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Andrew J. Dodgshun, Wirginia J. Maixner, Jordan R. Hansford and Michael J. Sullivan

OBJECTIVE

Pilocytic astrocytomas (PAs) are common brain tumors in children. Optimal management of PA is gross-total resection (GTR), after which event-free survival (EFS) is excellent. The tempo of recurrences, when they do occur, is relatively sparsely reported, and there is no agreed upon surveillance recommendation for patients in this category. It has been suggested that surveillance MRI is performed too frequently and could be safely reduced in both frequency and duration. The authors conducted a retrospective review of pediatric patients with PA who underwent GTR at a single institution over an 18-year period and who had documented recurrences.

METHODS

All patients under 18 years of age who had undergone GTR of a PA between 1996 and 2013 were included in the study. Clinical, radiological, and tumor characteristics were recorded.

RESULTS

Sixty-seven patients met the criteria for GTR over the period studied. The 5-year EFS rate was 95% (95% CI 89%–100%) and overall survival was 100%. Recurrences showed a nonsignificant trend of occurring more commonly in patients with persistent nonenhancing FLAIR abnormalities after surgery, but there was no difference with regard to tumor location. All recurrences occurred before 3 years postresection, all were asymptomatic, and all patients were observed for at least one additional scan after the initial detection during routine surveillance MRI before further therapy was undertaken.

CONCLUSIONS

EFS and overall survival are excellent after GTR in this population with PAs. Progression after recurrence occurs slowly and is asymptomatic. A less intensive schedule of MRI surveillance in this group of patients would result in time and cost savings, without compromising safety. The authors suggest a schedule of 6 MRI scans to be obtained postoperatively, at 3–6 months, then at 1, 2, 3.5, and 5 years.

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Ronnie E. Baticulon, Michael C. Dewan, Nunthasiri Wittayanakorn, Philipp R. Aldana and Wirginia J. Maixner

OBJECTIVE

There are limited data on the pediatric neurosurgical workforce in Asia and Australasia. The training and clinical practice of pediatric neurosurgeons need to be characterized in order to identify gaps in knowledge and skills, thereby establishing a framework from which to elevate pediatric neurosurgical care in the region.

METHODS

An online survey for pediatric neurosurgeons was created in REDCap (Research Electronic Database Capture), collecting demographic information and data on pediatric neurosurgical training and clinical practice. The link to answer the survey was sent to the mailing lists of the Asian Australasian Society for Pediatric Neurosurgery and the Japanese Society for Pediatric Neurosurgery, disseminated during the 2019 Asian Australasian Pediatric Neurosurgery Congress, and spread through social media. The survey was open to neurosurgeons who operated on patients ≤ 18 years old in Asian Australasian countries, whether or not they had completed fellowship training in pediatric neurosurgery. Descriptive statistics were computed and tabulated. Data were stratified and compared based on surgeon training and World Bank income group.

RESULTS

A total of 155 valid survey responses were analyzed, representing neurosurgeons from 21 countries. A total of 107 (69%) considered themselves pediatric neurosurgeons, of whom 66 (43%) had completed pediatric neurosurgery training. Neurosurgeons in East Asia commonly undergo a fellowship in their home countries, whereas the rest train mostly in North America, Europe, and Australia. A majority (89%) had operating privileges, and subspecialty pediatric training usually lasted from 6 months to 2 years. On average, trained pediatric neurosurgeons perform a higher number of pediatric neurosurgical operations per year compared with nonpediatric-trained respondents (131 ± 129 vs 56 ± 64 [mean ± SD], p = 0.0001). The mean number of total neurosurgical operations per year is similar for both groups (184 ± 129 vs 178 ± 142 [mean ± SD], p = 0.80). Respondents expressed the desire to train further in pediatric epilepsy, spasticity, vascular malformations, craniofacial disorders, and brain tumors.

