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Mark S. Dias

Object

Scoliosis in children with myelomeningocele occurs frequently and is multifactorial in origin. The aim of this paper is to review the evidence regarding the causal association, if any, between isolated scoliosis and spinal cord tethering, Chiari malformation, or syringomyelia in this population.

Methods

A Medline search of the English-language literature from 1966 to 2002 was undertaken. All of the pertinent articles that were identified underwent careful review to determine the strength of the evidence supporting the claim that isolated scoliosis in children with myelomeningocele is related to spinal cord tethering, Chiari malformation, or syringomyelia. The strength of the evidence was graded using the Oxford Centre for Evidence-Based Medicine Levels of Evidence (May 2001). A survey was also sent to practicing pediatric neurosurgeons and the returned responses were evaluated.

Conclusions

All available studies were classified as Level 4 studies (case series and flawed cohort and case-control studies). Based on the strength of the available data, there may be an association between spinal cord tethering and scoliosis, particularly in those patients with upper lumbar lesions and spinal curves less than 45°. There is little evidence to support a causal relationship between scoliosis and Chiari malformation or syringomyelia in this population.

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Mark S. Dias and Michael Partington

The authors review current views on of the embryogenesis of the neural tube defects (NTDs) myelomeningocele and anencephaly. In this context, the following four approaches to the study of NTDs are discussed: normal morphogenesis and timing of early human neural development from conception to the ascent of the conus medullaris; mechanical and molecular biology of neural tube closure derived from experimental and animal models; morphological and biomechanical features of the NTDs myelomeningocele and anencephaly; and the experimental evidence for the importance of both genetic and environmental influences on human NTDs. Although considerable insight into both normal neural tube closure and the factor(s) by which this process may be disrupted has been reported in recent years, the exact mechanism(s) by which human myelomeningoceles and anencephaly arise remain elusive.

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Ann-Christine Duhaime

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John C. Wellons III

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Mark S. Dias, Kim Smith, and Kathy deGuehery

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Amos O. Dare, Mark S. Dias, and Veetai Li

Object. The authors conducted a study to determine correlations between clinical syndromes and early magnetic resonance (MR) imaging—documented findings in children with spinal cord injury without radiographic abnormality (SCIWORA).

Methods. The authors retrospectively reviewed the records obtained in 20 patients who presented with SCIWORA to the Children's Hospital of Buffalo between 1992 and 1999. Initial neurological syndromes, subsequent hospital course and outcome, and early MR imaging findings obtained using conventional sequences on a 1.5-tesla unit were recorded. Neurological syndromes on presentation were complete (Frankel Grade A) in two patients (10%), severe partial (Frankel Grade C) in one patient (5%), and mild partial (Frankel Grade D) in 17 patients (85%). Partial neurological deficits resolved in 14 (78%) of 18 patients within 72 hours and lasted more than 72 hours in four patients (22%). Magnetic resonance imaging was performed in both patients presenting with complete injuries and in 17 of 18 patients presenting with partial neurological deficits. The studies were obtained within 24 hours in 17 patients (85%). Neuroimaging revealed spinal cord swelling at the cervical level in one of the children with complete injury and cord edema with associated hemorrhage at cervical and thoracic levels in the other. Neural and extraneural elements were shown to be normal in all 17 patients with partial injuries who underwent MR imaging, including in the four patients with partial motor deficits lasting more than 72 hours.

Conclusions. In this series, the predominant neurological presentation of SCIWORA was a mild, partial syndrome that resolved within 72 hours. Magnetic resonance imaging revealed abnormal features only in those patients with complete neurological deficits. These findings suggest that in the acute setting conventional MR imaging sequences may lack the sensitivity to demonstrate neural and extraneural abnormalities associated with partial or temporary neurological deficits of SCIWORA, even when those deficits persist beyond 72 hours.

