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Vijay M. Ravindra, Rajiv R. Iyer, Al-Wala Awad, Robert J. Bollo, Huirong Zhu and Douglas L. Brockmeyer

OBJECTIVE

The authors’ objective was to better understand the anatomical load-bearing relationship between the atlantooccipital joint and the upper cervical spine and its influence on the clinical behavior of patients with Chiari malformation type I (CM-I) and craniocervical pathology.

METHODS

In a single-center prospective study of patients younger than 18 years with CM-I from 2015 through 2017 (mean age 9.91 years), the authors measured the occipital condyle–C2 sagittal vertebral alignment (C–C2SVA; defined as the position of a plumb line from the midpoint of the occiput (C0)–C1 joint relative to the posterior aspect of the C2–3 disc space), the pB–C2 (a line perpendicular to a line from the basion to the posteroinferior aspect of the C2 body on sagittal MRI), and the CXA (clivoaxial angle). Control data from 30 patients without CM-I (mean age 8.97 years) were used for comparison. The primary outcome was the need for anterior odontoid resection and/or occipitocervical fusion with or without odontoid reduction. The secondary outcome was the need for two or more Chiari-related operations.

RESULTS

Of the 60 consecutive patients with CM-I identified, 7 underwent anterior odontoid resection or occipitocervical fusion and 10 underwent ≥ 2 decompressive procedures. The mean C–C2SVA was greater in the overall CM-I group versus controls (3.68 vs 0.13 mm, p < 0.0001), as was the pB–C2 (7.7 vs 6.4 mm, p = 0.0092); the CXA was smaller (136° vs 148°, p < 0.0001). A C–C2SVA ≥ 5 mm was found in 35% of CM-I children and 3.3% of controls (p = 0.0006). The sensitivities and specificities for requiring ventral decompression/occipitocervical fusion were 100% and 74%, respectively, for C–C2SVA ≥ 5 mm; 71% and 94%, respectively, for CXA < 125°; and 71% and 75%, respectively, for pB–C2 ≥ 9 mm. The sensitivities and specificities for the need for ≥ 2 decompressive procedures were 60% and 70%, respectively, for C–C2SVA ≥ 5 mm; 50% and 94%, respectively, for CXA < 125°; and 60% and 76%, respectively, for pB–C2 ≥ 9 mm. The log-rank test demonstrated significant differences between C–C2SVA groups (p = 0.0007) for the primary outcome. A kappa value of 0.73 for C–C2SVA between raters indicated substantial agreement.

CONCLUSIONS

A novel screening measurement for craniocervical bony relationships, the C–C2SVA, is described. A significant difference in C–C2SVA between CM-I patients and controls was found. A C–C2SVA ≥ 5 mm is highly predictive of the need for occipitocervical fusion/ventral decompression in patients with CM-I. Further validation of this screening measurement is needed.

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Ayguel Wurzer, Georgi Minchev, Claudia Cervera-Martinez, Alexander Micko, Gernot Kronreif and Stefan Wolfsberger

OBJECTIVE

Electromagnetic (EM) navigation provides the advantages of continuous guidance and tip-tracking of instruments. The current solutions for patient reference trackers are suboptimal, as they are either invasively screwed to the bone or less accurate if attached to the skin. The authors present a novel EM reference method with the tracker rigidly but not invasively positioned inside the nasal cavity.

METHODS

The nasal tracker (NT) consists of the EM coil array of the AxiEM tracker plugged into a nasal tamponade, which is then inserted into the inferior nasal meatus. Initially, a proof-of-concept study was performed on two cadaveric skull bases. The stability of the NT was assessed in simulated surgical situations, for example, prone, supine, and lateral patient positioning and skin traction. A deviation ≤ 2 mm was judged sufficiently accurate for clinical trial. Thus, a feasibility study was performed in the clinical setting. Positional changes of the NT and a standard skin-adhesive tracker (ST) relative to a ground-truth reference tracker were recorded throughout routine surgical procedures. The accuracy of the NT and ST was compared at different stages of surgery.

RESULTS

Ex vivo, the NT proved to be highly stable in all simulated surgical situations (median deviation 0.4 mm, range 0.0–2.0 mm). In 13 routine clinical cases, the NT was significantly more stable than the ST (median deviation at procedure end 1.3 mm, range 0.5–3.0 mm vs 4.0 mm, range 1.2–11.2 mm, p = 0.002). The loss of accuracy of the ST was highest during draping and flap fixation.

