A Comparison between Pediatric and Adult Patients after Cranioplasty: Aseptic Bone Resorption Causes Earlier Revision in Children

Autologous Cranioplasty with Bone Flap Preserved in Conventional Freezers: An Adequate Option in Low Resource Settings

BACKGROUND

Autologous cranioplasty has been used for decades and is the gold standard treatment in patients who underwent decompressive craniectomy (DC). One of the most common methods to store the cranial bone flap is cryopreservation at very low temperatures (-70 to -80°). The only way to achieve these low temperatures is by using special freezers which are not always available in all medical facilities, especially in low-resource centers. This paper describes our experience with the storage of cranial bone flaps in freezers of conventional refrigerators.

METHODS

This retrospective study included patients treated with autologous cranioplasty, operated between 2015 and 2020. The cranial bone flap was stored at -18°C in the freezer of conventional refrigerators. Complications and outcomes were analyzed and compared with reports of patients in whom ultra-low temperature freezers were used for bone flap preservation.

RESULTS

Twenty-five patients were included. The average follow-up period was 33 months. Trauma was the most common cause of DC, followed by stroke. The mean age was 36.7. Aseptic bone flap resorption was observed in 4 cases (16%). No cases of infection were observed.

CONCLUSIONS

The use of freezers from conventional refrigerators may be an acceptable alternative for the preservation of the cranial bone flap in facilities where special freezers are not available. The rate of aseptic bone necrosis and infections observed in this paper was similar to the incidence of these complications reported in studies where ultra-low temperatures were used.

Incidence of hydrocephalus following decompressive craniectomy for ischaemic stroke: A systematic review and meta-analysis

OBJECTIVE

Decompressive craniectomy (DC) following malignant ischaemic stroke is a potentially life-saving procedure. Event rates of ventriculomegaly following DC performed in this setting remain poorly defined. Accordingly, we performed a systematic review to determine the incidence of hydrocephalus and the need for cerebrospinal fluid (CSF) diversion following DC for malignant stroke.

METHODS

MEDLINE, EMBASE and Cochrane libraries were searched from database inception to 17 July 2021. Our search strategy consisted of "Decompressive Craniectomy", AND "Ischaemic stroke", AND "Hydrocephalus", along with synonyms. Through screening abstracts and then full texts, studies reporting on rates of ventriculomegaly following DC to treat ischaemic stroke were included for analysis. Event rates were calculated for both of these outcomes. A risk of bias assessment was performed to determine the quality of the included studies.

RESULTS

From an initial 1117 articles, 12 were included following full-text screening. All were of retrospective design. The 12 included studies reported on 677 patients, with the proportion experiencing hydrocephalus/ventriculomegaly being 0.38 (95% CI: 0.24, 0.53). Ten studies incorporating 523 patients provided data on the need for permanent CSF diversion, with 0.10 (95% CI: 0.07, 0.13) requiring a shunt. The included studies were overall of high methodological quality and rigour.

CONCLUSION

Though hydrocephalus is relatively common following DC in this clinical setting, only a minority of patients are deemed to require permanent CSF diversion. Clinicians should be aware of the incidence of this complication and counsel patients and families appropriately.

Decompressive Craniectomy in Pediatric Traumatic Brain Injury: A Retrospective Cohort Study

Decompressive craniectomy (DC) in children with traumatic brain injury (TBI) and refractory raised intracranial pressure (ICP) remains controversial. We aimed to describe the clinical and operative characteristics of children with moderate to severe TBI who underwent DC, and compare outcomes with those who had medical therapy. We performed a retrospective observational cohort study on children < 16 years of age with moderate to severe TBI (Glasgow coma scale [GCS] ≤13) who underwent DC in two pediatric centers in Singapore and China between 2014 and 2017, and compared their outcomes with children who underwent medical treatment, among participating centers of the Pediatric Acute and Critical Care Medicine Asian Network. We defined poor functional outcomes as moderate, severe disability, vegetative or comatose state, or mortality, using the Pediatric Cerebral Performance Category scale. We performed multivariable logistic regression to identify predictors for poor functional outcomes. We analyzed 18 children who underwent DC with 214 who had medical therapy. A greater proportion of children with DC (14, 77.8%) experienced poor functional outcomes, compared with those with medical therapy (87, 41.2%, p = 0.003). Children who underwent DC had fewer median 14-day intensive care unit (ICU)-free days (2.5 days, interquartile range [IQR]: 0.0–5.8 vs. 8.0 days, IQR: 0.0–11.0, p = 0.033), median 28-day hospital-free days (0 day, IQR: 0.0–3.5 vs. 11.0 days, IQR: 0.0–21.0, p = 0.002) and 14-day mechanical ventilation-free days (6.5 days, IQR: 0.0–12.3 vs. 11.0 days, IQR: 3.0–14.0, p = 0.011). After accounting for age, sex, GCS, cerebral edema, uncal herniation, nonaccidental injury, and need for intubation, there was no significant association between DC and poor functional outcomes (adjusted odds ratio: 1.59, 95% confidence interval: 0.35–7.24, p = 0.548). Children with DC had severe injuries, and prolonged hospital and ICU stays. Future studies are needed to understand the effectiveness of DC on children with TBI.

