bluuebunny/crossref_metadata_2025_split huggingface dataset:
Laser-assisted neuroendoscopy using a neodymium—yttrium aluminum garnet or diode contact laser with pretreated fiber tips
Authors: Vandertop William P. , Verdaasdonk Rudolf M. , van Swol Christiaan F. P. 
Published: June 2009

Object. Although lasers have proved to be valuable in neuroendoscopy, surgeons are still not comfortable using high-energy laser endoscopic probes in proximity to vital structures such as the basilar artery in third ventriculostomy. The authors have developed a special laser catheter for use in neuroendoscopy; the object of this paper is to present their experimental and clinical experiences using the catheter.
Methods. This laser catheter is fitted with an atraumatic ball-shaped fiber tip that is pretreated with a layer of carbon particles. These carbon particles absorb approximately 90% of the energy emitted, which is very effectively converted into heat. As the heat is generated in this very thin layer of carbon coating, the temperature at the surface of the ball-shaped tip reaches ablative temperatures instantly at powers of only a few watts per second, which has enabled the authors to limit drastically the amount of laser light used and the length of exposure needed, thereby increasing safety even around critical structures.
Conclusions. The authors present experimental data and their clinical experience using these pretreated fiber tips with a neodymium—yttrium aluminum garnet contact laser or a diode contact laser in 49 patients (22 males and 27 females) and a variety of procedures: third ventriculocisternostomy (33 patients), cyst fenestration (nine patients), colloid cyst resection (six patients), and fenestration of the septum pellucidum (one patient). There was no instance of mortality or increased morbidity. To date, the procedure success rate is 100% and the overall outcome success rate is 86%. The authors conclude that pretreated atraumatic ball-shaped fiber tips now make laser application safe and effective in a variety of neuroendoscopic procedures. Because of their low power range (only several watts), compact diode lasers will be the energy source of first choice.
Transfection of C6 glioma cells with the bax gene and increased sensitivity to treatment with cytosine arabinoside
Authors: Vogelbaum Michael A. , Tong Jianxin X. , Higashikubo Ryuji , Gutmann David H. , Rich Keith M. 
Published: June 2009

Object. Genes known to be involved in the regulation of apoptosis include members of the bcl-2 gene family, such as inhibitors of apoptosis (bcl-2 and bcl-xl) and promoters of apoptosis (bax). The authors investigated a potential approach for the treatment of malignant gliomas by using a gene transfection technique to manipulate the level of an intracellular protein involved in the control of apoptosis.
Methods. The authors transfected the murine bax gene, which had been cloned into a mammalian expression vector, into the C6 rat glioma cell line. Overexpression of the bax gene resulted in a decreased growth rate (average doubling time of 32.96 hours compared with 22.49 hours for untransfected C6, and 23.11 hours for clones transfected with pcDNA3 only), which may be caused, in part, by an increased rate of spontaneous apoptosis (0.77 ± 0.15% compared with 0.42 ± 0.08% for the vector-only transfected C6 cell line; p = 0.038, two-tailed Student's t-test). Treatment with 1 µM cytosine arabinoside (ara-C) resulted in significantly more cells undergoing apoptosis in the cell line overexpressing bax than in the vector-only control cell line (23.57 ± 2.6% compared with 5.3 ± 0.7% terminal deoxynucleotidyl transferase—mediated biotinylated—deoxyuridine triphosphate nick-end labeling technique—positive cells; p = 0.007). Furthermore, measurements of growth curves obtained immediately after treatment with 0.5 µM ara-C demonstrated a prolonged growth arrest of at least 6 days in the cell line overexpressing bax.
Conclusions. These results can be used collectively to argue that overexpression of bax results in increased sensitivity of C6 cells to ara-C and that increasing bax expression may be a useful strategy, in general, for increasing the sensitivity of gliomas to antineoplastic treatments.
Meningeal melanocytoma
Authors: Clarke David B. , Leblanc Richard , Bertrand Gilles , Quartey Gilbert R. C. , Snipes G. Jackson 
Published: June 2009

