bluuebunny/crossref_metadata_2025_split huggingface dataset:
Role of EEG monitoring and cross-clamping duration in carotid endarterectomy
Authors: Collice Massimo , Arena Orazio , Fontana Romero A. , Mola Manuela , Galbiati Nora 
Published: May 2009

✓ The usefulness of electroencephalographic (EEG) monitoring as well as the significance of the period of cross clamping in carotid endarterectomy have not been completely defined. In particular, the clinical importance of major EEG changes has not been fully investigated and some recent studies seem to indicate that the method has little value. As to the duration of cross clamping, there is strong evidence that occlusion times of about 15 minutes are tolerated under general anesthesia, but no information is available regarding longer periods of occlusion.
The authors describe a consecutive series of 141 carotid endarterectomies in which the patients with EEG changes were shunted only when occlusion was anticipated to last longer than 30 minutes. Early major EEG changes (during the first 4 minutes) occurred in 14% of the cases. In the absence of EEG changes, long occlusion periods of 40 to 50 minutes were well tolerated. In contrast, the 20 patients with major persistent EEG changes did not tolerate protracted occlusion and three of them had immediate postoperative neurological complications. It seems that, in these circumstances, the incidence of neurological deficit is a function of the duration of cross clamping: these three patients had undergone occlusion for 15 to 30 minutes. Their deficits partially resolved.
On the basis of these results it is concluded that: 1) EEG recording is a reliable monitoring system in carotid artery cross clamping. No major strokes due to temporary carotid artery occlusion occurred in the series. 2) The clinical significance of major persistent EEG changes is not negligible. Cross clamping for longer than 15 minutes in the presence of significant EEG alterations is potentially dangerous.
Beagle puppy model of perinatal cerebral infarction
Authors: Ment Laura R. , Stewart William B. , Duncan Charles C. , Pitt Bruce R. , Cole Judith S. 
Published: May 2009

✓ Perinatal cerebral infarction, or stroke, is a not uncommon finding in newborns who survive after intensive care. Asphyxia, with its component parts hypoxemia and hypotension, represents the most common cause of perinatal cerebral infarction and may result in neuropathological changes in the periventricular white matter. Previous studies have demonstrated regional alterations in cerebral blood flow (CBF) in response to hypoxemic insult. This work examines the effects of hypoxemia on regional cerebral prostaglandin levels in the developing brain, since some observers believe that local CBF is controlled in part by prostaglandins. In this study, newborn beagle pups were anesthetized, subjected to tracheotomy and artificially ventilated to maintain normoxemia and normocarbia. Mean arterial blood pressure (MABP) was continuously monitored by means of an indwelling catheter and transducer, and craniectomies were performed. When the pups were physiologically stabilized, they were randomly assigned to receive acute hypoxemic insult (pO2 14.0 ± 1.55 mm Hg, mean ± standard deviation) accomplished by altering the oxygen concentration in the inspired air) or to receive no insult (mean pO2 84.3 ± 13.0 mm Hg). Fifteen minutes following stable hypoxemic or normoxic conditions, all pups underwent in vivo freezing of the intracranial contents under anesthesia followed by rapid sacrifice.
No significant differences were noted between the MABP, pH, or pCO2 values for the control and hypoxemic pups during the experimental period. Regional cerebral prostaglandin data demonstrated a significant increase in prostaglandin (PG)E2 in the gray matter of hypoxemic pups when compared to the normoxic controls (p < 0.02). No significant differences were noted for 6-keto-PGE1α, the stable metabolite of prostacyclin, or thromboxane (TX)B2, the stable metabolite of TXA2, in the gray matter. In addition, although 6-keto-PGE1α was significantly lower in the periventricular white matter of the hypoxemic pups (p < 0.05), there were no changes in the white matter in either PGE2 or TXA2. This regional differential synthesis of PGE2 in response to hypoxemic insult may explain the relative failure of CBF to the periventricular white matter and thus the neuropathological alterations attributed to it.
Use of detachable balloons for proximal artery occlusion in the treatment of unclippable cerebral aneurysms
Authors: Fox Allan J. , Viñuela Fernando , Pelz David M. , Peerless Sydney J. , Ferguson Gary G. , Drake Charles G. , Debrun Gerard 
Published: May 2009

