How is a biopsy performed for brain tumors

A biopsy is a procedure used to obtain a small sample of tissue from a brain tumor for examination under a microscope. The biopsy helps in diagnosing the type of tumor, its grade, and sometimes its molecular and genetic characteristics, which are crucial for determining the most appropriate treatment plan. Here’s how a biopsy is typically performed for brain tumors:

1. Types of Biopsies

There are two main types of biopsies used for brain tumors:

• Stereotactic Needle Biopsy:
  • The most common type of biopsy for brain tumors, especially when the tumor is deep-seated or located in an area that is difficult to access surgically.
• Open Surgical Biopsy (Craniotomy):
  • Performed during open surgery when the tumor is more accessible or if the surgeon plans to remove as much of the tumor as possible during the procedure.

2. Stereotactic Needle Biopsy

This is a minimally invasive procedure often used when the tumor is located in a sensitive or hard-to-reach area of the brain.

Steps Involved:

• Preoperative Imaging:

  • Before the biopsy, imaging studies such as MRI or CT scans are performed to precisely locate the tumor.
  • The imaging data are used to create a 3D map of the brain, guiding the surgeon to the exact location of the tumor.

• Patient Positioning:

  • The patient’s head is positioned and stabilized, often using a stereotactic frame, which is a special headframe that ensures the head remains perfectly still during the procedure.
  • In some cases, frameless stereotactic systems are used, which utilize a custom-fit mask or other methods for stabilization.

• Creating a Small Incision:

  • A small incision is made in the scalp after local anesthesia is administered to numb the area.
  • A tiny hole, called a burr hole, is then drilled into the skull to allow access to the brain.

• Inserting the Biopsy Needle:

  • Using the stereotactic guidance system, a thin, hollow needle is carefully inserted through the burr hole and directed to the tumor.
  • The surgeon uses the imaging data to guide the needle to the precise location of the tumor.

• Tissue Sampling:

  • Once the needle reaches the tumor, a small sample of tissue is removed using a special device attached to the needle.
  • Multiple samples may be taken from different parts of the tumor to ensure a comprehensive diagnosis.

• Closing the Incision:

  • After the tissue samples are collected, the needle is withdrawn, the burr hole is closed with a small plate or screw, and the scalp incision is sutured.

• Postoperative Care:

  • The patient is usually monitored for a short period after the procedure. Recovery is generally quick, with many patients going home the same day or after an overnight stay.

3. Open Surgical Biopsy (Craniotomy)

This method is typically used when the surgeon plans to remove the tumor or a portion of it while obtaining a biopsy.

Steps Involved:

• Preoperative Preparation:

  • As with a needle biopsy, preoperative imaging guides the surgical approach.
  • General anesthesia is used, and the patient is completely unconscious during the procedure.

• Craniotomy:

  • The surgeon makes an incision in the scalp and removes a section of the skull (a bone flap) to expose the brain.
  • The tumor is located, and a small sample is taken for biopsy. If the tumor is accessible, the surgeon may attempt to remove as much of it as possible.

• Intraoperative Pathology:

  • During the surgery, a pathologist may examine the biopsy sample to provide an immediate, preliminary diagnosis, which can guide further surgical decisions.

• Closing the Craniotomy:

  • After the biopsy (and any tumor resection), the bone flap is replaced and secured with plates and screws.
  • The scalp is then closed with sutures or staples.

• Postoperative Care:

  • The patient typically stays in the hospital for several days for monitoring and recovery. Postoperative imaging may be performed to assess the extent of tumor resection.

4. Risks and Complications

While brain biopsies are generally safe, they do carry some risks, including:

• Bleeding (Hemorrhage):

  • Small blood vessels may be damaged during the procedure, leading to bleeding in the brain.

• Infection:

  • As with any surgical procedure, there is a risk of infection at the biopsy site.

• Neurological Damage:

  • Depending on the tumor's location, there is a risk of damaging critical brain areas, potentially leading to neurological deficits.

• Swelling (Edema):

  • Inflammation and swelling can occur in response to the procedure, sometimes requiring treatment with steroids.

5. After the Biopsy

• Pathological Examination:

  • The tissue sample is sent to a pathology lab, where it is examined under a microscope to determine the tumor type, grade, and any specific genetic or molecular features.

• Diagnosis and Treatment Planning:

  • The biopsy results guide the medical team in diagnosing the tumor and formulating a treatment plan, which may include surgery, radiation, chemotherapy, or a combination of therapies.

Conclusion

A brain biopsy is a critical step in diagnosing and planning the treatment of brain tumors. The choice of biopsy technique depends on the tumor’s location, size, and the overall condition of the patient. Stereotactic needle biopsy is less invasive and commonly used for deep or surgically challenging tumors, while open surgical biopsy may be performed when resection is planned or when the tumor is more accessible.