✓ Meningeal melanocytomas are rare tumors of the central nervous system that are found almost exclusively in the posterior fossa and spinal cord and whose natural history is poorly defined. In this report, the authors review the clinical presentation, radiological appearance, operative findings, and histological features in two cases of meningeal melanocytoma: one cranial and one spinal.
Two women, aged 21 and 30 years, were admitted to the hospital 60 years apart: the first because of progressive paraplegia and the second because of slowly progressive hearing loss. The first patient had an extradural tumor that was treated by laminectomy, subtotal resection, and postoperative radiotherapy in 1936. Her symptoms recurred 16 years later and she underwent reoperation of the residual tumor, which was found to have an intradural component. The authors' patient, who presented 60 years later, underwent plain and enhanced computerized tomography and magnetic resonance imaging that demonstrated a large posterior fossa lesion indicative of either an acoustic neuroma or a meningioma. She underwent posterior fossa decompression but only partial excision of the tumor could be accomplished because vigorous bleeding limited the extent of the resection. Surgery was followed by radiotherapy. The residual tumor enlarged despite these measures and required repeated resection 6 months later. At the second operation the tumor was much less vascular, perhaps reflecting the effects of radiotherapy, and was removed almost entirely. The patient died 6 months later from an anticoagulant-related cerebellar hemorrhage. In both cases the lesions were jet black, and histological examination revealed melanin-containing hypercellular tumors with rare mitotic figures.
Meningeal melanocytomas are being diagnosed with increased frequency in parallel with improvements in neuroimaging and clarification of histological features. Clinical presentation of patients with these tumors typically occurs in their fifth decade and women are affected twice as often as men. The posterior fossa lesions can mimic acoustic neuromas and meningiomas in location and radiological appearance; however, the internal auditory canal is normal. In the spine, meningeal melanocytomas present with the clinical features of myeloradiculopathy. Diagnosis is made intraoperatively from the gross, jet-black appearance of the tumor and from histological examination. Vascularity, size, and location may render complete resection unfeasible. Because of the tumor's propensity to recur, radiotherapy has been recommended but its role remains to be elucidated.
Magnetic resonance evaluation of ventrolateral medullary compression in essential hypertension
Authors: Colón Gary P. , Quint Douglas J. , Dickinson Lawrence D. , Brunberg James A. , Jamerson Kenneth A. , Hoff Julian T. , Ross Donald A. 
Published: June 2009

Object. The authors designed a blinded prospective study comparing patients with essential hypertension to patients without hypertension in which magnetic resonance (MR) imaging was used to evaluate the role of lateral medullary compression by adjacent vascular structures as a cause of neurogenic hypertension.
Methods. Patients with documented essential hypertension were recruited to undergo thin-slice axial brainstem MR imaging evaluation. Nonhypertensive (control) patients scheduled to undergo MR imaging for other reasons also underwent thin-slice MR imaging to form a basis for comparison. Magnetic resonance images obtained in patients from the hypertensive (30 patients) and the control (45 patients) groups were then compared by four independent reviewers (two neuroradiologists and two neurosurgeons) who were blinded to the patients' diagnosis and hypertensive status. Images were reviewed with regard to left versus right vertebral artery (VA) dominance, compression of the medulla on the left and/or right side, and brainstem rotation. Medullary compression was graded as either vessel contact without associated brainstem deformity or vessel contact with associated brainstem deformity.
Conclusions. There was a tendency toward left VA dominance in the hypertensive group compared with the control group, although a significant difference was shown by only one of the four reviewers. There were no differences in brainstem compression or rotation between the hypertensive and nonhypertensive groups.
These results are contrary to those of recently published studies in which MR imaging and/or MR angiography revealed lateral brainstem vascular compression in hypertensive patients but not in nonhypertensive (control) patients. Reasons for this discrepancy are discussed. On the basis of their own experience and that of others, the authors believe that neurogenic hypertension does exist. However, thin-slice MR imaging may not be a reliable method for detecting neurovascularly induced essential hypertension and the prevalence of neurovascular compression as the source of hypertension may be overestimated when using current imaging techniques.
Neurovascular decompression of the eighth cranial nerve in patients with hemifacial spasm and incidental tinnitus: an alternative way to study tinnitus
Authors: Ryu Hiroshi , Yamamoto Seiji , Sugiyama Kenji , Uemura Kenichi , Nozue Michihiko 
Published: June 2009

