bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cerebrovascular effects of hypocapnia during adenosine-induced arterial hypotension
Authors: Boarini David J. , Kassell Neal F. , Sprowell James A. , Olin Julie J. , Coester Hans C. 
Published: May 2009

✓ Profound arterial hypotension is à commonly used adjunct in surgery for aneurysms and arteriovenous malformations. Hyperventilation with hypocapnia is also used in these patients to increase brain slackness. Both measures reduce cerebral blood flow (CBF). Of concern is whether CBF is reduced below ischemic thresholds when both techniques are employed together. To determine this, 12 mongrel dogs were anesthetized with morphine, nitrous oxide, and oxygen, and then paralyzed with pancuronium and hyperventilated. Arterial pCO2 was controlled by adding CO2 to the inspired gas mixture. Cerebral blood flow was measured at arterial pCO2 levels of 40 and 20 mm Hg both before and after mean arterial pressure was lowered to 40 mm Hg with adenosine enhanced by dipyridamole.
In animals where PaCO2 was reduced to 20 mm Hg and mean arterial pressure was reduced to 40 mm Hg, cardiac index decreased 42% from control and total brain blood flow decreased 45% from control while the cerebral metabolic rate of oxygen was unchanged. Hypocapnia with hypotension resulted in small but statistically significant reductions in all regional blood flows, most notably in the brain stem. The reported effects of hypocapnia on CBF during arterial hypotension vary depending on the hypotensive agents used. Profound hypotension induced with adenosine does not eliminate CO2 reactivity, nor does it lower blood flow to ischemic levels in this model, even in the presence of severe hypocapnia.
Cerebral effects of isovolemic hemodilution with a hypertonic saline solution
Authors: Todd Michael M. , Tommasino Concezione , Moore Suzanne 
Published: May 2009

✓ In view of a growing interest in the resuscitative use of hypertonic saline solutions, the authors have examined the cerebral effects of isovolemic hemodilution carried out over 1 hour (hematocrit decreased from 40% to 20%, stable arterial and right arterial pressures), using a hypertonic lactated Ringer's solution (HT-LR:Na+ 252 mEq/liter, osmolality 480 mOsm/liter). Experiments were carried out in anesthetized ventilated rabbits. Measured variables included cerebral blood flow (using the H2 clearance method), intracranial pressure (ICP), the electroencephalogram, spinal cord and skeletal muscle water content (%H2O), and the specific gravity of small (10- to 30-mg) tissue samples taken from different areas of the left hemisphere (including the cortex, thalamus, internal capsule, and hippocampus). The changes produced by HT-LR were compared with those seen in both undiluted control animals and in rabbits hemodiluted with normal saline (Na+ 155 mEq/liter, osmolality 310 mOsm/liter). The results demonstrate that hemodilution with HT-LR leads to the expected increases in serum Na+ and osmolality (158 ± 6 mEq/liter and 320 ± 5 mOsm/kg, respectively, mean ± standard deviation) and that these were accompanied by reductions in the %H2O of all cerebral and extracerebral tissues, increases in the specific gravity of all tissue regions studied, and a decrease in ICP (1.9 ± 0.7 mm Hg). By contrast, rabbits with hemodilution by normal saline showed no changes in either %H2O or specific gravity, but had significant increases in ICP (3.3 ± 1.3 mm Hg). Cerebral blood flow increased in all animals hemodiluted with either HT-LR or normal saline by a combined average of +29 ml/100 gm/min.
Although these studies were performed in neurologically normal animals, the combination of cerebral changes seen with HT-LR (cerebral dehydration, less peripheral edema, decreased ICP but with increased cerebral blood flow) suggests that this approach may have some advantages over the use of isotonic fluids, and may have some utility in the resuscitation of head-injured patients.
Outcome evaluation following subarachnoid hemorrhage
Authors: Säveland Hans , Sonesson Bengt , Ljunggren Bengt , Brandt Lennart , Uski Tore , Zygmunt Stefan , Hindfelt Bengt 
Published: May 2009

