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Biomedical subjects

R Michael Scott

Publications and source records attributed to R Michael Scott.

29 records · Page 2Linked to original sources
PubMed2003

Reoperation for Chiari malformations.

BACKGROUND: We undertook this study to characterize those patients who required reoperations for Chiari malformation and to determine whether modifications in surgical technique at the initial procedure might have obviated the need for repeat surgery. METHODS: We reviewed the hospital records, imaging studies, operative reports, and follow-up data of those patients who were undergoing a second operation as part of a consecutive series of Chiari decompressions carried out by one neurosurgeon over a 14-year period. We wished to determine whether type of Chiari malformation, age at initial surgery, the presence of associated bony anomalies, or initial operative technique contributed to the need for reoperation. RESULTS: Twenty-two (17%) of the surgical procedures represented reoperations (16 of 100 Chiari I and 6 of 33 Chiari II decompressions). Of the patients in the series who were operated on at age 5 years or younger, 7 (16%) were reoperations (5 of 33 Chiari I and 2 of 10 Chiari II decompressions); 15 patients (17%) of those older than 5 years at surgery were reoperations (11 of 67 Chiari I and 4 of 23 Chiari II decompressions). 8 of the 16 patients who underwent reoperations for Chiari I malformation and 4 of the 6 patients who underwent reoperations for Chiari II malformation had their initial decompression surgery at age 5 years or younger. Reoperation was required because of failure to treat adequately an associated syrinx (n=11), because of persisting neurological symptoms or headache (n=9), or because of a possible faulty fourth ventricular stent placement (n=2). 5 of 9 patients in the operative series with Chiari malformations associated with craniosynostosis represented reoperations (55%), and all 3 of the patients whose syrinx persisted after reoperation had craniosynostosis syndromes. CONCLUSIONS: Approximately 17% of the patients with Chiari I and Chiari II malformations in this operative series were undergoing a second operation. Factors in this series which were associated with reoperation included a young age at initial surgery, the presence of complex bony anatomy at the foramen magnum, syndromic craniosynostosis, and failure of the surgeon at the initial operation either to assess patency of the foramen of Magendie or correctly place a fourth ventricular stent.

Age Factors↗
PubMed2003

Neuropsychological functioning after surgery in children treated for brain tumor.

OBJECTIVE: To describe the neuropsychological functioning of children treated with surgery only for localized brain tumors in Dana-Farber Cancer Institute Protocol 92-077. Subsequent reports will describe the neuropsychological functioning of children treated with surgery and stereotactic radiation therapy on Dana-Farber Cancer Institute 92-077. METHODS: The intellectual functioning of 106 patients was evaluated within 3 months after surgery. An in-depth assessment of the neuropsychological functioning, including an impairment index, was conducted for a subset of 77 school-age children (6-16 yr old) across six functional domains. Descriptive statistics were generated; binomial distribution analyses were performed to assess whether the proportion of individuals with impaired performance on each measure exceeded normative expectations. The impairment index assessed whether poor performance was attributable to a few children or reflected the performance of the cohort as a whole. RESULTS: Although the Full Scale IQ was within normative expectations, the Verbal IQ was higher than the Performance IQ with 45% of individuals showing a significant discrepancy (P < 0.01) between these scales. There was an increased prevalence of poor performance for measures of motor output, verbal memory, and visuospatial organization. The distribution of the impairment index indicated moderate impairment across the school-age cohort rather than severe impairment in a few patients. CONCLUSION: The results document a moderate level of neuropsychological morbidity among children with brain tumors before stereotactic radiation therapy, presumably referable to the tumor itself and the surgery. The extent to which stereotactic radiation therapy may increase this burden will be assessed in follow-up studies evaluating the longitudinal neuropsychological data.

Adolescent↗
PubMed2003

Mutational analysis of 206 families with cavernous malformations.

