A brain biopsy is used to help diagnose brain lesions. Samples may be taken from the gray matter, white matter, or other sites. Brain biopsies can be done using a minimally invasive or open approach.

A biopsy is a procedure that collects a cell or tissue sample from your body. A specialized type of doctor called a pathologist then evaluates the sample.

Your doctor may order a biopsy when a physical exam or imaging tests identify an area of concern. Analyzing a biopsy from this area can help identify cancer and other conditions.

Biopsies can be collected from most areas of the body, including the brain.

Continue reading to learn more about the different types of brain biopsies, when they’re done, and what the procedure entails.

A brain biopsy can help diagnose the cause of a brain lesion that your doctor has found on a CT scan or MRI scan. A brain lesion is an area of the brain that appears injured or damaged.

There are many potential causes of brain lesions. A few examples include:

Some brain lesions have specific characteristics that can be seen with imaging. In these situations, a biopsy may not be necessary. Your doctor can make a diagnosis based on your medical history, symptoms, and the results of other tests.

Sometimes the cause of the brain lesion remains unclear or more information is needed. In this scenario, a doctor may recommend a brain biopsy.

Generally, brain biopsies are most often used to characterize brain tumors.

What types of tissue are removed in a brain biopsy?

A brain biopsy can sample a variety of different tissues. This can include samples from the gray matter, white matter, or both.

Gray matter makes up the outermost layer of the brain. It has a high amount of nerve cell bodies, giving it its darker color. These nerve cells can process information and communicate it through the axons found in the white matter.

White matter is in the inner layer of brain. It has a high amount of nerve axons, along which information is sent to other nerve cells. Axons are often wrapped in a molecule called myelin. This gives the white matter its lighter color.

Brain biopsy samples may sometimes include other tissues as well. These may include samples from the scalp, nearby blood vessels, or the membranes covering the brain.

There are two primary types of brain biopsy:

  • minimally invasive biopsies
  • open brain biopsies

Let’s outline each of these biopsy techniques in a little more detail.

Minimally invasive brain biopsy

In a minimally invasive brain biopsy, a surgeon makes a small hole in your skull and uses a thin needle to remove the tissue sample. They typically use information from MRI or CT scans to help guide the needle to the biopsy site.

A minimally invasive approach may be used if more invasive biopsy techniques are too risky. This may happen if the lesion:

  • affects a vital area of the brain
  • is found very deep within the brain
  • is widespread throughout the brain

Open brain biopsy

An open, or surgical, brain biopsy involves an operation called a craniotomy. During a craniotomy, a surgeon removes a section of your skull.

The opening in the skull is typically small but still sufficient enough that your surgeon can insert several instruments to operate. As in minimally invasive brain biopsies, imaging is used to help guide the biopsy.

Your doctor may recommend an open approach if they believe the lesion, most often a brain tumor, can be safely and effectively removed using surgery.

A neurosurgeon performs both types of biopsy procedures. This surgeon specializes in treating conditions involving the brain, spinal cord, and nerves.

The procedure takes place in a hospital. It may be done while you’re in a deep sleep under general anesthesia or while you’re awake. You may be awake during your biopsy if your lesion is near vital areas of the brain, such as those that control movement, speech, or vision.

If you’re awake during your biopsy, your surgical team will give you a sedative and also a local anesthetic to minimize discomfort. During the biopsy, your surgeon may ask you simple questions or ask you to do basic movements to make sure they’re avoiding vital areas.

Now, let’s briefly go over the specific aspects of each biopsy procedure.

Minimally invasive brain biopsy

A surgeon makes an incision in your scalp after shaving away a small amount of hair. They then use a special type of drill to make a small hole in your skull.

With the help of imaging, the surgeon guides a thin needle to the biopsy site, where they collect a sample. After the biopsy is collected, the needle is withdrawn and the incision is closed.

Open brain biopsy

After shaving a part of your head, a surgeon makes an incision in your scalp and folds away the skin. They then use a special drill to carefully remove a section of the skull.

The surgeon then uses imaging to access the biopsy site. When they reach it, they may remove the lesion in various ways, depending on its consistency and location. Scalpels, scissors, and suction devices are examples of tools and techniques that may be used.

Once the biopsy sample is collected and all instruments have been withdrawn, the part of the skull that was removed is replaced and held in place with screws, plates, or special wires. The incision is then closed.

After your biopsy is complete, you’re taken to a recovery room and observed for a certain amount of time before you’re able to go home. Staff will monitor things like:

Before you leave the hospital, your doctor will give you instructions on how to care for your incision site and what types of activities to avoid as you recover at home.

Your surgeon will also schedule a follow-up visit. During this time, they will check your recovery progress and discuss the biopsy results and next steps.

Minimally invasive brain biopsy

If you’ve had a minimally invasive biopsy, you’ll receive a CT scan about 4 hours after your procedure. You may be able to return home the same day. It’s also possible that you’ll need to stay at the hospital overnight.

Open brain biopsy

If you’ve had an open brain biopsy, it’s possible that you’ll have a surgical drain in your incision. This helps cerebrospinal fluid (CSF) and other fluids to drain from the site. These are typically removed after a few days.

According to the American Cancer Society, you’ll have a CT or MRI scan 1 to 3 days after your biopsy. You may need to stay in the hospital for up to 6 days. Healing at your incision site can take several weeks.

Some of the potential side effects after a brain biopsy include:

Your doctor will prescribe a variety of medications to help prevent these side effects after your biopsy, such as:

Some of the more serious complications associated with a brain biopsy include:

A 2023 study followed 196 people who had a minimally invasive or open brain biopsy. Researchers found that these procedures are overall safe with a low rate of complications.

Researchers found that most procedures (90.9%) were uncomplicated. The rate of serious complications or death for both procedures was very low at 2%. All severe or fatal complications occurred within 2 hours of the biopsy.

Doctors may use a brain biopsy to diagnose the cause of a brain lesion. It’s often used for brain tumors but may be used to diagnose other conditions. Samples from the gray matter, white matter, or other sites may be taken.

You can have a brain biopsy using either a minimally invasive or an open procedure. Which type of procedure is selected can depend on the characteristics and location of your lesion.

Overall, brain biopsies are safe and have a low risk of serious complications. If you have questions about your upcoming brain biopsy, be sure to raise them with your doctor. They can address any concerns you may have.