Cranioplasty
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.
Indications
Contraindications
Timing
see Cranioplasty timing.
Classification
Ultra-early cranioplasty (defined here as <30 days from the original craniectomy)
Conventional cranioplasty for some (defined here as >30 days from the original craniectomy)
Early Cranioplasty (defined here as <60-90 days from the original craniectomy)
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).
Materials
Direct Consequences
Intracranial pressure (ICP) is a crucial factor that we need to take into account in all major pathophysiological changes of the brain after decompressive craniectomy (DC) and cranioplasty (CP). The purpose of a study was to check ICP values before and after cranioplasty and its relation to various parameters (imaging, demographics, time of cranioplasty, and type of graft) as well as its possible relation to postsurgical complications. The authors performed a prospective study in which they selected as participants adults who had undergone unilateral frontotemporoparietal DC and were planned to have cranioplasty. Intracranial pressure was measured with fiber-optic sensor in the epidural space and did not affect cranioplasty in any way.Twenty-five patients met the criteria. The mean vcICP (value change of ICP) was 1.2 mm Hg, the mean ΔICP (absolute value change of the ICP) was 2.24 mm Hg and in the majority of cases there was an increase in ICP. The authors found 3 statistically significant correlations: between gender and ΔICP, Δtime (time between DC and CP) and vcICP, and pre-ICP and ±ICP (quantitative change of the ICP).Μale patients tend to develop larger changes of ICP values during CP. As the time between the 2 procedures (DC and CP) gets longer, the vcICP is decreased. However, after certain time it shows a tendency to remain around zero. Lower pre-ICP values (close to or below zero) are more possible to increase after bone flap placement. It seems that the brain tends to restore its pre-DC conditions after CP by taking near-to-normal ICP values 3).
Complications
Technique
Review
2017
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 4).