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Guillermo Aldave

Craniopharyngioma represents one of the most challenging brain tumors to treat. Surgery may be the definitive treatment, and multiple surgical approaches have been described, each based on different anatomical considerations. Some approaches require working through narrow corridors that do not often provide a sufficient view of the critical anatomical structures around the tumor. The choice of the right approach is key for optimizing resection and minimizing risk. In this paper, the author presents the case of a pediatric patient with a large suprasellar craniopharyngioma who underwent complete resection of the tumor through a novel approach: a transcallosal translamina terminalis corridor. This particular transcallosal corridor, behind the anterior communicating artery, allows the optimal opening of the lamina terminalis extending up to the anterior commissure. This novel variation of the traditional operation provides a wider exposure of the tumor compared with the classic approaches through the lamina terminalis. This technique has not been sufficiently described in the pediatric literature. The author describes it here as an alternative method for treating patients with sellar and suprasellar tumors.

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Guillermo Aldave

The safe entry zones into the brainstem provide access to challenging lesions in this region that do not reach the surface. However, in large brainstem tumors there are two issues to bear in mind before deciding the approach. First, the anatomy can be distorted, and it can be difficult to recognize the entry zone. Second, for large brainstem lesions it may be challenging to address the whole tumor from only one zone and combined approaches may be required. Thus, we show a combined approach, infratentorial supracerebellar and telovelar transventricular, to remove a large brainstem tumor. Appropriate consent was obtained.

The video can be found here: https://youtu.be/nCcG9zPq7ug.

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Guillermo Aldave, Daniel Hansen, Steven W. Hwang, Amee Moreno, Valentina Briceño, and Andrew Jea

OBJECTIVE

Tethered cord syndrome is the clinical manifestation of an abnormal stretch on the spinal cord, presumably causing mechanical injury, a compromised blood supply, and altered spinal cord metabolism. Tethered cord release is the standard treatment for tethered cord syndrome. However, direct untethering of the spinal cord carries potential risks, such as new neurological deficits from spinal cord injury, a CSF leak from opening the dura, and retethering of the spinal cord from normal scar formation after surgery. To avoid these risks, the authors applied spinal column shortening to children and transitional adults with primary and secondary tethered cord syndrome and report treatment outcomes. The authors' aim with this study was to determine the safety and efficacy of spinal column shortening for tethered cord syndrome by analyzing their experience with this surgical technique.

METHODS

The authors retrospectively reviewed the demographic and procedural data of children and young adults who had undergone spinal column shortening for primary or secondary tethered cord syndrome.

RESULTS

Seven patients with tethered cord syndrome caused by myelomeningocele, lipomyelomeningocele, and transitional spinal lipoma were treated with spinal column shortening. One patient with less than 24 months of follow-up was excluded from further analysis. There were 3 males and 4 females; the average age at the time was surgery was 16 years (range 8–30 years). Clinical presentations for our patients included pain (in 5 patients), weakness (in 4 patients), and bowel/bladder dysfunction (in 4 patients). Spinal column osteotomy was most commonly performed at the L-1 level, with fusion between T-12 and L-2 using a pedicle screw-rod construct. Pedicle subtraction osteotomy was performed in 6 patients, and vertebral column resection was performed in 1 patient. The average follow-up period was 31 months (range 26–37 months). Computed tomography–based radiographic outcomes showed solid fusion and no instrumentation failure in all cases by the most recent follow-up. Five of 7 patients (71%) reported improvement in preoperative symptoms during the follow-up period. The mean differences in initial and most recent Scoliosis Research Society Outcomes Questionnaire and Oswestry Disability Index scores were 0.26 and –13%, respectively; minimum clinically important difference in SRS-22 and ODI were assumed to be 0.4% and –12.8%, respectively.

CONCLUSIONS

Spinal column shortening seems to represent a safe and efficacious alternative to traditional untethering of the spinal cord for tethered cord syndrome.

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Guillermo Aldave, Daniel Hansen, Valentina Briceño, Thomas G. Luerssen, and Andrew Jea

OBJECTIVE

The authors previously demonstrated the use of a validated Objective Structured Assessment of Technical Skills (OSATS) tool for evaluating residents' operative skills in pediatric neurosurgery. However, no benchmarks have been established for specific pediatric procedures despite an increased need for meaningful assessments that can either allow for early intervention for underperforming trainees or allow for proficient residents to progress to conducting operations independently with more passive supervision. This validated methodology and tool for assessment of operative skills for common pediatric neurosurgical procedures—external ventricular drain (EVD) placement and shunt surgery— was applied to establish its procedure-based feasibility and reliability, and to document the effect of repetition on achieving surgical skill proficiency in pediatric EVD placement and shunt surgery.

