|The patient is anesthetized and the skin incision is drawn. The head is then placed in three fixation points and the skin is prepped and draped for sterility. An opening through the frontal and temporal bones is made by making holes in the bone and connecting them with a side cutting saw. The scalp is pulled upward to expose the skull. The bone flap is removed using a suitable saw. The dural is opened and the front lobes are retracted to expose the arteries at the base of the brain.
If the surgery is performed for an aneurysm the brain's lobes are gently retracted (pulled back) until the location of the aneurysm is reached, using the surgical microscope and microsurgical instruments. The optic nerve and the internal carotid artery the left and the right lobe are also retracted suitably. The clip is placed across the neck of the aneurysm. All bleeding is controlled and the dura is closed. The bone flap is secured to the surrounding skull using suitable titanium plates and screws.
If the surgery is performed for a tumor the surgeon will make an incision, and reflect the scalp over the area of the tumor. An air powered drill is then used to make a hole in the skull and a flap of skull is cut open. The dura mater (tough covering of the brain) is then opened. An operating microscope is generally brought into the field, and the surgeon will approach the tumor within the brain. The surgery will vary depending upon the site of the tumor. Often the edges of the brain are gently supported using brain retractors. For an intracranial tumor, a small incision is made through the surface of the brain and into brain tissue until the tumor is reached. Ultrasound frequently is used to monitor the tumor's removal.
Specialized instruments may be used by the neurosurgeon to visualize, cut into, and remove the tumor, including a surgical microscope or special magnification glasses, a surgical laser that vaporizes the tumor (literally causing it to "go up in smoke"), and an ultrasonic tissue aspirator that breaks apart and suctions up the abnormal tissue. At this time the biopsy is sent to the laboratory for analysis.
Only the tissue that can clearly be identified as abnormal may be removed from the brain and even then only if its removal is possible without devastating consequences. With meningioma and metastatic tumors, usually easy to distinguish from healthy dura and brain tissue around them, the surgeon is more likely to be able to "get it all" than in the case of glioma, where the boundaries of the tumor are unclear and may be impossible to identify. Any visible bleeding points will be cauterized. Often, hemostatic promoting material is gently laid over the surfaces of the brain, and closure is begun. The surgeon will close the dura, and approximate the skull using titanium plates to hold the bone together. Next the scalp will be closed in layers, and a pressure monitor may be placed into the brain to allow the postoperative monitoring of pressure within the brain.
A cranioplasty is done in cases where the bone is chipped off or broken and cannot be joined to the rest of the skull. Materials used for carniotomy are Methyl methacrylate, Titanium plates, wire mesh, plastic etc