Increase In Intracranial Volume Research Articles

Posterior cranial vault distraction osteogenesis: a literature review

Introduction:Craniosynostosis is a congenital condition where one or more cranial sutures close prematurely, limiting skull growth and causing cranial deformities. Posterior cranial vault distraction (PCVD) is used to relieve intracranial pressure and improve cranial aesthetics. Its incidence is about 1 in 2000–2500 live births. Methods:This systematic review followed PRISMA guidelines. We searched PubMed, Scielo, and Lilacs for studies on PCVD in craniosynostosis, focusing on success, morbidity, and mortality. Six articles were included in the final review. Data were extracted and risk of bias was assessed using the ROBINS-I tool. Results:The included studies reported significant increases in intracranial volume (144 mL to 281 mL) post-PCVD. Most patients showed stable results without recurrence. Complications included wound infection (29%) and cerebrospinal fluid leaks, though few required re-operations. PCVD improved intracranial pressure symptoms in most cases. Conclusion:PCVD is an effective technique for treating craniosynostosis, increasing intracranial volume and improving symptoms of intracranial hypertension. Despite some complications, it remains a reliable and stable alternative for cranial expansion.

Changes in Ventricular Volume After Posterior Vault Distraction Osteogenesis in Patients With Syndromic and Nonsyndromic Craniosynostosis.

Little is known about the response of the ventricular system to cranial vault surgery in patients with craniosynostosis. This study aims to evaluate the changes in the cerebral ventricular system in response to posterior vault distraction osteogenesis (PVDO) in patients with syndromic and nonsyndromic craniosynostosis. A single-institution retrospective review of all patients with craniosynostosis undergoing PVDO from 2000 to 2022 was completed. Patients were included for analysis if they had pre and postoperative cranial computed tomography scans. Ventricular volume (VV) and intracranial volume (ICV) were calculated using segmentation software. Both patients with syndromic synostosis and nonsyndromic synostosis (NSS) experienced a significant increase in ICV after PVDO, but only patients with NSS experienced a significant VV change ( P = 0.004). After normalization by ICV, total, lateral, and third VV changes retained significance with percentage increases of 114%, 117%, and 89%, respectively ( P < 0.05 for all). The differing results between cohorts reinforce the concept that the intracranial milieu is different between patients with syndromic synostosis and NSS. The results of the NSS cohort suggest that these patients may exist in a compensated state in which a reduction in cerebral blood flow and VV allows for the maintenance of parenchymal health to prevent the development of intracranial hypertension. Further studies may explore VV as a surrogate marker of ICP elevation, and the utility of cranial vault remodeling on nonsynostotic pathologies with cephalocranial disproportion.

Posterior Cranial Distraction in Craniosynostosis: A Systematic Review of the Literature.

Posterior cranial distraction (PCD) is a surgical technique to address craniosynostosis, especially in syndromic patients. The technique has the ability to significantly expand the cranium, while requiring minimal dural dissection, compared to cranial remodeling. Our goals were to determine the patient characteristics and surgical outcomes of PCD. The two questions that we sought to answer were: 1) What is the average published complication rate and the most common complications of PCD? and 2) How much intracranial volume expansion can one expect with PCD? A PubMed database search of articles on PCD was performed. Case reports and articles with overlapping patients were excluded. A systematic review was performed using the remaining articles. Patient data were extracted in order to determine the total number of patients, patients with a syndrome, types of syndromes, mean age at surgery, mean distraction distance, mean increase in intracranial volume, and complications. 18 articles representing 325 patients were analyzed. A syndrome was present in 68.6% of patients. The mean age at time of surgery was 22.1 months. Mean distraction amount was 24.7 mm. Mean increase in intracranial volume was 253.2 cm3. The overall complication rate was 32.2%, with the most common complications being surgical-site infection, hardware-related complications and delayed wound healing. PCD is a powerful technique in the management of syndromic craniosynostosis, although complication rates are significantly higher than traditional remodeling techniques. Future studies should compare the effects of supratorcular and infratorcular osteotomies on intracranial volume, cosmesis and complications.

