Faculty Bibliography

We have analyzed expression of a receptor protein tyrosine phosphatase (RPTPzeta/beta) in tissue samples from 23 human gliomas. Using the reverse transcription-polymerase chain reaction (RT-PCR) technique, we assayed for the presence or absence of mRNA transcripts encoding the intact receptor and 2 alternatively spliced forms of RPTPzeta/beta. Transcripts encoding the intact and truncated receptors were expressed in all of the lower grade gliomas (WHO grade 1-3) analyzed, but not in 55% of the grade 4 glioblastomas multiforme (GBM). However, this subset of GBMs did express an alternatively spliced secreted form comprised of only the RPTPzeta/beta extracellular domain. Our data suggests there may be a correlation between the loss of transcripts encoding the receptor forms of RPTPzeta/beta and progression from low to high grade gliomas. This work provides additional evidence for the importance of phosphatase isoform expression in human tumors

Pathological differentiation of oligodendroglioma and mixed oligoastrocytoma from astrocytoma is difficult, relying on morphological characteristics due to the lack of reliable immunohistochemical stains. Oligodendrocytes, the presumed cell of origin of oligodendrogliomas, highly express the genes encoding myelin basic protein (MBP) and proteolipid protein (PLP). We analyzed the expression of these genes to determine whether they might be useful molecular markers of oligodendrocytic tumors. MBP and PLP were highly expressed in all oligodendrogliomas and minimally expressed in glioblastomas multiforme. MBP was highly expressed in mixed oligoastrocytomas, whereas PLP expression was minimal. The association between tumor classification and expression of the MBP and PLP genes was statistically significant. Expression of these genes may serve as a useful molecular marker for some subtypes of human gliomas

OBJECTIVE: To demonstrate the usefulness of the contralateral transcallosal approach for resecting lesions located laterally in or adjacent to the lateral ventricle. METHODS: Modifications to the standard ipsilateral transcallosal technique include positioning the head with the midline oriented horizontally, placing the side with the lesion up, and performing the craniotomy and interhemispheric dissection on the contralateral side. This approach avoids a transcortical incision, allows gravity to hold open the interhemispheric fissure, and increases the lateral exposure of the lesion. This approach was used in 32 patients with a variety of lesions, including 6 cavernous malformations, 7 arteriovenous malformations, and 19 tumors of various types. All but three lesions were located on the left side. RESULTS: All six cavernous malformations, all four benign tumors, and four of the seven arteriovenous malformations were resected completely. Malignant tumors were resected subtotally, and three arteriovenous malformations required stereotactic radiosurgery to treat residual deep nidus. There was no surgical mortality. Two patients experienced neurological deterioration. CONCLUSION: The contralateral transcallosal approach can be used to treat a variety of lesions safely and successfully

STUDY DESIGN: In a clinical retrospective study, the authors review long-term results of occipitocervical fusion using a wide diameter, contoured, threaded Steinmann pin. OBJECTIVES: To evaluate the clinical and radiographic results of occipitocervical fusion using this technique in a variety of abnormalities including rheumatoid arthritis. SUMMARY OF BACKGROUND DATA. The various surgical techniques and hardware developed for occipitocervical fusion have been associated with mixed results, particularly in patients with rheumatoid arthritis or basilar invagination. METHODS: Thirty-nine patients with occipitocervical instability were internally fixed with a wide diameter, contoured, threaded Steinmann pin wired to the occiput and cervical laminae or facets. Fusion was facilitated using autologous iliac crest bone graft and a cervical orthosis. Instability resulted from rheumatoid arthritis (n = 12), congenital anomalies (n = 12), trauma (n = 10), tumor (n = 4), or osteogenesis imperfecta (n = 1). Fifteen patients had radiographic evidence of basilar invagination. Long-term outcome (mean follow-up period, 38.9 months; range, 12-78 months) was based on clinical and radiographic review. RESULTS: Thirty-seven patients (97%) had a stable postoperative occipitocervical construct: there were 35 osseous unions, two fibrous unions, and one nonunion. There was on postoperative death from pulmonary complications. No patient developed evidence of new, recurrent, or progressive basilar invagination. CONCLUSION: The authors concluded that rigid segmental fixation of the craniovertebral junction using a wide diameter, contoured, threaded Steinmann pin and supplemental autograft creates excellent fusion with minimal complications. This technique is appropriate for a variety of abnormalities including rheumatoid arthritis

Two of the most significant developments in neurosurgery over the past ten years have been the application of intraoperative navigational units and the widespread use of 'skull base' surgical techniques. These developments have independently revolutionized the way in which neurosurgeons approach intracranial pathology. The combination of these two developments has had a profound effect in our clinical practice to improve outcome and extend our capabilities. This ability to see around the corner, 'x-ray' vision as some have called it, provides an added measure of safety for the patient while allowing the surgeon to treat the lesion in a more aggressive fashion