CONCLUSIONS

Application of the EM endonasal patient tracker was found to be feasible with high procedural stability ex vivo as well as in the clinical setting. This innovation combines the advantages of high precision and noninvasiveness and may, in the future, enhance EM navigation for neurosurgery.

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Nikhil Bellamkonda, H. Westley Phillips, Jia-Shu Chen, Alexander M. Tucker, Cassia Maniquis, Gary W. Mathern and Aria Fallah

OBJECTIVE

Rasmussen encephalitis (RE) is a rare inflammatory neurological disorder typically involving one hemisphere and resulting in drug-resistant epilepsy and progressive neurological decline. Here, the authors present seizure outcomes in children who underwent epilepsy surgery for RE at a single institution.

METHODS

The records of consecutive patients who had undergone epilepsy surgery for RE at the UCLA Mattel Children’s Hospital between 1982 and 2018 were retrospectively reviewed. Basic demographic information, seizure history, procedural notes, and postoperative seizure and functional outcome data were analyzed.

RESULTS

The cohort included 44 patients, 41 of whom had sufficient data for analysis. Seizure freedom was achieved in 68%, 48%, and 22% of the patients at 1, 5, and 10 years, respectively. The median time to the first seizure for those who experienced seizure recurrence after surgery was 39 weeks (IQR 11–355 weeks). Anatomical hemispherectomy, as compared to functional hemispherectomy, was independently associated with a longer time to postoperative seizure recurrence (HR 0.078, p = 0.03). There was no statistically significant difference in postoperative seizure recurrence between patients with complete hemispherectomy and those who had less-than-hemispheric surgery. Following surgery, 68% of the patients could ambulate and 84% could speak regardless of operative intervention.

CONCLUSIONS

A large proportion of RE patients will have seizure relapse after surgery, though patients with anatomical hemispherectomies may have a longer time to postoperative seizure recurrence. Overall, the long-term data in this study suggest that hemispheric surgery can be seen as palliative treatment for seizures rather than a cure for RE.

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Shih-Shan Lang, Amber Valeri, Bingqing Zhang, Phillip B. Storm, Gregory G. Heuer, Lauren Leavesley, Richard Bellah, Chong Tae Kim, Heather Griffis, Todd J. Kilbaugh and Jimmy W. Huh

OBJECTIVE

Head of bed (HOB) elevation to 30° after severe traumatic brain injury (TBI) has become standard positioning across all age groups. This maneuver is thought to minimize the risk of elevated ICP in the hopes of decreasing cerebral blood and fluid volume and increasing cerebral venous outflow with improvement in jugular venous drainage. However, HOB elevation is based on adult population data due to a current paucity of pediatric TBI studies regarding HOB management. In this prospective study of pediatric patients with severe TBI, the authors investigated the role of different head positions on intracranial pressure (ICP), cerebral perfusion pressure (CPP), and cerebral venous outflow through the internal jugular veins (IJVs) on postinjury days 2 and 3 because these time periods are considered the peak risk for intracranial hypertension.

METHODS

Patients younger than 18 years with a Glasgow Coma Scale score ≤ 8 after severe TBI were prospectively recruited at a single quaternary pediatric intensive care unit. All patients had an ICP monitor placed, and no other neurosurgical procedure was performed. On the 2nd and 3rd days postinjury, the degree of HOB elevation was varied between 0° (head-flat or horizontal), 10°, 20°, 30°, 40°, and 50° while ICP, CPP, and bilateral IJV blood flows were recorded.

RESULTS

Eighteen pediatric patients with severe TBI were analyzed. On each postinjury day, 13 of the 18 patients had at least 1 optimal HOB position (the position that simultaneously demonstrated the lowest ICP and the highest CPP). Six patients on each postinjury day had 30° as the optimal HOB position, with only 2 being the same patient on both postinjury days. On postinjury day 2, 3 patients had more than 1 optimal HOB position, while 5 patients did not have an optimal position. On postinjury day 3, 2 patients had more than 1 optimal HOB position while 5 patients did not have an optimal position. Interestingly, 0° (head-flat or horizontal) was the optimal HOB position in 2 patients on postinjury day 2 and 3 patients on postinjury day 3. The optimal HOB position demonstrated lower right IJV blood flow than a nonoptimal position on both postinjury days 2 (p = 0.0023) and 3 (p = 0.0033). There was no significant difference between optimal and nonoptimal HOB positions in the left IJV blood flow.

