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Jennifer L. Quon, Lily H. Kim, Peter H. Hwang, Zara M. Patel, Gerald A. Grant, Samuel H. Cheshier, and Michael S. B. Edwards

OBJECTIVE

Transnasal endoscopic transsphenoidal approaches constitute an essential technique for the resection of skull base tumors in adults. However, in the pediatric population, sellar and suprasellar lesions have historically been treated by craniotomy. Transnasal endoscopic approaches are less invasive and thus may be preferable to craniotomy, especially in children. In this case series, the authors present their institutional experience with transnasal endoscopic transsphenoidal approaches for pediatric skull base tumors.

METHODS

The authors retrospectively reviewed pediatric patients (age ≤ 18 years) who had undergone transnasal endoscopic transsphenoidal approaches for either biopsy or resection of sellar or suprasellar lesions between 2007 and 2016. All operations were performed jointly by a team of pediatric neurosurgeons and skull base otolaryngologists, except for 8 cases performed by one neurosurgeon.

RESULTS

The series included 42 patients between 4 and 18 years old (average 12.5 years) who underwent 51 operations. Headache (45%), visual symptoms (69%), and symptoms related to hormonal abnormalities (71%) were the predominant presenting symptoms. Improvement in preoperative symptoms was seen in 92% of cases. Most patients had craniopharyngiomas (n = 16), followed by pituitary adenomas (n = 12), Rathke cleft cysts (n = 4), germinomas (n = 4), chordomas (n = 2), and other lesion subtypes (n = 4). Lesions ranged from 0.3 to 6.2 cm (median 2.5 cm) in their greatest dimension. Gross-total resection was primarily performed (63% of cases), with 5 subsequent recurrences. Nasoseptal flaps were used in 47% of cases, fat grafts in 37%, and lumbar drains in 47%. CSF space was entered intraoperatively in 15 cases, and postoperative CSF was observed only in lesions with suprasellar extension. There were 8 cases of new hormonal deficits and 3 cases of new cranial nerve deficits. Length of hospital stay ranged from 1 to 61 days (median 5 days). Patients were clinically followed up for a median of 46 months (range 1–120 months), accompanied by a median radiological follow-up period of 45 months (range 3.8–120 months). Most patients (76%) were offered adjuvant therapy.

CONCLUSIONS

In this single-institution report of the transnasal endoscopic transsphenoidal approach, the authors demonstrated that this technique is generally safe and effective for different types of pediatric skull base lesions. Favorable effects of surgery were sustained during a follow-up period of 4 years. Further refinement in technology will allow for more widespread use in the pediatric population.

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Katalin A. Szabo, Samuel H. Cheshier, M. Yashar S. Kalani, Jonathan W. Kim, and Raphael Guzman

To the authors' knowledge, this is the first report of the use of anterior orbitotomy via the supraorbital eyelid crease to repair a dural tear caused by an orbital roof fracture. When transorbital penetrating injuries occur in children, they are commonly caused by accidental falls onto pointed objects. The authors report on their experience with a 7-year-old girl who fell onto a blunt metal rod hanger that penetrated her left eyelid, traversed superior to the eye globe, and penetrated the orbital roof at a depth of 3–4 cm, lacerating the dura mater and entering the cerebrum. An anterior transpalpebral transorbital approach was used to perform the microsurgical anterior skull base and dural repair. The authors advocate the application of this approach to orbital roof fractures because it provides excellent access to the orbital roof, eliminates the need for more invasive craniotomy, results in a small and well-hidden scar in the eye crease, and overall offers a shorter recovery time with less psychological stress to the patient.

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Jun Jae Shin, Sang Hyun Kim, Yong Eun Cho, Samuel H. Cheshier, and Jon Park

Object

Several controversial issues arise in the management of unstable hangman's fractures. Some surgeons perform external reduction and immobilize the patient's neck in a halo vest, while others perform surgical reduction and internal fixation. The nonsurgical treatments with rigid collar or halo vest immobilization present problems, including nonunion, pseudarthrosis, skull fracture, and scalp laceration and may also fail to achieve anatomical realignment of the local C2–3 kyphosis. With recent advances in surgical technique and technology, surgical intervention is increasingly performed as the primary treatment in high cervical fractures. The outcomes of such surgeries are often superior to those of conservative treatment. The authors propose that surgical intervention as a primary management for hangman's fracture may avoid risks inherent in conservative management when severe circumferential discoligamentous instability is present and may reduce the risk of catastrophic results at the fracture site.

The purposes of this study were to assess fracture healing following expedient reduction and surgical fixation and to propose a guideline for treatment of unstable hangman's fractures.

