bluuebunny/crossref_metadata_2025_split huggingface dataset:
Changes in contralateral brain-stem auditory evoked responses to cerebellopontine angle compression in rats
Authors: Zappulla Rosario A. , Wang Zhong Zhi , Malis Leonard I. , Karmel Bernard Z. 
Published: May 2009

✓ Eleven rats were subjected to graded compression of the brain stem at the cerebellopontine angle (CPA) following craniectomy and cerebellectomy. Clicks were delivered to the ear contralateral to the compression site, and brain-stem auditory evoked responses (BAER's) were collected before and during compression. With increasing compression, there was an increase in the latency and a decrease in the amplitude of the peaks of the BAER. The later peaks of the BAER (V and VI) demonstrated changes with minimal compression that progressed as compression increased, while changes in the amplitude and latency of the earlier peaks (II, III, and IV) occurred at the higher grades of compression. Following decompression of the brain stem, there was a decrease in the latencies of most of the BAER peaks. Peak amplitude remained depressed following brain-stem decompression.
These experimental findings corroborate clinical reports of abnormal BAER's elicited from stimulation of the ear contralateral to a CPA tumor. The relative sensitivity of the later peaks of the BAER to even minimal brain-stem compression explains the prolonged III to V interpeak latency reported in the literature in patients with brain-stem compression from a CPA lesion. The possible mechanisms for the BAER changes that were observed contralateral to compression are discussed.
Preservation of hearing in patients undergoing excision of acoustic neuromas and other cerebellopontine angle tumors
Authors: Tator Charles H. , Nedzelski Julian M. 
Published: May 2009

✓ Microsurgical techniques have made it possible to identify and preserve the cochlear nerve from its origin at the brain stem and along its course through the internal auditory canal in patients undergoing removal of small or medium-sized acoustic neuromas or other cerebellopontine angle (CPA) tumors. In a consecutive series of 100 patients with such tumors operated on between 1975 and 1981, an attempt was made to preserve the cochlear nerve in 23. The decision to attempt to preserve hearing was based on tumor size and the degree of associated hearing loss. In cases of unilateral acoustic neuroma, the criteria for attempted preservation of hearing were tumor size (2.5 cm or less), speech reception threshold (50 dB or less), and speech discrimination score (60% or greater). In patients with bilateral acoustic neuromas or tumors of other types, the size and hearing criteria were significantly broadened. All patients were operated on through a suboccipital approach.
Hearing was preserved postoperatively in six (31.6%) of the 19 patients with unilateral acoustic neuromas, although the cochlear nerve was preserved in 16. Of the six patients with postoperative hearing, three retained excellent hearing, and the other three had only sound awareness and poor discrimination. Hearing was preserved in three cases with other CPA tumors, including an epidermoid cyst and small petrous meningiomas in the internal auditory canal. Of the two cases with bilateral tumors, hearing was preserved in one. Of the 23 patients in whom hearing preservation was attempted, nine (39.1%) had some postoperative hearing, which in six was equal to or better than the preoperative level. Thus, it is worthwhile to attempt hearing preservation in selected patients with CPA tumors.
Increase in rat spinal cord blood flow with the calcium channel blocker, nimodipine
Authors: Guha Ab , Tator Charles H. , Piper Ian 
Published: May 2009

✓ Nimodipine, a calcium channel blocker, is known to increase cerebral blood flow. In the present study, the authors investigated the effect of nimodipine on spinal cord blood flow in normal rats. Cardiovascular parameters, including mean systemic arterial blood pressure, cardiac output, and heart rate, were recorded during infusion of nimodipine in a dose-response fashion. The experiment was a randomized blind study in which four groups of five rats received different doses of nimodipine (0.001, 0.01, 0.05, and 0.10 mg/kg) intravenously over 30 minutes, and a control group of five rats received only the diluent. The hydrogen clearance and thermodilution techniques were used to measure spinal cord blood flow and cardiac output, respectively.
The 0.05-mg/kg dose of nimodipine caused the largest increase in spinal cord blood flow, with a 40% increase over the preinfusion level, although there was a 25% reduction in mean arterial pressure. The 0.10-mg/kg dose did not increase spinal cord blood flow more than the 0.05-mg/kg dose, most likely due to the concomitant 37% reduction in mean arterial pressure. Cardiac output was significantly increased by the 0.05- and 0.10-mg/kg doses secondary to the drop in total peripheral resistance. The increase in spinal cord blood flow produced by nimodipine lasted approximately 20 minutes after the termination of the infusion. Thus, nimodipine at a dose of 0.05 mg/kg markedly increased blood flow in the normal spinal cord even though there were major changes in mean systemic arterial pressure and cardiac output. Further research is required to determine whether this drug might be beneficial in treating ischemic states of the spinal cord, such as posttraumatic ischemia.
Subarachnoid hemorrhage of unknown origin: prognosis and prognostic factors
Authors: Brismar Jan , Sundbärg Göran 
Published: May 2009