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Mark S. Dias, Jeffrey S. Sussman, Susan Durham, and Mark R. Iantosca

Object

Research suggests that there may be a growing disparity between the supply of and demand for both pediatric specialists and neurosurgeons. Whether pediatric neurosurgeons are facing such a disparity is disputable, but interest in pediatric neurosurgery (PNS) has waxed and waned as evidenced by the number of applicants for PNS fellowships. The authors undertook a survey to analyze current neurosurgical residents' perceptions of both benefits and deterrents to a pediatric neurosurgical career.

Methods

All residents and PNS fellows in the United States and Canada during the academic year 2008–2009 were invited to complete a Web-based survey that assessed 1) demographic and educational information about residents and their residency training, particularly as it related to training in PNS; 2) residents' exposure to mentoring opportunities from pediatric neurosurgical faculty and their plans for the future; and 3) residents' perceptions about how likely 40 various factors were to influence their decision about whether to pursue a PNS career.

Results

Four hundred ninety-six responses were obtained: 89% of the respondents were male, 63% were married, 75% were in at least their 3rd year of postgraduate training, 61% trained in a children's hospital and 29% in a children's “hospital within a hospital,” and 72% were in programs having one or more dedicated PNS faculty members. The residencies of 56% of respondents offered 6–11 months of PNS training and nearly three-quarters of respondents had completed 2 months of PNS training. During medical school, 92% had been exposed to neurosurgery and 45% to PNS during a clinical rotation, but only 7% identified a PNS mentor. Nearly half (43%) are considering a PNS career, and of these, 61% are definitely or probably considering post-residency fellowship. On the other hand, 68% would prefer an enfolded fellowship during residency. Perceived strengths of PNS included working with children, developing lasting relationships, wider variety of operations, fast healing and lack of comorbidities, and altruism. Perceived significant deterrents included shunts, lower reimbursement, cross-coverage issues, higher malpractice premiums and greater legal exposure, and working with parents and pediatric health professionals. The intrinsic nature of PNS was listed as the most significant deterrent (46%) followed by financial concerns (25%), additional training (12%), longer work hours (12%), and medicolegal issues (4%). The majority felt that fellowship training and PNS certification should be recommended for surgeons treating of all but traumatic brain injuries and Chiari I malformations and performing simple shunt-related procedures, although they felt that these credentials should be required only for treating complex craniosynostosis.

Conclusions

The nature of PNS is the most significant barrier to attracting residents, although reimbursement, cross-coverage, and legal issues are also important to residents. The authors provide several recommendations that might enhance resident perceptions of PNS and attract trainees to the specialty.

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Henry Kesler, Mark S. Dias, and Paul Kalapos

Object

The mean level of the conus medullaris (CM) has been estimated to lie opposite the L1/2 disc space in several previous studies using ultrasound, CT myelography, and magnetic resonance (MR) imaging, but these studies have been limited in examining only the lumbar spine and including patients being evaluated for back pain and sciatica (creating a selection bias). Moreover, significant variability was found in the termination of the CM, with a small subset of subjects having a CM as low as the mid-body of L4. The authors sought to determine the normal level of the CM and its variability.

Methods

Children with brain or spinal cord tumors who underwent whole-spine surveillance MR imaging were identified retrospectively. The level of the CM was identified in each subject by counting down from C1. Vertebral anomalies, such as lumbarized S1, sacralized L5, or fewer rib-bearing segments, and the presence of fatty filum were noted.

Results

Findings regarding the level of termination of the CM were tightly grouped; the average was at the lower third of L1 and the mode of the distribution was at the L1/2 disc space, with very little variation. No CM ended below the mid-body of L2. The level of the CM was not significantly different among individuals with lumbarized or sacralized vertebrae or 11 rib-bearing segments.

Conclusions

The CM terminates most commonly at the L1–2 disc space and in the absence of tethering, the CM virtually never ends below the mid-body of L2. A CM that appears more caudal on neuroimages should be considered tethered.

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Mark S. Dias, Michele L. Shaffer, Mark R. Iantosca, and Kenneth L. Hill Jr.

