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## Arnold Max Meirowsky: champion of the American mobile neurosurgical unit during the Korean War

Dr. Arnold Max Meirowsky (1910–1984) was enormously influential to military neurosurgery during the Korean War, introducing to the American military the concept of the mobile neurosurgical unit. After implementation of the neurosurgical detachment, meningocerebral infections saw a decrease from 41% to less than 1%, with similar improvements in mortality and complication rates. Additionally, Meirowsky developed many techniques and improvements in neurosurgery, specifically in the field of neurosurgical trauma, which he dedicated himself to even after reentering civilian practice. Furthermore, his mentorship of Korean surgeons and the influence of his mobile neurosurgical unit were major influences cited to be pivotal to the founding of neurosurgery as a specialty in South Korea. As he is underrecognized for these accomplishments in the neurosurgical literature, the authors seek to review his wartime and career contributions. They also specifically present details of his standardization of the mobile neurosurgical unit and showcase several of his other advancements in the treatment of neurosurgical trauma.

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## Socioeconomic and demographic factors in the diagnosis and treatment of Chiari malformation type I and syringomyelia

### OBJECTIVE

The goal of this study was to assess the social determinants that influence access and outcomes for pediatric neurosurgical care for patients with Chiari malformation type I (CM-I) and syringomyelia (SM).

### METHODS

The authors used retro- and prospective components of the Park-Reeves Syringomyelia Research Consortium database to identify pediatric patients with CM-I and SM who received surgical treatment and had at least 1 year of follow-up data. Race, ethnicity, and insurance status were used as comparators for preoperative, treatment, and postoperative characteristics and outcomes.

### RESULTS

A total of 637 patients met inclusion criteria, and race or ethnicity data were available for 603 (94.7%) patients. A total of 463 (76.8%) were non-Hispanic White (NHW) and 140 (23.2%) were non-White. The non-White patients were older at diagnosis (p = 0.002) and were more likely to have an individualized education plan (p < 0.01). More non-White than NHW patients presented with cerebellar and cranial nerve deficits (i.e., gait ataxia [p = 0.028], nystagmus [p = 0.002], dysconjugate gaze [p = 0.03], hearing loss [p = 0.003], gait instability [p = 0.003], tremor [p = 0.021], or dysmetria [p < 0.001]). Non-White patients had higher rates of skull malformation (p = 0.004), platybasia (p = 0.002), and basilar invagination (p = 0.036). Non-White patients were more likely to be treated at low-volume centers than at high-volume centers (38.7% vs 15.2%; p < 0.01). Non-White patients were older at the time of surgery (p = 0.001) and had longer operative times (p < 0.001), higher estimated blood loss (p < 0.001), and a longer hospital stay (p = 0.04). There were no major group differences in terms of treatments performed or complications. The majority of subjects used private insurance (440, 71.5%), whereas 175 (28.5%) were using Medicaid or self-pay. Private insurance was used in 42.2% of non-White patients compared to 79.8% of NHW patients (p < 0.01). There were no major differences in presentation, treatment, or outcome between insurance groups. In multivariate modeling, non-White patients were more likely to present at an older age after controlling for sex and insurance status (p < 0.01). Non-White and male patients had a longer duration of symptoms before reaching diagnosis (p = 0.033 and 0.004, respectively).

### CONCLUSIONS

Socioeconomic and demographic factors appear to influence the presentation and management of patients with CM-I and SM. Race is associated with age and timing of diagnosis as well as operating room time, estimated blood loss, and length of hospital stay. This exploration of socioeconomic and demographic barriers to care will be useful in understanding how to improve access to pediatric neurosurgical care for patients with CM-I and SM.

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## Hydrocephalus surveillance following shunt placement or endoscopic third ventriculostomy: a survey of surgeons in the Hydrocephalus Clinical Research Networks

### OBJECTIVE

Late failure is a well-documented complication of cerebrospinal fluid shunt placement and, less commonly, endoscopic third ventriculostomy (ETV). However, standards regarding the frequency of clinical and radiological follow-up in these patients have not been defined. Here, the authors report on their survey of surgeons at sites for the Hydrocephalus Clinical Research Network (HCRN) or its implementation/quality improvement arm (HCRNq) to provide a cross-sectional overview of practice patterns.

### METHODS

A 24-question survey was developed using the Research Electronic Data Capture (REDCap) platform and was distributed to the 138 pediatric neurosurgeons across 39 centers who participate in the HCRN or HCRNq. Survey questions were organized into three sections: 1) Demographics (5 questions), 2) Shunt Surveillance (12 questions), and 3) ETV Surveillance (7 questions).