The intracranial pressure-volume relationship following decompressive hinge craniotomy compared to decompressive craniectomy-a human cadaver study.

Decompressive hinge craniotomy (DHC) is an alternative treatment option to decompressive craniectomy (DC) for elevated intracranial pressure (ICP). The aim of this study was to characterize the difference in pressure-volume relationship between DHC and DC. We compared the intracranial pressure-volume relationship in a human cadaver model following either DHC, DC, or fixing of the bone plate by titanium clamps. We inserted an intracranial expandable device in two human cadaver specimens, performed either DHC, DC, or bone plate fixation, and gradually increased the intracranial volume while measuring ICP. Following DHC, we also performed CT-scans at pre-defined intervals. Before ICP exceeded a threshold of 20mmHg, a fixed bone plate tolerated an increase of 130ml of intracranial volume, while DHC and DC allowed an increase of 190ml and 290ml, respectively. CT-derived calculations following DHC determined that the increase in intracranial volume at ICP 22mmHg was 65ml, the maximal increase of intracranial volume was 84ml, the maximal bone displacement was 21mm, and the bone plate volume to be 82ml. Manual stress test of the hinged bone plate did not allow misalignment or intracranial displacement of the bone plate. DHC increases the intracranial volume by up to 84ml and allows for approximately 60ml increase of intracranial volume before ICP exceeds 20mmHg. This indicates, when comparing with results from previous studies of herniation volumes, that DHC will be sufficient in many patients with head injury or cerebral infarction with treatment refractory intracranial hypertension.

How Low Should We Go? Safety and Craniometric Impact of the Low Occipital Osteotomy in Posterior Vault Remodeling.

A larger volume cranial vault expansion is likely facilitated by a low posterior cranial osteotomy beneath the torcula; however, this may impart an increased risk of venous bleeding. The authors compared the safety of infratorcular versus supratorcular osteotomy in patients undergoing posterior vault reconstruction or posterior vault distraction osteogenesis and analyzed volumetric changes. Patients undergoing initial posterior vault reconstruction or distraction osteogenesis between 2009 and 2021 at the authors' institution were grouped by occipital osteotomy location and analyzed retrospectively. Craniometric analysis was performed if patients had high-resolution computed tomography scans available within 180 days preoperatively and postoperatively. A total of 187 patients were included: 106 (57 percent) who underwent posterior vault distraction osteogenesis and 81 (43 percent) who underwent posterior vault reconstruction. Infratorcular osteotomy was more common in reconstruction [ n = 65 (80 percent)] than in distraction osteogenesis [ n = 61 (58 percent); p < 0.002]. Blood transfused was similar between low and high osteotomy cohorts in the distraction osteogenesis ( p = 0.285) and reconstruction ( p = 0.342) groups. However, median transfused blood volume per kilogram of patient weight was greater in the low versus high osteotomy distraction osteogenesis ( p = 0.010) and reconstruction ( p = 0.041) cohorts. Intraoperative venous sinus injury was rare. In the distraction osteogenesis cohort, there was increased median intracranial volumetric gain in the low (263 ml) compared with the high osteotomy cohort (127 ml; p = 0.043); however, when controlled for distraction distance, only a trend was observed ( p = 0.221). Patients undergoing distraction osteogenesis showed a larger median intracranial volume increase (168 ml) compared with those undergoing reconstruction (73 ml; p < 0.001). Infratorcular osteotomy can be performed safely in most patients undergoing cranial vault remodeling and does not appear to be associated with greater hemodynamic instability or sinus injury. Therapeutic, III.

Early cranial vault distraction for a more balanced and enhanced expansion: a 3D craniometric analysis of anterior versus posterior distraction osteogenesis in patients with craniosynostosis.

