bluuebunny/crossref_metadata_2025 huggingface dataset:
Carefully Designed Water-Based Drill-In Fluid and Filter Cake Removal System Improve Reservoir Producibility and Reduce Well Completion Costs
Authors: Al-Mehailani M. , Al-Anzi N. Abdullah , Gohain A. , Hussain I. , Haider B. , Davidson E. , MacMillan B.
Published: May 2009

Kuwait Oil Company introduced new fluid practices to improve producibility in the Minagish oolitic limestone reservoir in Umm Gudair field. The approach was designed to minimise formation damage in the reservoir section and apply a more effective filter cake removal technique during the well completion.

Experience on offset wells and results of return permeability studies showed that specially designed water-based drill-in fluids with optimally sized acid-soluble bridging particles were the preferred fluids for open hole completions on the Minagish reservoir. For removal of the cake and low permeability crush zone created by the drilling process a formic acid precursor (FAP) was used. The precursor is added to the completion fluid and reacts slowly with brine to release formic acid in the reservoir section. Conventional acidisation with HCl can cause wormholes, localised leak-off and failure to treat the entire interval effectively; FAP is in a neutral condition when placed. Localised reaction and loss zones are avoided and the released acid can act uniformly on the entire interval.

Four wells in this area were sidetracked due to depletion in pressure and increasing water cut. All utilized the same drill-in fluid. Subsequently wells UG 116ST and UG126ST were stimulated with HCl, whereas UG 38STRE and UG 110ST were treated with the FAP.. The two wells treated with the FAP had producibilities about twice those treated with HCl.

The combination of well designed drill-in fluid and FAP has shown great promise of facilitating the drilling process and increasing the producibility of the well with significant economic benefit. This paper addresses practical applications of the drill-in fluid and the breaker and reports on several additional benefits that were obtained.
Predicting Well Inflow Using Computational Fluid Dynamics—Closer to the Truth?
Authors: Byrne Michael , Jimenez Maria Alejandra , Chavez Juan Carlos
Published: May 2009

One of the great challenges facing our industry is accurate prediction of well inflow. Conventional methods have been too cumbersome and imprecise and have suffered from a lack of accuracy and clarity. Informed use of computational fluid dynamics, fine scale modelling and improved computing power enable far more accurate prediction of the impact of formation damage and thus of well performance.

The accurate prediction of well performance helps with appraisal of development prospects, well planning and reliable prediction of true well and field value. If we know what the outcome of our actions and of our well designs will be, then we can make sensible and informed choices on damage impact and mitigation.

Results from laboratory simulations of drilling and completion operations were generated from "standard" return permeability testing. The detailed data obtained, and its millimetre scale resolution was incorporated in to a well specific model. The damaged and undamaged states were examined using flow rate predictive computational fluid dynamics. The impact on flow in a single and dual permeability reservoir interval were calculated. In a specific example presented, the case for underbalance drilling was clearly made as the impact of overbalance drilling was predicted to have a severe impact on well productivity.

The results of accurate and detailed laboratory simulation of formation damage have been translated using innovative software applications to give a prediction of well performance. This is the first time that computational fluid dynamics has been employed to predict well performance based on high quality laboratory testing. In future the laboratory tests will be designed to yield data most useful for the model and the model and grid scale will continue to be adjusted based on the specific challenge and objective. The detailed workflow used to achieve more accurate well performance prediction will be outlined in the paper.
Formation Damage Zone Radius and its Applications to Well Stimulation
Authors: Nunes M. , Bedrikovetsky P. , Newbery B. , Paiva R. , Furtado C. , de Souza A. L.
Published: May 2009

Flow of particulate suspension in porous media with particle retention and consequent permeability reduction is discussed. Using analytical model for suspension injection via single well, the permeability damage zone size was defined and expressed by transcendental equation. Analysis of field data shows that usually the size of damaged zone does not extend more than one meter beyond the injector. The definition of damage zone size is used for design of well stimulation via deposition removal.
A Successful Expandable Sand Screen Case History in a Deep, Corrosive Gas Well Application
Authors: Ginest Noel , Al-Sagr Abdulaziz , Al-Malki Bandar , Al-Khawajah Muhammad , Jones Colin , Morgan Quentin , Parry Keith
Published: May 2009

K Field is a gas field located in Saudi Arabia, with production from the Unayzah A reservoir, an unconsolidated sandstone reservoir notable for its comparative depth. The high corresponding bottomhole temperature combined with corrosive gas properties manifests in aggressive in-situ corrosion conditions. Sand control is needed in this reservoir due to the weak rocks and high tectonic stresses. Frac-pack completions have been used successfully for a number of years and typically manifest in a low positive skin. They tend to suffer from condensate banking and flow related skin.

A number of years ago it was decided to use the then novel expandable sand screen (ESS) technology in a long horizontal well to maximise reservoir drainage. This presented many challenges in terms of the metallurgy, the interaction with high stresses and the deployment in a deep hot well. In April 2004 Well K-3 was drilled as a horizontal open hole well and completed with ESS, setting three world records at that time for the hottest and deepest ESS installation and first ever Incoloy ESS system.

The well was shut-in almost immediately after clean-up operations began due to a mechanical failure in the upper completion, and remained shut-in for nearly 3 years. The well was successfully restarted after an upper completion workover.

