Jeffrey Leonard and Bruce Kaufman
Jeffrey R. Leonard, Dan X. Cai, Dennis J. Rivet, Bruce A. Kaufman, T. S. Park, Beth K. Levy and Arie Perry
Object. Medulloblastoma is the most common malignant central nervous system neoplasm found in children. A distinct variant designated large cell/anaplastic (LC/A) medulloblastoma is characterized by frequent dissemination of cerebrospinal fluid (CSF) at presentation and a more aggressive clinical course. The authors report on their examination of the clinicopathological and genetic features of seven such cases encountered at their institution.
Methods. Eighty cases of medulloblastomas were reviewed and seven (8.8%) of these were believed to fit the histological and immunohistochemical criteria for LC/A medulloblastoma. In three cases (43%) either desmoplastic or classic medulloblastoma was the underlying subtype, and in two cases (28%) the LC/A tumor was found within the setting of medullomyoblastoma. Fluorescence in situ hybridization was used in six of the seven cases to characterize the presence of isochromosome 17q, deletion of chromosome 22q (a deletion characteristically found in atypical teratoid/rhabdoid tumors), and c-myc amplification. The patients' clinical histories revealed CSF dissemination in all cases and lymph node metastasis in one case. Isochromosome 17q was found in five (83%) of six cases. Evidence of chromosomal gains indicated aneuploidy in three tumors (50%), and amplification of c-myc was found in three tumors (50%). No 22q deletions were encountered.
Conclusions. A high percentage of LC/A medulloblastomas arise within a background of typical medulloblastomas or medullomyoblastomas. As is the case in conventional medulloblastomas, the presence of 17q is a common early tumorigenic event; however, in a significant percentage of specimens there is also evidence of aneuploidy and/or amplification of c-myc. These findings indicate that LC/A morphological characteristics reflect a more advanced tumor stage than that found in pure medulloblastomas or in typical medullomyoblastomas.
Case report and review of the literature
William W. Ashley Jr., Prithvi Narayan, Tae Sung Park, Pang-hsien Tu, Arie Perry and Jeffrey R. Leonard
✓Juvenile xanthogranuloma (JXG) is a specialized form of non—Langerhans cell histiocyte proliferation that occurs in children. The majority of cases present as a solitary cutaneous lesion with a predilection for the head and neck region; however, isolated lesions occasionally have been identified in the central nervous system. The cutaneous forms of JXG usually follow a benign course. Other physicians have reported surgery as the first line of treatment in symptomatic patients with accessible lesions. Adjuvant therapies may be indicated for multicentric or surgically inaccessible lesions. The authors describe an unusual case of isolated intraparenchymal JXG in an asymptomatic child with no cutaneous manifestations and provide a review of the literature.
Donncha F. O'Brien, Tae-Sung Park, Joan A. Puglisi, David R. Collins, Eric C. Leuthardt and Jeffrey R. Leonard
A retrospective study was performed to determine the following: 1) whether children who walk independently after selective dorsal rhizotomy (SDR) undergo fewer subsequent orthopedic operations than those who walk with assistance; and 2) the effect of age at SDR on the rate of orthopedic operations.
The cases of 158 children with spastic diplegia who were 2 to 14 years of age when they underwent SDR were followed over a 5- to 9-year period. Patients were grouped by age at the time of SDR as follows: 2 to 3 years (Group 1), 4 to 7 years (Group 2), and 8 to 14 years (Group 3). Follow-up data showed that children in all age groups who walked independently after SDR underwent fewer orthopedic operations than did children who walked with assistance. Overall rates of orthopedic surgery 5 to 9 years after SDR at last follow up were 24% for independent walkers and 51% for assisted walkers. Two-way categorical analysis (age group by ambulation) yielded a highly significant effect of ambulation (p = 0.0003). Children in Group 1 needed the fewest orthopedic operations at follow-up evaluation. In the older age groups (Groups 2 and 3), those who walked independently at the time of SDR underwent fewer orthopedic operations after SDR than did walkers who required assistance (p = 0.01).