✓ Of 68 patients with unclippable aneurysms treated by proximal artery occlusion with detachable balloons, permanent occlusion was achieved in 65; of these patients, 37 had carotid artery aneurysms below the origin of the ophthalmic artery, 21 had aneurysms arising from the supraclinoid portion of the carotid artery, six had basilar trunk aneurysms, and one had a distal vertebral aneurysm. Examination for treatment selection included assessment of the circle of Willis by compression angiography and xenon blood flow studies, with the ultimate evaluation being test occlusion under systemic heparinization with the balloon temporarily placed in the desired position. Of 67 patients who underwent a formal occlusion test, eight with carotid artery aneurysms did not initially tolerate the occlusion test, and ischemic signs disappeared instantaneously with deflation and removal of the balloon. During test occlusion, two additional patients had ischemic events that proved to be embolic; these reversed immediately upon balloon deflation.
Of the 65 patients in whom permanent occlusion was effected by detachable balloon, there were nine instances of delayed cerebral events. One of these was a seizure leading to respiratory arrest and resuscitation 3 days following occlusion in a patient who had presented with seizures. The other eight cases were delayed ischemic events; seven were completely reversed and one patient had residual weakness in one leg (1.5% permanent morbidity). Extracranial-intracranial bypass procedures were performed in 25 of the 65 cases. All aneurysms of the carotid artery below the level of the ophthalmic artery presented angiographic proof of complete thrombosis. Ten of 21 aneurysms arising from the supraclinoid portion of the carotid artery were completely thrombosed by proximal occlusion alone, without additional trapping procedures. Similarly, in three of six basilar trunk aneurysms, proximal occlusion alone initiated complete aneurysm thrombosis without trapping. The conclusion is that proximal balloon occlusion for unclippable cerebral aneurysms is a convenient, safe, and effective way of producing arterial occlusion in these cases.
A review of the factors influencing the prognosis of medulloblastoma
Authors: Caputy Anthony J. , McCullough David C. , Manz Herbert J. , Patterson Kathleen , Hammock Mary Kathryn 
Published: May 2009

✓ The clinical, therapeutic, and histological features of 54 patients with medulloblastoma were analyzed retrospectively by a multivariate approach with regard to prognosis. The overall 5-year survival rate was 60%, with 48% of patients free of recurrence at 5 years. Cell differentiation, when present, was associated with a significantly longer recurrence-free period. Seventy-two percent of patients with the histological finding of cell differentiation were recurrence-free at 5 years. A marginally significant increase in the 5-year survival rate was also seen in association with differentiation. Only 34% of the patients whose tumor exhibited necrosis were alive at 5 years.
There was no statistically significant difference in 5-year survival for children under 3 years of age or for the group of children aged 5 years or under. However, a significantly larger fraction (72%) of the group aged 5 years or under had a recurrence-free period of 5 years or more. Other factors including sex, extent of surgical resection, Chang tumor stage, posterior fossa radiation dose, and adjuvant chemotherapy did not influence prognosis.
Principles of preparation of vein bypass grafts to maximize patency
Authors: Sundt Thoralf M. , Sundt Thoralf M. 
Published: May 2009

✓ Experience in cardiovascular and peripheral vascular surgery with saphenous vein bypass conduits is reviewed. It is clear that meticulous technique and graft preparation are crucial to short-term and long-term patency. The risk of early thrombosis is related to damage to the graft 's native intima, graft flow, and coagulability of the patient 's blood. Attention to atraumatic harvesting techniques and perfection of anastomoses are crucial to minimizing intimal damage. Graft inflow and outflow are fundamental principles. The use of vitamin K antagonists and platelet inhibitors may improve graft survival. Subacute occlusion is related to structural alterations in the grafts themselves. These include intimal hyperplasia and medial fibrosis as the grafts become “arterialized,” valve fibrosis, aneurysmal dilatation, clamp stenosis, and suture stenosis. Long-term patency is threatened primarily by atherosclerosis in the graft itself. There is some evidence that care in vein harvesting and implantation as well as the use of anticoagulant agents affect the development of this complication.
A technique for graft preparation is presented that is based on the experience of the authors in harvesting grafts for both cerebral and coronary bypass conduits.
Modulation in vitro and in vivo of ACNU resistance in a subline of C6 glioma with reserpine
Authors: Yoshida Tatsuo , Shimizu Keiji , Ushio Yukitaka , Mogami Heitaro , Sakamoto Yukiya 
Published: May 2009

