A brain biopsy, also called a brain puncture, is a medical examination method in which a piece of the brain is removed for further examination. Examination of the removed tissue can provide information about the nature of brain lesions, and confirm, for example, whether a brain tumor is present.
What is brain biopsy?
A brain biopsy, also called a brain puncture, is a medical examination method in which a piece of the brain is removed for further examination. When diagnosing diseases of the brain, a brain biopsy, the underlying tissue sample of which is taken through a hole drilled in the skull wall, allows a reliable diagnosis of the disease at hand. The goal of a biopsy of the brain is to distinguish brain lesions. These occur, for example, in the form of hemorrhages, infections, cerebral vasculitis (inflammation of the blood vessels), but also as tumors. Even if doctors cannot deduce from the course of the disease what type of brain lesion is present, a brain biopsy is appropriate. This is because with this tissue examination, the result is available quickly, which speeds up the diagnosis – and thus the appropriate therapy. A brain biopsy proves, for example, whether there is a benign tumor that does not require further treatment, or as of a malignant tumor must be eliminated immediately by chemotherapy.
Function, effect, and goals
A common procedure for obtaining a tissue sample from the brain is stereotactic biopsy. In this procedure, the physician fixes a helmet on the patient’s head in preparation for the brain biopsy. Due to the imaging procedure preceding the anesthesia, e.g., an MRI examination, the surgeon is already informed about the location of abnormalities in the brain. He now applies the coordinators on the helmet, which show him where to take the tissue sample. At the corresponding location, the surgeon finally drills through the skull wall and takes a tissue sample through a needle. Before this, the area in question is disinfected to prevent infection of the wound and prepared by making a skin incision about four centimeters wide. Since the hair only needs to be shaved in spots, the biopsy is not noticeable in the hairstyle. The drill hole through the skull wall is about 7 mm deep and less than one centimeter in diameter. The puncture can also be repeated at several sites to precisely examine different areas of a brain lesion. The puncture should damage as little brain tissue as possible. This is feasible due to the imaging resources available to the surgeon today, even during the operation. The operation takes about two hours, with about half of the time spent on determining the appropriate drill site. At those sites where a tissue sample was taken, the surgeon leaves a titanium bead, which is visible during later MRI examinations and can confirm that the puncture was made at the correct site. During the procedure, a neuropathologist is present in the operating room who immediately examines the removed tissue sample – this is done, for example, by staining the tissue sample and then examining it under a microscope. The use of cytological (cellular) diagnostics allows the neuropathologist to confirm or rule out the suspicion of a tumor based on the cellular activity in the tissue sample. The suspicion of cerebral vasculitis, i.e. inflammation of the vessels in the brain, can also be clarified quickly and very reliably with the help of a biopsy. If the results of the neuropathological examination require it, further tissue samples are taken. Otherwise, the neuropathologist declares the operation complete and prepares the report of the findings, which the physician discusses with the patient afterwards regarding the next steps of treatment. After the surgery, the patient remains in the hospital for a few days for observation. However, the physician can also perform the follow-up healing check on an outpatient basis.
Risks, side effects, and hazards
A brain biopsy is an invasive procedure, and so it comes with risks. Bleeding may occur in the puncture canal. To mitigate the risks here, a clotting test is taken before the procedure. Only if there are no blood clotting disorders is a brain biopsy appropriate.This is because bleeding in the brain carries the risk of permanent paralysis or speech disorders in the patient. In extreme cases, a fatal bleeding complication can occur – but the risk of this is extremely low at 0.2 percent. The location of any brain lesions and the patient’s age also influence the decision for or against a brain biopsy. After the brain puncture, an infection of the wound can occur in the rarest of cases, which in the worst case can also spread to the meninges or brain. To avoid this, compliance with the highest hygienic standards during surgery and wound care is mandatory. In addition, swelling of the brain tissue may occur after the puncture, and cerebrospinal fluid may also leak. Furthermore, the complications that can occur in the course of anesthesia, such as disturbances of the cardiovascular system, must also be taken into account during a brain biopsy. Overall, however, brain biopsy is considered an examination method that has a low complication rate and can provide valuable information for the treatment of the underlying disease. For example, before the patient decides to undergo chemotherapy, which itself carries high health risks, the brain biopsy provides definitive certainty as to whether a tumor or other brain lesion – requiring different treatment – is actually present. In 98 percent of brain biopsies, a definitive diagnosis can be made after tissue examination.