Methods

From April 2006 to December 2011, the authors treated 105 patients with high cervical fractures. This study included 23 (21.9%) of these patients (15 men and 8 women; mean age 46.4 years) with Type II, IIa, and III hangman's fractures according to the Levine and Edwards classification. The patient's age, sex, mechanism of injury, associated injuries, neurological status, and complications were ascertained. The authors retrospectively assessed the clinical outcome (Neck Disability Index), radiological findings (disc height, translation, and angulation), and bony healing.

Results

The average follow-up period was 28.9 months (range 12–63.2 months). The overall average Neck Disability Index score at the time of this study was 6.6 ± 2.3. The average duration of hospitalization was 20.3 days, and fusion was achieved in all cases by 14.8 ± 1.6 weeks after surgery, as demonstrated on dynamic radiographs and cervical 3D CT scans.

The mean pretreatment translation was 6.9 ± 3.2 mm, and the mean postoperative translation was 1.6 ± 1.8 mm (mean reduction 5.2 ± 3.1 mm). The initial angulation was 4.7° ± 5.3° and the postoperative angulation was 2.5° ± 1.8° (mean reduction 6.1° ± 5.3°). The preoperative and postoperative values for translation and angulation differed significantly (p < 0.05). The overall C2–3 disc height was 6.7 ± 1.2 mm preoperatively, whereas 3 months after surgery it was 6.4 ± 1.1 mm. These values did not differ significantly (p = 0.0963).

Conclusions

The authors observed effective reduction and bony healing in cases of unstable hangman's fractures after fixation, and all patients experienced favorable clinical outcomes with neck pain improvement. The protocols allowed for physiological reconstruction of the fractured deformities and avoided external fixation. The authors suggest that posterior reduction and screw fixation should be used as a primary treatment to promote stability of hangman's fracture in the presence of discoligamentous instability or combined fractures.

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Robert M. Lober, Raphael Guzman, Samuel H. Cheshier, Douglas R. Fredrick, Michael S. B. Edwards, and Kristen W. Yeom

Object

Magnetic resonance imaging is commonly used in diagnosis and surveillance for optic pathway glioma (OPG). The authors investigated the role of diffusion tensor (DT) tractography in assessing the location of visual pathway fibers in the presence of tumor.

Methods

Data in 10 children with OPG were acquired using a 3T MRI generalized autocalibrating parallel acquisitions DT–echo planar imaging sequence (25 isotropic directions with a b value of 1000 seconds/mm2, slice thickness 3 mm). Fiber tractography was performed, with seed regions placed within the optic chiasm and bilateral nerves on the coronal plane, including the tumor and surrounding normal-appearing tissue. Tracking was performed with a curvature threshold of 30°.

Results

For prechiasmatic lesions, fibers either stopped abruptly at the tumor or traversed abnormally dilated nerve segments. Similar findings were seen with chiasmatic lesions, with an additional arrangement in which fibers diverged around the tumor. For each patient, DT tractography provided additional information about visual fiber arrangement in relation to the tumor that was not evident by using conventional MRI methods. Retrospective reconstruction of visual fibers in 1 patient with new postoperative hemianopia revealed an unexpected superior displacement of the optic tract that might have been helpful information had it been applied to preoperative planning or surgical navigation.

Conclusions

Optic pathway DT tractography is feasible in patients with OPG and provides new information about the arrangement of visual fibers in relation to tumors that could be incorporated into surgical navigation for tumor biopsy or debulking procedures.

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Alexandra D. Beier, Samuel H. Cheshier, Aabir Chakraborty, and Peter Dirks

The syndrome of inappropriate antidiuretic hormone secretion (SIADH) is occasionally seen after hypothalamic injury or dysfunction, although it typically occurs in association with other endocrine disturbances. It is has never been described as a presenting feature of a suprasellar arachnoid cyst (SAC) in the pediatric population. The authors describe the case of an enlarging SAC resulting in SIADH as the only presenting feature, with an otherwise normal hypothalamic-pituitary axis.

An SAC was diagnosed in utero in this 5-month-old girl who had a normal functioning hypothalamic-pituitary axis on presentation. Because of cyst enlargement and hydrocephalus, the patient was scheduled for surgery; however, preoperative labs revealed SIADH. After stabilizing the serum sodium concentration with fluid restriction and the administration of 3% sodium chloride, the patient underwent endoscopic cyst fenestration. Postoperatively, she had complete resolution of the SIADH.

Syndrome of inappropriate antidiuretic hormone secretion as the presenting symptom of an SAC has not been previously described. In the aforementioned patient, the proposed mechanism for SIADH was enlargement of the suprasellar arachnoid cyst causing compression of the supraoptic and paraventricular nuclei and thus overstimulating the secretion of arginine vasopressin, which resulted in SIADH.

The association of SIADH with an SAC is reportable, as is the resolution of the SIADH via cyst fenestration. The authors suggest that SIADH is an uncommon presenting feature of SACs and that syndrome resolution is possible with cyst decompression.

