Cranioplasty

Cranioplasty is a surgical operation on the repairing of cranial defects caused by previous injuries or operations, such as decompressive craniectomy. It is performed by filling the defective area with a range of materials, usually a bone piece from the patient or a synthetic material. Cranioplasty is carried out by incision and reflection of the scalp after applying anaesthetics and antibiotics to the patient. The temporalis muscle is reflected, and all surrounding soft tissues are removed, thus completely exposing the cranial defect. The cranioplasty flap is placed and secured on the cranial defect. The wound is then sealed.

Cranioplasty was closely related to trephination, and the earliest operation is dated to 3000 BC. Currently, the procedure is performed for both cosmetic and functional purposes. Cranioplasty can restore the normal shape of the skull and prevent other complications caused by a sunken scalp, such as the "syndrome of the trephined". Cranioplasty is a risky operation, with potential risks such as bacterial infection and bone flap resorption.

The word cranioplasty can be broken down into two parts: cranio- and -plasty. Cranio- originates from the Ancient Greek word κρανίον, meaning "cranium", while -plasty comes from the Ancient Greek word πλαστός, meaning "moulded" or "fashioned".

The operation has its cosmetic value as the normal shape of the cranium of patients is restored instead of the presence of a sunken skin flap, which may affect the confidence of patients.

It also has its therapeutic value as the operation provides structure to the skull and protection to the brain from physical damage. The surgery restores regular cerebrospinal fluid (CSF) and cerebral blood flow dynamics, along with normal intracranial pressure. Cranioplasty may improve neurological function in some individuals. Furthermore, it can reduce the occurrence of headaches caused by injury or previous surgery.

The optimal timing of cranioplasty is controversial. Some experts put the time between a craniectomy and a cranioplasty at usually between 6 months and a year, while others say that the two operations should be more than a year apart.

The timing of cranioplasty is affected by multiple factors. Sufficient time is required for the recovery of the incision from the previous operation, as well as to clear any infections (both systemic and cranial). Some findings showed that a greater infection rate is associated with early cranioplasty due to interruption of wound healing, as well as an increased incidence of hydrocephalus. Contrarily, there is evidence of early cranioplasty limiting complications caused by "syndrome of the trephined", including changes in cerebral blood flow and abnormal cerebrospinal fluid hydrodynamics. Other researchers have reported no significant difference in infection rate with different operational timings.

Contraindications for cranioplasty include the presence of bacterial infection, brain swelling, and hydrocephalus. Cranioplasty is withheld until all contraindications are cleared.^{[citation needed]}