✓ Seventy-eight individuals among a population of 1.46 million suffered aneurysmal subarachnoid hemorrhage (SAH) during 1983. Within 24 hours after the bleed, 32 of the 78 patients were in Hunt and Hess neurological Grades I to II, 13 were in Grade III, 21 were in Grades IV to V, and 12 were dead on admission to a hospital or forensic department. When the amount of blood visualized on computerized tomography (CT) scanning was integrated with the Hunt and Hess neurological classification in order to improve prediction of prognosis, only 16 patients were considered to have a good prognosis (CT-modified Grades I to II), 21 had a less favorable prognosis (CT-modified Grade III), and 29 had a poor prognosis (CT-modified Grades IV to V).
Assessment at 1 year revealed that only 32 patients (41%) had a good physical recovery. The physical morbidity rate was 22%, and the overall mortality rate was 37%. Twenty-six individuals with a good neurological outcome and five with a fair outcome also underwent reexamination 1 year or more post-SAH, which included a comprehensive evaluation of the quality of life, assessment of cognitive dysfunction, and determination of general adjustment. Five of the patients with a good neurological outcome and all five with a fair outcome (four of whom had had a poor prognosis in the acute stage) showed severe psychosocial and cognitive incapacitation. When functional morbidity, based upon persistent severe cognitive and psychosocial impairment, was included in the outcome assessment, only 33% of the total series was considered to have a favorable outcome. Approximately 60% of the initially good-risk patients (Grades I and II) showed a good physical outcome without concomitant indications of severe cognitive dysfunction and/or psychosocial impairment. Among the good-risk patients with a CT-modified grade, the figure was 70%. It is suggested that in any outcome grading system, persistent cognitive and psychosocial disturbances be taken into account.
Drug streaming during intra-arterial chemotherapy
Authors: Blacklock J. Bob , Wright Donald C. , Dedrick Robert L. , Blasberg Ronald G. , Lutz Robert J. , Doppman John L. , Oldfield Edward H. 
Published: May 2009

✓ Treatment of brain tumors by intra-arterial (IA) chemotherapy is occasionally complicated by sites of focal toxicity in the brain and retina. A possible cause of focal toxicity is non-uniform drug delivery due to intravascular drug streaming. To investigate this phenomenon in vivo, the authors examined the distribution of drug delivery after internal carotid artery (ICA) infusion in rhesus monkeys. Carbon-14 (14C)-labeled iodoantipyrine was delivered into the ICA of eight monkeys at slow infusion rates (1% to 2% of ICA flow) or at fast infusion rates (20% of ICA flow) combined with additional techniques to promote mixing with ICA blood. Two monkeys received intravenous (IV) 14C-antipyrine. Uniformity of delivery was assessed by comparing high-to-low ratios of isotope concentration in four brain regions evaluated by quantitative autoradiography.
There was striking non-uniformity of drug delivery in the slow IA infusion group, with as much as 13-fold differences in drug concentration in anatomically contiguous areas. The values of high-to-low concentration ratios (mean ± standard deviation) in individual autoradiographic planes were: 1) frontoparietal cortex: slow IA infusion 4.54 ± 2.07, fast IA infusion 1.71 ± 0.31, IV infusion 1.30 ± 0.174; 2) frontoparietal white matter: slow IA infusion 2.94 ± 1.45, fast IA infusion 1.59 ± 0.41, IV infusion 1.34 ± 0.21; 3) temporal cortex: slow IA infusion 5.43 ± 3.57, fast IA infusion 1.69 ± 0.24, IV infusion 1.67 ± 0.25; 4) basal ganglia: slow IA infusion 3.6 ± 2.9, fast IA infusion 1.18 ± 0.10, IV infusion 1.09 ± 0.04. Differences between concentration ratios after slow IA and fast IA infusion are significant (p < 0.01); those between fast IA and IV infusion are not significant.
Intra-arterial drug administration at infusion rates analogous to those currently used clinically results in drug streaming with markedly heterogeneous drug deposition in the perfused hemisphere. This may cause suboptimal drug levels in the tumor, and toxic levels at sites within the perfused hemisphere. This effect can be abrogated by techniques that eliminate drug streaming.
Preoperative evaluation and surgical management of the Arnold-Chiari II malformation
Authors: Venes Joan L. , Black Keith L. , Latack Joseph T. 
Published: May 2009