### RESULTS

A total of 122 complete responses were obtained, for an overall response rate of 88%. The majority of respondents have been in practice for more than 10 years (58%) and exclusively treat pediatric patients (79%). Most respondents consider hydrocephalus to have stabilized 1 month (21%) or 3 months (39%) after shunt surgery, and once stability is achieved, 72% then ask patients to return for routine clinical follow-up annually. Overall, 83% recommend lifelong clinical follow-up after shunt placement. Additionally, 75% obtain routine imaging studies in asymptomatic patients, although the specific imaging modality and frequency of imaging vary. The management of an asymptomatic increase in ventricle size or an asymptomatic catheter fracture also varies widely. Many respondents believe that hydrocephalus takes longer to stabilize after ETV than after shunt placement, reporting that they consider hydrocephalus to have stabilized 3 (28%), 6 (33%), or 12 (28%) months after an ETV. Although 68% of respondents have patients return annually for routine clinical follow-up after an ETV, only 56% recommend lifelong follow-up. The proportion of respondents who perform lifelong follow-up increases with greater practice experience (p = 0.01). Overall, 67% of respondents obtain routine imaging studies in asymptomatic patients after an ETV, with “rapid” MRI the study of choice for most respondents.

### CONCLUSIONS

While there is a general consensus among pediatric neurosurgeons across North America that hydrocephalus patients should have long-term follow-up after shunt placement, radiological surveillance is characterized by considerable variety, as is follow-up after an ETV. Future work should focus on evaluating whether any one of these surveillance protocols is associated with improved outcomes.

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## Hydrocephalus surveillance following shunt placement or endoscopic third ventriculostomy: a survey of surgeons in the Hydrocephalus Clinical Research Networks

### OBJECTIVE

Late failure is a well-documented complication of cerebrospinal fluid shunt placement and, less commonly, endoscopic third ventriculostomy (ETV). However, standards regarding the frequency of clinical and radiological follow-up in these patients have not been defined. Here, the authors report on their survey of surgeons at sites for the Hydrocephalus Clinical Research Network (HCRN) or its implementation/quality improvement arm (HCRNq) to provide a cross-sectional overview of practice patterns.

### METHODS

A 24-question survey was developed using the Research Electronic Data Capture (REDCap) platform and was distributed to the 138 pediatric neurosurgeons across 39 centers who participate in the HCRN or HCRNq. Survey questions were organized into three sections: 1) Demographics (5 questions), 2) Shunt Surveillance (12 questions), and 3) ETV Surveillance (7 questions).

### RESULTS

A total of 122 complete responses were obtained, for an overall response rate of 88%. The majority of respondents have been in practice for more than 10 years (58%) and exclusively treat pediatric patients (79%). Most respondents consider hydrocephalus to have stabilized 1 month (21%) or 3 months (39%) after shunt surgery, and once stability is achieved, 72% then ask patients to return for routine clinical follow-up annually. Overall, 83% recommend lifelong clinical follow-up after shunt placement. Additionally, 75% obtain routine imaging studies in asymptomatic patients, although the specific imaging modality and frequency of imaging vary. The management of an asymptomatic increase in ventricle size or an asymptomatic catheter fracture also varies widely. Many respondents believe that hydrocephalus takes longer to stabilize after ETV than after shunt placement, reporting that they consider hydrocephalus to have stabilized 3 (28%), 6 (33%), or 12 (28%) months after an ETV. Although 68% of respondents have patients return annually for routine clinical follow-up after an ETV, only 56% recommend lifelong follow-up. The proportion of respondents who perform lifelong follow-up increases with greater practice experience (p = 0.01). Overall, 67% of respondents obtain routine imaging studies in asymptomatic patients after an ETV, with “rapid” MRI the study of choice for most respondents.

### CONCLUSIONS

While there is a general consensus among pediatric neurosurgeons across North America that hydrocephalus patients should have long-term follow-up after shunt placement, radiological surveillance is characterized by considerable variety, as is follow-up after an ETV. Future work should focus on evaluating whether any one of these surveillance protocols is associated with improved outcomes.

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## Resident operative experience in pediatric neurosurgery across the United States

### OBJECTIVE

Neurosurgical residents receive exposure to the subspecialty of pediatric neurosurgery during training. The authors sought to determine resident operative experience in pediatric neurosurgery across Accreditation Council for Graduate Medical Education (ACGME)–accredited neurosurgical programs.