This paper describes assessment of well performance from a multi-rate production test conducted following successful workover of Well K-3, and benchmarks key performance indices with those derived from analysis of neighbouring wells equipped with alternative sand control techniques.
Longer Hours and Larger Waistlines? The Relationship between Work Hours and Obesity
Authors: Courtemanche Charles
Published: May 2009

Additional work hours may lead to weight gain by decreasing exercise, causing substitution from meals prepared at home to fast food and pre-prepared processed food, or reducing sleep. Substitution toward unhealthy convenience foods could also influence the weight of one's spouse and children, while longer work hours for adults may further impact child weight by reducing parental supervision. I examine the effects of adult work hours on the body mass index (BMI) and obesity status of adults as well as the overweight status of children. Longer hours increase one's own BMI and probability of being obese, but have a smaller and statistically insignificant effect on these outcomes for one's spouse. Mothers', but not mother's spouse's, work hours affect children's probability of being overweight. My estimates imply that changes in labor force participation account for only 1.4% of the rise in adult obesity in recent decades, but a more substantial 10.4% of the growth in childhood overweight.
How Does Treatment Satisfaction Work?
Authors: Peyrot Mark , Rubin Richard R.
Published: May 2009

OBJECTIVE

This study tested a model hypothesizing that treatment affects objective clinical outcomes, which in turn affect perceived consequences, which in turn affect satisfaction and preference judgments.

RESEARCH DESIGN AND METHODS

The model was tested in a double-blind, randomized clinical trial in which 266 patients with type 1 diabetes added active or placebo pramlintide to their insulin regimens. Objective clinical outcomes included changes in glucose and weight control, insulin requirements, incidence of hypoglycemia, and study drug tolerance. At the end of the trial, patients completed the validated PRAM-TSQ questionnaire measuring treatment satisfaction and preference and perceived medication benefits and side effects.

RESULTS

Statistical modeling demonstrated that active pramlintide was significantly associated with greater treatment satisfaction, preference, and perceived benefits (all except hypoglycemia prevention), as well as objective clinical outcomes (weight loss, lower postprandial glucose [PPG], lower medication tolerance, more hypoglycemia). Perceptions of treatment consequences were sensitive and specific to their cognate objective clinical outcomes (no halo effects). Clinical outcomes (especially PPG) accounted for almost half of the effect of the study medication on treatment satisfaction and preference. Treatment satisfaction and preference were strongly related to the perceived benefits/side effects of the study medication, and these perceptions (especially glucose control) mediated most of the association of clinical outcomes with satisfaction and preference.

CONCLUSIONS

This model received substantial empirical support. Improvements in objective clinical outcomes accounted for a large part of the association of pramlintide treatment with higher treatment satisfaction and preference. Perceived treatment consequences mediated the effect of objective clinical benefits on satisfaction with and preference for the study medication.
Treatment of Symptomatic Polyneuropathy With Actovegin in Type 2 Diabetic Patients
Authors: Ziegler Dan , Movsesyan Lusine , Mankovsky Boris , Gurieva Irina , Abylaiuly Zhangentkhan , Strokov Igor
Published: May 2009

OBJECTIVE

To evaluate the efficacy and safety of actovegin in patients with diabetic polyneuropathy.

RESEARCH DESIGN AND METHODS

In this multicenter, randomized, double-blind trial, 567 patients with type 2 diabetes received 20 intravenous infusions of actovegin (2,000 mg/day) (n = 281) or placebo (n = 286) once daily followed by three tablets of actovegin (1,800 mg/day) or placebo three times daily for 140 days. Total symptom score (TSS) of the lower limbs and vibration perception threshold (VPT) were used as coprimary outcome measures, computed as the area under the curve (AUC) from repeated scores and divided by duration of exposure. Secondary end points included individual TSS symptoms, neuropathy impairment score of the lower limbs (NIS-LL), and quality of life (short form [SF]-36).

RESULTS

TSS was significantly improved during actovegin treatment compared with placebo, as assessed by AUC (−0.56 points [95% CI −0.85 to −0.27]; P = 0.0003), and from baseline to 160 days (−0.86 points [−1.22 to −0.50]; P < 0.0001). VPT (five sites per foot) decreased by 3% (95% CI 0–6; P = 0.084) with actovegin than placebo, as assessed by AUC, and by 5% (1–9; P = 0.017) after 160 days. NIS-LL sensory function, as assessed by AUC, was significantly improved with actovegin versus placebo (−0.25 [95% CI −0.46 to −0.04]; P = 0.021), as was the SF-36 mental health domain. There were no differences in the incidence of adverse events between the groups.

CONCLUSIONS

Sequential intravenous and oral actovegin treatment over 160 days improved neuropathic symptoms, VPT, sensory function, and quality of life in type 2 diabetic patients with symptomatic polyneuropathy.
Central neurocytoma: histopathological variants and therapeutic approaches
Authors: Yaşargil M. Gazi , Ammon Klaus von , Deimling Andreas von , Valavanis Anton , Wichmann Werner , Wiestler Otmar D.
Published: May 2009