METHODS

A procedure-based technical skills assessment for EVD placements and shunt surgeries in pediatric neurosurgery was established through the use of task analysis. The authors enrolled all residents from 3 training programs (Baylor College of Medicine, Houston Methodist Hospital, and University of Texas–Medical Branch) who rotated through pediatric neurosurgery at Texas Children's Hospital over a 26-month period. For each EVD placement or shunt procedure performed with a resident, the faculty and resident (for self-assessment) completed an evaluation form (OSATS) based on a 5-point Likert scale with 7 categories. Data forms were then grouped according to faculty versus resident (self) assessment, length of pediatric neurosurgery rotation, postgraduate year level, and date of evaluation (“beginning of rotation,” within 1 month of start date; “end of rotation,” within 1 month of completion date; or “middle of rotation”). Descriptive statistical analyses were performed with the commercially available SPSS statistical software package. A p value < 0.05 was considered statistically significant.

RESULTS

Five attending evaluators (including 2 fellows who acted as attending surgeons) completed 260 evaluations. Twenty house staff completed 269 evaluations for self-assessment. Evaluations were completed in 562 EVD and shunt procedures before the surgeons left the operating room. There were statistically significant differences (p < 0.05) between overall attending (mean 4.3) and junior resident (self; mean 3.6) assessments, and between overall attending (mean 4.8) and senior resident (self; mean 4.6) assessment scores on general performance and technical skills. The learning curves produced for the residents demonstrate a stereotypical U- or V-shaped curve for acquiring skills, with a significant improvement in overall scores at the end of the rotation compared with the beginning. The improvement for junior residents (Δ score = 0.5; p = 0.002) was larger than for senior residents (Δ score = 0.2; p = 0.018).

CONCLUSIONS

The OSATS is an effective assessment tool as part of a comprehensive evaluation of neurosurgery residents' performance for specific pediatric procedures. The authors observed a U-shaped learning curve, contradicting the idea that developing one's surgical technique and learning a procedure represents a monotonic, cumulative process of repetitions and improvement.

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Aditya Vedantam, Katie M. Stormes, Nisha Gadgil, Stephen F. Kralik, Guillermo Aldave, and Sandi K. Lam

OBJECTIVE

Resection of posterior fossa tumors in children may be associated with persistent neurological deficits. It is unclear if these neurological deficits are associated with persistent structural damage to the cerebellar pathways. The purpose of this research was to define longitudinal changes in diffusion tensor imaging (DTI) metrics in white matter cerebellar tracts and the clinical correlates of these metrics in children undergoing resection of posterior fossa tumors.

METHODS

Longitudinal brain DTI was performed in a cohort of pediatric patients who underwent resection of posterior fossa tumors. Fractional anisotropy (FA) of the superior cerebellar peduncles (SCPs) and middle cerebellar peduncles (MCPs) was measured on preoperative, postoperative, and follow-up DTI. Early postoperative (< 48 hours) and longer-term follow-up neurological deficits (mutism, ataxia, and extraocular movement dysfunction) were documented. Statistical analysis was performed to determine differences in FA values based on presence or absence of neurological deficits. Statistical significance was set at p < 0.05.

RESULTS

Twenty children (mean age 6.1 ± 4.1 years [SD], 12 males and 8 females) were included in this study. Follow-up DTI was performed at a median duration of 14.3 months after surgery, and the median duration of follow-up was 19.7 months. FA of the left SCP was significantly reduced on postoperative DTI in comparison with preoperative DTI (0.44 ± 0.07 vs 0.53 ± 0.1, p = 0.003). Presence of ataxia at follow-up was associated with a persistent reduction in the left SCP FA on follow-up DTI (0.43 ± 0.1 vs 0.55 ± 0.1, p = 0.016). Patients with early postoperative mutism who did not recover at follow-up had significantly decreased FA of the left SCP on early postoperative DTI in comparison with those who recovered (0.38 ± 0.05 vs 0.48 ± 0.06, p = 0.04).

CONCLUSIONS

DTI after resection of posterior fossa tumors in children shows that persistent reduction of SCP FA is associated with ataxia at follow-up.

