What Is Cranioplasty

Introduction

If a globe is broken, the glue can fix it. What if the skull bone is broken, is there a possible way to fix it? Interestingly, neurosurgeons have been studying this question and discovering the methods back in 7000 BC.¹ In clinical, a surgical operation on the repairing of cranial defects is called Cranioplasty. This type of surgery is usually after:

• A traumatic head injury (External Collision)
• Congenital skull defects (A birth defect in the skull)
• Decompressive Craniectomy (DC, a cranial surgery)

Most cranioplasties involve lifting the scalp and then performing with a range of materials by filling into the defective area to reshape the irregular skull and to allow the normalization of the cerebrospinal fluid (CSF), improve cerebral blood flow, and edema within the brain.² This needs to be distinct with craniotomy, while both involve removing skull bone, but cranioplasty also requires replacing it.

Indications for cranioplasty

The purpose of cranioplasty is not only a cosmetology programme, but the repair of defective areas also gives relief to psychological burdens, increases social performance, and improves the quality of life.³

The medical conditions or situations that may necessitate cranioplasty

• The diameter is more than 3 centimetres of skull defects
• Previous cranial surgery complications, for example, abnormal CSF circulation dynamic, hydrocephalus (buildup of fluid in the brain)
• Depression, anxiety, and other mental health disorders caused by irregular head appearance
• Severe sinking skin flap syndrome
• Serious headache and dizziness caused by brain construction issues

However, cranioplasty is a major head surgery, it not only requires the surgeon to have a fulfilling experience but also faces a series of complications and rehabilitation problems.

The potential risk of taking cranioplasty:

• Infection after surgery
• Blood clot formation
• Stroke
• Seizures disorder

Preoperative assessment 

Overview of the preoperative evaluation process

The health experts will consider your medical conditions and critical illness history before advising on cranioplasty. They may ask your permission to access your medical record. In order to decide whether your conditions are suitable for surgery, there will be a pre-operative clinical review to assess your general conditions, this clinic review usually takes about 1.5 -2 hours. And it will analyze your:

• Fitness for a general anaesthetic (you will be unconscious)
• Blood routine examination, and blood pressure measurement 
• Measurements of height and weight
• CT scans and magnetic resonance imaging

There are other things you may need to prepare before the surgery, usually, you will receive medical treatment using a solution to wash your hair in preop, this is to reduce the chance of risk of postoperative infection. You should stop eating anything from midnight before coming to the hospital. You can sip water until you come in.

Importance for patients to consideration

As mentioned before, cranioplasty enables to reshape the appearance of the head, increases cerebral blood flow, and benefits a patient's quality of life. Nevertheless, the safety and effectiveness of cranioplasty were queried by The National Surgical Quality Improvement Programme.⁴ The significant operative morbidity and mortality are always the key considerations and arguments of cranioplasty, according to this new clinical review of the risk analysis and adverse outcome after cranioplasty, the morbidity rate was between 5.0%-36.5% and the mortality rate was between 0.4%-3.2%. This information is essential for the patients and their families to consider these potential risks and predictable benefits of cranioplasty before decision-making.

Is cranioplasty a high-risk surgery?

It depends on defective conditions, there can be moderate to high-risk associations due to the location of surgery and the size of the repairing area. But generally speaking, it is a major surgery with a complication rate of 24.8% and a mortality rate of 3.0% in one national sample of an American study.⁵

Types of cranioplasty procedures

The material used in cranioplasty has strict requirements, there is no perfect material has been identified, but an ideal material will match at least one of the following features:⁶

• Resistance to infections
• Easy to shape
• Tissue acceptable
• Radiolucency
• Non-conductive heat or cold
• Ready and easy to use
• Able to achieve complete closure for the cranial defect
• Economical and practical

Generally, there are 2 main types of materials used for cranioplasty, A) biological, and B) synthetic: 

Autologous bone graft (Self-bone graft), is a biological material using the patient's bone for reconstruction. The advantages of it include:⁷

• High ability to be in contact with a living system without producing an adverse effect on your bone
• Lower costs

The biggest limitation of autologous bone graft is bone flap resorption event,⁸ which leads to incomplete repair and various skull sunken after a while, this potentially increases the frequency of operations. 