✓ The central neurocytoma has recently been added to the differential diagnosis of intraventricular tumors. Histopathologically, this tumor is characterized by a uniform neoplastic cell population with features of neuronal differentiation. Central neurocytomas occur in young adults, develop in the area of the foramen of Monro, and are usually associated with the septum pellucidum. Initial reports appeared to indicate that these tumors are benign lesions with a favorable postoperative prognosis. The authors present clinical and neuropathological findings in a series of eight patients with central neurocytoma. An anterior transcallosal microneurosurgical approach yielded good outcomes. Postoperative radiation therapy was restricted to two patients with a malignant variant of central neurocytoma and one patient with a recurrent tumor. Observations of anaplastic variants of this neoplasm in two cases and local tumor recurrences in three indicate that the biological behavior and postoperative prognosis of central neurocytoma may not always be as favorable as previously assumed.
Cavernous angiomas of the central nervous system in children
Authors: Scott R. Michael , Barnes Patrick , Kupsky William , Adelman Lester S.
Published: May 2009

✓ A surgical series of 19 patients under the age of 18 years with pathologically verified cavernous angioma is presented. Most lesions were located in the cerebral hemispheres, but four were in the pons or midbrain, two in the diencephalon, and one in the spinal cord. Fourteen patients presented with an acute or progressing neurological deficit, three with seizures, one infant with irritability, and one with headache alone. Five patients had family histories of vascular malformations of the central nervous system, and five had multiple lesions. Surgery for small or deep lesions was aided considerably by intraoperative ultrasonographic or stereotactic localization techniques. Pathological examination of the resected malformations revealed a complex histology containing not only typical closely approximated cavernous vessels, but also areas of marked proliferation of granulation tissue and partially re-endothelialized hemorrhage, suggesting a mechanism for the apparent growth of certain cavernous angiomas. The postoperative results were good, with only one patient suffering a permanent worsening of neurological status after surgery. Incomplete resection was initially carried out in five patients, two of whom rebled within 1 year after operation. Long-term follow-up findings in these patients have emphasized the unusual history of certain of these malformations.
Central and peripheral biogenic amine effects of brain missile wounding and increased intracranial pressure
Authors: Soblosky Joseph S. , Rogers N. Lynn , Adams Jeffery A. , Farrell J. Bryan , Davidson June F. , Carey Michael E.
Published: May 2009

✓ This study was performed to ascertain the acute effects of brain missile wounding on brain-stem and hypothalamic biogenic amines in a group of cats anesthetized with pentobarbital (40 mg/kg). Brain wounding is associated with a concomitant increase in intracranial pressure (ICP); to separate the effects of elevated ICP alone from the effects of wounding, a second group of cats had ICP artificially increased from a normal level of approximately 5 mm Hg to approximately 140 mm Hg by infusion of mock cerebrospinal fluid into the cisterna magna. In both groups, significant epinephrine depletions (47% to 74%) occurred in the nucleus tractus solitarius, area A1C1, locus ceruleus, raphe nuclei, and posterior hypothalamus. Epinephrine levels were also significantly decreased in the anterior hypothalamus in the wounded cats. In addition, both brain wounding and artificially induced ICP increases caused significant decreases of norepinephrine in the posterior hypothalamus, and of serotonin, 5-hydroxyindoleacetic acid, dopamine, and homovanillic acid in the raphe nuclei. Only brain wounding, however, caused significant reductions of norepinephrine, dopamine, and homovanillic acid in the nucleus tractus solitarius and area A1C1. The plasma catecholamine levels resulting from brain wounding or artificially induced ICP increases were dissimilar only in the amount of time required to attain maximum plasma levels, with the wounded animals responding faster. It is concluded that the hypothalamic and brain-stem biogenic amine changes resulting from either brain wounding or increased ICP alone are reflective of a stress response. Brain-stem distortion caused by brain wounding did not appear to be a factor and monoaminergic systems appeared to remain intact despite a severe and eventually lethal brain injury. If the detected depletion of epinephrine and serotonin levels is associated with potentially lethal brain injury, pharmacological intervention may be possible.
Autoradiographic analysis of 3H-MK-801 (dizocilpine) in vivo uptake and in vitro binding after focal cerebral ischemia in the rat
Authors: Wallace Michael C. , Teasdale Graham M. , McCulloch James
Published: May 2009

✓ The clinical utility of N-methyl-D-aspartate (NMDA) receptor antagonists is now being assessed in ischemic brain injury in humans. The uptake and retention of NMDA receptor antagonists in ischemic tissue will influence the design of clinical trials. The effects of permanent occlusion of the middle cerebral artery, induced 15 minutes prior to isotope administration, on the uptake of 3H-MK-801 (dizocilpine) have been assessed in the rat with quantitative autoradiography. In a group of three rats at 15 minutes after the intravenous administration of 3H-MK-801, the level (mean ± standard error of the mean) of isotopic tracer in the ischemic cortex and striatum was markedly less than that in the contralateral hemisphere (ipsilateral vs. contralateral caudate nucleus: 22 ± 4 vs. 84 ± 11 pmol/gm, p < 0.01). In contrast, in a group of five rats at 60 minutes after the intravenous administration of 3H-MK-801, the level of isotopic tracer in the ischemic cortex and striatum was greater than that in the contralateral hemisphere (ipsilateral vs. contralateral caudate nucleus: 52 ± 8 vs. 32 ± 4 pmol/gm, p < 0.05). There were no significant alterations in the specific binding of 3H-MK-801 in vitro in ischemic tissue at equivalent times. The early uptake of 3H-MK-801 into the central nervous system is dominated by the level of cerebral blood flow, whereas at later times after administration enhancement of MK-801 binding by elevated extracellular glutamate concentrations appears to be more important in determining the level of the drug in ischemic tissue.
Metastatic choriocarcinoma with neoplastic aneurysms cured by aneurysm resection and chemotherapy
Authors: Fujiwara Takashi , Mino Shogo , Nagao Seigo , Ohmoto Takashi
Published: May 2009