These data are of value in advising parents about the likelihood of orthopedic surgery based on the child's gait status both at the time of SDR and at follow-up evaluation. Orthopedic surgery is more likely in patients destined to be nonambulators.
William W. Ashley Jr., Robert C. McKinstry, Jeffrey R. Leonard, Matthew D. Smyth, Benjamin C. Lee and Tae Sung Park
The authors examine the use of rapid-sequence magnetic resonance (rsMR) imaging to make the diagnosis of malfunctioning and/or infected shunts in patients with hydrocephalus. Computerized tomography (CT) scanning is usually used in this context because it rapidly acquires high-quality images, yet it exposes pediatric patients to particularly high levels of radiation. Standard MR imaging requires longer image acquisition time, is associated with movement artifact, and, in children, usually requires sedation. Standard MR imaging provides greater structural resolution, yet visualization of ventricular catheters is relatively poor.
The authors analyzed a series of 67 rsMR imaging examinations performed without sedation in pediatric patients with hydrocephalus whose mean age was 4 years at the time of the examination. The mean study duration was 22 minutes. Catheter visualization was good or excellent in more than 75% of studies reviewed, and image quality was good or excellent in more than 60% of studies reviewed. The authors analyzed cancer risk with a model used for atomic bomb survivors. Fifty percent of their patients with hydrocephalus had undergone more than four brain imaging studies (CT or MR imaging) in their lifetimes. For the many patients who had undergone more than 15 studies, the total estimated lifetime attributable cancer mortality risk was calculated to be at least 0.35%.
Rapid-sequence MR imaging yields reliable visualization of the ventricular catheter and offers superior anatomical detail while limiting radiation exposure. The authors' protocol is rapid and each image is acquired separately; therefore, motion artifact is reduced and the need for sedation is eliminated. They recommend the use of rsMR imaging for nonemergent evaluation of pediatric hydrocephalus.
Francesco T. Mangano, Jose A. Menendez, Tracy Habrock, Prithvi Narayan, Jeffrey R. Leonard, Tae Sung Park and Matthew D. Smyth
The use of adjustable differential pressure valves has been recommended to improve ventriculoperitoneal (VP) shunt performance in selected patients; however, published data are scarce regarding their clinical reliability. Recently, the identification of a number of malfunctioning programmable valves during shunt revision surgery in children prompted a retrospective review of valve performance in this patient cohort.
The authors performed a retrospective chart analysis of 100 patients with programmable valve shunts and 89 patients with nonprogrammable valve shunts implanted at the St. Louis Children's Hospital between April 2002 and June 2004. They noted the cause of hydrocephalus, the type of shunt malfunction, and cerebrospinal fluid (CSF) protein levels. Regular clinical follow up ranged from 1 to 26 months, with a mean follow-up time of 9.75 months for patients with programmable valves and 10.4 months for patients with nonprogrammable valves.
Patient ages ranged from 2 weeks to 18 years. One hundred patients had 117 programmable valves implanted, and 35 of these patients (35%) underwent shunt revision because of malfunction. The programmable valve itself malfunctioned in nine patients who had undergone shunt revision (11.1%/year of follow up). The nonprogrammable valve group had no valve malfunctions. The overall VP shunt revision rate in the nonprogrammable valve group was 20.2%. No significant differences were identified when CSF protein levels and specific malfunction types were compared within the programmable valve and nonprogrammable valve groups.
In this study the authors demonstrated an annualized intrinsic programmable valve malfunction rate of 11.1%, whereas during the same period no intrinsic valve malfunctions were noted with nonprogrammable valve systems for similar causes of hydrocephalus. The CSF protein levels did not correlate with observed valve malfunction rates. Further evaluation in a prospective, randomized fashion will elucidate specific indications for programmable valve systems and better determine the reliability of these valves in the pediatric population.