OBJECT: A gene contributing to the autosomal-dominant cerebral cavernous malformation (CCM) phenotype, KRIT1 (an acronym for Krev Interaction Trapped 1), has been identified through linkage analysis and mutation screening. The authors collected blood samples from 68 patients with familial CCM and 138 patients with apparently sporadic CCM as well as from their families, in an effort to characterize the prevalence and spectrum of disease-causing sequence variants in the KRIT1 gene. METHODS: The authors used single-strand conformational polymorphism analysis to identify genomic variants in KRIT1, which were sequenced to determine the specific mutation. Among 43 Hispanic-American kindreds who immigrated to the southwestern US from northern Mexico, 31 share an identical founder mutation. This Q455X mutation is found in 18 (86%) of 21 persons with a positive family history and in 13 (59%) of 22 persons with apparently sporadic CCM. This mutation was not found among 13 persons with CCM who were recruited from Mexico. These findings establish the key role of a recent founder mutation in Hispanic persons with CCM who live in the US. Although nearly all Hispanic families in the US in which there are multiple CCM cases linked to the CCM1 locus, only 13 of 25 non-Hispanic CCM-carrying families have displayed evidence of linkage to the CCM1 locus. Among these 13 families, the authors identified eight independent mutations in nine kindreds. They identified four additional mutations among 22 familial CCM kindreds with no linkage information, bringing the total number of independent mutations to 12. Inherited KRIT1 mutations were not detected among 103 non-Hispanic persons in whom a family history of CCM was rigorously excluded. CONCLUSIONS: All mutations were nonsense mutations, frame-shift mutations predicting premature termination, or splice-site mutations located throughout the KRIT1 gene, suggesting that these are genetic loss-of-function mutations. These genetic findings, in conjunction with the clinical phenotype, are consistent with a two-hit model for the occurrence of CCM.

Codon↗
PubMed2002

Levels of soluble adhesion molecules are elevated in the cerebrospinal fluid of children with moyamoya syndrome.

OBJECTIVE: The pathogenesis of moyamoya syndrome is unknown; however, previous studies suggested an inflammatory component. Because adhesion molecules mediate inflammation during cerebral ischemia, we measured the levels of soluble isoforms of the endothelial adhesion molecules vascular cell adhesion molecule Type 1, intercellular adhesion molecule Type 1, and E-selectin in serum and cerebrospinal fluid (CSF) samples from children with moyamoya syndrome. METHODS: Serum and CSF samples were obtained from children with moyamoya syndrome (n = 20) and patients with congenital spinal deformities (n = 20). Soluble vascular cell adhesion molecule Type 1, intercellular adhesion molecule Type 1, and E-selectin levels were measured in enzyme-linked immunoassays. The correlation between the levels of soluble adhesion molecules and the Suzuki angiographic classification was analyzed. CSF/serum albumin index values were also measured, to determine the integrity of the blood-brain barrier. RESULTS: Compared with the control group, children with moyamoya syndrome exhibited significantly elevated CSF levels of soluble vascular cell adhesion molecule Type 1, intercellular adhesion molecule Type 1, and E-selectin. The albumin index for the moyamoya group was 9, which was significantly higher than that for the control group. However, there were no differences in the serum levels of the three soluble adhesion molecules and no correlations between age, Suzuki classification, and serum and CSF levels of adhesion molecules. CONCLUSION: Our study demonstrates increased CSF levels of soluble endothelial adhesion molecules, suggesting that children with moyamoya syndrome have ongoing central nervous system inflammation, with slight impairment of the blood-brain barrier. These soluble adhesion molecules may be clinically useful as indicators of this inflammatory process and may provide some insight into this enigmatic disease process.

Arnold-Chiari Malformation↗
PubMed2002

Spontaneous intracranial hemorrhage caused by pheochromocytoma in a child.

We report a 6-year-old boy who presented with left occipital spontaneous lobar hematoma and hypertension. Cerebral angiography failed to demonstrate a vascular malformation. Subsequently, a left adrenal tumor was found that proved to be a pheochromocytoma. This is the first report in the literature of a lobar hematoma in a child caused by a concomitant pheochromocytoma. In children with hypertension and resulting intracerebral hematoma, a pheochromocytoma should be considered in the differential diagnosis.

Adrenal Gland Neoplasms↗
PubMed2002

Biochemical characterization of pediatric brain tumors by using in vivo and ex vivo magnetic resonance spectroscopy.