✓ A case of choriocarcinoma with brain and lung metastasis is reported. The patient was admitted for treatment of a cerebral hemorrhage from neoplastic aneurysms and, following removal of the hematoma and resection of the aneurysms, her carcinoma was successfully managed with chemotherapy. She has survived for 6 years after onset without neuroimaging evidence of recurrence. Surgical treatment of metastatic lesions followed by prolonged intensive chemotherapy are indicated for the improved prognosis of choriocarcinoma.
Anterior cervical vertebrectomy and interbody fusion
Authors: Awasthi Deepak , Voorhies Rand M.
Published: May 2009

✓ This report discusses the authors' technique in performing anterior cervical vertebrectomy and interbody fusion for multilevel cervical disease. The technique is performed with a high-speed drill and bone-bank fibular strut graft. After decompression of the cervical canal, ledges are made in the intact vertebral bodies to create a rectangular bed for safe seating of the bone graft. The bone-bank fibular strut graft is a feasible alternative to autograft. The simplified and safe nature of this procedure reduces postoperative morbidity as well as the length of hospital stay.
Relationship of perfusion pressure and size to risk of hemorrhage from arteriovenous malformations
Authors: Spetzler Robert F. , Hargraves Ronald W. , McCormick Patrick W. , Zabramski Joseph M. , Flom Richard A. , Zimmerman Richard S.
Published: May 2009

✓ The relationship between the size of an arteriovenous malformation (AVM) and its propensity to hemorrhage is unclear. Although nidus volume increases geometrically with respect to AVM diameter, hemorrhages are at least as common, in small AVM's compared to large AVM's. The authors prospectively evaluated 92 AVM's for nidus size, hematoma size, and arterial feeding pressure to determine if these variables influence the tendency to hemorrhage.

Small AVM's (diameter ≤ 3 cm) presented with hemorrhage significantly more often (p < 0.001) than large AVM's (diameter > 6 cm), the incidence being 82% versus 21%. Intraoperative arterial pressures were recorded from the main feeding vessel(s) in 24 of the 92 patients in this series: 10 presented with hemorrhage and 14 presented with other neurological symptoms. In the AVM's that had hemorrhaged, the mean difference between mean arterial blood pressure and the feeding artery pressure was 6.5 mm Hg (range 2 to 15 mm Hg). In the AVM's that did not rupture, this difference was 40 mm Hg (range 17 to 63 mm Hg). Smaller AVM's had significantly higher feeding artery pressures (p < 0.05) than did larger AVM's, and they were associated with large hemorrhages. It is suggested that differences in arterial feeding pressure may be responsible for the observed relationship between the size of AVM's and the frequency and severity of hemorrhage.
Results of a prospective randomized trial for treatment of severely brain-injured patients with hyperbaric oxygen
Authors: Rockswold Gaylan L. , Ford Sandra E. , Anderson David C. , Bergman Thomas A. , Sherman Robert E.
Published: May 2009

✓ The authors enrolled 168 patients with closed-head trauma into a prospective trial to evaluate the effect of hyperbaric oxygen in the treatment of brain injury. Patients were included if they had a total Glasgow Coma Scale (GCS) score of 9 or less for at least 6 hours. After the GCS score was established and consent obtained, the patient was randomly assigned, stratified by GCS score and age, to either a treatment or a control group. Hyperbaric oxygen was administered to the treatment group in a monoplace chamber every 8 hours for 1 hour at 1.5 atm absolute; this treatment course continued for 2 weeks or until the patient was either brain dead or awake. An average of 21 treatments per patient was given.

Outcome was assessed by blinded independent examiners. The entire group of 168 patients was followed for 12 months, with two patients lost to follow-up study. The mortality rate was 17% for the 84 hyperbaric oxygen-treated patients and 32% for the 82 control patients (chi-squared test, 1 df, p = 0.037). Among the 80 patients with an initial GCS score of 4, 5, or 6, the mortality rate was 17% for the hyperbaric oxygen-treated group and 42% for the controls (chi-squared test, 1 df, p = 0.04). Analysis of the 87 patients with peak intracranial pressures (ICP) greater than 20 mm Hg revealed a 21 % mortality rate for the hyperbaric oxygen-treated patients, as opposed to 48% for the control group (chi-squared test, 1 df, p = 0.02). Myringotomy to reduce pain during hyperbaric oxygen treatment helped to reduce ICP. Analysis of the outcome of survivors reveals that hyperbaric oxygen treatment did not increase the number of patients in the favorable outcome categories (good recovery and moderate disability). The possibility that a different hyperbaric oxygen treatment paradigm or the addition of other agents, such as a 21-aminosteroid, may improve quality of survival is being explored.
Cerebral blood flow and metabolism following superficial temporal artery to superior cerebellar artery bypass for vertebrobasilar occlusive disease
Authors: Ogawa Akira , Kameyama Motonobu , Muraishi Kenji , Yoshimoto Takashi , Ito Masatoshi , Sakurai Yoshiharu
Published: May 2009