Object.The authors sought to clarify the clinical characteristics of tinnitus resulting from neurovascular compression (NVC) of the eighth cranial nerve.Methods.The authors explored the eighth cranial nerve in the cerebellopontine cistern during neurovascular decompression (NVD) of the facial nerve in 10 patients with hemifacial spasm who suffered from incidental tinnitus on the same side. The diagnosis of NVC of the eighth cranial nerve was confirmed in all patients. This condition was found in only seven of 114 patients with hemifacial spasm alone, indicating that NVC of the eighth cranial nerve is one of the causes of tinnitus (p < 0.001, chi-square test). The tinnitus resolved or was markedly improved after NVD of the eighth cranial nerve in eight patients (80%). Both pulsatile and continuous tinnitus responded well to NVD. All patients experienced various degrees of sensorineural hearing disturbance, but other neurotological examinations provided poor diagnostic value.Conclusions.It is the authors' opinion that sensorineural hearing loss and positive findings on magnetic resonance imaging are the most reliable evidence for the presence of tinnitus caused by NVC of the eighth cranial nerve.
Acquired Chiari I malformation secondary to spontaneous spinal cerebrospinal fluid leakage and chronic intracranial hypotension syndrome in seven cases
Authors: Atkinson John L. D. , Weinshenker Brian G. , Miller Gary M. , Piepgras David G. , Mokri Bahram 
Published: June 2009

Object. Spontaneous spinal cerebrospinal fluid (CSF) leakage with development of the intracranial hypotension syndrome and acquired Chiari I malformation due to lumbar spinal CSF diversion procedures have both been well described. However, concomitant presentation of both syndromes has rarely been reported. The object of this paper is to present data in seven cases in which both syndromes were present. Three illustrative cases are reported in detail.
Methods. The authors describe seven symptomatic cases of spontaneous spinal CSF leakage with chronic intracranial hypotension syndrome in which magnetic resonance (MR) images depicted dural enhancement, brain sagging, loss of CSF cisterns, and acquired Chiari I malformation.
Conclusions. This subtype of intracranial hypotension syndrome probably results from chronic spinal drainage of CSF or high-flow CSF shunting and subsequent loss of brain buoyancy that results in brain settling and herniation of hindbrain structures through the foramen magnum. Of 35 cases of spontaneous spinal CSF leakage identified in the authors' practice over the last decade, MR imaging evidence of acquired Chiari I malformation has been shown in seven. Not to be confused with idiopathic Chiari I malformation, ideal therapy requires recognition of the syndrome and treatment directed to the site of the spinal CSF leak.
Comparison of balloon angioplasty and papaverine infusion for the treatment of vasospasm following aneurysmal subarachnoid hemorrhage
Authors: Elliott J. Paul , Newell David W. , Lam Derek J. , Eskridge Joseph M. , Douville Colleen M. , Le Roux Peter D. , Lewis David H. , Mayberg Marc R. , Grady M. Sean , Winn H. Richard 
Published: June 2009

