bluuebunny/crossref_metadata_2025_split huggingface dataset:
Neurophysiological effects of dorsal column stimulation in man and monkey
Authors: Larson Sanford J. , Sances Anthony , Riegel Donald H. , Meyer Glenn A. , Dallmann Donald E. , Swiontek Thomas 
Published: May 2009

✓ In 18 patients with cancer and intractable pain, capacitatively coupled pulses of 0.25 msec duration were delivered transcutaneously at 100 Hz to sets of five in-line electrodes implanted subdurally over the dorsal columns. Averaged somatosensory-evoked potentials were recorded from scalp electrodes before, during, and after application of current. All but one patient experienced relief of pain during stimulation, persisting for as long as several hours afterward. Eleven patients developed hyperactive deep reflexes, pathological reflexes, and decreased perception of joint rotation, pain, and touch below the level of current application. Somatosensory-evoked potential amplitudes were markedly reduced. All neurological findings returned to control values within 1 hour after each of repeated applications of current. Histological examination of spinal cord sections from four cancer patients showed no changes secondary to long-term current application.
Similar currents were applied to the spinal cord of 15 monkeys with chronically implanted bipolar recording or stimulating electrodes over the lower, middle, and upper thoracic cord, in nucleus ventralis posterior lateralis (VPL), and over the sensory motor cortex (SMC). With application of current, the responses in VPL and SMC to peripheral stimulation were abolished. Evoked potential responses were abolished between bipolar stimulating electrodes and bipolar recording electrodes separated by the five in-line electrodes used to supply the 100 Hz current. However, when both stimulating and recording electrodes were either above or below the five in-line electrode set, evoked responses were unaffected. The findings indicate that applied currents blocked neuronal transmission by producing local changes in the cord. The prolonged alteration of cerebral evoked potentials and relief of pain, however, could also be related to involvement of supraspinal neurons.
The experimental effect of direct electrical current on intracranial arteries and the blood-brain barrier
Authors: Fox John L. , Yasargil M. Gazi 
Published: May 2009

✓ Direct electrical current (DC) was applied to the basilar artery of 20 dogs and the circle of Willis of five monkeys. The artery was in contact with microsurgical forceps acting as the monopolar electrode. The DC currents from 0 to 1 mA were used at voltages of 0 to 3 V with observable effect noted at levels above 0.5 mA at 1 V. Neither negative (−) nor positive (+) DC caused vasoconstriction unless the initial and terminal current change occurred too rapidly causing a stimulus pulse. Both − and + DC caused focal vasodilatation of the artery made spastic by needle puncture or topical 10% barium chloride (BaCl2). This dilatation was more rapid (30 to 60 sec) and more pronounced with −DC current. Angiography confirmed extreme focal dilatation lasting at least 4 days after −DC application. This appears to be secondary to the known production of hydroxyl (OH−) ions at the cathode and possibly hydrogen (H+ or H3O+) ions at the anode during electrolysis. We hypothesize that smooth muscle protein bonds are affected. The effects of DC on the systemic arteries also are described.
Also studied were the effects of similar DC on brain cortical microvasculature of 10 dogs and on the systemic arteries of 50 rats. It was discovered that not only did + DC cause the well-known local coagulation phenomena but also both − and + DC caused formation of micro-emboli with resulting occlusion of arterioles. These phenomena, which could be seen only under the operating microscope, occurred after a decomposition potential of about 1 V was reached. We theorize this was due to the formation of denatured protein and alkali-hematin at the − pole secondary to the formation of OH− ions during electrolytic reduction and due to formation of denatured protein and acid-hematin at the + pole secondary to the formation of H+ ions during electrolytic oxidation. For reasons not yet clear there was an acute breakdown in the blood-brain barrier to fluorescein around the negative pole but not around the positive pole.
Surgical treatment of arterial aneurysms of the vertebrobasilar circulation
Authors: Chou Shelley N. , Ortiz-Suarez Humberto J. 
Published: May 2009

