Owase Jeelani

Connecting raised intracranial pressure and cognitive delay in craniosynostosis: many assumptions, little evidence

The hypothesis that restricted skull growth is responsible for neurocognitive impairment (NCI) has a torrid history that can be traced back to the 19th century.22 However, not until 1982 did we see “modern” evidence coupling intracranial pressure (ICP) in children with craniosynostosis and NCI and supporting a causal relationship between the two in the literature.56 Given their findings, Renier et al.56 recommended that, especially in children with multisuture, complex, or syndromic forms of craniosynostosis, prophylactic vault expansion should be performed no later than the 1st year of life to avoid or at least minimize the degree of NCI for which raised ICP could be responsible—a policy followed by many craniofacial units to this day.68 Although it has long been known that raised ICP, whatever its cause, can through optic atrophy lead to impaired vision and even blindness, how secure is the evidence that in the absence of hydrocephalus (whose well-recognized ill effects are not discussed further here) the elevations of ICP recorded in children with craniosynostosis can be responsible for the NCI? Has the situation changed materially since Cohen and Persing wrote in 1996,12 “The premise that asymptomatic elevations of ICP in craniosynostosis are detrimental to normal intellectual development has been difficult to prove conclusively”? Indeed, in their classic 1982 paper,56 Renier et al. were careful to ring the conclusion that their results suggested “such a relationship, but [do] not prove it definitively” with the caveat that increased ICP and low IQ could be two consequences of a third variable. The subject is of particular importance to the craniofacial surgeon because if the connection between raised ICP and the NCI of children with craniosynostosis lacks a secure evidence base, there exists the real possibility that patients may be subjected to unnecessary surgical procedures with their never-absent risks.

Frontofacial advancement by distraction osteogenesis: a long-term review.

Background: Frontofacial advancement by distraction osteogenesis is known to produce significant functional and aesthetic gains in the short and medium term. Little is known about the long-term effects of this technique. The authors present a long-term review of frontofacial advancement by distraction in patients with syndromic craniosynostosis. Methods: In 2008, Witherow et al. presented functional outcomes in 20 consecutive patients who underwent frontofacial advancement by distraction osteogenesis using the rigid external distractor frame. This retrospective study has revisited the outcomes in these patients after a mean follow-up period of 10.2 years. Results: Records for the original 20 patients were assessed. Cephalometric analysis demonstrated stable advancements over the long term. No patient achieved any anterior growth of the midface after frontofacial advancement. Long-term follow-up demonstrated a later deterioration of respiratory function in the younger group of patients (36.4 percent). Four patients required adenotonsillectomy. One patient has a persistent tracheostomy. Only one patient required further procedures to correct recurrent raised intracranial pressure. None of the patients in the older group experienced a deterioration of function. Other procedures included reduction of the supraorbital ridge, bimaxillary osteotomies, and rhinoplasties. Conclusions: Frontofacial distraction produced long-term stable advancement in all cases, and 15 of the 17 living patients (88.2 percent) achieved stable functional gains. Anterior growth of the midface does not occur following monobloc distraction. Deterioration in function is seen in those who undergo this procedure at a young age. The authors recommend regular follow-up of these patients. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, IV.

Raised intracranial pressure in Crouzon syndrome: incidence, causes, and management.