✓ Reserpine enhanced in vitro the cytotoxicity of 1-(4-amino-2-methyl-5-pyrimidinyl) methyl-3-(2-chloroethyl)-3-nitrosourea hydrochloride (ACNU) in both the C6 glioma and its ACNU-resistant subline, C6/ACNU. Reserpine also enhanced the chemotherapeutic effect of ACNU in C6/ACNU-bearing (C6/ACNU-meningeal gliomatosis) rats, in which ACNU resistance could be modulated by combined ACNU and reserpine therapy.
When 10 μM reserpine was added to ACNU in culture, the concentration of drug required for 50% inhibition of cell growth (IC50) of ACNU for C6/ACNU cells decreased to the level of that for C6 cells. When 20 μM reserpine was added to the culture, intracellular uptake of ACNU in C6/ACNU cells increased further and the efflux of the drug from the cells decreased. In in vivo experiments in rats, combined chemotherapy with ACNU (1 mg/kg) and reserpine (250 μg/kg) by intrathecal injection significantly increased the life span of the rats as compared to results with ACNU chemotherapy alone. The enhanced cytotoxicity of ACNU in ACNU-resistant glioma cells in vitro and in vivo may be explained by the increase of intracellular concentration of ACNU resulting from the inhibition of ACNU efflux from the resistant cells by reserpine. It was concluded that ACNU resistance could be modulated in vitro and in vivo by combined therapy with ACNU and reserpine.
Thoracic spinal canal stenosis
Authors: Barnett Gene H. , Hardy Russell W. , Little John R. , Bay Janet W. , Sypert George W. 
Published: May 2009

✓ Hypertrophy of the posterior spinal elements leading to compromise of the spinal canal and its neural elements is a well-recognized pathological entity affecting the lumbar or cervical spine. Such stenosis of the thoracic spine in the absence of a generalized rheumatological, metabolic, or orthopedic disorder, or a history of trauma is generally considered to be rare. Over a 2-year period the authors have treated six cases of thoracic myelopathy associated with thoracic canal stenosis. In four patients the deficits developed gradually and painlessly. The three older patients had a clinical profile characterized by complaints of pseudoclaudication, spastic lower limbs, and evidence of posterior column dysfunction. Two patients were younger adults with low thoracic myelopathy associated with local back pain after minor trauma. Both patients also had congenital narrowing of the thoracic spinal canal.
Oil and metrizamide contrast myelography in the prone position were of limited value in diagnosing this condition; in fact, myelography may be misleading and result in erroneous diagnosis of thoracic disc protrusion, when the principal problem is dorsal and lateral compression from hypertrophied facets. Magnetic resonance imaging and computerized tomography sector scanning were more useful in the diagnosis of this disorder than was myelography. Thoracic canal stenosis may be more common than is currently recognized and account for a portion of the failures in anterior and lateral decompression of thoracic disc herniations.
The shaken baby syndrome
Authors: Duhaime Ann-Christine , Gennarelli Thomas A. , Thibault Lawrence E. , Bruce Derek A. , Margulies Susan S. , Wiser Randall 
Published: May 2009

✓ Because a history of shaking is often lacking in the so-called “shaken baby syndrome,” diagnosis is usually based on a constellation of clinical and radiographic findings. Forty-eight cases of infants and young children with this diagnosis seen between 1978 and 1985 at the Children's Hospital of Philadelphia were reviewed. All patients had a presenting history thought to be suspicious for child abuse, and either retinal hemorrhages with subdural or subarachnoid hemorrhages or a computerized tomography scan showing subdural or subarachnoid hemorrhages with interhemispheric blood. The physical examination and presence of associated trauma were analyzed; autopsy findings for the 13 fatalities were reviewed. All fatal cases had signs of blunt impact to the head, although in more than half of them these findings were noted only at autopsy. All deaths were associated with uncontrollably increased intracranial pressure.
Models of 1-month-old infants with various neck and skull parameters were instrumented with accelerometers and shaken and impacted against padded or unpadded surfaces. Angular accelerations for shakes were smaller than those for impacts by a factor of 50. All shakes fell below injury thresholds established for subhuman primates scaled for the same brain mass, while impacts spanned concussion, subdural hematoma, and diffuse axonal injury ranges. It was concluded that severe head injuries commonly diagnosed as shaking injuries require impact to occur and that shaking alone in an otherwise normal baby is unlikely to cause the shaken baby syndrome.
Effect of a calcium channel blocker on posttraumatic spinal cord blood flow
Authors: Guha Abhijit , Tator Charles H. , Piper Ian 
Published: May 2009