✓ The authors report their recent experience with 14 meningomyelocele patients with the Arnold-Chiari II malformation. Three major types of fourth ventricle anomalies seen in the Arnold-Chiari II malformation are defined, based on preoperative magnetic resonance imaging and intraoperative ultrasound studies. The Type A deformity is defined as no cystic dilatation of the fourth ventricle. In the Type B anomaly, there is intracranial dilatation of the fourth ventricle. The Type C deformity involves intraspinal dilatation of the fourth ventricle, either dorsal to the cord or within the substance of the cord. The Type A deformity was most common in infants, and in two cases progression from a Type A to Type B deformity was documented. Recognition of the type of Arnold-Chiari II malformation aids in designing an operative approach more specific to that structural abnormality. Intraoperative ultrasound is a valuable adjunct in localization of the underlying anomalies and permits safe decompression of the fourth ventricle.
The authors' indications for surgery now include failure to thrive due to either early respiratory and swallowing dysfunction, progressive spasticity, or upper-extremity weakness. Nine patients significantly improved following surgery and three patients with a progressively deteriorating course were stabilized by surgery. Decompression of the fourth ventricle by fenestration and internal shunting appears to be well tolerated, even in young infants, and is recommended in the treatment of the Arnold-Chiari II deformity.
Pressure-volume relationships in shunt-dependent childhood hydrocephalus
Authors: Shapiro Kenneth , Fried Arno 
Published: May 2009

✓ The pressure-volume index (PVI) technique of bolus manipulation of cerebrospinal fluid (CSF) was used to measure neural axis volume buffering capacity and resistance to absorption of CSF (Ro) in 20 shunt-dependent hydrocephalic children acutely ill from shunt malfunction. All children had had ventricles that were near normal or subnormal in size when the shunts were functioning.
The mean intracranial pressure (ICP, ± standard deviation (SD)) at the time of revision was 10.6 ± 6.4 mm Hg. The mean measured PVI (± standard error of the mean) was 18.4 ± 1.1 ml compared to the normal PVI of 17.5 ± 4.4 ml (± SD) predicted for these children. According to paired t-tests, these measured values were similar to those predicted on the basis of neural axis volume for each child, indicating that these children had normal neural axis volume buffering capacity. While the study was in progress, abrupt increases of ICP were documented in all children. These waves were observed spontaneously as well as in response to the addition of volume to the neural axis. In each child a specific threshold pressure along the pressure-volume curve corresponded to the appearance of unstable ICP. The threshold pressures at which this occurred corresponded to a mean neural axis compliance of 0.32 ± 0.07 ml/mm Hg (± SD). The Ro varied as a function of ICP. The Ro measured at ICP's below 15 mm Hg ranged from 2 to 7.5 mm Hg/ml/min and rose to 12 to 30 mm Hg/ml/min at pressures in the 20 to 25 mm Hg range.
The results of this study indicate that neural axis volume buffering capacity is normal in shunt-dependent children who respond to shunting by reconstitution of the cortical mantle. This study indicates that the proximate cause of their abrupt clinical deterioration is unstable ICP, which occurred at a similar point on the pressure-volume curve of all children studied. The correlation of Ro to ICP suggests that CSF absorption does not increase in these children as ICP rises, resulting in movement along relatively normal pressure-volume curves. The functional implications of these parameters are discussed.
Recognition of special qualifications in neurological surgery
Authors: Kline David G. , Mahaley Stephen 
Published: May 2009