Alloplastic cranioplasty (Synthetic grafts ), which is using man-made polyester materials or inert metals to replace natural body tissues. The commonly used synthetic materials like titanium or polyether ether ketone (PEEK). They also have obvious pros and cons:

• Titanium: Hardness and stability are the prime pros which can be implanted in the form of a plate, mesh, or 3D porous network. However, titanium has non-physiological thermal conduction, non- Radiolucency and it is uneasy to shape⁹
• PEEK material is rigid, radiolucent and does not resorb, it provides strength similar to the surrounding bone,¹⁰ and doesn’t incorporate into the overlying soft tissue, which eases the follow-up treatment. PEEK appears to have the lowest risk of cranioplasty revision.¹¹ However, Jeremie et al indicated that PEEK was associated with a significantly higher local complication rate compared with other synthetic implants.¹² The High cost of PEEK is another disadvantage

In addition to CT, 3D-printed technology has been broadly used in cranioplasty to customize and digitize the shape of the skulls. Fabian et al concluded that using 3D scanners in surgery can approach a more accurate image of the bone flap and reduce radiation exposure.¹³

Accordingly, a new analysis published in the American Society of Plastic Surgeons shows that autologous bone grafts result in lower complications than synthetic materials.¹⁴

Post-operative Care

After the procedure, you will go to the recovery room. Some people may need to transfer to an intensive care unit (ICU) or high dependency unit (HDU). The nurses will monitor you closely until you are stable and wake up from anaesthetics. Once you wake up, your nurse or doctor will go through neuro observation, assessing your blood pressure, heart rate, oxygen level, and consciousness level. If all features are okay, then you will move to the ward

Potential risks after cranioplasty

There is no 100% safety of surgery. Your surgeon will discuss these before you go through the procedures. Many risks are minors, but some of them can be life-threatening. The common risks such as infections, blood clot formation, seizures and stroke, are associated with cranioplasty. Your healthcare team will give you medicine to lower the risk of complications. 

Rehabilitation and recovery

It can take some time to recover from your surgery, you may stay in the hospital for about 3 or 10 days after the operation. As soon as safety, you are allowed to go home to continue recovery. You may experience pain and headache for a few days and restrict high-intensive activities for a while. In the early stages, your surgical area feels numb. This is because the nerves around the wounds have been cut. As the nerves grow back, you may feel tingling and itchy, please don’t scratch or touch it with your hands, as it can cause infections. Your surgeon may advise you to use antibiotic ointment on the wound for a few weeks, you can use medical sterility cotton swabs to apply to the site to minimize this risk.

Outcomes following cranioplasty

There is no certainty of neurological improvement following cranioplasty, although many descriptions discuss physical, functional and cognitive outcomes. However, given the different scenarios, such as the severity of injury, surgery location, timing and recovery, there is no standard answer to this question, the achieving outcomes are various for individuals. 

Summary

Cranioplasty is a broadly practised neurosurgical procedure with the purpose of reconstructing a skull defect. It commonly uses self-bone graft or synthetic materials such as Titanium, and PEEK to avoid resorptions. But currently, there aren't any perfect materials used for cranioplasty, and every major surgery has its risks. The most common risks of cranioplasty include infection, blood clot reformation, stroke, and seizures. However, the benefit of this surgery is attractive for many patients who have a CD history, including appearance restoration, cognitive function improvement, increased cerebral blood flow, and increased patient satisfaction and quality of life. However, cranioplasty is associated with a high rate of operative morbidity. Everything has its pros and cons, and it is essential to consider both sides of it, especially when you make a big decision, such as cranioplasty.