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Allen L. Ho, John G. D. Cannon, Jyodi Mohole, Arjun V. Pendharkar, Eric S. Sussman, Gordon Li, Michael S. B. Edwards, Samuel H. Cheshier, and Gerald A. Grant

OBJECTIVE

Topical antimicrobial compounds are safe and can reduce cost and complications associated with surgical site infections (SSIs). Topical vancomycin has been an effective tool for reducing SSIs following routine neurosurgical procedures in the spine and following adult craniotomies. However, widespread adoption within the pediatric neurosurgical community has not yet occurred, and there are no studies to report on the safety and efficacy of this intervention. The authors present the first institution-wide study of topical vancomycin following open craniotomy in the pediatric population.

METHODS

In this retrospective study the authors reviewed all open craniotomies performed over a period from 05/2014 to 12/2016 for topical vancomycin use, SSIs, and clinical variables associated with SSI. Topical vancomycin was utilized as an infection prophylaxis and was applied as a liquid solution following replacement of a bone flap or after dural closure when no bone flap was reapplied.

RESULTS

Overall, 466 consecutive open craniotomies were completed between 05/2014 and 12/2016, of which 43% utilized topical vancomycin. There was a 1.5% SSI rate in the nontopical cohort versus 0% in the topical vancomycin cohort (p = 0.045). The number needed to treat was 66. There were no significant differences in risk factors for SSI between cohorts. There were no complications associated with topical vancomycin use.

CONCLUSIONS

Routine topical vancomycin administration during closure of open craniotomies can be a safe and effective tool for reducing SSIs in the pediatric neurosurgical population.

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Yuhao Huang, Timothy G. Singer, Michael Iv, Bryan Lanzman, Siddharth Nair, James A. Stadler III, Jia Wang, Michael S. B. Edwards, Gerald A. Grant, Samuel H. Cheshier, and Kristen W. Yeom

OBJECTIVE

Children with intracranial arteriovenous malformations (AVMs) undergo digital DSA for lesion surveillance following their initial diagnosis. However, DSA carries risks of radiation exposure, particularly for the growing pediatric brain and over lifetime. The authors evaluated whether MRI enhanced with a blood pool ferumoxytol (Fe) contrast agent (Fe-MRI) can be used for surveillance of residual or recurrent AVMs.

METHODS

A retrospective cohort was assembled of children with an established AVM diagnosis who underwent surveillance by both DSA and 3-T Fe-MRI from 2014 to 2016. Two neuroradiologists blinded to the DSA results independently assessed Fe-enhanced T1-weighted spoiled gradient recalled acquisition in steady state (Fe-SPGR) scans and, if available, arterial spin labeling (ASL) perfusion scans for residual or recurrent AVMs. Diagnostic confidence was examined using a Likert scale. Sensitivity, specificity, and intermodality reliability were determined using DSA studies as the gold standard. Radiation exposure related to DSA was calculated as total dose area product (TDAP) and effective dose.

RESULTS

Fifteen patients were included in this study (mean age 10 years, range 3–15 years). The mean time between the first surveillance DSA and Fe-MRI studies was 17 days (SD 47). Intermodality agreement was excellent between Fe-SPGR and DSA (κ = 1.00) but poor between ASL and DSA (κ = 0.53; 95% CI 0.18–0.89). The sensitivity and specificity for detecting residual AVMs using Fe-SPGR were 100% and 100%, and using ASL they were 72% and 100%, respectively. Radiologists reported overall high diagnostic confidence using Fe-SPGR. On average, patients received two surveillance DSA studies over the study period, which on average equated to a TDAP of 117.2 Gy×cm2 (95% CI 77.2–157.4 Gy×cm2) and an effective dose of 7.8 mSv (95% CI 4.4–8.8 mSv).

CONCLUSIONS

Fe-MRI performed similarly to DSA for the surveillance of residual AVMs. Future multicenter studies could further investigate the efficacy of Fe-MRI as a noninvasive alternative to DSA for monitoring AVMs in children.

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Derek Yecies, Katie Shpanskaya, Rashad Jabarkheel, Maryam Maleki, Lisa Bruckert, Samuel H. Cheshier, David Hong, Michael S. B. Edwards, Gerald A. Grant, and Kristen W. Yeom

OBJECTIVE

Posterior fossa syndrome (PFS) is a common complication following the resection of posterior fossa tumors in children. The pathophysiology of PFS remains incompletely elucidated; however, the wide-ranging symptoms of PFS suggest the possibility of widespread cortical dysfunction. In this study, the authors utilized arterial spin labeling (ASL), an MR perfusion modality that provides quantitative measurements of cerebral blood flow without the use of intravenous contrast, to assess cortical blood flow in patients with PFS.

