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© Dirk Biddle
It is sometimes necessary, in suspected cases of CNS vasculitis, to undertake a brain biopsy. This is usually done on the patient’s non-dominant side (i.e., on the left side of the brain in a right-handed person). A biopsy of the meninges (the membrane covering the brain) is usually performed at the same time. There are two methods of performing a brain biopsy; Stereotactic (probing in three dimensions) brain needle biopsy and neuro-navigation.
For stereotactic biopsy, you will need to be fitted with a head frame, attached to the skull with screws. Once you've had a CT or MRI scan to locate the biopsy site three-dimensionally, the doctors use the image information to set the reference points on the head frame (as calculated from CT/MRI scan information fed into a computer) - to determine exactly where to guide the biopsy needle. The surgeon then makes a very small hole in the skull with a drill, as they would for any brain biopsy.
Historically, the patient's head was held in a rigid frame to direct the probe into the brain to exactly the right position to take the tissue sample. However, since the early nineties, it has been possible to perform these biopsies without the frame (neuro-navigation). Since the frame was attached to the skull with screws, this advancement is less invasive and better tolerated by the patient (1). You are most likely to have stereotactic biopsy done under local anaesthetic, enabling surgeons to communicate with you to ensure they are not entering areas of the brain required for proper functioning, but you may have a general anaesthetic. The procedure lasts for about one hour.
For neuro-navigation, the surgeon takes the biopsy with a fine needle in much the same way as a stereotactic biopsy - but without the head frame. Instead the neurosurgeon looks at the scan while guiding the needle into position. You may also have markers (fiducials) placed on your head before you have the scan so that the neurosurgeon can see them on the scan and use them to assess where the needle has to go. Sometimes surgeons also use the natural landmarks of your nose, eyes and ears to help them guide the needle into position.
Following the Stereotactic or Neuro-navigation needle biopsy, the patient is monitored in the recovery room for several hours and is usually required to spend a few days in the hospital.
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1) http://www.healthatoz.com/healthatoz/Atoz/ency/brain_biopsy.jsp
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