Overview of Craniotomy
A craniotomy is a surgical operation where a section of the skull is temporarily taken out in order to reach the brain and do surgery. This procedure is often used to treat conditions such as brain tumors, bleeding in the brain, or infections. Special tools are used to remove a section of the skull, called the “bone flap.” Usually, the bone flap is kept safe during surgery and then put back into place afterwards. However, in some cases, the bone might be discarded, stored in the belly fat, or kept in cold storage. If the bone flap isn’t put back in during the same surgery, this is called a craniectomy.
The technique we use today for a craniotomy has a long history, and it’s been refined and perfected over many years. The first procedures like this were called trephinations, which involved drilling one or more holes in the skull. The modern approach of connecting a series of holes, used in craniotomy, has its roots in procedures developed by a self-taught surgeon named Wilhelm Wagner in the late 19th century.
Nowadays, some craniotomies are guided by technology called “neuronavigation,” where MRI or CT scans are used to help the surgeon make the smallest incision possible and accurately locate the problem in the brain. This technology makes the operation safer for the patient and gives the surgeon more confidence.
The approach to craniotomy has changed over the thousands of years it’s been performed. Starting around 1400 BC, the Egyptians were known to have a technique similar to craniotomy. The use of the procedure for healing fractures was first documented around 500 BC by Hippocrates. Over time, the procedure has evolved and modern medical breakthroughs at the end of the 19th century, such as improved infection control and anesthesia, have helped the growth and evolution of craniotomy.
Anatomy and Physiology of Craniotomy
A craniotomy is a type of surgery where a piece of the skull is temporarily removed to access the brain. There are many different kinds of craniotomies and they are named based on which area of the skull is being opened. Different parts of the brain control different functions, so the type of craniotomy a doctor performs primarily depends upon which part of the brain is being targeted. The main areas include the front (frontal), top (parietal), side (temporal), and back (occipital) bones of the skull.
For example, one of the most traditional craniotomies is referred to as the pterional craniotomy. This type of craniotomy is performed above the ear, towards the front of the skull. It is often done to repair blood vessels, remove tumors, or gently push the brain to improve access to other areas.
Another type of craniotomy is called a temporal or subtemporal craniotomy. This is performed to operate on the side of the brain in a section called the temporal lobe. Doctors use it to carry out biopsies, remove tumors, perform epilepsy surgery, or reach the floor of the area known as the middle cranial fossa.
The frontal craniotomy is another type, where the front part of the skull is opened to access the frontal lobe of the brain (the front part of the brain). Surgeons use this for repairing issues with cerebrospinal fluid, dealing with certain tumors, and reaching the bottom center part of the skull, called the sellar region.
Other types of craniotomies focus on the parietal (top of the head), occipital (back of the head), and retrosigmoid (near the back on either side of the head) regions. Each is used to reach different structures within the brain for a variety of procedures.
Why do People Need Craniotomy
A craniotomy is a type of surgery where a piece of the skull is removed to access the brain. There are many reasons why someone might need a craniotomy. Here are some of them:
After Head Injury:
Sometimes, a head injury can lead to complications that need a craniotomy. These can include bleeding inside the skull, or, ‘brain bruises’, fractures where a piece of skull presses into the brain, or objects lodged in the brain. Sometimes, a craniotomy is done to repair a leak of cerebrospinal fluid, a substance that cushions the brain and spinal cord.
Cancer or growths:
A craniotomy can be done to remove different types of brain tumors. This could include any unusual growths, like meningiomas or gliomas, which start in the brain or spinal cord, or tumors that have spread from another part of the body. It could also include cysts in specific areas of the brain.
Blood Vessel Problems:
Abnormalities or problems with blood vessels in the brain can also require a craniotomy. This includes bleeding in the brain, blockages in arteries that supply blood to the brain, blood clots that lead to bleeding, or abnormalities like arteries and veins being tangled together (arterio-venous malformations). Sometimes, a craniotomy is done to relieve pressure on a nerve caused by a blood vessel (microvascular decompression).
Infections:
Sometimes an infection can lead to a pocket of pus, called an abscess, or a collection of pus between the brain and the skull, called a subdural empyema. These types of infections often need a craniotomy to remove the abscess or pus.
