Electrophysiological identification of a visual area in shark telencephalon.

Optic nerve stimulation in the shark evokes short-latency telencephalic field potentials localized to the ipsilateral, posterior central nucleus. Such a well-defined visual area in elasmobranch telencephalon further challenges classical formulations of forebrain evolution. Moreover, its ipsilateral representation confirms recent evidence for a crossed thalamotelencephalic visual projection.

Electron microscopic evidence of a ventronasal to dorsotemporal variation in fiber size in pigeon optic nerve.

Using a uniform sampling method, electron-microscopic examination of pigeon optic nerve revealed a dorsotemporal to ventronasal gradient in mean fiber size. In the dorsotemporal region small, myelinated axons (mean diameter = 0.87 micrometer, S.D. = 0.27) were predominant. Also unique to this region were scattered clusters of fine, unmyelinated fibers. A wider, bimodal spectrum in fiber size (mean diameter = 1.50 micrometer, S.D. = 0.66) was found in the ventronasal region of the nerve. Axons located in the area between these regions possessed a mean diameter of 1.15 micrometer, S.D. = 0.43. This gradient, constant throughout the length of the nerve, resulted from a nasal-to-temporal diminution in size and frequency of large fibers superimposed upon a relatively uniform small fiber base. The total number of fibers within the nerve, excluding those comprising the unmyelinated clusters, was calculated to be approximately 2.3 x 10(6). The overall distribution in fiber size appeared to be unimodal with the peak at 0.75 micrometer and mean diameter = 1.04 micrometer, S.D. = 0.44. Although previous investigators have reported that cross-sectional analysis of pigeon optic nerve revealed a homogeneous distribution in fiber size, the findings of the present study may be more compatable with anatomical and physiological features of pigeon retinotectal organization. These features include visual field acuity gradients, ganglion cell population pattern, and density fields of tectal afferent terminations.

Regional differences in pigeon optic tract, chiasm, and retino-receptive layers of optic tectum.

Electron-microscopic examination of the pigeon optic chiasm, tract, stratum opticum, and retino-receptive layers of the optic tectum revealed regional differences at each level. Axonal size in the fiber pathways paralleled that previously reported for pigeon optic nerve, with mean diameter values of 0.96 micrometer for optic chiasm and 1.06 micrometer for optic tract. The dorsolateral aspects of these pathways contained a heterogeneous population of fibers (mean diameter congruent to 1.44 micrometer) similar to that found in the nasal portion of optic nerve, while the ventromedial regions were occupied by a more homogeneous population of smaller fibers (mean diameter congruent to 0.82 micrometer) resembling those observed in the temporal portion of the nerve. The retino-receptive layers of anteroventral optic tectum (avT) differed ultrastructurally from those of posterodorsal tectum (pdT) with respect to the thickness of horizontal dendrites in layer 2-3, the size of optic terminals in layers 2-7, and the number of synaptic contacts per terminal. These findings point towards a regional variation in the processing of visual information throughout the retino-tectal system and suggest that neurons in avT vs. pdT should show differences in the way they modify the neurophysiological characteristics of their respective optic inputs.

Intracranial arteriovenous malformations. Current imaging and treatment.

Patients with intracranial arteriovenous malformations (AVM) can expect significant mortality (15% to 20%) and morbidity (20% to 30%) over a 15-year to 20-year period. Recent advances in interventional neuroradiology, neurosurgery, neuroanesthesia, and stereotactic radiotherapy provide the opportunity to obliterate many of these lesions that were untreatable previously. The overall risk from treatment is estimated to be less than 50% that associated with untreated AVMs. For these reasons, it is important for the diagnostic radiologist to understand the diagnosis, natural history, treatment choices, and risks associated with patients with intracranial AVMs.

Retinal afferents to the pigeon optic tectum: discharge characteristics in response to whole field illumination.

Responses of pigeon retinotectal afferents to changes in whole field illumination are quantitatively analyzed for 313 units recorded in the stratum opticum. One hundred per cent of these units were responsive in unanesthetized birds and 92.9 percent in urethane anesthetized preparations. Of the responsive units, 92.4 percent (anesthetized) and 100 percent (unanesthetized) gave on-responses whose discharge characteristics showed an orderly relationship to stimulus intensity. Following the on-response, discharge generally ceased during sustained illumination. At stimulus termination off-responses frequently occurred, their probability being a function of stimulus intensity and duration. This probability, as well as specific response characteristics, could be predicted to a large extent from on-response characteristics. Anesthesia and level of background illumination predictably affected these response characteristics quantitatively but did not alter them qualitatively. It is hypothesized that with respect to whole field illumination the pigeon's retinotectal afferents constitute a homogeneous population continuously distributed according to threshold for intensity change.

Vertebrobasilar junction aneurysms associated with fenestration: treatment with Guglielmi detachable coils.

Three patients with vertebrobasilar junction aneurysms and associated fenestration were treated with Guglielmi detachable coils. The structure and hemodynamics of fenestrations may account for their frequent association with aneurysms. The complex hemodynamics of these aneurysms requires evaluation of both vertebral arteries. One treatment complication occurred but resulted in no deficit. All patients have returned to normal activity and remain healthy at 14 to 46 months.

