bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ultrastructural changes in rat peripheral nerve following pneumatic tourniquet compression
Authors: Nitz Arthur J. , Matulionis Daniel H. 
Published: May 2009

✓ The sciatic nerves of 12 male rats were examined in the electron microscope 14 days after pneumatic tourniquet compression. Tourniquet pressure was maintained at 300 mmHg for varied lengths of time (30 minutes to 3 hours). Nerves compressed for 30 minutes showed very mild fissuring of the myelin without axonal degeneration. Examination of nerves compressed for 1 to 3 hours showed progressively more varied and extensive damage. Changes included splaying of myelin lamellae, axonal shrinkage with periaxonal edema, Schwann cell hypertrophy, and an increase in the number of microtubules and mitochondria per unit area. The myelin sheaths of some fibers, compressed for more than 2 hours, were completely ruptured. These changes resemble nerve lesions which could be induced by a variety of experimental procedures. Ultrastructural changes produced by tourniquet compression are apparently time-related and affect large-diameter nerves more profoundly than smaller-diameter nerves.
The data reported provide an explanation for delayed muscle rehabilitation experienced by patients who have undergone extremity surgery with pneumatic tourniquet application. The evidence presented suggests that the incidence of tourniquet palsy may be far greater than previously recognized.
Intraoperative monitoring of brain-stem auditory evoked potentials
Authors: Grundy Betty L. , Jannetta Peter J. , Procopio Phyllis T. , Lina Agnes , Boston J. Robert , Doyle Earl 
Published: May 2009

✓ Brain-stem auditory evoked potentials (BAEP) were monitored during 54 neurosurgical operations in the cerebellopontine angle. The BAEP were irreversibly obliterated in five patients who required deliberate section of the auditory nerve. Technical difficulties interfered with monitoring in three cases, and three patients had deafness and absent BAEP preoperatively.
Reversible alterations in BAEP were seen during 32 operations, with recovery after as long as 177 minutes of virtually complete obliteration. Changes in BAEP were associated with surgical retraction, operative manipulation, positioning of the head and neck for retromastoid craniectomy, and the combination of hypocarbia and moderate hypotension. In 19 cases, waveforms improved after specific interventions made by the surgeon or anesthesiologist because of deteriorating BAEP. In 13 other cases, BAEP recovered after maneuvers not specifically related to the electrophysiological monitoring, most often completion of operative manipulation. Whenever BAEP returned toward normal by the end of anesthesia, even after transient obliteration, hearing was preserved. Irreversible loss of BAEP occurred only when the auditory nerve was deliberately sacrificed. The authors conclude that monitoring of BAEP may help prevent injury to the auditory nerve and brain stem during operations in the cerebellopontine angle.
Cerebral and systemic circulatory effects of arterial hypotension induced by adenosine
Authors: Kassell Neal F. , Boarini David J. , Olin Julie J. , Sprowell James A. 
Published: May 2009

✓ In six dogs anesthetized with halothane and nitrous oxide, mean arterial pressure (MAP) was lowered to 40 mm Hg for an average of 90 minutes by intravenous infusion of adenosine. The hypotensive effect of the adenosine was potentiated by administering dipyridamole to block its intravascular inactivation. Blood flow to the brain, spinal cord, heart, kidneys, and skeletal muscle was measured six times in each animal using the radioactive microsphere technique. Determinations were made before, during, and 30 minutes after the hypotensive period.
During the hypotensive period, MAP was decreased 61% and was related to a proportional decrease in peripheral vascular resistance. Cardiac index decreased 14%. Total cerebral blood flow (CBF) decreased an average of 28% and cerebral vascular resistance decreased 53%. The reduction in CBF was heterogeneous; the cerebral cortex and corpus callosum were most affected and the brain stem least affected. No change occurred in the cerebral metabolic rate of oxygen usage (CMRO2). Left ventricle flow increased 147% and right ventricle flow increased 271%. Blood flow to the kidneys decreased 70%, and to the liver decreased to 6% of control. Jejunum blood flow increased 138% during recovery, while stomach flow varied but showed no statistical change. There was no tachyphylaxis, rebound hypertension, or toxicity associated with the adenosine-induced hypotension. These properties suggest that adenosine may be a useful agent for inducing arterial hypotension in neurosurgical patients.
Use of free latissimus dorsi musculocutaneous flaps in various neurosurgical disorders
Authors: Barrow Daniel L. , Nahai Foad , Fleischer Alan S. 
Published: May 2009