Severe Traumatic Brain Injury in children-paradigm of decompressive craniectomy compared to a historic cohort

PURPOSE

Traumatic brain injury (TBI) is one of the leading causes of death and disability in children. Medical therapy remains limited, and decompressive craniectomy (DC) is an established rescue therapy in case of elevated intracranial pressure (ICP). Much discussion deals with clinical outcome after severe TBI treated with DC, while data on the pediatric population is rare. We report our experience of treating severe TBI in two different treatment setups at the same academic institution.

METHODS

Forty-eight patients (≤ 16 years) were hospitalized with severe TBI (GCS ≤ 8 points) between 2008 and 2018 in a pediatric intensive care unit (ICU) at a specialized tertiary pediatric care center. Data on treatment, clinical status, and outcome was retrospectively analyzed. Outcome data included Glasgow Outcome Scale (GOS) at 3-, 12-, and 36-month follow-up. Data was compared to a historic cohort with 53 pediatric severe TBI patients treated at the same institution in a neurointensive care unit between 1996 and 2007. Ethical approval was granted (EA2/076/21).

RESULTS

Between 2008 and 2018, 11 patients were treated with DC. Compared to the historic cohort, patients were younger and GCS was worse, while in-hospital mortality and clinical outcome remained similar. A trend towards more aggressive EVD placement and the internal paradigm change for treatment in a specialized pediatric ICU was observed.

CONCLUSIONS

In children with severe TBI treated over two decades, clinical outcome was comparable and mostly favorable in two different treatment setups. Consequent therapy is warranted to maintain the positive potential for favorable outcome in children with severe TBI.

Cranioplasty with Autologous Bone Flaps Cryopreserved with Dimethylsulphoxide: Does Tissue Processing Matter

OBJECTIVE

The aim of this article was to study the outcome of patients who underwent cranioplasty with cryopreserved autologous bone after decompressive craniectomy.

METHODS

Data from 74 patients were retrospectively analyzed. They were divided into groups according to the storage time and the age at cranioplasty. To assess the predictive potential for complication, factors were related to successive stages (preoperative, craniectomy, tissue processing, cranioplasty, and postoperative). Cooling and warming rates applied on bone flap were calculated. The ability to inhibit microbial growth was determined exposing bone fragments to a panel of microorganisms. The concentration of antibiotics eluted from the bone was also determined. A bone explant culture method was used to detect living cells in the thawed cranial bone.

RESULTS

Hydrocephalus was significantly more frequent in pediatric patients (26.7%) than in adults (5.1%). The overall rate of bone flap resorption was 21.6% (43.7% of which required reoperation). Surgical site infection after cranioplasty was detected in 6.8% of patients. There was no correlation between infection as a postoperative complication and previous microbiological-positive culture during processing. The cause of craniectomy did not influence the risk of bone flap contamination. Vancomycin was the only antibiotic detected in the supernatant where the bone was incubated. Outgrowth from bone explants was observed in 36.8% of thawed skulls. An early start of bone flap processing at the tissue bank had a positive effect on cell viability.

CONCLUSIONS

The outcome after autologous cranioplasty is a multifactorial process, which is modulated by patient-related, surgery-related, and bone-related factors.

The storage of skull bone flaps for autologous cranioplasty: literature review

The use of autologous bone flap for cranioplasty after decompressive craniectomy is a widely used strategy that allows alleviating health expenses. When the patient has recovered from the primary insult, the cranioplasty restores protection and cosmesis, recovering fluid dynamics and improving neurological status. During this time, the bone flap must be stored, but there is a lack of standardization of tissue banking practices for this aim. In this work, we have reviewed the literature on tissue processing and storage practices. Most of the published articles are focused from a strictly clinical and surgical point of view, paying less attention to issues related to tissue manipulation. When bone resorption is avoided and the risk of infection is controlled, the autograft represents the most efficient choice, with the lowest risk of complication. Otherwise, depending on the degree of involvement, the patient may have to undergo new surgery, assuming further risks and higher healthcare costs. Therefore, tissue banks must implement protocols to provide products with the highest possible clinical effectiveness, without compromising safety. With a centralised management of tissue banking practices there may be a more uniform approach, thus facilitating the standardization of procedures and guidelines.

Cranial bone flap resorption-pathological features and their implications for clinical treatment

Cranioplasty following decompressive craniectomy (DC) has a primary complication when using the autologous bone: aseptic bone resorption (ABR). So far, risk factors such as age, number of fragments, and hydrocephalus have been identified but a thorough understanding of the underlying pathophysiology is still missing. The aim of this osteopathological investigation was to gain a better understanding of the underlying processes. Clinical data of patients who underwent surgical revision due to ABR was collected. Demographics, the time interval between craniectomy and cranioplasty, and endocrine serum parameters affecting bone metabolism were collected. Removed specimens underwent qualitative and quantitative histological examination. Two grafts without ABR were examined as controls. Compared to the controls, the typical layering of the cortical and cancellous bone was largely eliminated in the grafts. Histological investigations revealed the coexistence of osteolytic and osteoblastic activity within the necrosis. Bone appositions were distributed over the entire graft area. Remaining marrow spaces were predominantly fibrotic or necrotic. In areas with marrow cavity fibrosis, hardly any new bone tissue was found in the adjacent bone, while there were increased signs of osteoclastic resorption. Insufficient reintegration of the flap may be due to residual fatty bone marrow contained in the bone flap which seems to act as a barrier for osteogenesis. This may obstruct the reorganization of the bone structure, inducing aseptic bone necrosis. Following a path already taken in orthopedic surgery, thorough lavage of the implant to remove the bone marrow may be a possibility, but will need further investigation.