✓ In recent years, one-half of the 23 recognized specialty boards in medicine have begun formally to recognize subspecialization with some type of certification process. One such board, the American Board of Internal Medicine, examines and certifies in 11 subspecialty areas while the American Board of Pathology does so in nine, the American Board of Pediatrics in eight, the American Board of Obstetrics and Gynecology in four, and the American Board of General Surgery in three. Arguments for and against similar recognition of subspecialization within neurosurgery are reviewed. The present position of other specialties and their boards regarding this sensitive issue is summarized, as well as their certification structure. The various pathways available to certifying boards for recognition of subspecialization are also presented.
The American Board of Neurological Surgery (ABNS) has approved a subspecialty certificate called a “certificate of Special Qualification in Critical Care Medicine.” This is a subspecialty that is longitudinally oriented, touching on a number of other specialties in addition to neurosurgery, and thus differs from a vertical subspecialty such as Pediatric Neurosurgery or Cerebrovascular Neurosurgery. The background for development of such a certificate and the current requirements for obtaining it are reviewed. At the present time, the ABNS opposes the possible fragmentation of neurosurgery by offering certification in multiple subspecialty areas. Nonetheless, the current trend in medicine as a whole is in the direction of such subspecialization and its formal recognition. Increasing numbers of neurosurgeons tend to concentrate all or a good deal of their professional efforts in a specific area. Thus, organized neurosurgery must continue to consider methods for subspecialty recognition.
Management of symptomatic deep venous thrombosis and pulmonary embolism on a neurosurgical service
Authors: Swann Karl W. , Black Peter McL. , Baker Mary F. 
Published: May 2009

✓ The authors present a retrospective analysis of the management of deep vein thrombosis (DVT) and pulmonary embolism (PE) in neurosurgical patients at the Massachusetts General Hospital from January, 1978, through June, 1982. There were 44 cases of DVT and 13 cases of PE. Management modalities included observation only, femoral vein ligation, inferior vena cava clipping, transvenous placement of an inferior vena cava filter or umbrella, and anticoagulation therapy. Six (75%) of eight patients with symptomatic DVT who were managed by observation alone had subsequent pulmonary emboli, and three (38%) died. Femoral vein ligation was followed by PE in one of four cases and led to significant leg swelling in two others. Neither observation alone nor femoral vein ligation can be recommended as routine management options. Partial inferior vena cava interruption with a De Weese clip, Kim-Ray Greenfield filter, or Mobin-Uddin umbrella all successfully prevented pulmonary emboli. The major problem associated with these methods was leg edema, which occurred in 47% of patients with clip placement, 25% with filter placement, and 21% with a Mobin-Uddin umbrella. Anticoagulation therapy was associated with a complication rate of 29% and a mortality rate of 15%. Fatal PE and paradoxical hypercoagulability with gangrene of a lower extremity were the causes of death. In one patient, hemorrhage into a glioblastoma occurred following discontinuation of anticoagulation therapy when the coagulation parameters were normal.
The authors conclude that: 1) management with observation alone of patients with symptomatic DVT places the patient at risk for the development of life-threatening pulmonary emboli; 2) the safety and timing of therapeutic anticoagulation in postoperative neurosurgical patients or patients with tumors is unclear; and 3) partial interruption of the inferior vena cava with a transvenous filter successfully prevents PE and may represent a safer alternative to anticoagulation therapy.
Focal brain edema associated with acute arterial hypertension
Authors: Hatashita Shizuo , Hoff Julian T. , Ishii Shozo 
Published: May 2009

✓ Acute arterial hypertension was studied in normal cats to determine its role in the formation of brain edema. Arterial hypertension was induced for 30 minutes by inflation of a balloon catheter situated in the descending aorta. Cerebral edema was evaluated by gross and microscopic observations, tissue water content by wet/dry weights, and blood-brain barrier (BBB) permeability by extravasation of horseradish peroxidase (HRP) and Evans blue dye. For 1 hour after the hypertensive insult, tissue pressure and regional cerebral blood flow (rCBF) were measured from the arterial boundary zone and from a non-boundary region, and intracranial pressure was recorded from the lateral ventricle as ventricular fluid pressure.
Focal lesions with increased BBB permeability to Evans blue dye or HRP were usually located symmetrically in the cortex, corresponding to the occipitoparietal parts of the arterial boundary zones. The increase in water content was found only in areas of increased permeability. Tissue pressure increased simultaneously with the abrupt rise in blood pressure, and an increase in rCBF paralleled the elevation of blood pressure. Tissue pressure and rCBF returned to a steady state when blood pressure returned to normal. There were no differences in tissue pressure or rCBF between the arterial boundary zone and the non-boundary zone, even during arterial hypertension. In cerebral hemispheres examined 48 hours after the hypertensive challenge, brain edema had not continued to develop.
The data indicate that acute arterial hypertension may produce focal brain edema with increased permeability of the BBB in the cortex of normal brain, particularly in the arterial boundary zones. The authors postulate that increased cerebral blood volume, high intraluminal pressure, and breakthrough of autoregulation play an important role in the formation of hypertensive brain edema.
Neurological manifestations of intracranial dural arteriovenous malformations
Authors: Lasjaunias Pierre , Chiu Ming , Ter Brugge Karel , Tolia Atul , Hurth Michel , Bernstein Mark 
Published: May 2009