✓ The cases of 127 consecutive patients with subarachnoid hemorrhage (SAH), in whom cerebral panangiography revealed no cause for the bleeding nor any sign of an intraparenchymatous hemorrhage, were reviewed in a study of the long-term prognosis and the possible prognostic factors in this condition. Data for all 127 patients in the study were obtained, with an average follow-up period of 5.4 years. After the 1st week post-SAH, only three rebleeds had occurred. In all, 80% of the patients had returned to full activity, 91% to at least part-time work; if the patients with hypertension were excluded, these figures rose to 86% and 95%, respectively. Decreased wakefulness on admission related to a slightly poorer prognosis, whereas age and red blood cell count in the cerebrospinal fluid had no prognostic significance.
Of those patients who, at the end of the 2nd week following the SAH, were fully awake and had not developed any symptoms of delayed cerebral ischemia (87% of all patients admitted), 88% returned to full activity, 97% to at least part-time work. The survival rate for this group, as well as causes of death, seem to be within the range for normal individuals. It should thus be possible to inform these patients (at least the normotensive ones) of the benignity of their condition, directly after normal angiography. Even among the patients who were able to return to full activity, symptoms attributable to the SAH were common: 22% experienced problems such as frequent headaches, vertigo, irritability, and increased fatigability.
Radical resection of intramedullary spinal cord tumors in adults
Authors: Cooper Paul R. , Epstein Fred 
Published: May 2009

✓ The management of patients with intramedullary spinal cord tumors is controversial. In the past, these tumors have often been treated with biopsy or subtotal removal followed by irradiation — a therapy that is usually associated with early tumor recurrence and progressive neurological impairment. In an attempt to improve on the outcome of patients with intramedullary tumors, the authors performed radical resection in most of the 29 adult patients who had surgery for these tumors within the past 30 months. The mean duration of symptoms was 9½ years, and all patients presented because of progressive neurological deficit.
Patients were evaluated with metrizamide myelography-computerized tomography scanning and intraoperative ultrasound imaging to define the site of the tumor and cystic components. There were 14 ependymomas, 11 astrocytomas, two lipomas, and one case each of intramedullary fibrosis and astrogliosis. Solid tumor spanned a mean of five spinal cord segments and 16 tumors were associated with cysts. Twenty tumors were in the cervical and/or cervicothoracic regions. Total removal was achieved in 14 patients and “99% removal” in seven others. In 21 of 29 patients (72%), the neurological condition was stabilized or improved as a result of the operation. Postoperative deterioration occurred for the most part in patients who could not walk or who had minimal motor function at the time of operation, and these patients are no longer considered as operative candidates. Radical resection of intramedullary tumors can be achieved, with stabilization or improvement of neurological deficit in the majority of patients.
Somatosensory evoked potentials evaluated in normal subjects and spinal cord-injured patients
Authors: Chabot Robert , York Donald H. , Watts Clark , Waugh Wendy A. 
Published: May 2009