✓ Twenty patients with basilar bifurcation aneurysms and subarachnoid hemorrhage were treated surgically as a consecutive series irrespective of preoperative grading. There were six fatalities; eight of the survivors have done well while six are in poor condition.
The authors also report a series of 13 surgical cases of posterior fossa aneurysm not located at the basilar bifurcation, three on the posterior cerebral artery, five on the basilar trunk, and five on the vertebral origin of the posterior inferior cerebellar artery. There were two operative deaths and one late death due to pulmonary embolism. The other 10 have had good results.
Spinal evoked response in the cat
Authors: Sarnowski Robert J. , Cracco Roger Q. , Vogel Harold B. , Mount Fred 
Published: May 2009

✓ Summated evoked potentials to sciatic nerve stimulation were recorded from surface electrodes placed over the spine of cats. The response progressively increased in latency rostrally. It was largest and most complex in configuration in leads placed over the caudal spinal cord where sciatic nerve roots enter and begin to ascend the cord. The conduction velocity of the response was about 90 m/sec from rostral sacral to cervical regions.
A comparison of surface-recorded evoked responses to stimulation of the sural nerve, the nerve to the medial head of the gastrocnemius muscle and the sciatic nerve suggest that the peripheral nerve fibers that mediate the response to sciatic nerve stimulation are primarily muscle nerve afferents. In surface, lamina, and durai recordings made over similar segmental levels, the response to sciatic nerve stimulation progressively increased in amplitude, duration, and wave form complexity from surface to depth. Failure of transmission across complete cord transections was demonstrated. Results in preparations with partial cord sections suggest that the surface-recorded response is mediated by multiple spinal cord afferent pathways which are situated primarily ipsilateral to the stimulated peripheral nerve.
The data indicate that summated evoked responses arising in spinal cord afferent pathways can be recorded from surface-recording electrodes in cats. They suggest that this animal model may prove useful in the study of certain aspects of spinal cord pathology.
Treatment of mycotic intracranial aneurysms
Authors: Bingham William F. 
Published: May 2009

✓ Two patients with mycotic intracranial aneurysms were successfully treated with only antibiotic therapy. One patient, who had subacute bacterial endocarditis, rheumatic valvular disease, and an abscessed tooth, sustained a subarachnoid hemorrhage from a ruptured right middle cerebral artery trifurcation aneurysm. The other patient, who had Turner's syndrome and probable congenital aortic stenosis, developed multiple neurological findings during an episode of acute bacterial endocarditis precipitated by an infected ingrown toenail; a false aneurysm of the distal left middle cerebral artery and two lesions involving the left superior cerebellar artery were found. A study of the literature shows that only 45 patients with mycotic intracranial aneurysms have received adequate antibiotic therapy and angiographic documentation. Statistically, there does not appear to be a clear-cut advantage to antibiotics plus surgical therapy over antibiotics alone. In fact, in 21 patients who underwent serial angiography, lesions were smaller in six and not visualized in 11. In four patients the aneurysms increased in size; in two others fresh lesions formed.
The author proposes the following diagnostic and therapeutic regimen: 1) earliest possible diagnosis of the underlying disorder; 2) appropriate antibiotic therapy; 3) early four-vessel cerebral angiography and follow-up studies every 2 to 3 weeks; 4) definitive surgery without delay if the aneurysm is larger on the first repeat study; 5) definitive operation upon completion of antibiotic therapy if the lesion is larger or the same size; and 6) postoperative angiography to evaluate the effectiveness of treatment and to search for interim lesions.
Physiological consequences of experimental cerebral missile injury and use of data analysis to predict survival
Authors: Crockard H. Alan , Brown Frederick D. , Calica Arnold B. , Johns Lydia M. , Mullan Sean 
Published: May 2009