Posterior distraction osteogenesis (DO) is widely accepted for the treatment of craniosynostosis. The aim of this study was to quantitatively compare the effect of DO on the cranial vault according to the age of the patient and direction of distraction. This was a retrospective study of patients with craniosynostosis who underwent DO in the anteroposterior direction. Postdistraction changes in intracranial volume (ICV), anteroposterior distance, biparietal distance, cranial height, and frontal bossing angle were measured using Mimics software on CT scans. Craniometric data were analyzed using a multivariate regression model. Thirty-two patients (16 anterior and 16 posterior DOs) were included in the study. The mean ICV increase in the anterior and posterior DO group was 211 cm3 (range 142-281 cm3) and 214 cm3 (range 150-279 cm3), respectively. Patients who were aged 1 year or younger showed a greater percentage increase in ICV than patients older than 1 year. In the anterior DO group, a more balanced increase in both anterior and posterior anteroposterior distance was observed in patients aged 1 year or younger when compared to patients older than 1 year. In the posterior DO group, a bigger expansion and smoother contour in the posterior cranial fossa was observed in patients aged 1 year or younger. Both anterior and posterior DO are effective surgical options for expanding the cranial vault in patients with craniosynostosis. Early distraction appeared to show greater morphological changes in the growing cranial vault than those predicted with the vector of distraction.

Effect of a neck collar on brain turgor: a potential role in preventing concussions?

BackgroundMild internal jugular vein (IJV) compression, aimed at increasing intracranial fluid volume to prevent motion of the brain relative to the skull, has reduced brain injury markers in athletes suffering...

Comparisons of Intracranial Volume and Cephalic Index After Correction of Sagittal Craniosynostosis With Either Two or Three Springs.

In this retrospective study, the authors determined changes in intracranial volume (ICV) and cephalic index (CI) in patients with sagittal craniosynostosis and operated with craniotomy combined with either 2 or 3 springs. The authors included patients (n = 112) with complete follow-up that had undergone surgical correction for isolated sagittal craniosynostosis with craniotomy combined with springs between 2008 and 2017. All patients underwent computed tomography examination preoperative, at the time of spring extraction, and at 3 years of age. Intracranial volume was measured using a semiautomatic MATLAB program, and CI was calculated as the width/length of the skull. The authors found that craniotomy combined with 2 springs increased the ICV from a preoperative value of 792 ± 113 mL (mean ± standard deviation) to 1298 ± 181 mL at 3 years of age and increased the CI from 72.1 ± 4.1 to 74.6 ± 4.3, whereas craniotomy combined with 3 springs increased the ICV from 779 ± 128 mL to 1283 ± 136 mL and the CI from 70.7 ± 4.3 to 74.8 ± 3.7. The relative increase in ICV was 65 ± 21% in the two-spring group and 68 ± 34% in the three-spring group (P value = 0.559), and the relative increase in CI was 3.6 ± 3.3% in the two-spring group as compared with 6.0 ± 5.0% in the three-spring group (P = 0.004). These findings demonstrated that use of 3 springs resulted in additional absolute and relative CI-specific effects as compared with 2 springs during the time when the springs were in place, with this effect maintained at 3 years of age.

Rotation flap distraction osteogenesis for unicoronal synostosis.

Unicoronal craniosynostosis is notoriously difficult to treat, with long-term studies demonstrating high rates of relapse and the need for reoperation using open fronto-orbital advancement. Applying the principles of distraction osteogenesis to cranial vault remodeling has demonstrated promising short-term results that compare favorably with traditional methods, with simultaneous correction of both frontofacial and endocranial morphology, along with significant increases in intracranial volume. Here, the authors demonstrate their technique for rotation flap distraction osteogenesis in the treatment of unicoronal synostosis and provide case examples.The video can be found here: https://vimeo.com/519505008.

Posterior vault distraction osteogenesis: indications and expectations.