CONCLUSIONS

In pediatric patients with severe TBI, the authors demonstrated that the optimal HOB position (which decreases ICP and improves CPP) is not always at 30°. Instead, the optimal HOB should be individualized for each pediatric TBI patient on a daily basis.

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Jacob A. Kahn, Jeffrey T. Waltz, Ramin M. Eskandari, Cynthia T. Welsh and Michael U. Antonucci

The authors report an unusual presentation of juvenile xanthogranuloma (JXG), a non–Langerhans cell histiocytosis of infancy and early childhood. This entity typically presents as a cutaneous head or neck nodule but can manifest with more systemic involvement including in the central nervous system. However, currently there is limited information regarding specific imaging features differentiating JXG from other neuropathological entities, with diagnosis typically made only after tissue sampling. The authors reviewed the initial images of a young patient with shunt-treated hydrocephalus and enlarging, chronic, extraaxial processes presumed to reflect subdural collections from overshunting, and they examine the operative discovery of a mass lesion that was pathologically proven to be JXG. Their results incorporate the important associated histological and advanced imaging features, including previously unreported metabolic activity on FDG PET. Ultimately, the case underscores the need to consider JXG in differential diagnoses of pediatric intracranial masses and highlights the potential role of PET in the initial diagnosis and response to treatment.

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Shujhat Khan, Ismail Anwar and Rafiullah Akberzai

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Ignazio G. Vetrano and Vittoria Nazzi

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Scott L. Zuckerman, Natalie Limoges, Aaron M. Yengo-Kahn, Christopher S. Graffeo, Lola B. Chambless, Rohan Chitale, J Mocco and Susan Durham

OBJECTIVE

Residency interviews are integral to the recruitment process yet imperfect. Through surveys of neurosurgery residency applicants, the authors describe interview content and the perceived utility and stress of topics from the applicant’s perspective.

METHODS

All 2018–2019 neurosurgery resident applicants applying to three particular programs were surveyed. Across 10 interview topics, survey questions assessed topic frequency and the applicant’s opinion of the utility and stress of each topic (Likert scale 1–5). Analyses included descriptive statistics, Spearman’s rank correlation, and logistic regression.

RESULTS

One hundred thirty-three of 265 surveyed US residency applicants (50%) responded. Extracurricular activities, research, future career, non-medicine interests, and small talk were discussed in all interviews. The least frequent topics included neurosurgical knowledge assessment (79%) and manual dexterity tests (45%). The most useful topics according to respondents were future career objectives (4.78 ± 0.49) and prior research (4.76 ± 0.50); the least useful were neurosurgical knowledge assessment (2.67 ± 1.09) and manual dexterity tests (2.95 ± 1.05). The most stressful topics were neurosurgical knowledge assessment (3.66 ± 1.23) and ethical/behavioral scenarios (2.94 ± 1.28). The utility and stress of manual dexterity tests and neurosurgical knowledge assessments were inversely correlated (r = −0.40, p < 0.01; r = −0.36, p < 0.01), whereas no such correlation existed for ethical/behavioral questions (r = −0.12, p = 0.18), indicating that ethical/behavioral questions may have been stressful but were potentially useful topics. Respondents who attended ≥ 15 interviews were more likely to be asked about the three most stressful topics (each p < 0.05). Respondents with children were less likely to be asked about ethical/behavioral scenarios (OR 0.13, 95% CI 0.03–0.52, p < 0.01).

CONCLUSIONS

Applicants found several of the most frequently discussed topics to be less useful, indicating a potential disconnect between applicant opinion and the faculty’s preferred questions. Ethical/behavioral scenarios were rated as stressful but still useful, representing a potentially worthwhile type of question. These data provide several avenues for potential standardization and improvement of the interview process.