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Vijay M. Ravindra, Guillermo Aldave, Howard L. Weiner, Timothy Lee, Michael A. Belfort, Magdelena Sanz-Cortes, Jimmy Espinoza, Alireza A. Shamshirsaz, Ahmed A. Nassr, and William E. Whitehead

OBJECTIVE

The Management of Myelomeningocele Study demonstrated that fetal surgery, as compared to postnatal repair, decreases the rate of hydrocephalus and improves expected motor function. However, fetal surgery is associated with significant maternal and neonatal risks including uterine wall dehiscence, prematurity, and fetal or neonatal death. The goal of this study was to provide information about counseling expectant mothers regarding myelomeningocele in the era of fetal surgery.

METHODS

The authors conducted an extensive review of topics pertinent to counseling in the setting of myelomeningocele and introduce a new model for shared decision-making to aid practitioners during counseling.

RESULTS

Expectant mothers must decide in a timely manner among several potential options, namely termination of pregnancy, postnatal surgery, or fetal surgery. Multiple factors influence the decision, including maternal health, fetal heath, financial resources, social support, risk aversion, access to care, family planning, and values. In many cases, it is a difficult decision that benefits from the guidance of a pediatric neurosurgeon.

CONCLUSIONS

The authors review critical issues of prenatal counseling for myelomeningocele and discuss the process of shared decision-making as a framework to aid expectant mothers in choosing the treatment option best for them.

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Arvind C. Mohan, Howard L. Weiner, Carrie A. Mohila, Adekunle Adesina, Murali Chintagumpala, Daniel Curry, Andrew Jea, Jonathan J. Lee, Sandi K. Lam, William E. Whitehead, Robert Dauser, Daniel Yoshor, and Guillermo Aldave

OBJECTIVE

The indication for and timing of surgery for epilepsy associated with low-grade mixed neuronal-glial tumors may be controversial. The purpose of this study was to evaluate the effect of resection and associated variables on epilepsy and on progression-free survival (PFS).

METHODS

A retrospective chart review of patients treated between 1992 and 2016 was conducted to identify individuals with epilepsy and low-grade gliomas or neuronal-glial tumors who underwent resective surgery. Data analyzed included age at epilepsy onset, age at surgery, extent of resection, use of electrocorticography, the number of antiepileptic drugs (AEDs) before and after surgery, the presence of dysplasia, Engel class, histological findings, and PFS. The institutional review board protocol was specifically approved to conduct this study.

RESULTS

A total of 107 patients were identified. The median follow-up was 4.9 years. The most common pathology was dysembryoplastic neuroepithelial tumor (36.4%), followed by ganglioglioma (31.8%). Eighty-four percent of patients had Engel class I outcomes following surgery. Gross-total resection was associated with a higher likelihood of an Engel class I outcome (90%) as compared to subtotal resection (58%) (p = 0.0005). Surgery reduced the AED burden, with 40% of patients requiring no AEDs after surgery (p < 0.0001). Children with neurodevelopmental comorbidities (n = 5) uniformly did not experience seizure improvement following resection (0% vs 83% overall; p < 0.0001). Electrocorticography was used in 33% of cases and did not significantly increase class I outcomes. PFS was 90% at 5 years. Eleven percent of tumors recurred, with subtotal resection more likely to result in recurrence (hazard ratio 5.3, p = 0.02). Histological subtype showed no significant impact on recurrence.

CONCLUSIONS

Gross-total resection was strongly associated with Engel class I outcome and longer PFS. Further studies are needed to elucidate the suitable time for surgery and to identify factors associated with oncological transformation.

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Jonathan Roth, Or Bercovich, Ashton Roach, Francesco T. Mangano, Arvind C. Mohan, Guillermo Aldave, Howard L. Weiner, Ulrich-Wilhelm Thomale, Andreas Schaumann, Shimrit Uliel-Sibony, and Shlomi Constantini

OBJECTIVE

Resection of brain tumors may lead to new-onset seizures but may also reduce seizure rates in patients presenting with seizures. Seizures are seen at presentation in about 24% of patients with brain tumors. For lesional epilepsy in general, early resection is associated with improved seizure control. However, the literature is limited regarding the occurrence of new-onset postoperative seizures, or rates of seizure control in those presenting with seizures, following resections of extratemporal low-grade gliomas (LGGs) in children.