OBJECT: Magnetic resonance (MR) spectroscopy provides biochemical information about tumors. The authors sought to determine the relationship between in vivo and ex vivo biochemical characterization of pediatric brain tumors by using MR spectroscopy. Their hypothesis was that ex vivo MR spectroscopy provides a link between in vivo MR spectroscopy and neuropathological analysis. METHODS: In vivo proton MR spectroscopy was performed before surgery in 11 patients with neuroepithelial tumors. During resection, a total of 40 tumor biopsy samples were obtained from within the volume of interest identified on in vivo MR spectroscopy and were frozen immediately in liquid nitrogen. High-Resolution Magic Angle Spinning (HRMAS) was used to perform ex vivo MR spectroscopy in these 40 tumor biopsy samples. Neuropathological analysis was performed using the same biopsy samples, and the tumors were classified as ependymoma, choroid plexus carcinoma, pineoblastoma (one each), and pilocytic astrocytoma, medullobastoma, low-grade glioma, and glioblastoma multiforme (two each). Ex vivo HRMAS MR spectroscopy improved line widths and line shapes in the spectra, compared with in vivo MR spectroscopy. Choline (Cho) detected in vivo corresponded to three different peaks ex vivo (glycerophosphocholine, phosphocholine [PCho], and Cho). Metabolite ratios from in vivo spectra correlated with ratios from ex vivo spectra (Pearson correlation coefficient range r = 0.72-0.91; p < or = 0.01). Metabolite ratios from ex vivo spectra, such as PCho/ total creatine (tCr) and lipid/tCr, correlated with the percentage of cancerous tissue and percentage of tumor necrosis, respectively (r = 0.84; p < 0.001). CONCLUSIONS: Agreement between in vivo and ex vivo MR spectroscopy indicates that ex vivo HRMAS MR spectroscopy can improve resolution of this modality and provide a link between in vivo MR spectroscopy and neuropathological analysis.

Adolescent↗
PubMed2002

Neuroimaging in pediatric brain tumors: Gd-DTPA-enhanced, hemodynamic, and diffusion MR imaging compared with MR spectroscopic imaging.

BACKGROUND AND PURPOSE: Gadolinium-enhanced MR images assist in defining tumor borders; however, the relation between tumor cell extent and contrast-enhanced regions is unclear. Our aim was to improve conventional neuroimaging of pediatric brain tumors with hemodynamic, diffusion, and spectroscopic MR imaging. METHODS: We performed conventional MR and MR spectroscopic imaging in 31 children with neuroglial brain tumors. Hemodynamic MR imaging was performed in 16 patients with a first-pass intravenous bolus of gadolinium diethylenetriaminepentaacetic acid (Gd-DTPA); apparent diffusion coefficients (ADCs) were measured in 12 patients. To account for multiple measurements in a patient, we used a nested analysis of variance. RESULTS: At MR spectroscopy, choline (Cho)-containing compounds (indicating tumor) and lipid levels (indicating necrosis) did not correlate with percent Gd-DTPA enhancement on MR images. Percent enhancement was positively correlated with relative cerebral blood volumes (rCBVs) (P =.05) and negatively correlated with ADCs (P <.001). Stepwise multiple linear regression revealed that rCBV (P =.008), ADC (P =.022), and lipid (P <.001) levels were significant independent predictors of percent enhancement. Tumor spectral patterns were detected in tumor regions and outside enhancing tumor beds in patients with clinical progression; these were confirmed at neuropathologic analysis. CONCLUSION: MR spectroscopic imaging improves the assessment of pediatric brain tumors by adding biochemical information regarding tumor involvement and by depicting residual or recurrent tumor outside the Gd-DTPA-enhanced tumor bed. rCBV and ADC mapping complemented MR spectroscopic imaging. We recommend the use of MR spectroscopic imaging in addition to conventional MR imaging in assessing pediatric brain tumors.

Adolescent↗
PubMedDate not supplied

Chemotherapy for progressive low-grade gliomas in children older than ten years: the Dana-Farber experience.

The purpose of this retrospective study was to examine the clinical and radiographic response rates to and toxicity of chemotherapy for low-grade gliomas in children older than 10 years of age. Between June 1999 and January 2001, seven consecutive children between the ages of 10 and 18 were treated with vincristine and carboplatin +/- thioguanine, procarbazine, CCNU [lomustine], and vincristine (TPCV) for progressive low-grade gliomas. All 7 children completed a 10-week induction course of vincristine and carboplatin; 3 were switched to TPCV during the maintenance phase of therapy after developing an allergic reaction to carboplatin. Overall, 4 patients had a radiographic response to treatment with chemotherapy (3 partial responses and 1 minor response: objective response rate of 57%), and 2 more showed stable disease. One patient progressed while on treatment and 1 patient progressed off treatment, and after 31 months had elapsed. The resulting progression-free survival at the time of this report was 71%. The median duration of follow-up was 32 months (range 25-42 months). Hematologic toxicity was common, but did not result in cessation of therapy. No other significant treatment-related toxicities were observed. The results suggest that the clinical response/disease stabilization rate in children older than 10 years of age does not differ markedly from that observed in younger children. A prospective clinical trial of chemotherapy for progressive low-grade gliomas in children older than 10 years is therefore warranted.

Adolescent↗