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Feifei Zhou, Shuyang Li, Yanbin Zhao, Yilong Zhang, Kevin L. Ju, Fengshan Zhang, Shengfa Pan and Yu Sun

OBJECTIVE

The authors aimed to identify factors that may be useful for quantifying the amount of degenerative change in preoperative patients to identify ideal candidates for cervical disc replacement (CDR) in patients with a minimum of 10 years of follow-up data.

METHODS

During the period from December 2003 to August 2008, 54 patients underwent CDR with a Bryan cervical disc prosthesis performed by the same group of surgeons, and all of the patients in this group with at least 10 years of follow-up data were enrolled in this retrospective analysis of cases. Postoperative bone formation was graded in radiographic images by using the McAfee classification for heterotopic ossification. Preoperative degeneration was evaluated in radiographs based on a quantitative scoring system. After univariate analysis, the authors performed multifactor logistic regression analysis to identify significant factors. To determine the cutoff points for the significant factors, a receiver operating characteristic (ROC) curve analysis was conducted.

RESULTS

Study patients had a mean age of 43.6 years and an average follow-up period of 120.3 months. The patients as a group had a 68.2% overall incidence of bone formation. Based on univariate analysis results, data for patient sex, disc height, and the presence of anterior osteophytes and endplate sclerosis were included in the multivariate analysis. According to the analysis results, the identified independent risk factors for postoperative bone formation included disc height, the presence of anterior osteophytes, and endplate sclerosis, and according to a quantitative scoring system for degeneration of the cervical spine based on these variables, the ROC curve indicated that the optimal cutoff scores for these risk factors were 0.5, 1.5, and 1.5, respectively.

CONCLUSIONS

Among the patients who were followed up for at least 10 years after CDR, the incidence of postoperative bone formation was relatively high. The study results indicate that the degree of degeneration in the target level before surgery has a positive correlation with the incidence of postoperative ossification. Rigorous indication criteria for postoperative ossification should be applied in patients for whom CDR may be a treatment option.

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Jeffrey J. Quezada and J. Gordon McComb

OBJECTIVE

The authors sought to determine the reliability of a radiopharmaceutical (RP) shunt flow study for the detection of a CSF-diverting shunt malfunction in the presence of stable ventricular size.

METHODS

After the authors obtained IRB approval, all CSF RP shunt flow studies done between January 1, 2014, and January 1, 2019, in pediatric patients at Children’s Hospital Los Angeles were identified. Included in the study were only those patients in whom an MRI or CT scan was done during the hospital admission for shunt malfunction and showed no increase in ventricular size compared with the most recent prior MRI or CT scan when the patient was asymptomatic. Data recorded for analysis were patient age and sex, etiology of the hydrocephalus, shunt distal site, nonprogrammable versus programmable valve, operative findings if the shunt was revised, and follow-up findings for a minimum of 90 days after admission. The RP shunt flow study consisted of tapping the reservoir and injecting technetium-99m DTPA according to a set protocol.

RESULTS

The authors identified 146 RP flow studies performed in 119 patients meeting the above criteria. Four of the 146 RP studies (3%) were nondiagnostic secondary to technical failure and were excluded from statistical analysis. Of the 112 normal flow studies, operative intervention was not undertaken in 102 (91%). The 10 (9%) remaining normal studies were performed in patients who underwent operative intervention, in which 8 patients had a proximal obstruction, 1 had a distal obstruction, and 1 patient had no obstruction. Of the 30 patients with abnormal flow studies, symptoms of shunt malfunction subsided in 9 (30%) patients and these patients did not undergo operative intervention. Of the 21 (70%) operated patients, obstruction was proximal in 9 patients and distal in 5, and for 7 patients the shunt tubing was either fractured or disconnected. Regression analysis indicated a significant association between the flow study interpretation and the odds for shunt revision (OR 27, 95% CI 10–75, p < 0.0001). No other clinical variables were significant. The sensitivity of a shunt flow study alone for detection of shunt malfunction in cases with stable ventricular size was the same as a shunt flow study plus an MRI or CT (70% vs 70%), but performing a shunt flow in addition to MRI or CT did increase the specificity from 92% to 100% and the accuracy from 87% to 94%.

CONCLUSIONS

RP shunt flow studies were of definite value in deciding whether to operatively intervene in patients with symptoms of shunt malfunction in whom no change in ventricular size was detected on current MRI or CT scans compared to scans obtained when the patients were asymptomatic.