What is a brain biopsy?
A brain biopsy is a diagnostic surgical procedure to remove small samples of abnormal tissue from the brain. A pathologist analyzes the tissue under a microscope, and the results help the neurosurgeon arrive at a diagnosis and plan appropriate treatment.
Brain biopsy may be done using two methods:
- Open brain biopsy: A piece of bone from the skull is removed (craniotomy) to access the brain. Open brain biopsy is usually performed in one of the following situations:
- Stereotactic brain biopsy: A stereotactic equipment uses a three-dimensional coordinate system to accurately pinpoint the target area of tissue removal. A computerized navigation system guides the position and trajectory of the biopsy needle.
The targeted tissue is extracted by inserting the biopsy needle through a small hole known as a burr hole in the skull. Stereotactic biopsies are minimally invasive and of two kinds:
- Framed stereotactic brain biopsy: A rigid frame is fixed to the patient’s head to immobilize it and the stereotactic equipment which guides the biopsy needle is attached to the frame.
- Frameless stereotactic brain biopsy: There is no frame, instead pins are used to fix the stereotactic equipment to the head, and tiny metal disks placed on the scalp from reference points (fiducial markers) for guiding the biopsy needle.
Why is a brain biopsy done?
A brain biopsy is performed only when less invasive methods do not yield results and a tissue sample is essential for a conclusive diagnosis and treatment. A brain biopsy may be required
- To confirm a suspected tumor detected in imaging tests
- To plan nonsurgical treatments when removal of the tumor/lesion is not considered safe
- To identify any other cause of lesions in the brain
Brain biopsy is not performed if:
- The lesions are too small to safely and accurately target
- The patient has any bleeding disorders
- The patient is unable to tolerate general anesthesia
Conditions that brain biopsy can help diagnose include:
- Type and stage of tumors
- Abscesses from infection
- Inflammatory conditions such as encephalitis
- Multiple sclerosis
- Alzheimer’s disease
How is a stereotactic brain biopsy done?
A neurosurgeon usually performs a brain biopsy in consultation with a neuro-oncologist. The patient is under general anesthesia during the procedure, which may take up to two hours. Results from the analysis of the samples may take up to a week.
- In preparation for the procedure the patient undergoes tests to assess their fitness for surgery which may include
- Blood and urine tests
- Chest X-ray and electrocardiography (ECG)
- Imaging tests such as MRI or CT scan
Prior to the procedure, the patient must
- Avoid eating or drinking for eight hours
- Check with the doctor before taking any regular medications
- Inform the doctor of any allergies
Other pre-procedural steps include
- Shaving the hair in the operative area
- Sterilization of the scalp
- Administration of antibiotics
Framed stereotactic brain biopsy
- The patient remains seated during frame placement.
- The anesthesiologist administers mild IV sedation so the patient can sit erect and respond to instructions.
- The patient also receives local anesthetic injections at the points on the scalp where the frame is fixed with pins.
- The surgeon fixes the frame on the patient’s head based on three-dimensional coordinates from MRI and CT scans.
- The patient is in a supine or prone position during the procedure, depending on the area of biopsy.
- The anesthesiologist administers general anesthesia and monitors the patient’s vital functions.
- The neurosurgeon
- Makes a small incision in the scalp.
- Drills a burr hole through the skull.
- Makes an opening in the brain’s membrane (dura mater)
- Advances the biopsy needle using the stereotactic equipment’s neuron (or neuronal) navigation system which can be viewed on a computer monitor.
- Extracts required samples of tissue.
- Withdraws the needle and closes the incision with sutures or staples.
Frameless stereotactic biopsy
- The patient lies supine or prone depending on the biopsy area.
- The anesthesiologist administers general anesthesia and monitors the patient’s vital signs.
- The surgeon
- Secures the patient’s head and places fiducial (standard of reference) markers.
- Determines the coordinates of the targeted area with MRI or CT scan.
- Fixes the stereotactic equipment to the patient’s head.
- The rest of the procedure is similar to the framed stereotactic biopsy.
How long does it take to recover from a brain biopsy?
Most neurosurgeons perform a post-operative CT scan and keep the patient under observation for at least four hours after the biopsy. Most patients require no more than an overnight hospital stay. Majority of the people are able to resume normal activities within a day or two.
What are the risks of a brain biopsy?
Though minimally invasive, stereotactic brain biopsy is not without risks. State-of-the-art stereotactic equipment and software technology have made brain biopsy an accurate procedure with minimal complications.
- General anesthesia side effects such as
- Intracranial hemorrhage
- Infection at the pin site or incision site
- Nondiagnostic tissue sample, which is rare
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