✓ The normal rat spinal cord blood flow (SCBF) has been shown to increase after administration of nimodipine, a calcium channel blocker. The present study investigates the capability of nimodipine to improve SCBF, as measured by the hydrogen clearance technique, after a 53.0-gm clip compression injury to the T-1 segment of the rat spinal cord.
The profound drop in mean systemic arterial blood pressure (MSAP) after cervical cord injury precluded any improvement in posttraumatic SCBF by nimodipine alone. Hence, in a randomized controlled study with five rats per group, pressor agents (whole blood, angiotensin, or adrenaline) were infused to maintain MSAP between 100 and 120 mm Hg after injury. Control animals received only a saline infusion. Nimodipine at the optimal dose found in normal animals (1.5 µg/kg/min) was added to the pressor agents. The MSAP and other physiological parameters were measured in rats receiving the pressor agents only and in those receiving pressor agents combined with nimodipine.
In rats receiving whole blood, angiotensin, or adrenaline the posttraumatic MSAP improved to between 100 and 120 mm Hg, but there was no improvement in SCBF compared to the saline group. The addition of nimodipine decreased MSAP and SCBF in all groups except those animals also receiving adrenaline, where the MSAP was maintained at 109 ± 5 mm Hg. In these animals a significant increase in posttraumatic SCBF from 16.5 ± 2.1 to 20.2 ± 2.3 ml/100 gm/min (mean ± standard error of the mean) occurred at the site of injury with the addition of nimodipine.
The maintenance of an adequate MSAP by a pressor agent was crucial for nimodipine to improve posttraumatic SCBF by its ability to dilate the spinal vascular bed. Adrenalin was the only pressor agent that could fulfill the above criteria, although other pressor agents need to be investigated. Experiments are underway with the combination of adrenaline and nimodipine to further verify these encouraging results demonstrating an improvement in posttraumatic ischemia of the spinal cord.
Influence of the rate of ventricular enlargement on the white matter water content in progressive feline hydrocephalus
Authors: Takei Futoshi , Shapiro Kenneth , Kohn Ira 
Published: May 2009

✓ The effectiveness of transependymal absorption of cerebrospinal fluid in hydrocephalus was studied by correlating the measured water content of feline hydrocephalic white matter with the rate of enlargement of the ventricles. Two groups of cats were subjected to opening of either the calvaria or the calvaria and dura before the intracisternal injection of kaolin to obtain two profiles of ventricular enlargement. The water content 1, 2, and 3 mm from the lateral ventricles was measured in each group using the dry/wet weight and microgravimetric techniques after sacrificing the animals in each group at 2, 3, or 6 weeks after inducing hydrocephalus.
In the animals with both calvarial and dural opening, the ventricles enlarged rapidly in the first 2 to 3 weeks and then continued to increase but at a slower rate. Concomitant with this early increase of ventricular size was a progressive increase in white matter water content both adjacent to and remote from the ventricles, which continued through 6 weeks. When only the calvaria was opened, ventricular size increased gradually, but continued to increase at a constant rate throughout the 6 weeks. Water content adjacent to the ventricle did not increase until the 3rd week, with little spread to adjacent areas by the 6th week. The central canals of the spinal cord were enlarged in both groups at all sampling levels.
Neither increased periventricular water nor dilatation of the central canal was associated with stabilization of ventricular size in these studies. The authors conclude that these pathways are not sufficient to arrest the hydrocephalic process in these models.
A laboratory model of shunt-dependent hydrocephalus
Authors: Fried Arno , Shapiro Kenneth , Takei Futoshi , Kohn Ira 
Published: May 2009