✓ The authors describe cerebrovascular and cerebral metabolic changes in monkeys subjected to cerebral missile injury. After injury with a BB pellet at 90 m/sec, there is a rapid rise in intracranial pressure (ICP), which reaches a peak 2 to 5 minutes posttrauma, and then falls to about 20 to 30 mm Hg. This, with a fall in mean blood pressure (MBP), results in a 50% reduction in cerebral perfusion pressure (CPP). Cerebral blood flow (CBF) is also reduced, although acutely there is no close relationship with CPP. Cerebrovascular resistance falls initially and then at 30 minutes rises to very high values. Cerebral metabolic rates (CMR's) for oxygen fall after injury and remain low for the rest of the animal's life; CMR's for lactate rise immediately after injury and persist for 5 hours, then fall. After injury with a faster missile (180 m/sec), the ICP rises higher and faster, and the peak is shorter. The CPP is reduced in this injury to approximately 30 mm Hg, and only one animal survived more than 1 hour.
With the conventional forms of data analysis, the length of survival after injury correlates well with MBP, ICP, and CBF, but separately they were completely unsatisfactory for prediction of an individual's prognosis. With the technique of multiple linear regression analysis, the survival of individual animals could be predicted with great accuracy. This is possible also when two postinjury parameters, CBF and MBP, are used.
Effects of positive end-expiratory pressure on intracranial pressure and compliance in brain-injured patients
Authors: Frost Elizabeth A. M. 
Published: May 2009

✓ Hypoxic pulmonary disorders and head injuries associated with increased intracranial pressure (ICP) frequently co-exist. Positive end-expiratory pressure (PEEP) improves hypoxemia but has been reported to impede cerebral venous return, potentially causing a further increase in ICP. This study examined the effects of PEEP on ICP at different levels of brain compliance.
Continuous ICP recordings were obtained after insertion of Scott cannulas to the lateral ventricles of seven comatose patients. Brain compliance was assessed by calculation of the pressure volume index. Patients were maintained in a 30° head-up position. Maintenance of PEEP to levels of 40 cm H2O pressure for as long as 18 hours did not increase ICP in patients with either normal or low intracranial compliance, and did not increase ICP in the absence of pulmonary disease. Central venous pressure and pulmonary artery wedge pressure increased proportionately as PEEP was increased. No consistent changes were found in blood pressure recordings, nor were there any reductions in cardiac output found during the studies. Abrupt discontinuation of PEEP did not result in increased ICP except for a transient rise on two occasions when respiratory secretions became copious and the patients were inadequately ventilated. Improved oxygenation in two patients as a result of PEEP was concomitant with improved intracranial compliance and neurological status.
In patients with brain injuries, PEEP improves arterial oxygenation without increasing ICP as previously supposed. Consequently, PEEP is a valuable form of therapy for the comatose patient with pulmonary disorders such as pneumonia or pulmonary edema.
An audible alarm for monitoring air embolism during neurosurgery
Authors: Brechner Theresa M. , Brechner Verne L. 
Published: May 2009

✓ The sensitivity of various monitors during experimental pulmonary air embolization was measured in five dogs. Changes in vital signs, electrocardiogram, Doppler sound, and end tidal CO2 were observed. An audible alarm was incorporated in the end tidal CO2 monitor. The results showed that a 0.01 cc to 0.02 cc/kg dose of air triggered the Doppler consistently, but the changes in heart sounds were heard only transiently. The fall in end tidal CO2 occurred at 0.5 to 1.0 cc/kg of intravenously injected air and was confirmed by pen write-out. The audible alarm device was constructed to sound after four consecutive breaths with preset percentage fall in end tidal CO2. The changes in vital signs occurred at doses of 4 to 8 cc/kg of air and death occurred at 8 to 10 cc/kg.
The sound alarm was used in 30 patients during sitting craniotomies. Eight patients developed air emboli initially detected by transient change in Doppler sound. The alarm called attention to the fall in end tidal CO2 and confirmed the occurrence of air emboli.
Experimental head injury in the rat
Authors: Nilsson Bengt , Pontén Urban , Voigt Gerhard 
Published: May 2009

✓ Impact acceleration was used to elicit cerebral concussion in the albino rat. The pathophysiological response and morphological damage from the concussion were studied in groups of animals. The animals were grouped according to impact velocity (6–11 m/sec), and the threshold and different degrees of the concussive response were established. The concept of concussion as primarily a neuronal, functional disturbance was confirmed. However, this reaction was readily influenced by respiratory and circulatory changes, and morphological damage.
Defined reactions could be elicited in groups of animals according to impact velocity. Thus, the model appeared well standardized for further studies of concussion pathophysiology, expressed in terms of cerebral energy metabolism and blood flow.
Criteria for evaluating patients undergoing chemotherapy for malignant brain tumors
Authors: Levin Victor A. , Crafts David C. , Norman David M. , Hoffer Paul B. , Spire Jean-Paul , Wilson Charles B. 
Published: May 2009