### METHODS

During 2018–2019, pediatric neurosurgical case logs for recent graduates or current residents who completed their primary pediatric exposure were collected from US continental ACGME training programs. Using individual resident reports and procedure designations, operative volumes and case diversity were analyzed collectively, according to training site characteristics, and also correlated with the recently described Resident Experience Score (RES).

### RESULTS

Of the 114 programs, a total of 316 resident case logs (range 1–19 residents per program) were received from 86 (75%) programs. The median cumulative pediatric case volume per resident was 109 (IQR 75–161). Residents at programs with a pediatric fellowship reported a higher median case volume (143, IQR 96–187) than residents at programs without (91, IQR 66–129; p < 0.0001). Residents at programs that outsource their pediatric rotation had a lower median case volume (84, IQR 52–114) compared with those at programs with an in-house experience (117, IQR 79–170; p < 0.0001). The case diversity index among all programs ranged from 0.61 to 0.80, with no statistically significant differences according to the Accreditation Council for Pediatric Neurosurgery Fellowships designation or pediatric experience site (p > 0.05). The RES correlated moderately (r = 0.44) with median operative volumes per program. A program’s annual pediatric operative volume and duration of pediatric experience were identified as significant predictive factors for median resident operative volume.

### CONCLUSIONS

Resident experience in pediatric neurosurgery is variable within and between programs. Case volumes are generally higher for residents at programs with in-house exposure and an accredited fellowship, but case diversity is relatively uniform across all programs. RES provides some insight on anticipated case volume, but other unexplained factors remain.

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## The economic value of an on-call neurosurgical resident physician

### OBJECTIVE

The cost of training neurosurgical residents is especially high considering the duration of training and the technical nature of the specialty. Despite these costs, on-call residents are a source of significant economic value, through both indirectly and directly supervised activities. The authors sought to identify the economic value of on-call services provided by neurosurgical residents.

### METHODS

A personal call log kept by a single junior neurosurgical resident over a 2-year period was used to obtain the total number of consultations, admissions, and procedures. Current Procedural Terminology (CPT) codes were used to estimate the resident’s on-call economic value.

### RESULTS

A single on-call neurosurgical resident at the authors’ institution produced 8172 work relative value units (wRVUs) over the study period from indirectly and directly supervised activities. Indirectly supervised procedures produced 7052 wRVUs, and directly supervised activities using the CPT modifier 80 yielded an additional 1120 wRVUs. Using the assistant surgeon billing rate for directly supervised activities and the Medical Group Management Association nationwide median neurosurgery reimbursement rate, the on-call activities of a single resident generated a theoretical billing value of $689,514 over the 2-year period, or$344,757 annually. As a program, the on-call residents collectively produced 39,550 wRVUs over the study period, or 19,775 wRVUs annually, which equates to potential reimbursements of \$1,668,386 annually.

### CONCLUSIONS

Neurosurgery residents at the authors’ institution theoretically produce enough economic value exclusively from on-call activities to far exceed the cost of their education. This information could be used to more precisely estimate the true overall cost of neurosurgical training and determine future graduate medical education funding.

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## Safety and efficacy of brainstem biopsy in children and young adults

### OBJECTIVE

Biopsies of brainstem lesions are performed to establish a diagnosis in the setting of an atypical clinical or radiological presentation, or to facilitate molecular studies. A better understanding of the safety and diagnostic yield of brainstem biopsies would help guide appropriate patient selection.

### METHODS

All patients who underwent biopsy of a brainstem lesion during the period from January 2011 to June 2019 were reviewed. Demographic, radiological, surgical, and outcome data were collected.

### RESULTS

A total of 58 patients underwent 65 brainstem biopsies during the study period. Overall, the median age was 7.6 years (IQR 3.9–14.2 years). Twenty-two of the 65 biopsies (34%) were open, 42 (65%) were stereotactic, and 1 was endoscopic. In 3 cases (5%), a ventriculoperitoneal shunt was placed, and in 9 cases (14%), a posterior fossa decompression was performed during the same operative session as the biopsy. An intraoperative MRI (iMRI) was performed in 28 cases (43%). In 3 of these cases (11%), the biopsy was off target and additional samples were obtained during the same procedure. New neurological deficits were noted in 5 cases (8%), including sensory deficits, ophthalmoparesis/nystagmus, facial weakness, and hearing loss; these deficits persisted in 2 cases and were transient in 3 cases. A pseudomeningocele occurred in 1 patient; no patients developed a CSF leak or infection. In 8 cases (13%) an additional procedure was needed to obtain a diagnosis.