Cranial vault remodeling (CVR) in patients with craniosynostosis serves to correct abnormal skull morphology and increase intracranial volume to prevent or treat pathologic increases in intracranial pressure (Taylor and Bartlett, Plast Reconstr Surg 140: 82e-93e, 2017). Distraction osteogenesis is a well-established technique for bony repositioning and growth stimulation in the facial and long bones, in which the gradual separation of bony segments at an osteotomy site results in generation of new bone and subsequent bone lengthening (Greene, 2018). While initially described in the orthopedic literature, the relevance and applicability of distraction osteogenesis to craniofacial surgery has been well-studied and is now well-established (Steinbacher et al., Plast Reconstr Surg 127: 792-801, 2011). Posterior cranial vault distraction osteogenesis (PVDO) was introduced as a treatment option for cranial vault expansion in patients with craniosynostosis in 2009 by White et al., based upon the premise that posterior vault distraction could provide greater intracranial volume expansion than fronto-orbital advancement and remodeling (FOAR), but that acute posterior cranial vault expansions were limited by the soft tissue envelope of the infant scalp and prone to relapse related to the supine positioning typical of infants (White et al., Childs Nerv Syst 25: 231-236, 2009). Since this introduction, significant evidence has accrued regarding the safety of, and outcomes after, PVDO. PVDO is now known to provide larger increases in intracranial volume in comparison to anterior cranial vault remodeling procedures (Derderian et al., Plast Reconstr Surg 135:1665-1672, 2015) and to provide morphologic improvements in both the posterior and anterior cranial vaults (Goldstein et al., Plast Reconstr Surg 131:1367-1375, 2013). Perioperative major morbidity is comparable to conventional vault remodeling (Taylor et al., Plast Reconstr Surg 129:674e-680e, 2012) and the procedure has been safely applied to patients of various ages with syndromic and non-syndromic craniosynostosis (Zhang et al., J Craniofac Surg 29:566-571, 2018; Li et al., J Craniofac Surg 27:1165-1169, 2016). Many high-volume craniofacial centers now consider PVDO the preferred first operation in infants with syndromic craniosynostosis, and indications for this procedure continue to expand as evidence accrues regarding its utility and safety (Steinbacher et al., Plast Reconstr Surg 127: 792-801, 2011; Swanson et al., Plast Reconstr Surg 137:829e-841e, 2016).

Отек головного мозга: от истоков описания к современному пониманию процесса

The article, which is a review-lecture, reflects the historical milestones in the description and study of cerebral edema (CE) from ancient times to the present. Great attention is paid to the Monroe–Kellie doctrine, without which it is impossible to understand the mechanism of development of a vitally significant complication of CE – intracranial hypertension. The importance of the Monroe–Kellie doctrine in substantiating the symptomatic treatment of increased intracranial pressure is emphasized. The possible involvement of the glymphatic system in both the decrease and the increase in increased intracranial pressure is discussed. The modern ideas about the blood-brain barrier (BBB), its role in the development of CE and an increase in intracranial volume are analyzed. With the study of the molecular mechanisms of BBB damage and the development of targeted therapy, the researchers associate future advances in the treatment of CE. The great interest of modern authors in the state of the BBB in various diseases, as well as in the violation of its integrity in COVID-19 is reflected. It is noted that the main and only, today, method for diagnosing CE is neuroimaging. Development has begun on the isolation of potential biochemical markers of CE from blood.

Brain biomechanics: monitoring the biomechanical properties of the human craniospinal system