✓ Somatosensory evoked cortical potentials (SSEP's) were recorded in 27 healthy subjects using tibial and peroneal nerve stimulation with cephalic and non-cephalic references. Four major peaks were present in all recordings. Analysis of these components showed that SSEP's collected after tibial nerve stimulation with non-cephalic reference (linked earlobes) produced the most consistent clearly defined component peaks. Average latency, amplitude, and interpeak latency differences are presented for these SSEP's. Significant correlations were obtained between the height of the individual and the P1, N2, P2, and N3 latencies, and the N3-P1 interpeak latency. These results suggest that reproducible SSEP's can be obtained from tibial nerve stimulation in normal subjects using minimal numbers of stimulus presentations (28 to 64).
The SSEP's from 34 patients with varying degrees of spinal cord trauma were compared with the SSEP's from normal subjects. These comparisons involved the P1, N2, P2, and N3 latencies and the interpeak latency values, as well as the amplitude values. Patients with normal sensory and motor neurological examinations could be distinguished from patients showing decreased sensory and motor findings or clinically complete lesions on the basis of peak latency and interpeak latency values. The latter two groups could not be distinguished from one another. In general, all patient groups had SSEP's of lower amplitude than did normal individuals, but the groups could not be distinguished from one another. These results indicate that SSEP's can be a useful clinical tool for differentiation of complete from incomplete spinal cord lesions, but do not invariably predict recovery of function.
Safe use of PEEP in patients with severe head injury
Authors: Cooper Kevin R. , Boswell Peter A. , Choi Sung C. 
Published: May 2009

✓ Thirty-three patients with severe head trauma were studied to determine whether the use of positive end-expiratory pressure (PEEP) would cause an increase in intracranial pressure (ICP). Changes in ICP induced by PEEP were then correlated with a panel of physiological variables to try to explain these changes. Mean ICP increased from 13.2 ± 7.7 mm Hg (± standard deviation) to 14.5 ± 7.5 mm Hg (p < 0.005) due to 10 cm H2O PEEP, but the eight patients with elevated baseline ICP experienced no significant increase. Cardiac output and venous admixture (Qs/Qt) declined significantly, while central venous pressure, peak inspiratory pressure, functional residual capacity, and arterial pCO2 increased significantly due to PEEP. Blood pressure and cerebral perfusion pressure were unchanged.
The change in ICP due to PEEP correlated significantly with a combination of cardiac output, peak inspiratory pressure, Qs/Qt, and changes in blood pressure and arterial pCO2 due to PEEP, indicating that the effect of PEEP on ICP could be largely explained by its effect on hemodynamic and respiratory variables. No patient deteriorated clinically due to PEEP. It is concluded that 10 cm H2O PEEP increases ICP slightly via its effect on other physiological variables, but that this small increase in ICP is clinically inconsequential.
Reduced systemic drug exposure by combining intra-arterial chemotherapy with hemoperfusion of regional venous drainage
Authors: Oldfield Edward H. , Dedrick Robert L. , Yeager Russell L. , Clark W. Craig , DeVroom Hetty L. , Chatterji Dulal C. , Doppman John L. 
Published: May 2009

✓ Four patients with malignant cerebral gliomas received 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) into the internal carotid artery (ICA) while the ipsilateral jugular drainage was pumped extracorporeally through a hemoperfusion cartridge containing a nonionic adsorbant resin. Each patient received 220 mg/sq m BCNU, infused over 45 minutes through a toposcopic catheter positioned with the tip in the ICA beyond the origin of the ophthalmic artery. Jugular blood was pumped extracorporeally at 300 ml/min through a large-bore catheter in the jugular bulb. Plasma samples were obtained for BCNU measurement at frequent intervals from the right atrium. During a separate treatment, 6 weeks before or after the hemoperfusion treatment, the same dose of BCNU was infused into the ICA and atrial samples were obtained on a similar schedule.
Hemoperfusion of the jugular blood during intracarotid infusion reduced the systemic exposure by 56% to 87% and increased total body clearance of BCNU by two- to eightfold. The calculated pharmacokinetic advantage (brain:body exposure ratio) was between 21 and 55:1 when the combined treatment was used.
Immunoregulatory role in gamma interferon production by a T cell growth factor-dependent experimental malignant glioma-specific cytotoxic T lymphocyte clone
Authors: Yamasaki Toshiki , Handa Hajime , Yamashita Junkoh , Watanabe Yoshihiko , Taguchi Masaaki , Kuwata Shigeki , Namba Yuziro , Hanaoka Masao 
Published: May 2009