✓ In order to clarify the effectiveness of extracranial-intracranial bypass operations in patients with vertebrobasilar occlusive disease, the authors used positron emission tomography to investigate the cerebral blood flow (CBF) and metabolism of eight patients undergoing superficial temporal artery (STA)-superior cerebellar artery (SCA) bypass procedures. In the preoperative studies, CBF in the region of the posterior fossa was low and the oxygen extraction fraction (OEF) was high, the so-called “misery perfusion syndrome.” Such changes were evident in both the posterior circulation and the anterior circulation regions. Postoperatively, there was a significant increase in CBF, a significant decrease in the OEF not only in the region of posterior circulation but also over the entire brain, and a disappearance of the uncoupling between CBF and oxygen metabolism. The STA-SCA bypass procedure is effective in improving CBF and metabolism in patients with vertebrobasilar occlusive disease.
The cerebral hemodynamics of normotensive hypovolemia during lower-body negative pressure
Authors: Giller Cole A. , Levine Benjamin D. , Meyer Yves , Buckey Jay C. , Lane Lynda D. , Borchers D. John
Published: May 2009

✓ Although severe hypovolemia can lead to hypotension and neurological decline, many patients with neurosurgical disorders experience a significant hypovolemia while autonomic compensatory mechanisms maintain a normal blood pressure. To assess the effects of normotensive hypovolemia upon cerebral hemodynamics, transcranial Doppler ultrasound monitoring of 13 healthy volunteers was performed during graded lower-body negative pressure of up to −50 mm Hg, an accepted laboratory model for reproducing the physiological effects of hypovolemia. Middle cerebral artery flow velocity declined by 16% ± 4% (mean ± standard error of the mean) and the ratio between transcranial Doppler ultrasound pulsatility and systemic pulsatility rose 22% ± 8%, suggesting cerebral small-vessel vasoconstriction in response to the sympathetic activation unmasked by lower-body negative pressure. This vasoconstriction may interfere with the autoregulatory response to a sudden fall in blood pressure, and may explain the common observation of neurological deficit during hypovolemia even with a normal blood pressure.
Anomalous arrangement of the origins of the anterior choroidal and posterior communicating arteries
Authors: Moyer Donald J. , Flamm Eugene S.
Published: May 2009

✓ A case of anomalous origin of the anterior choroidal and posterior communicating arteries in a 36-year-old woman with aneurysmal subarachnoid hemorrhage is presented. Preoperative four-vessel angiography revealed a reverse relationship of these vessels, wherein the anterior choroidal artery origin was proximal to the origin of the posterior communicating artery. This arrangement is extremely rare; the only other reported case was in a patient undergoing angiography prior to acoustic neurinoma resection. It is believed that this is the first case reported in a patient with subarachnoid hemorrhage from rupture of an aneurysm arising from a vessel of such anomalous origin.
Rupture of previously documented small asymptomatic saccular intracranial aneurysms
Authors: Schievink Wouter I. , Piepgras David G. , Wirth Fremont P.
Published: May 2009

✓ In a recent study from the Mayo Clinic on the natural history of intact saccular intracranial aneurysms, none of the aneurysms smaller than 10 mm in diameter ruptured. It was concluded that these aneurysms carry a negligible risk for future hemorrhage and that surgery for their repair could not be recommended. These findings and recommendations have been the subject of much controversy. The authors report three patients with previously documented asymptomatic intact saccular intracranial aneurysms smaller than 5 mm in diameter that subsequently ruptured. In Case 1, a 70-year-old man bled from a 4-mm middle cerebral artery aneurysm that had been discovered incidentally 2½ years previously during evaluation of cerebral ischemic symptoms. A 10-mm internal carotid artery aneurysm and a contralateral 4-mm middle cerebral artery aneurysm had not ruptured. Case 2 was that of a 66-year-old woman who bled from a 4-mm pericallosal aneurysm that had been present 9½ years previously when she suffered subarachnoid hemorrhage (SAH) from a 7 × 9-mm posterior inferior cerebellar artery aneurysm. Although the pericallosal aneurysm had not enlarged in the intervening years, a daughter aneurysm had developed. The third patient was a 45-year-old woman who bled from a 4- to 5-mm posterior inferior cerebellar artery aneurysm that had measured approximately 2 mm on an angiogram obtained 4 years previously; at that time she had suffered SAH due to rupture of a 5 × 12-mm posterior communicating artery aneurysm. These cases show that small asymptomatic intact saccular intracranial aneurysms are not innocuous and that careful consideration must be given to their surgical repair and long-term follow-up study.
Blood pressure and intracranial pressure-volume dynamics in severe head injury: relationship with cerebral blood flow
Authors: Bouma Gerrit J. , Muizelaar J. Paul , Bandoh Kuniaki , Marmarou Anthony
Published: May 2009

✓ Increased brain tissue stiffness following severe traumatic brain injury is an important factor in the development of raised intracranial pressure (ICP). However, the mechanisms involved in brain tissue stiffness are not well understood, particularly the effect of changes in systemic blood pressure. Thus, controversy exists as to the optimum management of blood pressure in severe head injury, and diverging treatment strategies have been proposed. In the present study, the effect of induced alterations in blood pressure on ICP and brain stiffness as indicated by the pressure-volume index (PVI) was studied during 58 tests of autoregulation of cerebral blood flow in 47 comatose head-injured patients. In patients with intact autoregulation mechanisms, lowering the blood pressure caused a steep increase in ICP (from 20 ± 3 to 30 ± 2 mm Hg, mean ± standard error of the mean), while raising blood pressure did not change the ICP. When autoregulation was defective, ICP varied directly with blood pressure. Accordingly, with intact autoregulation, a weak positive correlation between PVI and cerebral perfusion pressure was found; however, with defective autoregulation, the PVI was inversely related to cerebral perfusion pressure. The various blood pressure manipulations did not significantly alter the cerebral metabolic rate of oxygen, irrespective of the status of autoregulation.

