brain surgery is not uncommon.
The most feared and dangerous risks of brain biopsy are infection. Since holes are drilled into the skull during the examination, there is now a direct connection between the outside world and the otherwise particularly well-shielded brain. Therefore, the holes and the biopsy instruments are ideal for infections caused by bacteria, fungi or viruses. Once the pathogens get into the brain, they can often cause greater damage, destroy important structures and lead to life-threatening brain inflammation (encephalitis).
Read more on the subject at: Inflammation in the brain
The duration of a brain biopsy is usually determined by how many biopsies have to be taken and how easily the affected areas can be reached. If the biopsy is performed under general anesthesia, the duration of the induction and discharge must also be added. Due to the good technical preparation through computer models from three-dimensional images, brain biopsies can be carried out in ever shorter time. The removal of the tissue sample itself often only takes a few minutes. Including disinfection and drilling the holes in the skull, the procedure usually only takes a few hours.
How long have I been in the hospital?
Since many brain biopsies are performed under general anesthesia, one should stay in the clinic for at least one day for monitoring after the biopsy. In this way, possible damage to brain structures can be monitored at the same time. The subsequent length of stay in the clinic is usually no longer determined by the biopsy, but by the subsequent therapy decisions. If there is a suspicion of malignant changes in the brain, therapy can be immediately followed, which can take several days to weeks.
What are the alternatives?
The alternatives to a brain biopsy are usually limited, as a biopsy is only chosen in special situations. Most of the time, a lot of brain imaging has been done beforehand, with the help of which one tries to narrow down the diagnoses. Instead of a brain biopsy, some processes can be performed using a CSF puncture, i.e. an examination of the cerebral water. However, a biopsy is often unavoidable for an accurate diagnosis.
Read more on the subject at: Lumbar puncture