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Jeffrey R Leonard

Publications and source records attributed to Jeffrey R Leonard.

11 recordsLinked to original sources
PubMed2006

Simultaneous image-guided and endoscopic navigation without rigid cranial fixation: application in infants: technical case report.

OBJECTIVE AND IMPORTANCE: Infants and young children demonstrate a variety of intraventricular and periventricular lesions. Endoscopy has proven useful in the treatment of many of these lesions, but its benefit is limited if it is applied to complex loculated cysts or if the disease is concealed by normal ependymal boundaries. In adults and older children, endoscopy can be augmented by the simultaneous use of frameless stereotaxy, but this combined modality has not been possible in infants and young children without rigid cranial fixation. We describe a method of achieving simultaneous stereotactic and endoscopic navigation in infants and young children by using a pinless, frameless stereotactic assembly. CLINICAL PRESENTATION: The first patient was a 6-week-old boy with macrocephaly and a bulging fontanelle. Computed tomographic and magnetic resonance imaging revealed a complex arachnoid cyst and obstructive hydrocephalus. The second patient was a 7-month-old, ex-premature (27-wk gestational age) boy who developed posthemorrhagic hydrocephalus. He underwent multiple shunt revisions, one of which was complicated by enterococcal ventriculitis. Despite bilateral ventriculoperitoneal shunts, he developed increasing head circumference, listlessness, and irritability. Imaging revealed an enlarged, multiloculated, and asymmetric ventricular system. INTERVENTION: Simultaneous image-guided and endoscopic neuronavigation was implemented in both patients. Before the procedure, a cranial reference arc was secured to the outer table of the cranium through a small incision adjacent to the operative field. After the stereotactic apparatus was registered, the software was used to plan a trajectory for the approach. A burr hole was then made, and a rigid 6-mm endoscope was inserted for direct visualization. Once advanced past the endoscopic port tip, the electromagnetic coil stylet was used to stereotactically track position and identify areas for fenestration, biopsy, and catheter insertion. CONCLUSION: Endoscopic views of complex hydrocephalus and arachnoid cysts alone are often difficult to interpret. Simultaneous image-guided and endoscopic neuronavigation may be advantageous in the management of complex cases that are anatomically related to the ventricular system in infants for whom rigid cranial fixation could lead to increased procedure-related morbidity.

Brain Diseases↗
PubMed2006

Pediatric atlantoaxial fixation with bilateral, crossing C-2 translaminar screws. Technical note.

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.

Adolescent↗
PubMed2006

Pediatric neurosurgical injuries associated with all-terrain vehicle accidents: a 10-year experience at St. Louis Children's Hospital.

OBJECT: 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. METHODS: 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. CONCLUSIONS: 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.

Adolescent↗
PubMed2005

The efficacy of radiation therapy in the management of grade I astrocytomas.

INTRODUCTION: The purpose of this study was to analyze the outcome of patients with grade I astrocytomas treated with radiation therapy, specifically looking at the prognostic significance of age, timing of radiation therapy (immediately after surgery or delayed until progression) and tumor location. MATERIALS AND METHODS: The records of patients with grade I astrocytomas treated at Washington University Medical Center between 1982 and 2002 were reviewed. Twenty patients with grade I pilocytic astrocytoma (n=19) or subependymal giant cell astrocytoma (n=1) were treated with radiation therapy with curative intent. RESULTS: The median follow-up was 6.4 years. The 5-year overall survival for all patients was 100%. The 5-year progression-free survival (PFS) following radiation therapy for all patients was 68%. Patients who received radiation therapy immediately after biopsy or surgery had a 5-year PFS of 77% versus 50% for patients who received radiation therapy after initial disease progression (P=0.013). Patients with infratentorial tumors had an improved outcome with a 5-year PFS of 80% versus 59% for those with supratentorial tumors (P=0.0076). Patient age did not significantly influence outcome. All tumor recurrences were local. CONCLUSIONS: While this study reports an excellent overall survival, approximately one third of patients with grade I astrocytomas had progressive disease following radiation therapy. In particular, patients with supratentorial tumors and delayed radiation therapy had a worse PFS. Additional investigation is needed to improve the outcome in these patients.