✓ The authors have established a murine malignant glioma-specific cytotoxic T lymphocyte clone (G-CTLL 1) by T cell growth factor (TCGF) using 203-glioma (a methylcholanthrene-induced ependymoblastoma of C57BL/6 mouse origin). The cloned cells were found to release a large amount of gamma interferon (IFN) in response to glioma-associated antigen-specific stimulation. The authors have investigated whether the IFN produced can contribute to killing the target cells. Adding anti-mouse gamma IFN antibody to the mixed clone-target cell culture inhibited IFN production by the cloned cells but the toxicity of the cells was minimally diminished. Therefore, it is suggested that the endogenous gamma IFN produced by the TCGF-dependent cloned cytotoxic T lymphocyte line does not have direct cytotoxic action on the target cells. Furthermore, IFN production as well as cytotoxicity was blocked by anti-Lyt-2 monoclonal antibody in the absence of complement. This suggests that IFN plays a role in the process of antigen recognition of target cells because the Lyt-2 molecule is involved in an antigen-specific function on the cytotoxic T lymphocyte receptor.
The role of TCGF in gamma IFN production was also investigated. The spontaneous production of gamma IFN by the cloned cells paralleled the amounts of exogenous TCGF added to the cultures, but TCGF had no synergistic effect on IFN production in the presence of mitogen or tumor antigen. Accordingly, it is possible that TCGF stimulates the cloned cells to proliferate, causing IFN release.
Glycerol neurolysis: neurophysiological effects of topical glycerol application on rat saphenous nerve
Authors: Burchiel Kim J. , Russell Lisa C. 
Published: May 2009

✓ The effect of topical glycerol application on normal and previously injured saphenous nerves was tested in 20 Sprague-Dawley rats. Anhydrous glycerol treatment of five normal nerves showed a rapid loss of C-fiber conduction within 5 minutes of application, while after 10 to 30 minutes, a complete conduction blockade in all fiber types was produced. The effect of anhydrous glycerol on both spontaneous firing from the neuroma and impulse propagation within the nerve was examined in 11 rats that had undergone saphenous neurotomy 7 days previously. In these animals, cessation of spontaneous action potential production from the neuroma was the earliest electrophysiological change noted, followed by loss first of C-fiber, then of A-fiber conduction. Graded concentrations of glycerol (25%, 50%, 75%, and 100%) were used in four rats with saphenous neuromas, which allowed selective blockade of spontaneous action potential generation and C-fiber conduction with minimal effect on A-fibers.
The neurophysiological mechanism of glycerol neurolysis appears to be a nonspecific conduction blockade of large and small fibers, which is established within minutes of its application. Spontaneous firing within damaged axons, which may play a role in a variety of cranial and peripheral nerve sensorimotor syndromes, is also exquisitely sensitive to glycerol application.
Incidence and etiology of intracerebral hemorrhage following carotid endarterectomy
Authors: Solomon Robert A. , Loftus Christopher M. , Quest Donald O. , Correll James W. 
Published: May 2009

✓ In a consecutive series of 1930 carotid endarterectomies there were eight cases of postoperative intracerebral hemorrhage. One of these patients was operated on 2 weeks following cerebral infarction and had severe uncontrollable hypertension after surgery. A second patient had an intraoperative embolus and bled while fully heparinized on the 3rd postoperative day. Only one patient in the series bled into an area of documented cerebral infarction. The remainder of the cases represented hemorrhage into essentially normal brain.
Seven of the eight patients with intracerebral hemorrhage had high-grade internal carotid artery stenosis preoperatively. Although several factors have contributed to the brain hemorrhages in this series of patients, postoperative cerebral hyperperfusion which often follows endarterectomy may have played an important role. Defective cerebrovascular autoregulation in chronically ischemic brain regions may predispose patients to intracerebral hemorrhage after removal of a high-grade stenosis of the internal carotid artery.
Bifrontal interhemispheric approach to aneurysms of the anterior communicating artery
Authors: Suzuki Jiro , Mizoi Kazuo , Yoshimoto Takashi 
Published: May 2009

