Electromagnetic navigation for percutaneous guide-wire insertion: accuracy and efficiency compared to conventional fluoroscopic guidance.

The combination of electromagnetic (EM) navigation with intraoperative fluoroscopic images has the potential to create the ideal environment for spinal surgical applications. This technology enhances standard intraoperative fluoroscopic information for localization of the pedicle entry point and trajectory and may be an effective alternative to other image-guided surgery (IGS) systems. This study was performed to assess the accuracy and time efficiency (placement and fluoroscopy) using EM navigation versus conventional fluoroscopy in the placement of pedicle guide-wires. Kirschner wire (K-wire) placement was performed in cadavers from T8 to S1 using EM navigation versus conventional fluoroscopy. Time for set-up, placement, and fluoroscopy was recorded. After insertion, the accuracy for each level was assessed for the presence and location of facet joint, pedicle, or vertebral cortical perforation using computed tomography imaging with multiplanar reconstructions. K-wire placements were 100% successful for both methods. Comparing EM-based IGS-assisted placement with the conventional fluoroscopy method showed a longer set-up time of 9.6 min versus 3.6 min, respectively. However, mean placement times of 6.3 min versus 9.7 min (P=0.005) and mean fluoroscopy times of 11 s versus 48 s (P<0.0001) were both shorter for the EM group. There were no significant differences in the proportion of pedicle, vertebral body, or facet joint breaches. A higher proportion of ideal trajectories was achieved in the EM group. Therefore, we have shown that an EM IGS system can assist the spine surgeon in minimally invasive pedicle screw insertion by providing high-accuracy K-wire placement with a significant reduction in fluoroscopy time.

The use of the Olympus EndoArm for spinal and skull-based transsphenoidal neurosurgery.

Minimally invasive surgical techniques have evolved to reduce soft-tissue injury associated with open surgical techniques. The use of endoscopic visualization allows the exposure of deep structures and provides a mechanism to perform all the components of an open surgical procedure through small portals, thus satisfying a basic requirement of minimally invasive surgical procedures. Surgeons in the field of skull-base and spine surgery are now taking advantage of the benefits of such endoscopes. The pneumatically powered EndoArm endoscopic holder has been used extensively in both cranial and spinal neurosurgical cases at the University of Utah. These cases include minimally invasive cervical and lumbar decompression procedures, as well as more recently the resection of larger and more extensive pituitary tumors. In this paper, the multiple advantages of the Olympus EndoArm endoscopic holder are described in detail. As more surgeons gain experience with endoscopes in skull-base surgery, the hope is that operative times will be shorter and more extensive surgical resections will be possible with less patient morbidity.

Cell adhesion molecule Nr-CAM is over-expressed in human brain tumors.

Using the technique of differential display-polymerase chain reaction (DD-PCR), we isolated a cDNA fragment that is over-expressed in glioblastoma multiforme tissue as compared to normal brain tissue. Sequence analysis indicated that this sequence is identical to the previously isolated human neuron-glia-related cell adhesion molecule hNr-CAM. Gene-specific RT-PCR analysis indicated that hNr-CAM is over-expressed in high-grade astrocytomas, gliomas and glioblastoma tumor tissues as compared to normal brain tissue. High levels of hNr-CAM expression also were observed in cell lines derived from astrocytomas, gliomas and glioblastoma multiforme tumors. Low levels of hNr-CAM expression were observed in neuroblastoma, meningiomas, melanoma, normal breast and prostate tumor tissues. Northern blot analysis showed an alternatively spliced mRNA of 1.4 kb in several tumors as compared to the 7.5 kb transcript found in normal brain tissue. Genomic Southern blot analysis of DNA from 3 brain tumor cell lines showed that over-expression of hNr-CAM in brain tumors was not due to gene amplification. In situ hybridization analysis indicated that 11 of the 20 human brain tumor samples studied showed hNr-CAM over-expression. Our results suggest that hNr-CAM is over-expressed in malignant brain tumors and can serve as a novel marker for brain tumor detection and perhaps therapy.

Application of the differential hybridization of Atlas Human expression arrays technique in the identification of differentially expressed genes in human glioblastoma multiforme tumor tissue.

BACKGROUND AND OBJECTIVES: Several molecular biology techniques are utilized to study changes in gene expression during the genesis of human tumors. Our objective was to identify genes that showed altered expression between normal brain tissue (NBT) and glioblastoma multiforme tumor tissue (GMTT). METHODS: The technique of differential hybridization of two Atlas Human cDNA expression array was used. In this technique, dCTP32-labeled complimentary DNA from NBT and GMTT was hybridized to two identical human cDNA expression array membranes containing 588 known genes. RESULTS: Autoradiographic analysis showed that of the 588 genes analyzed, 52 are overexpressed in GMTT and 57 in NBT. A gene-specific semiquantitative reverse transcription polymerase chain reaction (RT-PCR) method was used to confirm the expression pattern of seven known genes. RT-PCR results demonstrate that the expression pattern of a majority of genes agreed with the expression pattern observed on expression array. The known tumor suppressor genes retinoblastoma (RB) and p53 showed loss of expression in GMTT compared with NBT. CONCLUSIONS: We conclude that the differential hybridization technique of Atlas Human cDNA expression array can be a useful method in identifying genes that are differentially expressed either in NBT or GMTT.

Cloning, sequence, and developmental expression analysis of C4-2, a potential brain tumor-suppressor gene.

