✓ This study was undertaken to evaluate the role of two sets of growth factors, platelet-derived growth factor (PDGF) and transforming growth factor-beta (TGF-β), in the induction and maintenance of glial tumors and their phenotypic expression. Explants from eight malignant tumors, five benign tumors, and two nontumor glial cells were analyzed for levels of messenger ribonucleic acid (mRNA) expression of PDGFA, PDGFB, TGF-β1, and TGF-β2. Results were normalized to the mRNA expression of tubulin, a “housekeeping” gene present in glial cells. Of the 15 explants tested, PDGFB was seen in six, all of which were malignant tumors; PDGFA was seen in all 15 with much higher levels expressed in malignant tumors; and TGF-β1 and TGF-β2 were seen in all 15 without a clear difference between cell types, although expression tended to be higher in malignant tumors. This project supports the theory that the induction and maintenance of glial tumors is likely to be a multifactorial phenomenon.
Timothy B. Mapstone
Daniel Y. Suh and Timothy Mapstone
A variety of mass lesions can arise within or in proximity to the ventricular system in children. These lesions are relatively uncommon, and they present a unique diagnostic and surgical challenge. The differential diagnosis is determined by tumor location in the ventricular system, clinical presentation, age of the patient, and the imaging characteristics of the lesion. In this report the authors provide an introduction to and an overview of the most common pediatric supratentorial intraventricular tumors. The typical radiographic features of each tumor and location preference within the ventricular system are reviewed. Management and treatment considerations are discussed. Examination of tissue samples to obtain diagnosis is usually required for accurate treatment planning, and resection without adjuvant therapies is often curative. The critical management decision frequently involves determining which lesions are appropriate for surgical therapy. Care ful preoperative neuroimaging is extremely useful in planning surgery. Knowledge of the typical imaging characteristics of these tumors can help to determine the diagnosis with relative certainty when a tissue sample has not been obtained, because a small subset of these lesions can be managed expectantly.
Timothy B. Mapstone
Vagus nerve stimulation (VNS) has become an accepted treatment option for pharmacologically resistant epilepsy. Although initially approved for adults, it increasingly has gained acceptance in children. In this article the author reviews the current state of knowledge of VNS therapy and discusses its potential utility.
Timothy Mapstone and Robert F. Spetzler
✓ A case is described in which vertebral artery occlusion, caused by a fibrous band, occurred whenever the patient turned his head to the right side, resulting in vertigo and syncope whenever the head was turned to the right. Release of a fibrous band crossing the vertebral artery 2 cm from its origin relieved the patient's vertebral artery constriction and symptoms.
Haiguang Xiao, David A. Goldthwait and Timothy Mapstone
✓ Levels of protein kinase C (PKC) isoforms in eight human glioblastoma cell lines and two normal human glial cell cultures were determined. Earlier studies identified PKC-α and PKC-γ in these cell lines but PKC-β was not present. In this study, PKC-ϵ and PKC-ζ are demonstrated immunologically in these cell lines and also in two normal human glial cell cultures. Protein kinase C-δ was not present. When levels of the four isoforms in the tumor cells were compared to levels in the normal cells, no increase was observed in PKC-α or PKC-γ, but PKC-ϵ was elevated three to 30 times in six of the eight tumors, and PKC-ζ was elevated approximately two times in all of the tumors. Incubation of cell line A172 with phorbol ester for 6 hours resulted in a 48-fold maximum increase in the nuclear PKC-ϵ and a sevenfold increase in the plasma membrane fraction with no change in the cytoplasmic fraction. A similar incubation for 4 hours produced a 0.5- to onefold increase of PKC-ζ in cytoplasmic, nuclear, and plasma membrane fractions. Other researchers have shown that overexpression of PKC-ϵ in fibroblasts results in tumorigenesis, and that blocking PKC-ζ function inhibits deoxyribonucleic acid synthesis. These data suggest that alteration in the expression of PKC-ϵ and PKC-ζ could be a factor in the conversion of normal glial cells to glioblastomas.
Luis M. Tumialán and Timothy B. Mapstone
William B. Schueler, Timothy B. Mapstone and Naina L. Gross
The authors present a case of migration of a ventricular tapping system into the third ventricle of a 6-year-old boy who is was born prematurely. As an infant, the patient was treated with serial lumbar punctures for hydrocephalus associated with intraventricular hemorrhage. The patient progressed to requiring a ventricular tapping reservoir and eventually a ventriculoperitoneal shunt. The patient presented for suspected shunt malfunction 4 years after placement of his ventriculoperitoneal shunt, and the migrated ventricular tapping system was discovered. The authors discuss several management strategies that could be used to prevent this complication.
Timothy B. Mapstone, Benjamin Kaufman and Robert A. Ratcheson
✓ This paper presents a rare case of intradural chordoma which involved the pons but had no radiological or surgical evidence of bone involvement. The appearance of this tumor on nuclear magnetic resonance imaging is presented.
Allison Strickland, Cordell M. Baker, R. Michael Siatkowski and Timothy B. Mapstone
The authors present a case of Chiari type 1.5 malformation with the uncommon presenting symptoms of esotropia and diplopia due to divergence insufficiency in a 12-year-old girl. Imaging at initial diagnosis revealed cerebellar herniation with extension of the tonsils to the C2 vertebral body, a retroflexed odontoid, and a small cervical syrinx. The patient was initially treated with an uncomplicated Chiari malformation decompression without dural opening. Repeat imaging revealed an adequate decompression. Three months postoperatively the patient’s diplopia recurred and she underwent repeat posterior fossa decompression with dural opening and duraplasty. Following repeat decompression with dural opening and duraplasty, the patient’s diplopia had not recurred by the 2-year follow-up.