It is concluded that the changes in ICP can be explained by changes in cerebral blood volume due to cerebral vasoconstriction or dilatation, while the changes in PVI can be largely attributed to alterations in transmural pressure, which may or may not be attenuated by cerebral arteriolar vasoconstriction, depending on the autoregulatory status. The data indicate that a decline in blood pressure should be avoided in head-injured patients, even when baseline blood pressure is high. On the other hand, induced hypertension did not consistently reduce ICP in patients with intact autoregulation and should only be attempted after thorough assessment of the cerebrovascular status and under careful monitoring of its effects.
Long-term ictal monitoring with subdural strip electrodes: prognostic factors for selecting temporal lobectomy candidates
Authors: Weinand Martin E. , Wyler Allen R. , Richey E. T. , Phillips Barbara B. , Somes Grant W.
Published: May 2009

✓ Long-term electrocorticographic (ECoG) monitoring data from subdural strip electrodes are analyzed to determine factors associated with seizure-free outcome from anterior temporal lobectomy. A total of 89 consecutive patients with complex partial seizures, in whom long-term ictal video/scalp electroencephalographic monitoring was insufficient to localize their epileptogenic focus, were subsequently evaluated with long-term ictal ECoG monitoring using subdural strip electrodes. Each patient underwent anterior temporal lobectomy based on the ictal ECoG data and has been followed for at least 1 year. The following parameters were found to be statistically significant in predicting a seizure-free outcome: unilateral onset, electrical onset pattern beginning as fast spike trains, absence of frontal lobe background desynchronization at onset, and an interhemispheric propagation time of greater than 8 seconds. Electrocorticographic criteria that were not associated with seizure outcome included: right- versus left-sided onset, time from electrical to clinical ictal onset, focality of onset (number of strip electrode contacts involved), and stereotypical ECoG onset. When present, the interictal focus was concordant with the ictal focus in most patients (96%), but was falsely lateralizing in 4% of cases. It is suggested that these data should improve patient selection for temporal lobectomy when subdural strip monitoring is used during preoperative evaluation.
Selection and combination of various endovascular techniques in the treatment of giant aneurysms
Authors: Taki Waro , Nishi Shogo , Yamashita Kohsuke , Sadatoh Akiyo , Nakahara Ichiro , Kikuchi Haruhiko , Iwata Hiroo
Published: May 2009

✓ Between April, 1989, and January, 1991, a total of 19 cases of giant aneurysm were treated by the endovascular approach. The patients included seven males and 12 females aged 15 to 72 years. Detachable balloons, occlusion coils, and ethylene vinyl alcohol copolymer liquid were used as embolic materials. In seven cases, thrombosis of the aneurysmal sac and/or base was achieved while sparing the parent arterial flow; complete obliteration of the aneurysm was achieved in four of these. Of these four patients, the thrombotic material was a detachable balloon in two, a combination of a detachable balloon and coils in one, and occlusion liquid in one. In the other three cases, complete occlusion was not achieved; one aneurysm was occluded with a detachable balloon and two with coils. In 11 patients, the parent artery was occluded either by trapping or by proximal arterial occlusion, and all patients showed complete occlusion of the aneurysms. In one patient, a combined bypass procedure and parent artery occlusion was performed.

Among the 19 cases in this series there were four transient ischemic attacks, one reversible ischemic neurological deficit, and one death due to aneurysmal rupture during the procedure. Two patients died in the follow-up period, one from pneumonia 2 months postoperatively and the other from acute cardiac failure 2 weeks following surgery. Both deaths were unrelated to the endovascular procedure. It is concluded that the endovascular treatment of giant aneurysms remains difficult because of the large and irregular shape of the aneurysmal base and thrombus in the aneurysmal sac. The proper selection and combination of the available endovascular techniques is therefore of critical importance.
Long-term results of spinal accessory nerve-facial nerve anastomosis
Authors: Ebersold Michael J. , Quast Lynn M.
Published: May 2009

✓ A number of methods have been developed to reduce the cosmetic and functional disability resulting from facial nerve loss. It has often been suggested that the major trunk of the spinal accessory nerve should not be sacrificed for providing dynamic facial function because of shoulder disability and pain. A review of Mayo Clinic records has revealed that, between the years of 1975 and 1983, 25 patients underwent spinal accessory nerve-facial nerve anastomosis using the major division (branch to the trapezius muscle) of the spinal accessory nerve.

There were 11 males and 14 females, ranging in age from 16 to 60 years (mean 41 years). The interval between facial nerve loss and anastomosis was 1 week to 34 months (mean 4.62 months). The duration of follow-up study ranged from 7 to 15 years (mean 10.8 years).

