Burr holes are small holes that a neurosurgeon makes in the skull. These holes help to relieve pressure on the brain when a blood clot (also called hematomas) builds up and starts to compress the brain tissue. Basically, a layer of thin tissues called meninges surround and help in protecting the brain, these tissues carry blood to and from the brain. In case of a head injury, these blood vessels get tear and bleed. Hematomas usually require removal as they are life threatening in nature, and result in trauma in the head. The major causes for development of a hematoma are older age, excessive alcohol consumption and repetitive injuries to the head.