OBJECT Patients with Crouzon syndrome (CS) are at risk for developing raised intracranial pressure (ICP), which has the potential to impair both vision and neurocognitive development. For this reason, some experts recommend early prophylactic cranial vault expansion on the basis that if ICP is not currently raised, it is likely to become so. The aim of this study was to examine the justification for such a policy. This was done by analyzing the incidence, causes, and subsequent risk of recurrence in a series of patients with CS, in whom raised ICP was treated only after it had been diagnosed. METHODS This study was a retrospective review of the medical records and imaging data of patients with a clinical diagnosis of CS. RESULTS There were 49 patients in the study, of whom 30 (61.2%) developed at least 1 episode of raised ICP. First episodes occurred at an average age of 1.42 years and were attributable to craniocerebral disproportion/venous hypertension (19 patients), hydrocephalus (8 patients), and airway obstruction (3 patients). They were managed, respectively, by vault expansion, ventriculoperitoneal shunt insertion, and airway improvement. Fourteen of the 30 patients developed a second episode of raised ICP an average of 1.42 years after treatment for their initial episode, and 3 patients developed a third episode an average of 3.15 years after that. Causes of subsequent episodes of raised ICP often differed from previous episodes and required different management. Patients who were < 1 year old when the first episode was diagnosed were at increased risk of recurrence. CONCLUSIONS Although the incidence of raised ICP in CS is high, it did not occur in nearly 40% of children during the course of this study. The several possible causes of CS require different management and may vary from episode to episode. The authors recommend an expectant policy toward these children with careful clinical, ophthalmological, respiratory, and radiological monitoring for raised ICP, reserving intervention for when it has been detected and the appropriate treatment can be initiated.

Monobloc and bipartition in craniofacial surgery.

Background The frontofacial monobloc advancement with osteogenic distraction is increasingly used as a surgical treatment for children with complex craniosynostosis-associated syndromes. However, the subfrontal osteotomy cuts to free the facial skeleton from the skull base require extradural retraction of the frontal lobes. The purpose of this study was to determine the frequency and degree of radiologically identifiable frontal lobe changes and whether any such changes affected the patients’ outcome. Methods The clinical records and preoperative and postoperative computed tomography imaging of all patients undergoing monobloc frontofacial distraction advancement (with or without bipartition) were reviewed. A retrospective medical notes review was undertaken to assess any patient or surgically related factors that might predispose to frontal lobe changes and evaluate outcome from surgery. Where available, magnetic resonance imaging scans were reviewed to compare outcome with that on computed tomography. Results Fifty cases were identified as suitable for the study. Eighteen patients (36%) had no frontal lobe changes. Thirty-two cases (64%) did have changes that appeared related to the position of maximum retraction during subfrontal osteotomy cuts. There were no changes in the incidence/extent of these changes over time or of any link to the patients’ diagnosis, age at surgery, phenotype severity, surgery type, or any surgical or postoperative adverse events. We found no evidence that these changes were responsible for neurologic problems (eg, epilepsy) or reduced cognitive function. Conclusions This study reveals a high incidence of frontal lobe changes demonstrable on neuroimaging following the frontofacial monobloc procedure reflecting the retraction points during surgery. Although no postoperative disability was reported, it is clearly important to consider more detailed neuropsychologic testing and review current surgical techniques to ensure that such changes are kept to a minimum.

Hypertelorism correction with facial bipartition and box osteotomy: does soft tissue translation correlate with bony movement?

ObjectiveHypertelorism may be corrected by either transcranial box osteotomy or facial bipartition. Despite radical bony resection, the associated soft tissue translation often seems disproportionate. The purpose of this study was to review bony and soft tissue movements in a series of 15 consecutive hypertelorism correction cases. MethodsTwo surgical residents in training independently analyzed preoperative and postoperative axial and three-dimensional reconstructed computed tomography data from 15 consecutive patients undergoing facial bipartition (n = 7) or transcranial box osteotomy correction (n = 8) between 2001 and 2010. Anterior interorbital distance, lateral interorbital distance, midpoint globe distance, and globe protrusion were measured along with intercanthal distance and palpebral fissure width. ResultsThe mean preoperative anterior interorbital distance was 35.5 mm; postoperatively, there was a mean reduction of 9.5 mm, to 26 mm. The mean preoperative intercanthal distance was 48.1 mm; there was a mean reduction of 10.3 mm, to 37.8 mm. The mean preoperative midpoint globe distance was 69.5 mm; there was a mean reduction of 9.6 mm, to 59.9 mm. The mean preoperative globe protrusion was 17.6 mm; there was a mean reduction of 5 mm, to 12.6 mm (28.5%). The mean interclass correlation (a measurement of interrater congruency with 1 being complete agreement) was 0.85 ConclusionsTranscranial box osteotomy and facial bipartition correct hypertelorism. The medial canthal tendons, lateral canthal tendons, and globes move in proportion to the bony attachments. We observed a reduction in globe protrusion an average of 29%, therefore risking enophthalmos.