✓ This study was designed to determine whether implanting shunts in hydrocephalic cats produced the same biomechanical changes as have previously been found in children with shunts. Neuraxis volume-buffering capacity (pressure-volume index: PVI) and the resistance to the absorption of cerebrospinal fluid (CSF) were determined before and 3 weeks after placing shunts in 16 hydrocephalic cats. Intracranial pressure (ICP) was monitored for at least 6 hours after the shunts were occluded. The brains were perfused in vivo and removed to assess the size of the ventricles.
The mean PVI of the hydrocephalic cats was 3.6 ± 0.2 ml (± standard error of the mean) before the shunts were placed. Three weeks after adequate shunt function was first established, the mean PVI decreased to 1.1 ± 0.1 ml and was similar to values determined in control animals. Prior to shunt placement, the resistance to the absorption of CSF was 28.4 ± 4.5 mm Hg/ml/min and did not vary with ICP. This parameter changed after shunting and increased as a function of ICP (r = 0.87, p < 0.001). At ICP's below 20 mm Hg, the resistance to the absorption of CSF was 65.0 ± 18.0 mm Hg/ml/min but increased to 220.0 ± 40.5 mm Hg/ml/min when determined at ICP's above 20 mm Hg. Corroborating evidence for this linkage of resistance to the absorption of CSF to ICP was found in the inexorable rise of ICP during the 6 hours of monitoring after the shunts were occluded. After shunt placement, the ventricles were normal in size in 12 cats and slightly enlarged in four.
The biomechanical profile and pressure response to shunt occlusion in this laboratory model resembles that previously described in shunt-dependent children. As in humans, shunt placement in hydrocephalic cats results in normalization of the PVI and a linkage of the resistance to the absorption of CSF to ICP. The significance of these changes as they relate to shunt dependency is discussed.
One-knot microvascular anastomosis
Authors: Iwasa Hideaki , Sato Fumiaki , Shimabukuro Hiroshi , Yamada Naoshi , Ikada Yoshito , Hyon S. H. 
Published: May 2009

✓ Experimental microvascular anastomosis using a glutide copolymer (lactide:glycolide, 80:20) as an external splint was undertaken in 33 rats between the carotid artery and the jugular vein. Both vessels were dissected free over a 1-cm length and cut at the cranial end of the dissected part. The carotid artery was then introduced into a glutide pipe-splint. The arterial wall was turned 180° over the edge of the splint. This reflected artery wall and the glutide were covered by the freed-up jugular vein. One stitch was made around the vein, the artery, and the glutide in a manner similar to binding steel wire over a barrel. Thus, the “one-knot anastomosis” was completed.
The patency rate at the anastomosed site was 100%, confirmed by angiography in 30 rats and by direct surgery in three. The time required to produce the anastomosis was between 5 and 7 minutes. Light microscopic observation showed that there was no obstruction by thrombus formation at 1 and 5 weeks after the anastomotic surgery. This technique may be clinically applicable for extracranial-intracranial bypass surgery, reconstruction of venous sinuses, and other vascular procedures.
Emergency carotid endarterectomy
Authors: Walters Bradford B. , Ojemann Robert G. , Heros Roberto C. 
Published: May 2009

✓ A retrospective review of carotid endarterectomies performed by the Neurosurgical Service at Massachusetts General Hospital from July, 1976, through December, 1985, disclosed 64 procedures that were performed on an emergency basis. The patients included 40 men and 24 women, with a mean age of 64 years (range 32 to 87 years). Correlation of angiographic findings with outcome revealed that of the 27 patients with severe stenosis, usually with delay in blood flow, 25 (93%) were the same or improved postoperatively; of the 11 patients with stenosis and an intraluminal filling defect (six of whom had an intraluminal clot), eight (73%) were the same or improved after surgery; of the 16 patients with complete occlusion, 14 (88%) were the same or improved (backflow was established in all cases); and of the 10 patients with moderate to severe stenosis and/or severe ulceration (including three with transient ischemic attacks who were receiving heparin), eight (80%) were the same or improved.
Pre- and postoperative clinical status were graded into five categories: intact; mild deficit; moderate deficit (significant impairment but able to perform activities of daily living); severe deficit (requiring assistance for daily activities); and death. Of the 36 patients who preoperatively were intact or had mild deficits, 33 (92%) were the same or improved postoperatively, three were worse, and there were no deaths. Among 15 patients presenting with moderate deficits, 12 (80%) were the same or improved, two were worse, and one died. Of the 13 patients with severe deficits, 10 (77%) were the same or improved and three died. Two patients with sudden severe deficits associated with loss of contralateral bruit were operated on without angiography and were intact postoperatively. Of the four deaths in the total series, two were attributed to cardiac causes and two to unrelated disease processes. The indications for emergency carotid endarterectomy are discussed.