✓ Musculocutaneous (skin-muscle) flaps have been used predominantly by plastic surgeons for a variety of reconstructive purposes. With the advent of microvascular techniques, the area to be reconstructed is no longer limited to the arc of rotation of the vascular pedicle of the muscle. Instead, the muscle and overlying skin that is best suited for the reconstructive procedure may be dissected out as a free flap, with microvascular anastomosis of an arterial supply and venous drainage to locally existing vessels.
This report demonstrates the usefulness of musculocutaneous free flaps in the repair of large defects of the scalp, cranium, and dura after trauma or resection of invasive neoplasms. The authors describe the use of a latissimus dorsi free musculocutaneous flap in eight patients who would have required multiple operations to provide coverage by other techniques. There have been no major complications, and adequate repair has been accomplished, even in cases involving exposed brain.
Comparison of middle cerebral artery trunk occlusion by silicone cylinder embolization and by trapping
Authors: Okada Yoshikazu , Shima Takeshi , Yokoyama Noboru , Uozumi Tohru 
Published: May 2009

✓ The authors produced occlusion of the middle cerebral artery (MCA) trunk in dogs by two methods: silicone cylinder embolization and trapping. Comparative analyses of the clinicopathological features in these models, extending from the acute to chronic stage, were performed.
Within 24 hours after embolization, the brain exhibited swelling without macroscopic infarction. Microangiograms revealed impaired filling in the deep areas of the brain with midline shift. At 4 to 7 days after embolization, the animals showed major neurological deficits, evident deep cerebral infarction, and poorly perfused areas in the deep cerebrum with prominent midline shift. At 3 to 4 weeks after embolization, the neurological deficits improved and the affected regions showed cavities or localized lesions. Microangiograms demonstrated hypervascular areas with abnormal vessels in the affected cerebrum. On the other hand, trapping of the MCA trunk produced mild neurological deficits, although there was no evidence of macroscopic lesions or impairment of filling. This study shows that silicone cylinder embolization in the MCA trunk produces a reliable and reproducible deep cerebral infarction in dogs.
The oval pupil: clinical significance and relationship to intracranial hypertension
Authors: Marshall Lawrence F. , Barba David , Toole Belinda M. , Bowers Sharon A. 
Published: May 2009

✓ The oval pupil, or what has also been termed the “oblong” or “football” pupil, has been observed in 15 neurosurgical patients over a 2-year period. In 14 of the 15 patients, the intracranial pressure (ICP) was elevated, ranging from 18 to 38 mm Hg. While the oval pupil was primarily seen in patients suffering closed head injuries (11 cases), it was also observed in two patients with elevated ICP following hemorrhage from an arteriovenous malformation. In nine of the 14 patients in whom the pupillary abnormality was associated with intracranial hypertension, the oval pupil disappeared when the ICP was reduced to below 20 mm Hg. In four cases, the ICP could not be controlled and the pupil became progressively larger, and finally fixed and unreactive.
The oval pupil represents a transitional stage indicating transtentorial herniation with third nerve compression. Although it may be seen in the absence of intracranial hypertension (one case in this series), this appears to be relatively uncommon. The presence of such a pupil on examination in a patient suffering an intracranial catastrophe, be it head injury, subarachnoid hemorrhage, or intracerebral hemorrhage, suggests impending transtentorial herniation with brain-stem compression.
Operative management of selected brachial plexus lesions
Authors: Kline David G. , Judice Donald J. 
Published: May 2009