Object

The thresholds for shunting CSF in children with asymptomatic hydrocephalus are unclear; there are neither guidelines nor sufficient research to determine what degree of hydrocephalus should be treated. The authors hypothesize that 1) pediatric neurosurgeons currently have high thresholds for recommending treatment for these children, but 2) there is significant variability among these treatment thresholds.

Methods

The authors surveyed attendees of the Joint Pediatric Neurosurgery Section meeting in Spokane, Washington, in December 2008, regarding their treatment thresholds for 22 clinical scenarios. Each participant was provided an illustration of 5 imaging studies (3 slices each) showing progressively larger ventricles. For each scenario, respondents were asked to indicate the minimum ventricular size they would treat, if any. Responses were quantified from 1 to 6 from smaller to larger, with 6 being no treatment, and a mean theoretical treated ventricular size (MTTVS) was calculated for each scenario.

Results

Respondents were relatively conservative in recommending treatment, with MTTVSs of 3.7–6.0; in 13 scenarios, the MTTVS was greater than 5.0 (larger than the largest presented ventricular size). For scenarios in which a mean frontooccipital ratio could be calculated, the value ranged from 0.55 to 0.67 (moderate to severe hydrocephalus). Although there were clear majority responses for each scenario, there was also significant variability. There were no patterns of association with the respondent's age, training, board certification, or type or location of practice.

Conclusions

This study demonstrates that pediatric neurosurgeons' thresholds for treating asymptomatic children with hydrocephalus are generally high, but there is also significant variability.

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Ray Bradford, Arabinda K. Choudhary, and Mark S. Dias

Object

The appearance and evolution of neuroimaging abnormalities following abusive head trauma (AHT) is important for establishing the time frame over which these injuries might have occurred. From a legal perspective this frames the timing of the abuse and therefore identifies and excludes potential perpetrators. A previous pilot study involving 33 infants with AHT helped to refine the timing of these injuries but was limited by its small sample size. In the present study, the authors analyzed a larger group of 210 cases involving infants with AHT to chronicle the first appearance and evolution of radiological (CT, MRI) abnormalities.

Methods

All children younger than 24 months admitted to the Penn State Hershey Medical Center with AHT over a 10-year period were identified from a medical record review; the time of injury was determined through an evaluation of the clinical records. All imaging studies were analyzed, and the appearance and evolution of abnormalities were chronicled on serial neuroimaging studies obtained in the days and weeks after injury.

Results

One hundred five infants with specific injury dates and available imaging studies were identified; a subset of 43 children additionally had documented times of injury. In infants with homogeneously hyperdense subdural hematomas (SDHs) on initial CT scans, the first hypodense component appeared within the SDH between 0.3 and 16 days after injury, and the last hyperdense subdural component disappeared between 2 and 40 days after injury. In infants with mixed-density SDHs on initial scans, the last hyperdense component disappeared between 1 and 181 days. Parenchymal hypodensities appeared on CT scans performed as early as 1.2 hours, and all were visible within 27 hours after the injury. Rebleeding into SDHs was documented in 17 cases (16%) and was always asymptomatic.

Magnetic resonance imaging of the brain was performed in 49 infants. Among those with SDH, 5 patterns were observed. Patterns I and II reflected homogeneous SDH; Pattern I (T1 hyperintensity and T2/FLAIR hypointensity, “early subacute”) more commonly appeared on scans performed earlier after injury compared with Pattern II (T1 hyperintensity and T2/FLAIR hyperintensity, “late subacute”), although there was considerable overlap. Patterns III and IV reflected heterogeneous SDH; Pattern III contained relatively equal mixtures having different intensities, whereas Pattern IV had fluid that was predominantly T1 hypointense and T2/FLAIR hyperintense. Again, Pattern III more commonly appeared on scans performed earlier after injury compared with Pattern IV, although there was significant overlap.

Conclusions

These data extend the preliminary data reported by Dias and colleagues and provide a framework upon which injuries in AHT can be timed as well as the limitations on such timing estimates.