Some circumstances require that a biopsy of a tumor is recommended rather than performing significant removal or debulking. Stereotactic biopsy is recommended in this case and is performed using a computer system as noted in the paragraph above to guide placement of a 2.5 mm blunt tipped biopsy needle. The aperture created in the skull is either called a bur hole or twist drill hole depending on its dimension but is usually no greater than the diameter of a dime or nickel. Biopsy is typically indicated for patients in whom the tumor is located in a functional or eloquent portion of the brain. It may also be recommended in patients who are elderly or infirmed or in circumstances where the tumor is one that can be treated effectively without surgical resection. Risks of this procedure include bleeding infection and failure to establish diagnosis.