✓ A 12-year operative experience with 171 consecutive patients with severe brachial plexus lesions who had at least 1½ years of follow-up review is analyzed. Selection for and timing of operation was helped by categorization of each individual plexus element as “completely” or “incompletely” injured and as “in continuity” or “not in continuity.” Results for each element could be given a single grade by a system which defined that element's proximal and distal input.
For most lesions in continuity, an operative delay of several months is advocated so that intraoperative electrical evaluation can be used. Thus, in 282 gunshot wounded and stretch-injured elements of which 210 were thought to be clinically complete, 63 were spared resection because of nerve action potentials (NAP's) found at intraoperative testing, and 57 recovered function with only neurolysis. Elements resected (120) were confirmed as neurotmetic both by intraoperative electrical and subsequent histological studies. Acceptable results were achieved in 16 of 24 sutures, in 43 of 89 grafts, and in each of seven split repairs. Upper trunk and lateral and posterior cord elements fared better than lower trunk and medial cord lesions unless the latter were shown, with evidence of NAP's, to be regenerating and could be spared resection. Some stretched elements could, however, not be repaired, even though an attempt was made to exclude such cases from operation.
Lacerations to the brachial plexus where continuity is lost are best repaired primarily if the injury is sharp; in this series, 14 of 18 elements having such repair recovered, whereas in 37 elements with secondary repair, grafts were often necessary and only 50% recovered function. Although associated with skin lacerations, 17 elements with complete loss were in continuity, and six of these were shown to be regenerating and were not resected. Despite intraneural location, large size, and prior operation, many benign tumors (including neurofibromas) can be removed without significant loss by use of the surgical loupes or microscope and repetitive NAP recording. Surgery for selected brachial plexus lesions is worthwhile.
Early versus delayed heparin reversal after carotid endarterectomy in the dog
Authors: Ercius Mark S. , Chandler William F. , Ford John W. , Burkel William E. 
Published: May 2009

✓ The present study investigates the hematological reaction to arterial injury during the first 10 minutes after endarterectomy in dogs to determine if heparin reversal during this early period predisposes to thrombus formation. Known platelet physiology would predict that heparinization during this early period would be useful to allow a fibrin-free platelet monolayer to form.
After systemic heparinization (145 µ/kg) of the experimental animals, 42 endarterectomies were performed. Blood flow was then resumed for specific periods of time, and the vessels were prepared for scanning electron microscopy. Group 1 vessels (from the unheparinized control group) revealed mural thrombus formation after 10 minutes of blood flow. Group 2 vessels revealed the progressive formation of a fibrin-free platelet monolayer after 2, 5, or 10 minutes of blood flow resumption under systemic heparinization. Group 3 arteries, harvested at 10 minutes, underwent immediate (within 1 to 2 minutes after resumption of flow) heparin reversal with protamine sulfate, and demonstrated numerous patches of fibrin covering the platelet monolayer. Group 4 arteries, studied after 3 hours of blood flow, also underwent immediate heparin reversal. Two of these seven specimens had clumps of fibrin overlying the platelet monolayer. The Group 5 vessels had heparin reversal at 10 minutes, and demonstrated no fibrin overlying the platelet monolayer after 3 hours of blood flow.
This study demonstrates the formation of a fibrin-free platelet monolayer over the endarterectomized vessel wall within 10 minutes of resumption of flow under systemic heparinization. These findings suggest that heparin may safely be reversed following a carotid endarterectomy if one awaits the initial critical 10 minutes of blood flow.
Control of blood flow in the cat spinal cord
Authors: Scremin Oscar U. , Decima Emilio E. 
Published: May 2009

✓ Spinal cord blood flow (SCBF) and the effect of end-tidal CO2 concentration (ETCO2) on SCBF (CO2 reactivity) were studied in the lumbar spinal cord of cats by means of the hydrogen-clearance technique. Hydrogen gas was administered by inhalation, and its level in spinal cord tissue was estimated amperometrically with small (75 µm) platinum electrodes. The average SCBF's at normocapnia (ETCO2 = 4%) of the ventral horn gray matter and of the white matter at several locations were 43.2 and 16.2 ml·100 gm−1·min−1, respectively. For gray and white matter, the values of CO2 reactivity, estimated by the coefficient of the regression of SCBF (ml·100 gm−1·min−1) on ETCO2 (ml·100 ml−1) were 11.6 and 2.1, respectively. No differences in SCBF or CO2 reactivity were observed between intact animals kept under N2O-O2 ventilation and decerebrated animals with no anesthesia.
After an acute spinal section, ventral horn SCBF and CO2 reactivity (measured eight segments below the cordotomy) were not altered, in spite of the profound neural depression present (that is, spinal shock). Orthodromic (dorsal root) stimulation of the ventral horn neurons induced an average increase in blood flow of 128% above control values. Antidromic (ventral root) motoneuron activation failed to produce any significant changes in ventral horn blood flow.
The favorable effect of early parenteral feeding on survival in head-injured patients
Authors: Rapp Robert P. , Pharm D. , Young Byron , Twyman Diana , Bivins Brack A. , Haack Dennis , Tibbs Phillip A. , Bean James R. 
Published: May 2009