Adolescent↗
PubMed2005

Postoperative radiation therapy for grade II and III intracranial ependymoma.

PURPOSE: To retrospectively determine the long-term outcome of intracranial ependymoma patients treated with surgery and postoperative radiation therapy. METHODS AND MATERIALS: Sixty patients were treated at our institution between 1964 and 2000. Forty patients had World Health Organization Grade II ependymoma, and 20 patients had Grade III ependymoma. The median patient age was 10.7 years. The majority of patients were male (55%), had infratentorial tumors (80%), and had subtotal resections (72%). Postoperative radiation therapy was delivered to all patients to a median total dose of 50.4 Gy. Craniospinal radiation therapy was used in the earlier era in only 12 patients (20%). RESULTS: The median follow-up of surviving patients was 12.5 years. The 5-year and 10-year disease-free survival rates for all patients were 58.4% and 49.5%, respectively. The 5-year and 10-year overall survival rates for all patients were 71.2% and 55.0%, respectively. Supratentorial tumor location was independently associated with a worse disease-free survival. Subtotal resection and supratentorial location predicted a worse overall survival, but this failed to reach statistical significance. No statistically significant effect on prognosis was observed with tumor grade, patient age, or radiation dose or volume. CONCLUSION: Our long-term follow-up indicates that half of ependymoma patients will have disease recurrences, indicating the need for more effective treatments.

Adolescent↗
PubMed2005

Incidental pediatric intraparenchymal xanthogranuloma: case report and review of the literature.

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.

Antigens, CD↗
PubMed2005

Orthopedic surgery after selective dorsal rhizotomy for spastic diplegia in relation to ambulatory status and age.

OBJECT: 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. METHODS: 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). CONCLUSIONS: 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.

Activities of Daily Living↗
PubMed2005

Use of rapid-sequence magnetic resonance imaging for evaluation of hydrocephalus in children.

OBJECT: 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. METHODS: 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%. CONCLUSIONS: 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.

Adolescent↗
PubMed2005

Early programmable valve malfunctions in pediatric hydrocephalus.

OBJECT: 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. METHODS: 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. CONCLUSIONS: 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.

Adolescent↗
PubMed2002

Strain-dependent neurodevelopmental abnormalities in caspase-3-deficient mice.

Targeted gene disruptions have revealed significant roles for caspase family members in the regulation of neuronal programmed cell death. Both caspase-3- and caspase-9-deficient mice exhibit a variably severe neurodevelopmental phenotype that may include marked ventricular zone expansion, exencephaly, and ectopic neuronal structures. Our previous studies of caspase-3- and caspase-9-deficient mice were performed using mice on mixed genetic backgrounds, raising the possibility that strain-specific generic factors influence the effects of caspase deficiency on nervous system development. To directly test this hypothesis. we backcrossed the caspase-3 mutation for 7-10 generations onto pure C57BL/6J and 129X1/SvJ genetic backgrounds. Caspase-3-deficient 129X1/SvJ mice were uniformly and severely affected. These mice died during the perinatal period and exhibited marked neural precursor cell expansion and exencephaly. In contrast, caspase-3-deficient C57BL/6J mice reached adulthood, were fertile and showed minimal brain pathology. Intercrosses of C57BL/6J and 129X1/SvJ mutants revealed that the vast majority of caspase-3-/- F1 mice displayed the severe 129X1/SvJ-"like" phenotype. These findings are consistent with an incompletely penetrant strain-dependent genetic modifier (or modifiers) that alters the neurodevelopmental consequences of caspase-3 deficiency. Since caspase-9- and Apaf-1-deficient mice also display variably severe developmental neuropathology, this strain-dependent modifier(s) may be involved in the activation of a caspase-independent death pathway; alternatively, strain-dependent compensatory caspase activation and/or its inhibition may influence the severity of the caspase-3-deficient neuronal phenotype.

Animals↗