Object. The purpose of this study was to test the hypothesis that balloon angioplasty is superior to papaverine infusion for the treatment of proximal anterior circulation arterial vasospasm following subarachnoid hemorrhage (SAH). Between 1989 and 1995, 125 vasospastic distal internal carotid artery or proximal middle cerebral artery vessel segments were treated in 52 patients.
Methods. Blood flow velocities of the involved vessels were assessed by using transcranial Doppler (TCD) monitoring in relation to the day of treatment with balloon angioplasty or papaverine infusion. Balloon angioplasty and papaverine infusion cohorts were compared based on mean pre- and posttreatment velocity at 24 and 48 hours using the one-tailed, paired-samples t-test. Balloon angioplasty alone was performed in 101 vessel segments (81%) in 39 patients (75%), whereas papaverine infusion alone was used in 24 vessel segments (19%) in 13 patients (25%). Although repeated treatment after balloon angioplasty was needed in only one vessel segment, repeated treatment following papaverine infusion was required in 10 vessel segments (42%) in six patients because of recurrent vasospasm (p < 0.001). Seven vessel segments (29%) with recurrent spasm following papaverine infusion were treated with balloon angioplasty. Although vessel segments treated with papaverine demonstrated a 20% mean decrease in blood flow velocity (p < 0.009) on posttreatment Day 1, velocities were not significantly lower than pretreatment levels by posttreatment Day 2 (p = 0.133). Balloon angioplasty resulted in a 45% mean decrease in velocity to a normal level following treatment (p < 0.001), a decrease that was sustained.
Conclusions. Balloon angioplasty is superior to papaverine infusion for the permanent treatment of proximal anterior circulation vasospasm following aneurysmal SAH.
Radiosurgery for cavernous malformations
Authors: Karlsson Bengt , Kihlström Lars , Lindquist Christer , Ericson Kaj , Steiner Ladislau 
Published: June 2009

Object. The authors examined 22 patients with cavernous malformations (CMs) who had undergone gamma knife radiosurgery (GKRS) to assess the value of this procedure in treating these lesions.
Methods. At the Karolinska Hospital, GKRS was used to treat 23 patients with CMs during the period of 1985 through 1996. One of the patients was lost to follow up and the treatment results of the 22 remaining patients were analyzed. In the first half of the series, the CMs were treated with high doses of radiation (> 15-Gy dose to the periphery); in the second half of the series, lower doses were used.
Nine of the 22 patients suffered a post-GKRS hemorrhage and six developed a radiation-induced complication (two of these patients experienced both). Some time after GKRS was performed, surgical removal of the CM had to be undertaken in four patients because of hemorrhage and in two patients because of radiation-induced complications. Four of the nine patients who experienced no post-GKRS hemorrhage or radiation-induced complication were treated before 1990; recent magnetic resonance imaging revealed a decrease in the size of the CM in three of these individuals and no size change in the other.
The annual post-GKRS hemorrhage rate was 8% in this group. There was a trend in the hemorrhage rate to decrease 4 years postsurgery. There was also a trend for higher radiation doses administered to the periphery of the lesion to result in a lower risk of posttreatment hemorrhage. However, it could not be concluded whether GKRS affects the natural course of a CM. The incidence of radiation-induced complications was approximately seven times higher than that expected if the same number of patients had been treated by GKRS with the same radiation dose distributions for arteriovenous malformations instead of CMs.
Conclusions. The high incidence of radiation-induced complications does not seem to justify the limited protection the treatment may afford in only exceptional cases. A prospective randomized study is needed before the role of radiosurgery in the management of these lesions can be defined. Until such a study has proved differently, a caveat must be raised for the treatment of CM with GKRS.
Platelet-activating factor and edema surrounding meningiomas
Authors: Hirashima Yutaka , Hayashi Nakamasa , Fukuda Osamu , Ito Hideki , Endo Shunro , Takaku Akira 
Published: June 2009