The existing methods of assessing the biomechanical properties of the human craniospinal system are reduced to the study of the dynamics of changes in intracranial pressure with a dosed increase in intracranial volume by introducing a certain volume of fluid into the cranial space. These studies are discrete, traumatic. In different neurosurgical clinics, retrospective analysis of 1732 studies of biomechanical properties of the human craniospinal system (compliance, pressure-volume ratio, elasticity) in the period 1988–2014 were conducted. In order to establish a diagnosis or clarify the tactics of surgical treatment, a relationship between the amplitude of the intracranial pressure oscillation at the pulse rate, intracranial pressure and the compliance of the craniospinal system was established. In a single classical test with the introduction of a bolus of a small volume of fluid, and the indicators of biomechanical properties of the human craniospinal system are numerically evaluated. It is assumed that between two pulse waves (in the second range), these indicators do not change significantly, that is, in fact, we are talking about monitoring biomechanical properties of the human craniospinal system. A mathematical model is proposed that formalizes the relationship between biomechanical properties of the human craniospinal system and the dynamics of intracranial pressure oscillations at the pulse rate. Comparison of the results of the assessment of the main biomechanical indicators by the classical method and the proposed method established their high correlation. On the basis of this, an algorithm is proposed that can be used to create the original biomechanical properties of the human craniospinal system and intracranial pressure monitor.

Cardiac-gated intracranial elastance in a swine model of raised intracranial pressure: a novel method to assess intracranial pressure-volume dynamics.

Previous studies have demonstrated the importance of intracranial elastance; however, methodological difficulties have limited widespread clinical use. Measuring elastance may offer potential benefit in helping to identify patients at risk for untoward intracranial pressure (ICP) elevation from small rises in intracranial volume. The authors sought to develop an easily used method that accounts for the changing ICP that occurs over a cardiac cycle and to assess this method in a large-animal model over a broad range of ICPs. The authors used their previously described cardiac-gated intracranial balloon pump and swine model of cerebral edema. In the present experiment they measured elastance at 4 points along the cardiac cycle-early systole, peak systole, mid-diastole, and end diastole-by using rapid balloon inflation to 1 ml over an ICP range of 10-30 mm Hg. The authors studied 7 swine with increasing cerebral edema. Intracranial elastance rose progressively with increasing ICP. Peak-systolic and end-diastolic elastance demonstrated the most consistent rise in elastance as ICP increased. Cardiac-gated elastance measurements had markedly lower variance within swine compared with non-cardiac-gated measures. The slope of the ICP-elastance curve differed between swine. At ICP between 20 and 25 mm Hg, elastance varied between 8.7 and 15.8 mm Hg/ml, indicating that ICP alone cannot accurately predict intracranial elastance. Measuring intracranial elastance in a cardiac-gated manner is feasible and may offer an improved precision of measure. The authors' preliminary data suggest that because elastance values may vary at similar ICP levels, ICP alone may not necessarily best reflect the state of intracranial volume reserve capacity. Paired ICP-elastance measurements may offer benefit as an adjunct "early warning monitor" alerting to the risk of untoward ICP elevation in brain-injured patients that is induced by small increases in intracranial volume.

Biomechanics of a novel reversibly expandable dynamic craniotomy bone flap fixation plate.

Biomechanical evaluation of a novel expandable cranial fixation plate was assessed in cadavers. The dynamic craniotomy procedure uses low-profile reversibly expandable plates that allow cranial decompression by providing for intracranial volume expansion without removal of the bone flap. The plates allow reversible outward movement of the bone flap upon an increase in intracranial pressure (ICP) and also retract the bone flap and prevent it from sinking inside the cranium once the ICP normalizes. A comparative evaluation of the extent of ICP control with an increase in intracranial volume between various bone flap fixation techniques was undertaken along with testing of the expandable plate compliance. Static compression tests of the plates were performed to assess bone flap fixation and prevention of sinking. Quasi-static shear tension testing of the plates was undertaken to test the tolerance of the plates for expansion. Fatigue shear tension evaluation of the plates was undertaken to assess tolerance for repetitive expansion and contraction. The dynamic craniotomy provided superior control of ICP with an increase in intracranial volume compared to the hinged craniotomy and standard craniotomy techniques (p < 0.001). Static compression results revealed that the plates withstood bone flap sinkage with a mean peak load of 643.3 ± 26.1 N and a mean inward bone flap displacement of 1.92 ± 0.09 mm. Static shear tension results indicated that the plates could withstand a peak expansion of 71.6 mm. Dynamic shear tension testing of the plates with repetitive 15-mm outward expansion and retraction for a total of up to 500 cycles revealed no cracking and no failure points. The reversibly expandable plates provide for a low-profile bone flap fixation with rigid restriction of bone flap sinking and also enable cranial decompression with a high tolerance for repetitive expansion and contraction.