METHODS

Data were collected retrospectively from 4 large tertiary centers for children (< 18 years of age) who underwent resection of a supratentorial extratemporal (STET) LGG. The patients were divided into 4 groups based on preoperative seizure history: no seizures, up to 2 seizures, more than 2 seizures, and uncontrolled or refractory epilepsy. The authors analyzed the postoperative occurrence of seizures and the need for antiepileptic drugs (AEDs) over time for the various subgroups.

RESULTS

The study included 98 children. Thirty patients had no preoperative seizures, 18 had up to 2, 16 had more than 2, and 34 had refractory or uncontrolled epilepsy. The risk for future seizures was higher if the patient had seizures within 1 month of surgery. The risk for new-onset seizures among patients with no seizures prior to surgery was low. The rate of seizures decreased over time for children with uncontrolled or refractory seizures. The need for AEDs was higher in the more active preoperative seizure groups; however, it decreased with time.

CONCLUSIONS

The resection of STET LGGs in children is associated with a low rate of postoperative new-onset epilepsy. For children with preoperative seizures, even with uncontrolled epilepsy, most have a significant improvement in the seizure activity, and many may be weaned off their AEDs.

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Nisha Gadgil, Ganesh Rao, Raymond Sawaya, Daniel Yoshor, Lucia Ruggieri, Natalie Cormier, Daniel J. Curry, William E. Whitehead, Guillermo Aldave, David F. Bauer, Samuel McClugage III, and Howard L. Weiner

Texas Children’s Hospital opened its doors in 1954, and since that time the institution has remained dedicated to a three-part mission: patient care, education, and research. Dr. William R. Cheek developed an early interest in pediatric neurosurgery, which led to his efforts in building and developing a service at Texas Children’s Hospital at a time when the field was just emerging. His work with other early pioneers in the field led to the establishment of organized societies, educational texts, and governing bodies that have led to significant advances in the field over the past 50 years.

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Vijay M. Ravindra, M. Fatih Okcu, Lucia Ruggieri, Thomas S. Frank, Arnold C. Paulino, Susan L. McGovern, Vincent E. Horne, Robert C. Dauser, William E. Whitehead, and Guillermo Aldave

OBJECTIVE

The authors compared survival and multiple comorbidities in children diagnosed with craniopharyngioma who underwent gross-total resection (GTR) versus subtotal resection (STR) with radiation therapy (RT), either intensity-modulated radiation therapy (IMRT) or proton beam therapy (PBT). The authors hypothesized that there are differences between multimodal treatment methods with respect to morbidity and progression-free survival (PFS).

METHODS

The medical records of children diagnosed with craniopharyngioma and treated surgically between February 1997 and December 2018 at Texas Children’s Hospital were reviewed. Surgical treatment was stratified as GTR or STR + RT. RT was further stratified as PBT or IMRT; PBT was stratified as STR + PBT versus cyst decompression (CD) + PBT. The authors used Kaplan-Meier analysis to compare PFS and overall survival, and chi-square analysis to compare rates for hypopituitarism, vision loss, and hypothalamic obesity (HyOb).

RESULTS

Sixty-three children were included in the analysis; 49% were female. The mean age was 8.16 years (95% CI 7.08–9.27). Twelve of 14 children in the IMRT cohort underwent CD. The 5-year PFS rates were as follows: 73% for GTR (n = 31), 54% for IMRT (n = 14), 100% for STR + PBT (n = 7), and 77% for CD + PBT (n = 11; p = 0.202). The overall survival rates were similar in all groups. Rates of hypopituitarism (96% GTR vs 75% IMRT vs 100% STR + PBT, 50% CD + PBT; p = 0.023) and diabetes insipidus (DI) (90% GTR vs 61% IMRT vs 85% STR + PBT, 20% CD + PBT; p = 0.004) were significantly higher in the GTR group. There was no significant difference in the HyOb or vision loss at the end of study follow-up among the different groups. Within the PBT group, 2 patients presented a progressive vasculopathy with subsequent strokes. One patient experienced a PBT-induced tumor.

CONCLUSIONS

GTR and CD + PBT presented similar rates of 5-year PFS. Hypopituitarism and DI rates were higher with GTR, but the rate of HyOb was similar among different treatment modalities. PBT may reduce the burden of hypopituitarism and DI, although radiation carries a risk of potential serious complications, including progressive vasculopathy and secondary malignancy. Further prospective study comparing neurocognitive outcomes is necessary.