Parasites:
There might also be a need for a craniotomy to remove cysts caused by parasites, like the Hydatid worm or the pork tapeworm.
Other Reasons:
In some cases, a craniotomy is done to treat epilepsy, a condition that causes seizures. It can also be a part of surgeries that place devices to stimulate the brain and treat conditions like Parkinson’s disease (deep brain stimulation). Sometimes, doctors use special tools to do a craniotomy (stereotaxic or neuroendoscopic procedures).
When a Person Should Avoid Craniotomy
In some cases, a person may not be able to have a craniotomy, which is a type of surgery to open the skull. Here are some reasons why:
- High risk from anesthesia, often due to being older or having serious health problems.
- In a state near death.
- Having poor physical abilities.
- Being weak or easily exhausted.
- Having a severe breakdown of the body’s overall functions, such as sepsis or failure of multiple body systems.
- Having a condition that affects blood clotting or causes abnormal bleeding.
- In situations where an effective treatment can be achieved through a less invasive procedure; specifically, by creating a single small opening (called a burr hole) in the skull.
For surgeries where the patient is awake (awake craniotomy), there are also several reasons why the procedure may not be possible:
Absolute reasons (meaning the procedure absolutely cannot be conducted) are:
- If the patient does not agree to the procedure.
- If the patient is not willing to follow medical instructions.
Relative reasons (meaning the procedure is more risky or difficult, but not impossible) are:
- If the patient is overweight.
- If the patient has obstructive sleep apnea, which is a condition where a person stops breathing while sleeping.
- If it’s difficult to keep the patient’s airway open.
- If the patient has a chronic cough that is hard to control.
- If the patient has injuries that bleed profusely.
- If the patient has injuries at the back of the skull.
Equipment used for Craniotomy
A craniotomy is a type of surgery that’s performed on the skull. It needs specific tools and equipment. Here is what your surgeon would use during a craniotomy:
* Suction tips: These are used to remove fluid from the surgery area.
* Bipolar cautery forceps: These are special tweezers that use electricity to stop bleeding.
* Scalpel handle and blades: The scalpel is the main tool used for cutting in surgery.
* Needle holders: These are used to hold the needles for suturing or stitching.
* Hemostatic clip: This clip is to help control bleeding.
* Scalp retractors: These are used to hold the scalp back to expose the skull.
* Periosteal elevator: This tool is used to separate the skin from the bone.
* Various types of forceps (like Bayonet and Adson forceps): These tools, similar to tweezers, are used to hold and move tissues.
* Head-fixation system: This device keeps the head still during surgery.
* High-speed pneumatic cranial drill (or craniotome): This tool drills holes into the skull.
* Hudson brace with perforating bit attached: This brace is used to drill manually, with control.
* Round burr for Hudson brace: The burr, a type of drill bit, is used for cutting bone.
* Gigli wire saw, guide and handles: This is a special wire saw for cutting bone.
* Perforating bits, narrow burr attachment and extension pieces: These are all parts that are used with the Hudson brace.
* Bone curette: This scoop-shaped instrument removes tissue.
* Kerrison bone rongeur: This tool is used to cut small pieces of bone.
* Penfield dissector: This tool is used to separate and lift tissue layers.
* Gerald forceps: These forceps are used for grasping and stabilizing tissue.
* Hemostatic agents (like bone wax and surgicel): These substances control bleeding.
* Dural scissors: These scissors are used to cut the dura, the tough outermost membrane covering the brain and spinal cord. [36]
Who is needed to perform Craniotomy?
A successful craniotomy, which is a surgery to open the skull, requires a team of specialized medical professionals. Here are the people who are needed:
A neurosurgeon is a doctor who specializes in surgery of the brain and nerves. This person leads the surgery and is responsible for the operation.
The head nurse in the operating room oversees the nursing staff and helps make sure everything is ready for the surgery. They also assist with patient care before, during, and after the surgery.
A surgical technologist, also known as an operating room technologist, is a trained professional who helps prepare the operating room and assists the surgeon during the operation.
An anesthesiologist is a doctor who specializes in giving patients medication to either numb a specific area of the body or to make the patient unconscious during surgery. Their role is to monitor the patient’s vital signs and adjust the anesthesia as needed.
An anesthetist, who can be a nurse or doctor, also helps with anesthesia care for the patient.