✓ The authors describe their experience with four cases of dural arteriovenous malformation (AVM) which led them to analyze the clinical aspects of these lesions in an attempt to understand their pathophysiology. An additional 191 previously reported cases of dural AVM's were reviewed with special attention to the mechanism of intradural, central, and peripheral nervous system manifestations. Apart from the peripheral cranial nerve symptoms, which are most likely due to arterial steal, the central nervous system (CNS) symptoms appear to be related to passive venous hypertension and/or congestion. Generalized CNS symptoms can be related to cerebrospinal fluid malabsorption due either to increased pressure in the superior sagittal sinus, to venous sinus thrombosis, or to meningeal reaction resulting from minimal subarachnoid hemorrhages. These phenomena are not related to the anatomical type of venous drainage. On the other hand, focal CNS symptoms are specifically indicative of cortical venous drainage. Seizures, transient ischemic attacks, motor weakness, and brain-stem and cerebellar symptoms can be encountered depending on the territory of the draining vein or veins. Therefore, the localizing value of focal CNS symptomatology relates to the venous territory and not to the nidus or to the arterial supply characteristics of dural AVM's. Furthermore, the venous patterns of various dural AVM's at the base of the skull are expressed by differences in their clinical presentation. Dural AVM's of the floor of the anterior cranial fossa and of the tentorium are almost always drained by the cortical veins and, therefore, have a high risk of intradural bleeding.
The remarkable similarities in the manifestations of dural and brain AVM's and the differences in the manifestations of dural and spinal dural AVM's are pointed out. High-quality angiograms and a multidisciplinary approach to the study of dural AVM's will provide the best understanding of their symptoms and, therefore, the most appropriate treatment strategy.
Surgical management of craniopharyngiomas
Authors: Baskin David S. , Wilson Charles B. 
Published: May 2009

✓ A series of 74 patients with craniopharyngiomas were treated during a 15-year period. Of the 74 patients, 40 were males and 34 were females, with a mean age of 27 years (range 3 to 65 years). Twenty-eight patients (38%) were less than 18 years of age. Remission was defined as clinical improvement with stable ophthalmological and neurological status, radiological evidence of a decrease in tumor size, and either a continued decrease or a stable tumor size on follow-up radiological evaluations. A fair result was considered remission with new neurological deficits related to surgical intervention. All other results were considered a failure. The mean follow-up period in this study was 4 years, with 100% of the patients monitored.
In children, the most common presentation was that of growth failure (93%). In adults, sexual dysfunction was the most common presentation, with 88% of males presenting with impotence or marked decrease in sexual drive, and 82% of females presenting with primary or secondary amenorrhea, often associated with galactorrhea. Considering the pediatric and adult populations together, the most common presenting symptom was visual dysfunction, with 71% of patients presenting in this manner. Fifty percent of patients presented with severe headache. The most frequent preoperative finding was a visual field defect, with 72% of patients so affected; 42% of patients had preoperative hypothyroidism and 24% had hypoadrenalism. Diabetes insipidus was present preoperatively in 23%. Hydrocephalus was uncommon, being present in only 15%.
A subfrontal craniotomy was used in 47% of patients, a transsphenoidal approach in 39%, a subtemporal approach in 11%, a transcallosal approach in 5%, and a suboccipital craniectomy in 2%. Multiple procedures were required in 15% of patients in order to provide significant relief of compressive symptomatology. The results of therapy indicate that total tumor removal was deemed to have been achieved in only seven patients, six of whom have had no recurrence. However, 91% of patients are in remission, one had a fair result, and two died as a direct result of surgical intervention. One patient died from uncontrolled disease, and three patients died from unrelated causes. The results of this study indicate that radical subtotal removal followed by radiotherapy is an acceptable treatment for craniopharyngioma.