Twenty patients had no complaints or symptoms related to their shoulder or arm at the time of this review and no patient had significant shoulder morbidity. The facial function achieved was “minimal” in five cases, “moderate” in six, and good to excellent in 14. Most patients appeared to benefit significantly from the spinal accessory nerve-facial nerve anastomosis. The morbidity of the procedure seemed quite minimal even in the young and active. The authors continue to believe that the spinal accessory nerve-facial nerve anastomosis, even when using the major trunk of the spinal accessory nerve, is a very useful and beneficial procedure.
An in vitro comparative study of conducting vessels and penetrating arterioles after experimental subarachnoid hemorrhage in the rabbit
Authors: Vollmer Dennis G. , Takayasu Masakazu , Dacey Ralph G.
Published: May 2009

✓ The reactivity of rabbit basilar artery and penetrating arteriolar microvessels was studiedin vitrousing an isometric-tension measurement technique and an isolated perfused arteriole preparation, respectively. Comparisons were made between reactivities of normal vessels and those obtained from animals subjected to experimental subarachnoid hemorrhage (SAH) 3 days prior to examination. Subarachnoid hemorrhage produced significant increases in basilar artery contraction in response to increasing concentrations of serotonin (5-hydroxytryptamine) (10−9to 10−5M) and prostaglandin F2α(10−9to 10−5M) when compared to normal arteries. In addition, SAH attenuated the relaxing effect of acetylcholine following serotonin-induced contraction and of adenosine triphosphate after KCl-induced basilar artery contractions. In contrast to the changes observed in large arteries, cerebral microvessels did not demonstrate significant differences in spontaneous tone or in reactivity to a number of vasoactive stimuli including application of calcium, serotonin, and acetylcholine. On the other hand, small but significant changes in arteriolar responsiveness to changes in extraluminal pH and to application of KCl were noted.

Findings from this study suggest that intracerebral resistance vessels of the cerebral microcirculation are not greatly affected by the presence of subarachnoid clot, in contrast to the large arteries in the basal subarachnoid space. The small changes that do occur are qualitatively different from those observed for large arteries. These findings are consistent with the observation of significant therapeutic benefit with the use of calcium channel blockers without changes in angiographically visible vasospasm in large vessels. It is likely, therefore, that calcium antagonists may act to decrease total cerebrovascular resistance at the level of the relatively unaffected microcirculation after SAH without changing large vessel diameter.
Inflammatory leukocytes associated with increased immunosuppression by glioblastoma
Authors: Black Keith L. , Chen K. , Becker Donald P. , Merrill Jean E.
Published: May 2009

✓ In order to determine thein vivoimmune response in glioblastoma, monoclonal and polyclonal antibodies specific for inflammatory leukocytes and immunoregulatory products were utilized to stain tissue from four surgical specimens. The more activated the inflammatory cells, the more activated the tumors appeared to be. In the tumor with the largest infiltration (Case 3), inflammatory cells were stained for interferon-γ interleukin-2. interleukin-1β. lymphotoxin, tumor necrosis factor-µ, and transforming growth factor-β. The tumor cells also expressed interleukin-1β, interleukin-6, transforming growth factor-β, tumor necrosis factor-µ, and prostaglandin E. In contrast, in the tumor with the least inflammatory response (Case 1), the tumor cells did not express any cytokines. Expression of cytokines by glioma cells was modest in the two cases with modest inflammatory responses. Cellular inflammation, primarily consisting of T cells and macrophages with few or no B cells or natural killer cells, was two- to 15-fold greater outside the tumor than within. In contrast to leukocytes outside the tumor, which were activated and expressing class II major histocompatibility antigens, leukocytes within the tumor parenchyma or at the tumor's edge were negative for these antigens. In the four specimens studied here, the tumor cells themselves were also negative for class II major histocompatibility antigens. These findings, although preliminary, suggest that inflammatory cells within gliomas are inactivated and that glioma cells may increase the expression of immunosuppressive cytokines in response to an increased lymphocyte infiltrate. This observation, if corroborated by more extensive studies, may help to explain the failure of immune treatments in glioblastoma multiforme.
Emergency embolectomy for embolic occlusion of the middle cerebral artery after internal carotid artery balloon test occlusion
Authors: Linskey Mark E. , Sekhar Laligam N. , Hecht Stephen T.
Published: May 2009

✓ Balloon test occlusion of the internal carotid artery (ICA) is useful in preoperatively assessing the risk of temporary occlusion or permanent sacrifice of the carotid artery. The incidence of symptomatic complications from this procedure is 1.7%. The case is reported of a 57-year-old woman in whom a balloon test occlusion of the left ICA was attempted. She developed a left ICA dissection/occlusion with subsequent embolization to the left middle cerebral artery, leading to right-sided hemiplegia and expressive aphasia. She was successfully treated by an emergency embolectomy followed by surgical repair of the left ICA, with an excellent outcome. This case represents the most serious complication encountered by the authors in more than 300 balloon test occlusions. Means of avoiding this complication during balloon test occlusion as well as the important factors in managing this problem are emphasized.
Radiation therapy for juvenile pilocytic astrocytoma of the pituitary stalk
Authors: Takeuchi Juji , Kikuchi Kiyoshi , Shibamoto Yuta , Fujisawa Ichiro
Published: May 2009