CONCLUSIONS

Both pediatric and general neurosurgeons provide neurosurgical care to children in Asia and Australasia. There is a need to increase pediatric neurosurgery fellowship programs in the region. Skill sets and training needs in pediatric neurosurgery vary depending on the country’s economic status and between pediatric-trained and nonpediatric-trained surgeons.

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Shaun P. Appaduray, James A. J. King, Alison Wray, Patrick Lo and Wirginia Maixner

Pediatric dural arteriovenous malformations (dAVMs) are rare lesions that have a high mortality rate and require complex management. The authors report 3 cases of pediatric dAVMs that presented with macrocrania and extracranial venous distension. Dural sinus thrombosis developed in 2 of the cases prior to any intervention, which is an unusual occurrence for this particular disease. All 3 cases were treated using staged endovascular embolization with a favorable outcome in 1 case and a poor outcome in the other 2 cases. Complications developed in all cases and included dural sinus thrombosis, parenchymal hemorrhage, intracranial venous hypertension, and seizures. The strategies and challenges used in managing these patients will be presented and discussed, along with a review of the literature. While outcomes remain poor, the authors conclude that prompt treatment with endovascular embolization provides the best results for children with these lesions. A well-established venous collateral circulation draining directly to the internal jugular veins may further improve the rate of favorable outcome after embolization.

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Joseph Yuan-Mou Yang, Richard Beare, Marc L. Seal, A. Simon Harvey, Vicki A. Anderson and Wirginia J. Maixner

OBJECTIVE

Characterization of intraoperative white matter tract (WMT) shift has the potential to compensate for neuronavigation inaccuracies using preoperative brain imaging. This study aimed to quantify and characterize intraoperative WMT shift from the global hemispheric to the regional tract-based scale and to investigate the impact of intraoperative factors (IOFs).

METHODS

High angular resolution diffusion imaging (HARDI) diffusion-weighted data were acquired over 5 consecutive perioperative time points (MR1 to MR5) in 16 epilepsy patients (8 male; mean age 9.8 years, range 3.8–15.8 years) using diagnostic and intraoperative 3-T MRI scanners. MR1 was the preoperative planning scan. MR2 was the first intraoperative scan acquired with the patient's head fixed in the surgical position. MR3 was the second intraoperative scan acquired following craniotomy and durotomy, prior to lesion resection. MR4 was the last intraoperative scan acquired following lesion resection, prior to wound closure. MR5 was a postoperative scan acquired at the 3-month follow-up visit. Ten association WMT/WMT segments and 1 projection WMT were generated via a probabilistic tractography algorithm from each MRI scan. Image registration was performed through pairwise MRI alignments using the skull segmentation. The MR1 and MR2 pairing represented the first surgical stage. The MR2 and MR3 pairing represented the second surgical stage. The MR3 and MR4 (or MR5) pairing represented the third surgical stage. The WMT shift was quantified by measuring displacements between a pair of WMT centerlines. Linear mixed-effects regression analyses were carried out for 6 IOFs: head rotation, craniotomy size, durotomy size, resected lesion volume, presence of brain edema, and CSF loss via ventricular penetration.

RESULTS

The average WMT shift in the operative hemisphere was 2.37 mm (range 1.92–3.03 mm) during the first surgical stage, 2.19 mm (range 1.90–3.65 mm) during the second surgical stage, and 2.92 mm (range 2.19–4.32 mm) during the third surgical stage. Greater WMT shift occurred in the operative than the nonoperative hemisphere, in the WMTs adjacent to the surgical lesion rather than those remote to it, and in the superficial rather than the deep segment of the pyramidal tract. Durotomy size and resection size were significant, independent IOFs affecting WMT shift. The presence of brain edema was a marginally significant IOF. Craniotomy size, degree of head rotation, and ventricular penetration were not significant IOFs affecting WMT shift.

CONCLUSIONS

WMT shift occurs noticeably in tracts adjacent to the surgical lesions, and those motor tracts superficially placed in the operative hemisphere. Intraoperative probabilistic HARDI tractography following craniotomy, durotomy, and lesion resection may compensate for intraoperative WMT shift and improve neuronavigation accuracy.