BACKGROUND: Previously, we reported the isolation of C4-2 as a potential tumor suppressor gene in human brain tumors. To understand the function of this gene, we investigated its molecular characterization and expression during development. METHODS: Human fetal brain library screening and 5'RACE-PCR method was used to isolate the full-length cDNA. The coding region of C4-2 was used for in situ hybridization to study its expression during development. RESULTS: We report here the complete sequence of this gene. Sequence analysis indicated that C4-2 has a 94% sequence identity to a family of cAMP-regulated phosphoproteins (ARPP-16/19) in the coding region. C4-2 has a 3.1 Kb long 3'UTR with variable identity to ARPP-16 and ARPP-19. Northern blot analysis indicated that C4-2 is expressed at high levels in normal brain compared to other tissues. Zoo blot analysis demonstrated that the coding region of C4-2 is highly conserved among different animals. In situ hybridization using C4-2 coding region demonstrated that it follows a unique expression pattern during mouse brain development. High level of C4-2 expression was also observed in the spinal cord and somites of the developing embryo. CONCLUSION: Expression analysis during brain development strongly suggests that this family of proteins may play an important role not only in normal functioning of the brain, but also during brain development.

Isolation and characterization of a novel gene from human glioblastoma multiforme tumor tissue.

Using the technique of DD-PCR (differential display-polymerase chain reaction) we isolated a novel gene (D2-2) that is overexpressed in glioblastoma multiforme tissue (GMT) as compared to normal brain tissue (NBT). D2-2 is also highly expressed in recurrent glioma, colon tumor metastatic to brain, breast tumors, prostate tumors and a prostate tumor cell line (LNCaP). Northern blot analysis showed that D2-2 is highly expressed in several tumor cell lines (MOLT lymphoblastic leukemia, SW480 colorectal adrenocarcinoma, A549 lung carcinoma, HL-60 promyelocytic leukemia, S3 HeLa cells, K-562 chronic myelogeneous leukemia and G361 melanoma) as compared to NBT. Additionally, D2-2 is very highly expressed in cell lines derived from glioblastomas, grade IV astrocytomas, normal human fetal astrocytes (NHFA) and glioma. D2-2 is moderately expressed in neuroblastoma, neuroectodermal and medulloblastoma tumor cell lines. D2-2 expression is localized to the frontal lobe, occipital lobe and the cerebellum in the normal brain. Normal tissues such as thyroid, stomach, adrenal cortex, small intestine and pancreas show high expression of D2-2. We also show that D2-2 is expressed 28-fold higher in fetal brain (20 weeks) than in adult brain. Sequence analysis of a 2.0-kb fragment for D2-2 shows no homology to known sequences in the data base.

Characterization of C4-2 as a tumor-suppressor gene in human brain tumors.

BACKGROUND: Brain tumors claimed the lives of 13,300 people in 1995. Our objective was to isolate and characterize unique tumor-suppressor genes from human brain tumors derived from patients in the United States. METHODS: Differential display-polymerase chain reaction was used to isolate tumor suppressor genes. RESULTS: Clone C4-2 was isolated and is expressed in normal adult human brain, but not in brain tissue from glioblastoma multiforme tumors. C4-2 has 66% homology to the previously isolated ARPP-16 (cAMP-regulated phosphoprotein of Mr = 16,000) based on limited sequencing. C4-2 is expressed at high levels in normal brain and is not expressed or expressed at low levels in several brain tumor cell lines. Expression of C4-2 was also either not expressed or expressed at low levels in meningioma, B-cell lymphoma, recurrent glioma, LNCAP (prostate tumor cell line), breast tumor, or prostate tumor tissue. CONCLUSION: We conclude that C4-2 may function as a potential tumor-suppressor gene.

Ossification of the posterior longitudinal ligament of the spine: a case report.

Ossification of the posterior longitudinal ligament of the spine (OPLL) is a common cause of severe myelopathy and radiculopathy in Oriental populations. It typically involves the cervical spine. We present a 60-year-old Asian male with OPLL who developed progressively worsening cervical myopathy. The diagnosis and management are discussed.

Broviac ventriculostomy for long-term external ventricular drainage.

A closed external ventricular drainage system that incorporates a Broviac catheter, with its dacron cuff, is described and its use is detailed. This device has been placed in 17 patients who have undergone 19 procedures. Indications for prolonged cerebrospinal fluid (CSF) drainage were: CSF leak (1 child) and shunt infection (16 children). Drainage was maintained for an average of 19 days, with a range of 6-47 days. The child with the CSF leak had resolution of this problem after 15 days, whereupon the system was removed. Thirteen of the 16 patients with shunt infections eventually underwent shunt placement. Two of the children in this group developed a shunt infection unrelated to their original septic episode that required placement of a second Broviac ventriculostomy. Two of the 3 children who did not undergo permanent shunt placement expired from other causes. Both of these children had clinically functioning Broviac ventriculostomies and culture-proven sterile CSF at the time of death. The remaining child with an infected shunt died of overwhelming sepsis. Complications included: ventricular catheter revision (4 cases), irrigation of the system (4 cases), and secondary CSF infection (1 case). The infection attack rate was 1 in 361 patient-catheter days, or 2.77/1,000 patient-catheter days. The advantages of the Broviac ventriculostomy are two. First, this system is highly resistant to infection. Second, the device is difficult to dislodge.