✓ This prospective randomized controlled clinical trial compares the effects of early parenteral nutrition and traditional delayed enteral nutrition upon the outcome of head-injured patients. Thirty-eight head-injured patients were randomly assigned to receive total parenteral nutrition (TPN) or standard enteral nutrition (SEN). Clinical and nutritional data were collected on all patients until death or for 18 days of hospitalization. Survival and functional recovery were monitored in survivors for 1 year. Of the 38 patients, 18 were randomized to the SEN group and 20 to the TPN group. Demographically, the two groups of patients were similar on admission. There was no significant difference in the severity of head injury between the two groups as measured by the Glasgow Coma Scale (p = 0.52). The outcome for the two groups was quite different, with eight of the 18 SEN patients dying within 18 days of injury, whereas no patient in the TPN group died within this period (p < 0.0001).
The basis for the improved survival in the TPN patients appears to be improved nutrition. The TPN patients had a more positive nitrogen balance (p < 0.06), and a higher serum albumin level and total lymphocyte count. More adequate nutritional status may have improved the patients' immunocompetence, resulting in decreased susceptibility to sepsis. The data from this study strongly support the favorable effect of early TPN on survival from head injury.
Sphenoethmoidal cephalocele with cleft palate: transpalatal versus transcranial repair
Authors: Lewin Michael L. 
Published: May 2009

✓ Two cases of sphenoethmoidal encephalocele with cleft palate are reported in detail. The encephaloceles had prolapsed into the nose and nasopharynx, and protruded into the mouth. Previous examples of this entity are reviewed. Such patients have a typical facial appearance: hypertelorism, median cleft lip, and bifid nose of varied severity. Ocular findings include coloboma of the optic nerve or anophthalmia. The prolapsed cerebral tissue varies from nonfunctional glia elements to vital structures of the hypothalamus-pituitary area. Agenesis of the corpus callosum has been reported consistently.
Transcranial access to the bone defect, particularly its posterior portion, is difficult because of distorted cerebral anatomy and abnormal vasculature. The fragility of the prolapsed cerebral tissue makes it difficult to preserve the cerebral tissue intact and to reposition it into the cranium. When there is a cleft palate, it is possible to repair the encephalocele extracranially through a transoral, transpalatal approach, preserving and repositioning the content of the sac. Dural closure and obliteration of the bone defects are other essential steps of the operation. Both patients reported here were successfully operated on by the transoral, transpalatal route, at the age of 3 months and 4 years, respectively. They were followed for several years and had comprehensive endocrinological work-ups. One patient exhibited some pituitary deficiency requiring substitution therapy.
The National Traumatic Coma Data Bank
Authors: Marshall Lawrence F. , Becker Donald P. , Bowers Sharon A. , Cayard Carol , Eisenberg Howard , Gross Cynthia R. , Grossman Robert G. , Jane John A. , Kunitz Selma C. , Rimel Rebecca , Tabaddor Kamran , Warren Joseph 
Published: May 2009

✓ This paper describes the pilot phase of the National Traumatic Coma Data Bank, a cooperative effort of six clinical head-injury centers in the United States. Data were collected on 581 hospitalized patients with severe non-penetrating traumatic head injury. Severe head injury was defined on the basis of a Glasgow Coma Scale (GCS) score of 8 or less following nonsurgical resuscitation or deterioration to a GCS score of 8 or less within 48 hours after head injury.
A common data collection protocol, definitions, and data collection instruments were developed and put into use by all centers commencing in June, 1979. Extensive information was collected on pre-hospital, emergency room, intensive care, and recovery phases of patient care. Data were obtained on all patients from the time of injury until the end of the pilot study.
The pilot phase of the Data Bank provides data germane to questions of interest to neurosurgeons and to the lay public. Questions are as diverse as: what is the prognosis of severe brain injury; what is the impact of emergency care; and what is the role of rehabilitation in the recovery of the severely head-injured patient?
Intra-arterial ACNU therapy for malignant brain tumors
Authors: Yamashita Junkoh , Handa Hajime , Tokuriki Yasuhiko , Ha Young Soo , Otsuka Shin-Ichi , Suda Kinya , Taki Waro 
Published: May 2009