✓ A case of juvenile pilocytic astrocytoma of the pituitary stalk is reported. The patient presented with diabetes insipidus and growth retardation. Magnetic resonance (MR) imaging was useful in diagnosing the lesion. Although the tumor could not be completely removed by surgery, radiotherapy was effective and the residual tumor disappeared 6 months after irradiation. The patient's condition has remained stable and no recurrence has been observed by MR imaging in the 4 years since radiation therapy.
Direct thrombosis of aneurysms with cellulose acetate polymer
Authors: Kinugasa Kazushi , Mandai Shinya , Terai Yoshinori , Kamata Ichiro , Sugiu Kenji , Ohmoto Takashi , Nishimoto Akira
Published: May 2009

✓ The authors report the treatment of seven intracranial aneurysms in six patients with direct infusion of cellulose acetate polymer solution, a new liquid thrombotic material. These aneurysms were considered inoperable because of their size or location, or because of the patient's neurological condition. This material avoids the difficulties associated with balloon occlusion, and completely fills even irregularly shaped aneurysms. Cellulose acetate polymer solution hardens in about 5 minutes and remains solid once inside the aneurysm. Because this technique is less invasive than surgery, it can be used for high-risk patients in the acute stage of subarachnoid hemorrhage. Transient motor aphasia occurred in one patient. A small residual neck, which caused rebleeding 3 months after the treatment, remained in another patient. This article describes the new material, the procedure for direct thrombosis, and preliminary clinical results.
Endovascular treatment of posterior circulation aneurysms by electrothrombosis using electrically detachable coils
Authors: Guglielmi Guido , Viñuela Fernando , Duckwiler Gary , Dion Jacques , Lylyk Pedro , Berenstein Alex , Strother Charles , Graves Virgil , Halbach Van , Nichols Douglas , Hopkins Nick , Ferguson Robert , Sepetka Ivan
Published: May 2009

✓ In a multicenter study, 120 patients with intracranial aneurysms presenting a high surgical risk were treated using electrolytically detachable coils and electrothrombosis via an endovascular approach. The results of treatment in patients with posterior fossa aneurysms (42 patients with 43 aneurysms) are presented. The most frequent clinical presentation was subarachnoid hemorrhage (24 cases). The clinical follow-up periods ranged from 1 week to 18 months. Complete aneurysm occlusion was obtained in 13 of 16 aneurysms with a small neck and in four of 26 wide-necked aneurysms. A 70% to 98% thrombosis of the aneurysm was achieved in 22 of 26 aneurysms with a wide neck and in three of 16 small-necked aneurysms. One aneurysm could not be treated due to a technical complication. Two cases required postprocedural surgical clipping of a residual aneurysm.

One patient (originally in Hunt and Hess Grade V) experienced procedural rupture of the aneurysm requiring an emergency parent artery occlusion. He eventually died 5 days later. Another patient (originally in Grade IV) had coil migration and posterior cerebral artery territory ischemia. A third patient developed a permanent neurological deficit (hemianopsia) after complete occlusion of a wide-necked basilar bifurcation aneurysm. One patient, harboring an inoperable giant basilar bifurcation aneurysm, died from aneurysm bleeding 18 months after partial occlusion.

Overall morbidity and mortality rates related to treatment were 4.8% (two cases) and 2.4% (one case), respectively (2.6% and 0% if considering only patients in Hunt and Hess Grades I, II, and III).

It is suggested that this technique is a viable alternative in the management of patients with posterior fossa aneurysms associated with high surgical risk. Longer angiographic and clinical follow-up study is necessary to determine the long-term efficacy of this recently developed endovascular occlusion technique. Close postoperative angiographic and clinical monitoring of patients with wide-necked subtotally occluded aneurysms is mandatory to check for potential aneurysmal recanalization, regrowth, and rupture.
The influence of transoral odontoid resection on stability of the craniovertebral junction
Authors: Dickman Curtis A. , Locantro Jacqueline , Fessler Richard G.
Published: May 2009

✓ Twenty-seven cases of craniovertebral junction compression treated with transoral surgery were reviewed to assess the influences of pathological processes and surgical interventions on spinal stability. All patients presented with signs and symptoms of spinal-cord or brain-stem dysfunction. Pathology included rheumatoid arthritis in 11 patients, congenital osseous malformations in 11, spinal fractures in two, plasmacytoma in one, osteomyelitis in one, and a gunshot injury in one. Instability was defined as clear radiographic evidence of mobile subluxation in conjunction with clinical assessment.

Of 19 patients (70%) requiring internal fixation, nine underwent upper cervical fusion and 10 had occipitocervical fusion. When instability occurred, all subluxations were at the C1–2 level. There were no occipitoatlantal subluxations. Eight patients (30%) had preoperative instability of the craniovertebral junction due solely to their pathology, 11 patients (40%) suffered instability after transoral surgery, and eight (30%) were without clinical or radiographic evidence of instability (mean follow-up period 14 months).

Craniovertebral junction instability predominated among patients with rheumatoid arthritis: 91% required fusion and 45% presented with pre-existing instability. Among individuals with congenital osseous malformations, 45% required fusion and only one patient (9%) had pre-existing instability. Patients who required subsequent posterior decompression of a Chiari malformation were at risk for developing instability; three of four became unstable after posterior decompression.

Transoral resection of the dens, the anterior arch of C-1, and the lower clivus does not fully destabilize the spine; however, this operation may potentiate incipient pathological instability. The primary determinants of instability are the extent of pathological bone destruction, ligamentous weakening, and operative bone removal. Long-term follow-up monitoring is needed after transoral surgery to detect cases of late instability.