Cranioplasty is a surgical intervention to repair cranial defects, frequently performed in neurosurgery.

It is one of the oldest known neurosurgical procedures, dating from the year 3000 B. C., when the Paracas Indians in Peru performed procedures to correct large cranial defects.

Archeologic findings proved that the use of inorganic materials for cranioplasty had begun before the organic materials ¹⁾.

Across the centuries, many materials have been used for covering bony defects, including coconut shells, bones from both human and non-human donors, metals including gold, silver, tantalum, and titanium and more recently, biosynthetic materials such as resins and ceramics.

see Cranioplasty Indications.

The presence of hydrocephalus, infection, and brain swelling. In children below 4 years old, if there is an intact dura mater, cranium can achieve self closure.

see Cranioplasty timing.

see Custom made cranioplasty.

The pediatric patient for this procedure is distinct from the adult one because of the growing skulls and thinner bones of the calvarium. A paucity of data on the outcomes of this procedure in the pediatric population has been identified repeatedly.

Wagas et al conducted a retrospective cohort study to investigate the outcomes in a pediatric population that underwent cranioplasty after craniectomy at a institute in a developing-world country. The cohort showed no association of complication rate or cosmetic outcomes with the timing of cranioplasty, area of skull defect, type of implant used, or method of storage ²⁾.

see Cranioplasty materials.

see Sonolucent cranioplasty.

see Cranioplasty complications.

A PubMed, Google Scholar, and MEDLINE search adhering to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines included studies reporting patients who underwent DC and subsequent cranioplasty in whom cerebral hemodynamics were measured before and after cranioplasty.

The search yielded 21 articles with a total of 205 patients (range 3-76 years) who underwent DC and subsequent cranioplasty. Two studies enrolled 29 control subjects for a total of 234 subjects. Studies used different imaging modalities, including CT perfusion (n = 10), Xenon-CT (n = 3), single-photon emission CT (n = 2), transcranial Doppler (n = 6), MR perfusion (n = 1), and positron emission tomography (n = 2). Precranioplasty CBF evaluation ranged from 2 days to 6 months; postcranioplasty CBF evaluation ranged from 7 days to 6 months. All studies demonstrated an increase in CBF ipsilateral to the side of the cranioplasty. Nine of 21 studies also reported an increase in CBF on the contralateral side. Neurological function improved in an overwhelming majority of patients after cranioplasty.

This systematic review suggests that cranioplasty improves CBF following DC with a concurrent improvement in neurological function. The causative impact of CBF on neurological function, however, requires further study ³⁾.

Paredes et al., prospectively studied cranioplasties performed at a hospital over a 5-year period. The National Institute of Health Stroke Scale and Barthel index were recorded prior to and within 72 h after the cranioplasty. A perfusion computed tomography (PCT) and transcranial Doppler sonography (TCDS) were performed prior to and 72 h after the surgery. For the PCT, regions irrigated by the anterior cerebral artery, the middle cerebral artery (MCA), the posterior cerebral artery, and the basal ganglia were selected, as well as the mean values for the hemisphere. The sonography was performed in the sitting and the supine position for the MCA and internal carotid. The velocities, pulsatility index, resistance index, and Lindegaard ratio (LR) were obtained, as well as a variation value for the LR (ΔLR = LR sitting - LR supine). Fifty-four patients were included in the study. Of these, 23 (42.6%) patients presented with objective improvement. The mean cerebral blood flow of the defective side (m-CBF-d) increased from 101.86 to 117.17 mL/100 g/min (p = 0.064), and the m-CBF of the healthy side (m-CBF-h) increased from 128.14 to 145.73 mL/100 g/min (p = 0.028). With regard to the TCDS, the ΔLR was greater on the defective side prior the surgery in those patients who showed improvement (1.295 vs. -0.714; p = 0.002). Cranioplasty resulted in clinical improvement in 40% of the patients, with an increase in the post-surgical CBF. The larger variations in the LR when the patient is moved from the sitting to the supine position might predict the clinical improvement ⁴⁾.

Wachter et al., performed a retrospective chart analysis of patients that underwent DC and subsequent bone flap reimplantation between 2001 and 2011 at the Department of Neurosurgery, Georg-August-University Göttingen, Göttingen, Germany.

They registered demographic data, initial clinical diagnosis and surgery-associated complications.

They identified 136 patients that underwent DC and subsequent reimplantation. Forty-one patients (30.1%) had early or late surgery-associated complications after bone flap reimplantation. Most often, bone flap resorption and postoperative wound infections were the underlying causes (73%, n=30/41). Multivariate analysis identified age (p=0.045; OR=16.30), GOS prior to cranioplasty (p=0.03; OR=2.38) and nicotine abuse as a prognostic factor for surgery-associated complications (p=0.043; OR=4.02). Furthermore, patients with early cranioplasty had a better functional outcome than patients with late cranioplasty (p<0.05).

Almost one-third of the patients that are operated on for bone flap reimplantation after DC suffer from surgery-associated complications. Most often, wound healing disorders as well as bone flap resorption lead to a second or even third operation with the need for artificial bone implantation. These results might raise the question, if subsequent operations can be avoided, if an artificial bone is initially chosen for cranioplasty ⁵⁾.

Cranioplasty surgical technique.