A novel soft tissue prediction methodology for orthognathic surgery based on probabilistic finite element modelling

Repositioning of the maxilla in orthognathic surgery is carried out for functional and aesthetic purposes. Pre-surgical planning tools can predict 3D facial appearance by computing the response of the soft tissue to the changes to the underlying skeleton. The clinical use of commercial prediction software remains controversial, likely due to the deterministic nature of these computational predictions. A novel probabilistic finite element model (FEM) for the prediction of postoperative facial soft tissues is proposed in this paper. A probabilistic FEM was developed and validated on a cohort of eight patients who underwent maxillary repositioning and had pre- and postoperative cone beam computed tomography (CBCT) scans taken. Firstly, a variables correlation assessed various modelling parameters. Secondly, a design of experiments (DOE) provided a range of potential outcomes based on uniformly distributed input parameters, followed by an optimisation. Lastly, the second DOE iteration provided optimised predictions with a probability range. A range of 3D predictions was obtained using the probabilistic FEM and validated using reconstructed soft tissue surfaces from the postoperative CBCT data. The predictions in the nose and upper lip areas accurately include the true postoperative position, whereas the prediction under-estimates the position of the cheeks and lower lip. A probabilistic FEM has been developed and validated for the prediction of the facial appearance following orthognathic surgery. This method shows how inaccuracies in the modelling and uncertainties in executing surgical planning influence the soft tissue prediction and it provides a range of predictions including a minimum and maximum, which may be helpful for patients in understanding the impact of surgery on the face.

Intracranial Neoplasms in the First Year of Life: Results of a Third Cohort of Patients From a Single Institution

BACKGROUND Brain tumors in the first year of life are rare and their management remains challenging. OBJECTIVE To report on the contemporary management of brain tumors in infants with reference to previous series from our institution. METHODS Retrospective cohort study design. Electronic/paper case note review of all brain tumors diagnosed at our institution in children aged <1 yr since the publication of our previous series. RESULTS Ninety-eight patients were seen. The most common presentations were with vomiting and macrocrania, at a median age of 184 d. Sixty-two percent of tumors were supratentorial. Ninety-one patients underwent 230 procedures; 7 patients had no surgery. One hundred eighteen operations were directly on brain tumors (biopsy 37, subtotal resection 47, gross total resection 34). Ninety-one cerebrospinal fluid diversions, 9 endoscopic procedures, and 13 preoperative embolizations were performed. Operative mortality was 4.4%. Tumor types in order of frequency were choroid plexus papillomas (CPP, 17), primitive neuroectodermal tumor (12), atypical teratoid/rhabdoid tumor (10), high-grade glioma (9), optic glioma (9), ependymoma (8), low-grade glioma (6), pilocytic astrocytoma (6), choroid plexus carcinoma (5), and teratoma (5), with 11 miscellaneous tumors. Survival was 93% at 1 mo (91/98), 64% at 1 yr (61/95), 44% at 5 yr (32/73), 28% at 10 yr (16/58). No patients with CPP or low-grade glioma died. Five-year survival rates were lowest for anaplastic ependymoma, primitive neuroectodermal tumor, and atypical teratoid/rhabdoid tumor. Seventy-seven percent of children reaching school age were in mainstream schooling. CONCLUSION Overall survival from neonatal brain tumors remains similar to previous series; analysis of tumor subtypes reveals improvements for CPP and gliomas. Despite increasing operative intervention, operative mortality continues to decline for this group of challenging patients.