✓ The authors describe their criteria for evaluating brain-tumor patients, and present a numerical rating scale devised to designate response to testing. They discuss the reliability of test combinations that permit accurate prediction of response or deterioration during therapy in their experience with 100 patients treated on the Chemotherapy Service at the Brain Tumor Research Center, University of California, San Francisco School of Medicine. Specifically, the paper summarizes the predictive value of the neurological examination, radionuclide scintiscan, computerized tomographic brain scan (CT scan), and electroencephalogram (EEG), in the determination of response (tumor regression) or deterioration (tumor growth) during brain-tumor chemotherapy and chemotherapy-radiotherapy.
By retrospective analysis, the neurological examination, radionuclide scintiscan, and CT scan were of equal value individually as tests to predict response to therapy. However, the prognostic values of the neurological examination or the radionuclide scintiscan proved moderately superior to the CT scan in predicting deterioration during therapy. Under circumstances whereby a neurological examination, radionuclide scintiscan, and CT scan were all performed during the same testing session, and steroid dosage was carefully monitored, two of the three tests accurately predicted deterioration in 65% of patients, and response to therapy in 82% of patients. Two of the three tests correctly established deterioration in the remaining 35% of patients, and response in the remaining 18% of patients, when the two positively correlated tests had occurred within a mean period of 7 weeks.
The spinal cord central canal in kaolin-induced hydrocephalus
Authors: Torvik Ansgar , Murthy V. S. 
Published: May 2009

✓ In order to study the cause of the great individual variations in kaolin-induced hydrocephalus, the lower brain stem and upper spinal cord were examined histologically in a series of young rabbits that had received injections of kaolin into the cisterna magna.
Animals with complete occlusion of the outlets from the fourth ventricle into the subarachnoid space showed only a moderate ventricular dilatation, while cases with marked hydrocephalus also had plugs of kaolin in the caudal part of the fourth ventricle. The intraventricular kaolin was adherent to the roof of the fourth ventricle by strands of connective tissue and it is suggested that the plugs served as valves that initially occluded the opening of the central canal and were then lifted away as the ventricle dilated and the roof moved posteriorly. The animals with marked hydrocephalus also had extensive dilatation of the central canal with cleft formation in the posterior columns. The observations support the concept that in hydrocephalus the central canal may serve as an alternative resorption route for the cerebrospinal fluid through communication with the spinal subarachnoid space.
The effect of norepinephrine on the spinal cord circulation and its possible implications in the pathogenesis of acute spinal trauma
Authors: Crawford Robert A. , Griffiths Ian R. , McCulloch James 
Published: May 2009

✓ The effect of intra-arterially administered norepinephrine (NE) upon spinal cord blood flow (SCBF), before and after disruption of the blood-cord barrier was studied in dogs. Barrier disruption was accomplished with an intra-arterial bolus injection of 2.5 M urea. Multiple ligations of branches of the posterior aorta and cannula placements ensured that the urea was directed to the lumbar and sacral segments of the cord. The SCBF was measured by the hydrogen clearance method. Intra-arterial urea by itself had no significant effect on SCBF.
The intra-arterial infusion of NE (12 µg/min and 30 µg/min) was without overall effect on SCBF. However, if the blood-cord barrier had been previously disrupted with hypertonic urea, both concentrations of NE resulted in large reductions in SCBF. No such reductions in SCBF were seen with blood-cord barrier disruption and NE if the animals had been pre-treated with the α-blocker, phenoxybenzamine (1.5 mg/kg). Some aspects of the possible involvement of NE in the pathophysiology of acute spinal injury are discussed.
The pressure-volume function of brain elasticity
Authors: Sklar Frederick H. , Elashvili Ilya 
Published: May 2009