Nicholas Theodore and Harold L. Rekate
Jeffrey R. Leonard and Neill M. Wright
✓ The authors describe the cases of three children in whom atlantoaxial instability was caused by os odontoideum, all requiring surgical fixation. Although C1–2 rod/cantilever constructs involving C-2 pedicle screws and C1–2 transarticular screws have been widely applied in adults, only C1–2 transarticular screw fixation has been reported in children. Both of these constructs potentially place the vertebral artery (VA) at risk because of the variable location of the transverse foramen. Atlantoaxial fixation with C-2 translaminar screws has recently been reported in adult cases in which the risk of VA injury was reduced. The authors report the successful results of rigid atlantoaxial fixation in three children in whom bilateral crossing C-2 translaminar screws were placed, and they discuss the possible advantages of this technique in the pediatric population.
Francesco T. Mangano, Jose A. Menendez, Matthew D. Smyth, Jeffrey R. Leonard, Prithvi Narayan and Tae Sung Park
All-terrain vehicles (ATVs) have been characterized as inherently unstable and are associated with significant pediatric injuries in the US. The authors performed a study to analyze data obtained in pediatric patients who had sustained neurological injuries in ATV-related accidents, identify potential risk factors, and propose preventive measures. The study is based on a 10-year experience at the St. Louis Children’s Hospital.
The authors retrospectively analyzed data obtained in all patients admitted to the St. Louis Children’s Hospital between 1993 and 2003, limiting their focus to pediatric cases involving ATV-related accidents. A total of 185 patients were admitted with these criteria. Sixty-two patients (33.5%) suffered neurological injuries; there were 42 male and 20 female patients whose age ranged from 2 to 17 years. The most common injuries included skull fracture (37 cases) and closed head injury (30 cases). There were 39 cases of intracranial hemorrhage and 11 of spinal fracture. A total of 15 types of neurosurgical procedure were performed: six craniotomies for hematoma drainage, five craniotomies for elevation of depressed fractures, two procedures to allow placement of an intracranial pressure monitor, one to allow placement of an external ventricular drain, and one to allow the insertion of a ventriculoperitoneal shunt. Two patients had sustained spinal cord injury, and three procedures were performed for spinal decompression or stabilization. The duration of hospital stay ranged from 1 to 143 days (mean 6.6 days). Fifty-seven patients (30.8%) were eventually discharged from the hospital, three (1.6%) were transferred to another hospital, two (1.1%) died, and 123 (66.4%) required in-patient rehabilitation.
Children suffered significant injuries due to ATV accidents. In passengers there was a statistically significant increased risk of neurological injury. The relative risk of neurological injury in patients not wearing helmets was higher than that in those who wore helmets, but the difference did not reach statistical significance. Further efforts must be made to improve the proper operation and safety of ATVs, both through the education of parents and children and through the creation of legislation requiring stricter laws concerning ATV use.
Nathan P. Dean, Susan Boslaugh, P. David Adelson, Jose A. Pineda and Jeffrey R. Leonard
The aim of this study was to evaluate physician agreement with published recommendations and guidelines for the management of severe traumatic brain injury (TBI) in children and to identify markers associated with physician responses matching published guidelines.
An Internet survey was created based on recommendations and guidelines published in 2003 and was sent to US physicians and neurosurgeons caring for pediatric patients with severe TBI. Agreement with each recommendation was tabulated. Characteristics of the surveyed physicians and their institutions were compared to identify markers of conformity with first-tier recommendations (intracranial pressure [ICP] treatment threshold, monitoring cerebral perfusion pressure, use of sedation/neuromuscular blockade, and use of hyperosmolar therapy).
One hundred ninety-four US physicians responded: 36 neurosurgeons and 158 nonsurgeons. Overall, physician responses matched most recommendations more than 60% of the time. The serum osmolality threshold of hypertonic saline, use of prophylactic hyperventilation, and differences in ICP thresholds based on a child's age comprised the recommendations with the least agreement. No physician variable was linked to increased agreement with first-tier recommendations.
Overall, physician responses coincided with the published guidelines and recommendations. Examples of variable conformance most likely reflect the paucity of available data and lack of randomized controlled trials in the field of severe TBI.