Lastly, the intensive care unit nursing personnel are a team of nurses who specialize in taking care of patients after surgery, particularly those who require close monitoring and high levels of care.
Preparing for Craniotomy
Before having surgery, it’s important for the patient to be in the best health possible to endure the procedure. The patient is generally expected to have an empty stomach for surgery, a state often referred to as “nil per os” or “nothing through the mouth.” However, this may not be possible in emergency cases. If a patient is taking medications that thin the blood, like antiplatelet or antithrombotics, they should stop taking these anywhere from 3 to 10 days before surgery, depending on the specific medication. It is also recommended to have a doctor from internal medicine or cardiology check the patient’s health to assess the surgical risk.
Most craniotomy surgeries (operations on the brain) take place with the patient under general anesthesia (put to sleep). However, the anesthesiology team must know all details about the patient’s health and the reason for the surgery before proceeding. In certain cases, a patient may need to stay awake during the operation under a local anesthetic. This is typically for surgeries involving speech and movement areas of the brain. Patients need to give informed consent before the procedure, and doctors will always double-check to make sure they are operating on the correct patient and side of the brain. In addition, blood should be readily available in case the patient needs a transfusion during the operation.
Patients commonly receive antibiotics to prevent infection before the surgery starts. Other medications may be necessary too, such as anti-seizure drugs or corticosteroids (medicines reducing inflammation). There is usually special equipment used in these operations like a surgical microscope and neuromonitoring tools, which are set up before the surgery. Availability in the intensive care unit after surgery is something that should be discussed prior to the operation, since a lot of patients will need this level of care after a craniotomy.
For anesthesia during a craniotomy, there are generally two main types used: general (asleep) and awake. Awake anesthesia can result in similar outcomes to general anesthesia in terms of function and operation. For anesthesia that’s maintained with a medication called propofol, it’s been found that it can help produce similar brain relaxation scores with lower intracranial pressure (pressure inside the skull) and higher cerebral perfusion pressure (blood flow to the brain) than other types of anesthesia.
How is Craniotomy performed
When a person undergoes brain surgery, once anesthesia has taken effect, the doctor carefully positions their head based on the part of brain that needs to take a closer look or operated upon. Much care is taken to avoid causing discomfort or pressure to other parts of the body, with appropriate padding used where necessary.
Where the cut (also called an incision) is made on the patient’s head depends on which part of the brain is being operated on. In some cases, technology can aid the surgeon in guiding where the incision should be made. If the area in the upper part of the brain (known as the supratentorial area) is being operated upon, the cut might be made over different parts of the skull like the forehead or back of the head. Alternatively, if the lower part of the brain (known as the infratentorial area) needs to be accessed, the cut will be made on the back part of the skull.
Before the surgeon makes a cut, the area might be shaved. The medical professional will clean the area and use a local anesthetic to control bleeding. Then, the surgeon makes the cut and separates the muscles below the scalp to reach the skull. Devices called retractors may be used to keep the incision open and provide visibility to the surgeon. Sometimes, small pieces of bone from the skull are removed using certain tools to allow access to the brain.
When the necessary procedures on the brain are completed, the piece of bone removed earlier is put back in its place, attached with plates and screws. The surgeon checks again to make sure there’s no excessive bleeding. The cut is then closed methodically, layer by layer, starting from the scalp to the outer layer of the skin. A drain might be left in place to remove blood that may have accumulated during the procedure.
While there is a general approach to these surgeries, specific strategies depend on the situation and the surgeon’s preference. It is a complex operation and involves many careful and precise steps to ensure that it’s as safe and effective as possible.
There are also different types of incisions and positioning depending on the specific case. The doctor considers factors such as shortest path to the target, minimum disturbance to the normal brain and if the incision will be along the natural skin tension lines. Importantly, all measures are taken to ensure that the appearance after surgery is as close to normal as possible.
Overall, brain surgery is a detailed and meticulous process that involves several steps – from the proper positioning of the patient, the marking the appropriate surgical site, to the closure of the site, the steps are aimed at ensuring a safe and successful procedure.