Object.The purpose of this study was to evaluate the involvement of platelet-activating factor (PAF) in the formation of edema surrounding meningiomas.Methods.Volumes of tumor and peritumoral edema were calculated based on three-dimensional reconstructed magnetic resonance images in 31 patients with intracranial meningiomas. The authors measured tumor concentrations of PAF and localized PAF and leukocytes in the tumors by using immunohistochemical studies. A significant positive correlation was found between peritumoral edema and PAF concentration. Both PAF and leukocyte common antigen were localized to the interstitial tissue of the tumor. Edema production was related to the degree of leukocyte infiltration in meningiomas.Conclusions.It appears that PAF, which may arise from infiltrating leukocytes, is important to the development of peritumoral edema in patients with meningioma.
Ruptured giant intracranial aneurysms. Part I. A study of rebleeding
Authors: Khurana Vini G. , Piepgras David G. , Whisnant Jack P. 
Published: June 2009

Object. The present study was conducted to estimate the frequency and timing of rebleeding after initial subarachnoid hemorrhage (SAH) from ruptured giant aneurysms.Methods. The authors reviewed records of 109 patients who suffered an initial SAH from a giant aneurysm and were treated at the Mayo Clinic between 1973 and 1996. They represented 25% of patients with giant intracranial aneurysms seen at this institution during that 23-year period. Seven of the patients were residents of Rochester, Minnesota, and the rest were referred from other institutions. The aneurysms ranged from 25 to 60 mm in diameter, and 74% were located on arteries of the anterior intracranial circulation. The cumulative frequency of rebleeding at 14 days after admission was 18.4%. Cerebrospinal fluid drainage, cerebral angiography, and delayed aneurysm recurrence were implicated in rebleeding in some of the patients. Rebleeding was not precluded by intraaneurysm thrombosis. Among those who suffered recurrent SAH at the Mayo Clinic, 33% died in the hospital.Conclusions. Rebleeding from giant aneurysms occurs at a rate comparable to that associated with smaller aneurysms, a finding that should be considered in management strategies.
Compound anterior cranial base fractures: classification using computerized tomography scanning as a basis for selection of patients for dural repair
Authors: Sakas Damianos E. , Beale David J. , Ameen Ameen A. , Whitwell Helen L. , Whittaker Karl W. , Krebs Axel J. , Abbasi Khalid H. , Dias Palithe S. 
Published: June 2009

Object. A classification is proposed to organize anterior cranial base fractures systematically according to their location and size. The goal of this study was to determine whether these two variables, irrespective of cerebrospinal fluid (CSF) rhinorrhea, are related to the long-term risk of posttraumatic meningitis and, hence, to standardize decision making concerning surgical repair of associated CSF fistulas.Methods. With the aid of high-resolution thin-section coronal computerized tomography (CT) scanning, anterior cranial base fractures were classified into the following four major types: I, cribriform; II, frontoethmoidal; III, lateral frontal; and IV, complex (any combination of the other three types). Fractures with a maximum bone displacement that extended farther than 1 cm in any plane were classified as “large” and those less than 1 cm as “small.”The authors used this classification in a study of 48 patients who were treated by conservative (20 patients) or surgical (28 patients) means. The results showed a gradation of risk: the fracture most likely to develop infection was a large cribriform (Type I) and the least likely was a small lateral frontal (Type III). Statistical analysis showed that the trend for an increased infection rate was related to the cumulative effect of three variables in the following order: 1) prolonged duration of rhinorrhea (analysis of variance [ANOVA], p = 0.017); 2) large size of fracture displacement (ANOVA, p = 0.079); and 3) fracture's proximity to the midline (ANOVA, p = 0.015).Conclusions. In this series, microsurgical repair was accompanied by a minimum complication rate. Hence, the authors recommend that patients with fractures that combine the aforementioned variables should be considered to have a high long-term risk of infection and their injury should be surgically repaired as soon as the posttraumatic edema has subsided. This applies to the following fractures: large cribriform (Type I) with transient rhinorrhea lasting 5 to 8 days and large frontoethmoidal (Type II) with prolonged rhinorrhea lasting longer than 8 days. Furthermore, the authors conclude that this classification can improve the management of posttraumatic CSF fistulas of the anterior cranial base and may provide insights into the mechanisms underlying their spontaneous repair and susceptibility to meningitis.