What is it?
A stereotactic biopsy is a surgical procedure where a thin needle is inserted into the brain by a neurosurgeon to extract a small piece of tissue to examine under a microscope.
What is its goal?
The goal of a biopsy is to diagnose an abnormality seen on an MRI or CT scan. While MRI and CT scans are very good at showing parts of the brain that are abnormal, they can’t yet tell us with 100% certainty what an abnormality represents - a cancerous tumor, a benign tumor, an infection, an inflammatory process, a vascular abnormality, or other pathology. Because the treatments for these abnormalities are so different, it is important to determine what a lesion is so that appropriate treatment can be recommended.
How is it done?
Stereotactic Biopsies are done either with a “frame” or “frameless”, depending on the surgeon’s preference and the location and size of the lesion.
For a frameless biopsy, you will be asked to get a special MRI or CT one or two days before the planned biopsy. This image is imported into a computer system that provides us with a 3-dimensional image of your brain and our biopsy target while we are in the operating room. We use this image, along with a biopsy guidance arm to guide our needle safely into the tumor target (picture).
For a frame based biopsy, we attach a device known as a stereotactic frame to your head before obtaining the MRI or CT scan to be used with the image guidance system (picture). The frame is particularly useful for guiding the biopsy needle to small targets, or targets that are deeper in the brain. Both approaches have the same safety and success record.
For both frame and frameless biopsies, a small incision is used and a small hole is drilled in the skull to allow the needle to pass through to the target. At the end of the operation the needle is removed and the incision is sutured or stapled closed. The operation can be done either with general anesthesia where you are asleep or with sedation where you are drowsy, but not fully unconscious.
What is the success rate?
The success rate for obtaining a definitive diagnosis is >95%, but does depend on the type of pathology being tested for. In general, the diagnostic success rate is highest for tumor cases.
What are the risks?
The biggest risk is bleeding in the tumor and brain from the biopsy needle. Bleeding can cause anything from a mild headache up to a stroke, coma, or even death. The risk of bleeding following biopsy is around 5% and the risk of mortality is around 1%. Additional risks can include headache from the biopsy site, infection, and seizures. Additional risks can be posed by the anesthesia itself. To minimize risk, we ensure that a patient’s medical condition is optimized before beginning surgery, use intraoperative antibiotics, stop all blood thinners including aspirin before surgery, and keep everyone overnight in the hospital for observation at the completion of surgery.
How long will I stay in the hospital?
The surgery itself generally requires an overnight stay, but because some patients will have other problems such as seizures, weakness, or coordination problems associated with their disease, additional hospital time may be needed to address or treat those problems separate from the surgery.
How long does it take to get the results of the biopsy?
The surgeons and pathologists will take a quick look at the biopsy specimen at the time of surgery using a process known as a frozen section. This quick look allows the surgeon and pathologist to be sure that the biopsy specimen is abnormal, but is not sufficient to completely diagnose the problem. The final sections, which are chemically processed and stained portions of the specimen that are used to determine the final diagnosis, take 48-72 hours to process and examine.
- In 2007, a total of 34 stereotactic biopsies were performed at Strong Memorial Hospital.
- The inpatient mortality rate was 2.9% (1 death) that occurred in a patient with an advanced tumor who was admitted through the emergency department and who refused all medical intervention following his biopsy.
- There were no readmissions for infection or deep venous thrombosis.
- The majority of patients were discharged to home with a length of stay of 1-day.