✓ The authors examined the growth rate of mouse 203 glioma cells in vitro and found it to be markedly inhibited after exposure to ACNU for 5 minutes at a drug concentration of 100 µg/ml. Rats that had undergone intracranial implantation of T1 neurogenic tumor were treated by 5 mg/kg of ACNU administered either intravenously or intra-arterially. The median survival times for the control animals and the animals undergoing intravenous or intracarotid administration of ACNU were 23, 29, and 46 days, respectively. The difference in survival time between the intravenous and intracarotid administration groups was statistically significant (p < 0.01) when examined by the Cox-Mantel test.
In a clinical trial, 17 patients with glioblastoma were treated by ACNU, eight intravenously and nine by the intra-arterial route. The drug was given in doses of 2 to 3 mg/kg at least twice before and twice after a course of postoperative radiotherapy. Intra-arterial administration was performed over a period of 5 minutes under local anesthesia. The median postoperative survival time for the patients in the intra-arterial group was 12.5 months, compared with 9.0 months for those in the intravenous group. The survival rate for the intra-arterial group was slightly higher, although statistically not significant, probably because the number of cases was small. The degree of thrombocytopenia due to ACNU tended to be less marked in the intra-arterially treated patients. The theoretical advantages of the intra-arterial administration of ACNU are discussed.
Scanning electron microscope study of human arachnoid villi
Authors: D'Avella Domenico , Cicciarello Rocco , Albiero Francesca , Andrioli Giancarlo 
Published: May 2009

✓ The functional morphology of human arachnoid villi obtained from surgical biopsy specimens has been studied by scanning electron microscopy (SEM). On SEM examination, the villi appeared to be distended, as if functioning normally. The endothelial cells constituting the cerebrospinal fluid (CSF)-blood interface were covered by numerous microvilli, uniformly oriented along the major axis of the villus. Examination for cell-to-cell contact revealed only occasional areas of tight adherence between adjacent endothelial cells, while widened intercellular spaces were frequently observed. Generally corresponding to the apex of the villus, points of emergence of endothelium-lined hollow structures were identified; these may represent apical openings of open pathways from the subarachnoid space to the venous system. Ultrastructural arrangements consistent with a closed system of CSF reabsorption were also observed. Large cells maximally distended and protruding into the sinus lumen were commonly seen; these were interpreted as the result of the formation of giant vacuoles within the endothelium covering the villus.
This study has provided ultrastructural evidence for both closed and open systems of CSF reabsorption. Ultrastructural findings, such as gaps between endothelial cells and tubule-like endothelium-lined structures as previously identified in animals and observed in man by transmission electron microscopy, were demonstrated in human biopsy specimens by SEM.
An experimental study of the acute stage of subarachnoid hemorrhage
Authors: Kamiya Ken , Kuyama Hideyuki , Symon Lindsay 
Published: May 2009

✓ A baboon model of subarachnoid hemorrhage (SAH) has been developed to study the changes in cerebral blood flow (CBF), intracranial pressure (ICP), and cerebral edema associated with the acute stage of SAH. In this model, hemorrhage was caused by avulsion of the posterior communicating artery via a periorbital approach, with the orbit sealed and ICP restored to normal before SAH was produced. Local CBF was measured in six sites in the two hemispheres, and ICP monitored by an implanted extradural transducer. Following sacrifice of the animal, the effect of the induced SAH on ICP, CBF, autoregulation, and CO2 reactivity in the two hemispheres was assessed. Brain water measurements were also made in areas of gray and white matter corresponding to areas of blood flow measurements, and also in the deep nuclei.
Two principal patterns of ICP change were found following SAH; one group of animals showed a return to baseline ICP quite quickly and the other maintained high ICP for over an hour. The CBF was reduced after SAH to nearly 20% of control values in all areas, and all areas showed impaired autoregulation. Variable changes in CO2 reactivity were evident, but on the side of the hemorrhage CO2 reactivity was predominantly reduced. Differential increase in pressure lasting for over 7 minutes was evident soon after SAH on the side of the ruptured vessel. There was a significant increase of water in all areas, and in cortex and deep nuclei as compared to control animals.