### CONCLUSIONS

Brainstem biopsies are safe and effective. Target selection and approach should be a collaborative effort. iMRI can be used to assess biopsy accuracy in real time, thereby allowing any adjustment if necessary.

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## Association between supratentorial pediatric high-grade gliomas involved with the subventricular zone and decreased survival: a multi-institutional retrospective study

### OBJECTIVE

The subventricular zone (SVZ), housed in the lateral walls of the lateral ventricles, is the largest neurogenic niche in the brain. In adults, high-grade gliomas in contact or involved with the SVZ are associated with decreased survival. Whether this association holds true in the pediatric population remains unexplored. To address this gap in knowledge, the authors conducted this retrospective study in a pediatric population with high-grade gliomas treated at three comprehensive centers in the United States.

### METHODS

The authors retrospectively identified 63 patients, age ≤ 21 years, with supratentorial WHO grade III–IV gliomas treated at three academic centers. Basic demographic and clinical data regarding presenting signs and symptoms and common treatment variables were obtained. Preoperative MRI studies were evaluated to assess SVZ contact by tumor and to quantify tumor volume.

### RESULTS

Sixty-three patients, including 34 males (54%), had a median age of 12.3 years (IQR 6.50–16.2) and a median tumor volume of 39.4 ml (IQR 19.4–65.8). Tumors contacting the SVZ (SVZ+) were noted in 34 patients (54%) and overall were larger than those not in contact with the SVZ (SVZ−; 51.1 vs 27.3, p = 0.002). The SVZ+ tumors were also associated with decreased survival. However, age, tumor volume, tumor grade, and treatment with chemotherapy and/or radiation were not associated with survival in the 63 patients. In the univariable analysis, near-total resection, gross-total resection, and seizure presentation were associated with increased survival (HR = 0.23, 95% CI 0.06–0.88, p = 0.03; HR = 0.26, 95% CI 0.09–0.74, p = 0.01; and HR = 0.46, 95% CI 0.22–0.97, p = 0.04, respectively). In a multivariable stepwise Cox regression analysis, only SVZ+ tumors remained significantly associated with decreased survival (HR = 1.94, 95% CI 1.03–3.64, p = 0.04).

### CONCLUSIONS

High-grade glioma contact with the SVZ neural stem cell niche was associated with a significant decrease in survival in the pediatric population, as it is in the adult population. This result suggests that tumor contact with the SVZ is a general negative prognosticator in high-grade glioma independent of age group and invites biological investigations to understand the SVZ’s role in glioma pathobiology.

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## A hospital-based analysis of pseudomeningoceles after elective craniotomy in children: what predicts need for intervention?

### OBJECTIVE

In pediatric patients, the development of a postoperative pseudomeningocele after an elective craniotomy is not unusual. Most will resolve with time, but some may require intervention. In this study, the authors analyzed patients who required intervention for a postoperative pseudomeningocele following an elective craniotomy or craniectomy and identified factors associated with the need for intervention.

### METHODS

An institutional operative database of elective craniotomies and craniectomies was queried to identify all surgeries associated with development of a postoperative pseudomeningocele from January 1, 2010, to December 31, 2017. Demographic and surgical data were collected, as were details regarding postoperative events and interventions during either the initial admission or upon readmission. A bivariate analysis was performed to compare patients who underwent observation with those who required intervention.

### RESULTS

Following 1648 elective craniotomies or craniectomies, 84 (5.1%) clinically significant pseudomeningoceles were identified in 82 unique patients. Of these, 58 (69%) of the pseudomeningoceles were diagnosed during the index admission (8 of which persisted and resulted in readmission), and 26 (31%) were diagnosed upon readmission. Forty-nine patients (59.8% of those with a pseudomeningocele) required one or more interventions, such as lumbar puncture(s), lumbar drain placement, wound exploration, or shunt placement or revision. Only race (p < 0.01) and duraplasty (p = 0.03, OR 3.0) were associated with the need for pseudomeningocele treatment.

### CONCLUSIONS

Clinically relevant pseudomeningoceles developed in 5% of patients undergoing an elective craniotomy, with 60% of these pseudomeningoceles needing some form of intervention. The need for intervention was associated with race and whether a duraplasty was performed.