✓ The authors review their experience with the bifrontal interhemispheric approach in 603 cases of single anterior communicating artery (ACoA) aneurysms and describe the operative technique. With this approach, the olfactory tracts are dissected, and both A1 segments of the anterior cerebral arteries are identified subfrontally. The interhemispheric fissure is then dissected and A2segments are followed from the distal portion toward the ACoA complex. Following the administration of a combination of mannitol, vitamin E, and dexamethasone, a temporary clip is placed on at least the dominant A1 segment prior to dissection of the aneurysm itself. Once the aneurysm has been completely freed from the surrounding structures, the neck is ligated and clipped. If the aneurysm ruptures during surgery, temporary clips are placed on both A1 and A2 segments bilaterally and the operation proceeds in a completely dry field. With this method, it is possible to occlude any of the intracranial vessels for up to 40 minutes within 100 minutes of drug administration.
To prevent the possibility of rerupture and the development of vasospasm in the period before aneurysm surgery, the authors have adopted a policy of performing ultra-early operations within 48 hours of the onset of symptoms. Among the 257 cases operated on during the 9 years since 1975, one-fifth have been operated on within 48 hours of rupture, and the in-hospital mortality rate has been only 4.3% (11 cases). Follow-up studies have shown that 87% of the 246 surviving patients have returned to useful lives.
Antifibrinolytic therapy of experimentally grown malignant brain tumors
Authors: Sawaya Raymond , Mandybur Thaddeus , Ormsby Illona , Tew John M. 
Published: May 2009

✓ This study was designed to evaluate the effect of an inhibitor of plasminogen activation on the growth of a human glioblastoma line grown in nude mice up to the seventh passage. The tumors produced plasminogen activators and showed histological characteristics similar to those of the original tumor. Three groups of mice were studied. Group A received 5% epsilon aminocaproic acid (EACA); Group B received 2.5% EACA; and Group C served as a control. There was no statistical difference among the three groups with regard to: 1) age at time of tumor transplantation; 2) the interval between implant and treatment; or 3) tumor volume at time of treatment. Blood measurements of EACA, performed in a limited number of animals, have shown that the drug at 5% concentration had reached toxic levels. Statistically significant differences between the three groups were noted in the following categories: 1) rate of tumor growth; 2) tumor volume at time of death, where Group A had smaller tumors than Group C; and 3) mean survival times of Groups A and B as compared to Group C.
A statistically significant negative correlation was found between the rate of tumor growth and the length of survival of animals in Group C, while no correlation could be found for either Group A or B, indicating that the antifibrinolytic therapy modified this important biological variable. This study supports the hypothesis that the fibrinolytic system plays a role in the growth and development of malignant gliomas and that interference with the fibrinolytic system may retard the growth of these tumors grown in nude mice.
Computer-assisted stereotaxic laser resection of intra-axial brain neoplasms
Authors: Kelly Patrick J. , Kall Bruce A. , Goerss Stephan , Earnest Franklin 
Published: May 2009

✓ Computer interpolation of stereotaxic computerized tomography (CT) scanning data allows the transposition of a tumor volume in stereotaxic space. A stereotaxically directed and computer-monitored CO2 laser is then utilized to vaporize that volume as the surgeon monitors the position of a cursor representing the laser beam against planar contours of the tumor displayed on an operating room computer monitor. Computer-assisted stereotaxic laser microsurgery provides precise three-dimensional control for aggressive resection of deep-seated tumors from neurologically important areas with acceptable postoperative results. Thus, a significant cytoreduction can be achieved in addition to providing a tissue diagnosis and internal decompression.
The authors report 83 computer-assisted stereotaxic laser procedures for tumor excision in 78 patients. The tumors were located in the thalamus/basal ganglia in 15 patients, ventricular system in five, corpus callosum in four, brain stem in three, and deep and centrally in the hemispheres in 51. Histologically, there were 26 glioblastomas, seven grade III astrocytomas, 14 grade II astrocytomas, 14 metastatic tumors, nine vascular lesions, and eight miscellaneous lesions. Resection of these subcortical lesions was confirmed by postoperative contrast-enhanced CT scanning. Neurological examinations performed 1 week after the 83 procedures revealed that 48 patients had improved from their preoperative level and 23 were unchanged (12 were neurologically normal preoperatively). Twelve patients had an increase in a preoperative neurological deficit, three of whom died in the postoperative period: one from infection, one from pulmonary emboli, and one from brain-stem edema.
The average survival period (37.6 weeks) of patients having glioblastomas treated by this technique and irradiation was no different from that of patients having glioblastomas in more favorable locations treated by conventional surgery and irradiation. Patients with circumscribed lower-grade astrocytomas did better in terms of morbidity and completeness of resection than those with infiltrative neoplasms. Other circumscribed lesions, such as metastatic tumors, vascular lesions, and intraventricular tumors, were easily resected by the technique described.