Clinical and Head Ultrasound Findings in Neonates after Administration of High Dose of Vitamin A

Vitamin A deficiency is a major cause of blindness and severe morbidity and mortality in young children. Supplementation of vitamin A in the community might reduce child mortality rates. The safety of high dose of vitamin A administered to neonates is not clear. We randomized 2058 neonates to receive either a single dose of 50 000 IU oral vitamin A (n=l031) or placebo (n=l027). Bulging fontanel and head circumference were assessed before and throughout 48 hours following dosing. Cranial ultrasound examination was carried out in 972 infants before and 24 hours after dosing to rule out intracranial hemorrhage and determine resistive index (Rl) of the anterior cerebral artery. Slight bulging fontanel occurred in 2. 7% and 4.4% of the infants at 24 hours. Moderate bulging fontanel was seen in 0.1% of study group, no severe bulging was observed. At 48 hours slight bulging fontanel was observed in 2.4% of control group and 4.5% in study group. No intracranial hemorrhage was found. Mean RI values were normal in both groups at baseline or 24 hours. Bulging fontanel was not associated with increased signs or symptom, or with increase in RI. Single oral dose of 50 000 vitamin A may cause a small increase in intracranial volume in a small proportion of infants, without increase in intracranial pressure.

Results Following Adoption of a Modified Melbourne Technique of Total Scaphocephaly Correction.

The Melbourne technique was described in 2008 as a novel method for complete correction of scaphocephaly. Since 2015, it has become our operation of choice for children with sagittal synostosis who are too old at presentation for minimally invasive techniques. Our modifications were 2-position (initially supine then prone) technique and undertaking a formal fronto-orbital remodeling to correct forehead contour. Retrospective chart review was used to record demographics, blood transfusion frequency and volumes, operating time, length of stay, clinical outcome, and complications. Eleven underwent modified Melbourne procedure between July 2015 and March 2017; 9 of 11 were male. All had a diagnosis of nonsyndromic sagittal synostosis. Mean age at surgery was 29 months. Mean surgical time was 6 hours. All patients required blood transfusion with a mean volume transfused of 29 mL/kg (range 13-83 mL/kg). For those 5 patients where preoperative and postoperative measurements were available, there was an increase in mean cephalic index (CI) from 0.64 to 0.75. All postoperative patients had a CI of over 0.70. Three-dimensional shape analysis indicated head shape change addressing all phenotypic aspects of scaphocephaly. In the 5 patients in which analysis could be undertaken, the mean intracranial volume increased from 1481 cm preoperatively to 1671 cm postoperatively, a mean increase in intracranial volume of 14%. The postoperative intracranial volume was higher than preoperative in all 5 patients. There were 4 minor and no major complications. Modified Melbourne procedure is safe and effective for the treatment of severe scaphocephaly in sagittal synostosis.

Does risk of brain cancer increase with intracranial volume? A population-based case control study.

Glioma is the most common primary brain tumor and is believed to arise from glial stem cells. Despite large efforts, there are limited established risk factors. It has been suggested that tissue with more stem cell divisions may exhibit higher risk of cancer due to chance alone. Assuming a positive correlation between the number of stem cell divisions in an organ and size of the same organ, we hypothesized that variation in intracranial volume, as a proxy for brain size, may be linked to risk of high-grade glioma. Intracranial volume was calculated from pretreatment 3D T1-weighted MRI brain scans from 124 patients with high-grade glioma and 995 general population-based controls. Binomial logistic regression analyses were performed to ascertain the effect of intracranial volume and sex on the likelihood that participants had high-grade glioma. An increase in intracranial volume of 100 mL was associated with an odds ratio of high-grade glioma of 1.69 (95% CI: 1.44‒1.98; P < 0.001). After adjusting for intracranial volume, female sex emerged as a risk factor for high-grade glioma (odds ratio for male sex = 0.56, 95% CI: 0.33‒0.93; P = 0.026). Intracranial volume is strongly associated with risk of high-grade glioma. After correcting for intracranial volume, risk of high-grade glioma was higher in women. The development of glioma is correlated to brain size and may to a large extent be a stochastic event related to the number of cells at risk.

