|Before the operation, the individual is given a general anesthetic and part, or all, of the scalp is shaved. The layers of skin, muscle, and membrane are cut away from the skull. A series of holes (burr holes) are bored into the skull to create a pattern for the incision depending on which area of the brain must be accessed. The incision line, for example, can be at the nape of the neck around the occipital bone at the back of the skull (posterior craniotomy) or a curved incision line reaching from the front of the ear to above the eye (anterior craniotomy or anterior cranio-facial resection). A high-speed drill (craniotome) is used to cut the skull between the burr holes. The bone flap is then either lifted back on a hinge of muscle or removed completely. The outer membrane lining the brain (dura) is opened, and small blood vessels are sealed off (cauterized) to reduce bleeding. A small incision is made through the inner membranes (arachnoid and pia mater) to access the area of the brain that requires surgery.|
Once the brain tissue is revealed, the surgeon removes, stimulates electrically, disconnects, repairs, or otherwise treats the area of the brain that has been identified as the site of the problem needing correction. Various types of surgical procedures can be performed through the opening created by craniotomy. For example, tumors, cysts, or nodules are excised, removing as much of the diseased tissue as possible. Surgery to repair an artery with a cerebral aneurysm involves removing weakened tissue and sealing the artery at the site of leakage. AVMs are excised and blood flow is redirected to normal blood vessels.
After the surgical procedure on the brain is completed, tissue and vessels within the brain are sealed, usually with cautery technique, the bone flap is replaced and secured with soft wire, and external membranes, muscle, and skin are sewn (sutured) back into place. The individual will be observed closely for vital signs, mental status, and mobility. Breathing exercises may be started to help clear the lungs. Leg stockings (thrombo-embolism deterrent [TED] stockings) may be used after surgery to help prevent blood clot formation in the veins of the legs. The sutures will be removed, but soft wires that secure the bone flap remain in place. Patients may be hospitalized from 5 days to two weeks. Fatigue is normal after craniotomy and brain surgery, but mobility is encouraged.
An "awake" craniotomy is sometimes performed to localize a seizure focus in temporal lobe epilepsy when the focus is close the cortical area of the brain that controls speech, motor function, or short-term memory. By having the patient sedated but awake, the surgeon is able to assess speech, motor, or sensory response to cortical stimulation via continuous electroencephalogram (EEG). In this type of craniotomy, electrodes are placed in the subdural layer beneath the skull while the patient is given small doses of local anesthesia. Video telemetry is used to guide electrode placement and localization of the seizure focus. Once the electrodes are in place, seizure medication is discontinued and the individual is continuously monitored by EEG during the surgery, so that any motor, sensory, or speech interruption is recorded. Patients are instructed about minimizing movement during the procedure, and an anesthetist is available to administer local anesthesia, sedatives, and analgesics as needed.
An awake craniotomy also may be done to allow performance of procedures in patients whose lymphadenopathy may complicate administration of general anesthesia or to access a tumor when the site of surgical intervention lies close to the cortical area of the brain that controls speech, short-term memory, and responses to cortical stimuli. Having the patient sedated but awake ensures patient responsiveness in the phases of the procedure when these functions are tested, allowing the surgeon to make sure they are not affected.
Source: Medical Disability Advisor