Possible Complications of Craniotomy
There can be some complications when a device is used to fix a person’s head in place during a medical procedure. These complications include:
– Cuts to the scalp
– Skull fractures
– Infections where the pin was placed, which could lead to osteomyelitis (a type of bone infection)
– An air bubble reaching the veins (venous air embolism)
– Swelling due to blood accumulation under the skin or in the brain (acute epidural or subdural hematomas), or brain bruises (contusions)
These complications are more common if the patient is lying on their stomach or side, if the procedure is done in an emergency, if the anesthesia isn’t deep enough, if the operation is lengthy, or if the patient’s scalp is thin.
When the scalp is cut or moved away from the skull for surgery (a scalp flap), there can be specific complications. Depending on where on the scalp the flap is, these complications can include things like changes to appearance, a leak of cerebrospinal fluid (the fluid around the brain and spinal cord), injuries to various brain veins, and even injuries to different parts of the brain.
In the worst cases, a procedure where a small hole is drilled into the skull (burr holes), a surgery to remove part of the skull (craniotomy), or a treatment to open the covering of the brain (durotomy) could lead to severe complications. These could include a cut causing a sinus to open, bleeding from the bone, tearing of the dura (the tough outermost layer of the membranes surrounding the brain and spinal cord), injury to veins, and even the drilling tool plunging into the brain, which would cause a bruise on the brain.
After surgery to the brain (craniotomy), complications can occur. These could include headaches, blood collecting outside of the brain’s blood vessels, seizures, changes in body salts, build-up of air inside the skull, infection, bleeding within the brain, lung infection related to a ventilator machine, swelling of the brain, decreased brain blood flow, constriction of blood vessels, and the presence of air within the skull. Leaking cerebrospinal fluid is another possible issue, but while sealing the dura (a membrane surrounding the brain) doesn’t reduce the number of leaks, it can reduce the risk of infection at the surgical site. Other possible complications are buildup of cerebrospinal fluid in the brain (hydrocephalus) and different types of infections.
A study showed that the likelihood of infection at the surgical site increased with certain factors. These include a high score on a scale measuring how well the body can withstand surgery (the American Society of Anesthesiologists score), presence of another infection, a surgery longer than 4 hours, entry into one of the sinuses, leakage of cerebrospinal fluid, use of a drain following surgery, multiple previous operations, and use of implants. However, use of antibiotics before surgery was shown to reduce the risk of meningitis after a craniotomy.
Major complications after such procedures occur in about 8.3% of cases, with minor complications going up to 60%. The risk of death due to major complications is about 22%, while for minor ones it’s 0.5%. Factors that increase the chances of major complications include age, any signs of a problem with the nervous system after surgery, and low oxygen levels during the operation.
What Else Should I Know About Craniotomy?
A craniotomy, a type of surgery involving the removal of a section of the skull to expose the brain, has become a crucial medical procedure in treating a variety of neurological disorders today. Without this procedure, conditions like brain tumors, blood vessel disorders (vascular pathologies), and injuries to the brain could have potentially life-threatening consequences. Thanks to advancements in technology, the craniotomy procedure has become increasingly efficient and safer.
Doctors decide whether a patient needs a craniotomy based on their specific medical condition and judgment. Despite the development of techniques like endovascular surgery (a minimally invasive procedure inside large blood vessels) for vascular disorders and radiosurgery (a non-invasive treatment that uses targeted radiation) for tumors, the craniotomy remains the primary treatment option for most brain-related conditions.
After the surgery, doctors use several tools to evaluate the patient’s recovery. These include:
- The American Society of Anesthesiologists (ASA) physical status classification, which rates the patient’s physical health.
- The Karnofsky Performance Score (KPS), measuring the patient’s ability to carry out daily activities.
- The Charlson Co-morbidity Score, which estimates the risk of death considering the patient’s age and health conditions.
- The Modified Rankin Scale, gauging the patient’s level of disability.
- A combination of factors including the Sex, KPS, ASA physical status classification, location of the issue and presence of edema (SKALE).
The Karnofsky Performance Score is often the best in predicting how a patient will recover after the surgery. However, none of these scores can predict non-surgical outcomes. The KPS and ASA scores are useful in predicting early health complications in tumor patients within 30 days after surgery. The Charlson Co-morbidity Score is used to predict the death risk for patients undergoing surgery for an aneurysm (a weakened area in a blood vessel that can possibly burst).