✓ The intracranial pressure-volume function as determined by brain elasticity is reported in normal dogs. Rapid subarachnoid infusions clearly define an exponential relationship between pressure and volume. An aliquot technique to measure elastance (dP/dV) at multiple intracranial pressures demonstrates a linear relationship between elastance and pressure. This follows mathematically from the exponential nature of the basic pressure-volume function.
The clinical significance of brain elastance measurements is discussed. It is emphasized that the effects of pressure on CSF dynamics are superimposed on the pressure-volume function of brain elasticity and probably account for the process of spatial compensation for an expanding mass lesion. It is not apparent that elastance measurements can serve as indicators of impending decompensation, since the pressure-volume function of brain elasticity provides no direct information about CSF dynamics. Accordingly, the clinical usefulness of elastance measurements is seriously questioned.
Transsphenoidal microhypophysectomy in acromegaly
Authors: Hoi Sang U , Wilson Charles B. , Tyrrell J. Blake 
Published: May 2009

✓ From July, 1970, to March, 1975, 62 transsphenoidal operations were performed on 61 acromegalic patients (39 males, 22 females). Of these patients, 58 presented with symptoms of hypersecretion of human growth hormone (HGH), with relatively infrequent local effects. Each patient was evaluated neuroradiologically, and each tumor was classified as an enclosed or an invasive adenoma, with or without suprasellar extension. Anterior pituitary function was also evaluated for each patient, pre- and postoperatively. During the transsphenoidal procedure, selective gross total removal of the adenomatous tissue was attempted, and was successful in 53 patients; selective subtotal tumor removal was performed in eight patients.
In 38 patients who had not undergone prior therapy, a selective total excision was achieved in 36; of these, 30 patients were considered cured, on the basis of relief of clinical symptoms and reduction of the serum HGH level to below 10 mg/ml. There was no significant difference in cure rates between the enclosed and the invasive adenomas, and no cures were achieved by any procedure short of selective total tumor removal. In these latter cases, postoperative irradiation was employed. Eighteen patients had received prior therapy in the forms of cryohypophysectomy (eight cases), cryohypophysectomy and irradiation (two cases), craniotomy (two cases), craniotomy and irradiation (two cases), and irradiation alone (four cases). The treatment results in this group were less favorable. In the entire series of 62 operations, complications occurred in eight patients in the form of cerebrospinal fluid leak, meningitis, sinusitis, nasal-oral fistula, transient diabetes insipidus (six cases), and carotid and cavernous injuries. In the group of 43 previously untreated patients, endocrine complications occurred in five, of which only three have permanent deficits. In the previously treated 18 patients, one developed compromised pituitary function from the transsphenoidal procedure. In the entire series, there was no surgical mortality, although two patients died of surgically unrelated causes.
Clinical and endocrinological evaluation of 16 acromegalic patients treated by transsphenoidal surgery
Authors: Leavens Milam E. , Samaan Naguib A. , Jesse Richard H. , Byers Robert M. 
Published: May 2009

✓ Sixteen patients with acromegaly treated with transsphenoidal pituitary surgery were evaluated with the measurement of serum human growth hormone (HGH) before and after intravenous stimulation with thyrotropin-releasing hormone (TRH). Fourteen of these patients showed a significant rise of serum HGH after TRH stimulation before surgery. After surgery, 12 patients with Grade 2 noninvasive adenomas had normal fasting serum HGH levels which did not stimulate with TRH. Two of these patients showed high serum HGH levels both at fasting and after TRH stimulation and required a second operation to remove residual adenoma within the sella before adequate lowering of HGH was achieved. Evidence of recurrent adenoma has not occurred clinically or biochemically in this group of 12 patients followed for an average of 24 months (2 to 60 months).
The results were unsatisfactory in four of these 16 patients. One patient who has a postoperative HGH of 9 ng/ml which still stimulates with TRH has made clinical improvement, but must have residual adenoma in the sella or invasive adenoma in the dura and tumor capsule. Additional treatment with irradiation has been given. Failure to achieve satisfactory results in the other three patients was attributed to the presence of locally invasive adenoma; one in the sphenoid sinus, and the other two possibly as a consequence of previous operative procedures.