Spring assisted cranioplasty: A patient specific computational model

Implantation of spring-like distractors in the treatment of sagittal craniosynostosis is a novel technique that has proven functionally and aesthetically effective in correcting skull deformities; however, final shape outcomes remain moderately unpredictable due to an incomplete understanding of the skull-distractor interaction. The aim of this study was to create a patient specific computational model of spring assisted cranioplasty (SAC) that can help predict the individual overall final head shape. Pre-operative computed tomography images of a SAC patient were processed to extract a 3D model of the infant skull anatomy and simulate spring implantation. The distractors were modeled based on mechanical experimental data. Viscoelastic bone properties from the literature were tuned using the specific patient procedural information recorded during surgery and from x-ray measurements at follow-up. The model accurately captured spring expansion on-table (within 9% of the measured values), as well as at first and second follow-ups (within 8% of the measured values). Comparison between immediate post-operative 3D head scanning and numerical results for this patient proved that the model could successfully predict the final overall head shape. This preliminary work showed the potential application of computational modeling to study SAC, to support pre-operative planning and guide novel distractor design.

Proof of Concept Study for the Design, Manufacturing, and Testing of a Patient-Specific Shape Memory Device for Treatment of Unicoronal Craniosynostosis

Abstract Treatment of unicoronal craniosynostosis is a surgically challenging problem, due to the involvement of coronal suture and cranial base, with complex asymmetries of the calvarium and orbit. Several techniques for correction have been described, including surgical bony remodeling, early strip craniotomy with orthotic helmet remodeling and distraction. Current distraction devices provide unidirectional forces and have had very limited success. Nitinol is a shape memory alloy that can be programmed to the shape of a patient-specific anatomy by means of thermal treatment. In this work, a methodology to produce a nitinol patient-specific distractor is presented: computer tomography images of a 16-month-old patient with unicoronal craniosynostosis were processed to create a 3-dimensional model of his skull and define the ideal shape postsurgery. A mesh was produced from a nitinol sheet, formed to the ideal skull shape and heat treated to be malleable at room temperature. The mesh was afterward deformed to be attached to a rapid prototyped plastic skull, replica of the patient initial anatomy. The mesh/skull construct was placed in hot water to activate the mesh shape memory property: the deformed plastic skull was computed tomography scanned for comparison of its shape with the initial anatomy and with the desired shape, showing that the nitinol mesh had been able to distract the plastic skull to a shape close to the desired one. The shape-memory properties of nitinol allow for the design and production of patient-specific devices able to deliver complex, preprogrammable shape changes.

Intracranial Volume Measurement: A Systematic Review and Comparison of Different Techniques

Abstract The ability to calculate intracranial volume (ICV) from 3-dimensional imaging is a useful tool in a craniofacial teams armamentarium. Intracranial volume uses range from decision making to assessment. Various methods to calculate ICV exist including fully manual, semiautomatic, and fully automatic techniques and they are used with varying frequency in craniofacial centres globally. This study aimed to systematically analyze and compare ICV calculations across the 3 methods and provide information to allow the reader to utilize these processes in practice. Twenty-six computed tomography scans from Apert patients were used to compare ICV measurements calculated using the following techniques: fully manual segmentation with OsiriX (taken as the gold standard); semiautomatic segmentation using Simpleware ScanIP; and fully automatic segmentation using FSL neuroimaging software. In addition, to assess the effect that a reducing CT scan slice number had on ICV measurement, 13 scans were remeasured using half, quarter, and an eighth of the slices of the full scan. The manual and semiautomatic techniques had intraclass correlation coefficients of 0.997, and 0.993 respectively. Intracranial volume measurements using the semi- and fully automatic techniques showed high linear correlation with manual techniques (R2 = 0.993 and R2 = 0.995). The coefficients of determination for full scan versus half, quarter, and eighth scan were R2 = 0.98, 0.96, and 0.94 respectively. Similar ICV results can be obtained using manual, semiautomatic, or automatic techniques with decreasing amount of time required to perform each method. Command line code for the fully automatic method is provided.