Increases in Cranial Volume with Posterior Cranial Vault Distraction in 31 Consecutive Cases

Posterior cranial vault distraction (PCVD) is a technique widely used in surgical treatment of craniosynostosis when cranial expansion is required. It has proven to be safe and to allow a significant increase of intracranial volume. To evaluate increases in intracranial volume as a result of PCVD performed in Oulu Craniofacial center using 2 different methods based on 3-dimensional (3-D) photogrammetric imaging or plain skull radiographs. All children less than 16 yr of age who were treated by PCVD (n = 31) from 2009 to 2015 at the Oulu Craniofacial Center were included. All patients were followed at outpatient clinics with plain radiographs performed for follow-up. In 5 patients, additional 3-D photogrammetric imaging was done pre- and postoperatively. The mean intracranial volume increase was 25.0%, ranging from 16.9% to 39.4%. In 5 patients, the increase in volume was calculated from the photogrammetric 3-D images comprising a mean of 17.4%. Volume calculations from cephalograms in the same patients gave a mean of 20.8%. Whether the distraction was a primary operation or patient had undergone previous cranioplasty did not influence the achieved volumetric results. There were no statistically significant differences in the distraction results between different diagnostic groups. PCVD is an effective surgical method to increase intracranial volume in a variety of clinical entities. Volumetric results of this procedure could be easily evaluated using 3-D photogrammetric imaging or plane radiographs that expose the patients to only low ionizing radiation doses.

Dimensional, Geometrical, and Physical Constraints in Skull Growth.

After birth, the skull grows and remodels in close synchrony with the brain to allow for an increase in intracranial volume. Increase in skull area is provided primarily by bone accretion at the sutures. Additional remodeling, to allow for a change in curvatures, occurs by resorption on the inner surface of the bone plates and accretion on their outer surfaces. When a suture fuses too early, normal skull growth is disrupted, leading to a deformed final skull shape. The leading theory assumes that the main stimulus for skull growth is provided by mechanical stresses. Based on these ideas, we first discuss the dimensional, geometrical, and kinematic synchrony between brain, skull, and suture growth. Second, we present two mechanical models for skull growth that account for growth at the sutures and explain the various observed dysmorphologies. These models demonstrate the particular role of physical and geometrical constraints taking place in skull growth.

Dynamic Decompressive Craniotomy with a Novel Reversibly Expandable Plate.

Objective To assess the feasibility of a dynamic craniotomy procedure with the use of a novel reversibly expandable cranial bone flap fixation plate. The expandable plate allows outward bone flap migration with an increase in intracranial volume or intracranial pressure (ICP). Methods Dynamic craniotomy intracranial hypertension compliance was evaluated in a skull model with progressive increase in intracranial volume and compared with the standard craniotomy with fixed plates. Results Dynamic craniotomy provided significant control of ICP with increasing intracranial volume compared with the standard craniotomy. With an incremental increase in intracranial volume from 360 mL to 600 mL, the ICP increased from 2.6 to 91.9 mm Hg with the standard craniotomy, whereas with the dynamic craniotomy the ICP for similar intracranial volume increased from 2.5 to 25 mm Hg (p < 0.00001). Conclusions The dynamic craniotomy procedure provides superior control of ICP with an abrupt intracranial volume increase when compared with the standard craniotomy.