METHODS

A database of medulloblastoma treated at the authors’ institution from 2004 to 2016 was retrospectively reviewed, and 14 patients with PFS were identified. Immediate postoperative ASL for patients with PFS and medulloblastoma patients who did not develop PFS were compared. Additionally, in patients with PFS, ASL following the return of speech was compared with immediate postoperative ASL.

RESULTS

On immediate postoperative ASL, patients who subsequently developed PFS had statistically significant decreases in right frontal lobe perfusion and a trend toward decreased perfusion in the left frontal lobe compared with controls. Patients with PFS had statistically significant increases in bilateral frontal lobe perfusion after the resolution of symptoms compared with their immediate postoperative imaging findings.

CONCLUSIONS

ASL perfusion imaging identifies decreased frontal lobe blood flow as a strong physiological correlate of PFS that is consistent with the symptomatology of PFS. This is the first study to demonstrate that decreases in frontal lobe perfusion are present in the immediate postoperative period and resolve with the resolution of symptoms, suggesting a physiological explanation for the transient symptoms of PFS.

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Katie Shpanskaya, Jennifer L. Quon, Robert M. Lober, Sid Nair, Eli Johnson, Samuel H. Cheshier, Michael S. B. Edwards, Gerald A. Grant, and Kristen W. Yeom

OBJECTIVE

While conventional imaging can readily identify ventricular enlargement in hydrocephalus, structural changes that underlie microscopic tissue injury might be more difficult to capture. MRI-based diffusion tensor imaging (DTI) uses properties of water motion to uncover changes in the tissue microenvironment. The authors hypothesized that DTI can identify alterations in optic nerve microstructure in children with hydrocephalus.

METHODS

The authors retrospectively reviewed 21 children (< 18 years old) who underwent DTI before and after neurosurgical intervention for acute obstructive hydrocephalus from posterior fossa tumors. Their optic nerve quantitative DTI metrics of mean diffusivity (MD) and fractional anisotropy (FA) were compared to those of 21 age-matched healthy controls.

RESULTS

Patients with hydrocephalus had increased MD and decreased FA in bilateral optic nerves, compared to controls (p < 0.001). Normalization of bilateral optic nerve MD and FA on short-term follow-up (median 1 day) after neurosurgical intervention was observed, as was near-complete recovery of MD on long-term follow-up (median 1.8 years).

CONCLUSIONS

DTI was used to demonstrate reversible alterations of optic nerve microstructure in children presenting acutely with obstructive hydrocephalus. Alterations in optic nerve MD and FA returned to near-normal levels on short- and long-term follow-up, suggesting that surgical intervention can restore optic nerve tissue microstructure. This technique is a safe, noninvasive imaging tool that quantifies alterations of neural tissue, with a potential role for evaluation of pediatric hydrocephalus.

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Jennifer L. Quon, Michelle Han, Lily H. Kim, Mary Ellen Koran, Leo C. Chen, Edward H. Lee, Jason Wright, Vijay Ramaswamy, Robert M. Lober, Michael D. Taylor, Gerald A. Grant, Samuel H. Cheshier, John R. W. Kestle, Michael S. B. Edwards, and Kristen W. Yeom

OBJECTIVE

Imaging evaluation of the cerebral ventricles is important for clinical decision-making in pediatric hydrocephalus. Although quantitative measurements of ventricular size, over time, can facilitate objective comparison, automated tools for calculating ventricular volume are not structured for clinical use. The authors aimed to develop a fully automated deep learning (DL) model for pediatric cerebral ventricle segmentation and volume calculation for widespread clinical implementation across multiple hospitals.

METHODS

The study cohort consisted of 200 children with obstructive hydrocephalus from four pediatric hospitals, along with 199 controls. Manual ventricle segmentation and volume calculation values served as “ground truth” data. An encoder-decoder convolutional neural network architecture, in which T2-weighted MR images were used as input, automatically delineated the ventricles and output volumetric measurements. On a held-out test set, segmentation accuracy was assessed using the Dice similarity coefficient (0 to 1) and volume calculation was assessed using linear regression. Model generalizability was evaluated on an external MRI data set from a fifth hospital. The DL model performance was compared against FreeSurfer research segmentation software.

RESULTS

Model segmentation performed with an overall Dice score of 0.901 (0.946 in hydrocephalus, 0.856 in controls). The model generalized to external MR images from a fifth pediatric hospital with a Dice score of 0.926. The model was more accurate than FreeSurfer, with faster operating times (1.48 seconds per scan).

CONCLUSIONS

The authors present a DL model for automatic ventricle segmentation and volume calculation that is more accurate and rapid than currently available methods. With near-immediate volumetric output and reliable performance across institutional scanner types, this model can be adapted to the real-time clinical evaluation of hydrocephalus and improve clinician workflow.