Intravenous video arteriography of the intracranial vasculature: early experience.

A computerized fluoroscopic apparatus developed by members of the University of Wisconsin Medical Physics Section was used for 12 months to perform intravenous video arteriography. In previous papers, the apparatus was described and its use was illustrated for performing time subtraction intravenous video arteriography of the extracranial carotid arteries, the arteries of the abdomen and extremities, as well as angiocardiography. In this report, the use and current limitations of this technique for evaluation of the intracranial vasculature are described and illustrated.

Effect of prophylactic methicillin on cerebrospinal fluid shunt infections in children.

This study retrospectively and prospectively analyzes uncomplicated, noninfected, primary ventriculoperitoneal shunting procedures and ventriculoperitoneal shunt revisions in children done at the University of Wisconsin Hospital from July 1973 to December 1979. We compared the infection rates between patients whose procedures were done without prophylactic antibiotics and those who received prophylactic single dose methicillin at the time of operation. Among 105 procedures done without prophylactic methicillin, there were 8 infections; 4 occurred after 73 primary shunt placements and 4 followed 32 shunt revisions. Among 66 procedures done with prophylactic methicillin, there were 3 infections; all followed primary shunt insertions. There was no infection after 32 shunt revisions in which prophylactic antibiotics were used.

Nonsurgical management of spontaneous intracerebral hematoma.

This report describes our experience with the use of osmotic diuretics, governed by continuous monitoring of intracranial pressure (ICP), as the primary treatment for 12 consecutive patients suffering from an acute, supratentorial intracerebral hematoma. In all cases the hematoma, as shown by computed tomographic scan, had a long axis of greater than 4.0 cm. ICP and cerebral perfusion pressure were successfully maintained within the assigned limits in all patients, and in none was surgical evacuation required. There was one death during the 6-month follow-up period. With appropriate weighting to differences in admission status, statistical comparison of the patient outcome in the present series with that reported by McKissock et al. suggests that ICP monitoring can improve the outcome of conservatively (and perhaps surgically) treated patients.

Early treatment of ruptured aneurysms with Guglielmi detachable coils: effect on subsequent bleeding.

The major causes of mortality and morbidity in patients surviving the rupture of a saccular aneurysm are subsequent bleeding and vasospasm. The purpose of this study was to evaluate the influence of early treatment of ruptured aneurysms with Guglielmi detachable coils on the incidence of subsequent bleeding. Thirteen patients were treated within 72 hours of initial aneurysm rupture with Guglielmi detachable coils. Excluding three patients who died 2, 4, and 12 weeks after initial hemorrhage, all others have been followed up for intervals between 6 and 36 months (mean, 16 mo). None of these have had either clinical or radiographic evidence of subsequent bleeding. Assuming that there is a 30% incidence of subsequent bleeding in conservatively (nonsurgically) treated patients, the 0% subsequent bleed rate observed in this subgroup was significant at a P value of 0.01. Only one procedure-related complication occurred in this series, and 9 of 13 (69%) aneurysms were 100% occluded at the time of initial treatment. All aneurysms were at least 90% occluded at the end of initial treatment. In addition to reducing the risk of subsequent bleeding, early treatment facilitated the institution of an aggressive approach for management of both vasospasm and increased intracranial pressure. Patient outcome, as measured by the Glasgow Outcome Scale, was good in 9 of 13 (69%), poor in 1 of 13 (8%), and death in 3 of 13 (23%) patients. The results of this study suggest that early Guglielmi detachable coil treatment of ruptured aneurysms may be effective in reducing the incidence of subsequent bleeding and can be performed with a low incidence of complications.(ABSTRACT TRUNCATED AT 250 WORDS)

Treatment of increased intracranial pressure: a comparison of different hyperosmotic agents and the use of thiopental.

Long term intracranial pressure (ICP) monitoring was carried out in over 200 patients with various intracranial abnormalities; a fiberoptic epidural intracranial pressure monitor was used. Ninety of these patients had significantly elevated ICP or exhibited pressure waves requiring therapy. Initial therapy consisted of hyperventilation with a respirator and administration of hyperosmotic agents. Comparison studies utilizing 30% urea, 20% mannitol, and furosemide intravenously and 30% urea and 10% glycerol orally were randomly done. In 45 patients two or more of these agents were used at different times in the same patient for comparison of effectiveness. When equimolar amounts of intravenous urea and mannitol were used, similar effects on increased ICP were obtained. There was no significant reduction of increased ICP with the use of furosemide alone. No rebound effect was observed with either mannitol or urea. Orally, urea was more effective than glycerol in equimolar amounts. Again no rebound was observed. In 14 patients who required doses of hyperosmotic agents more frequently than every 4 hours, continuous infusion of thiopental was used in conjunction with the hyperosmotic agents to control pressure. This regimen resulted in good ICP control in 12 patients. A rational protocol for the medical management of increased ICP utilizing hyperosmotic agents and, in refractory cases, hyperosmotic agents plus thiopental has resulted in effective control of ICP in 96% of our patients throughout their course without the need to resort to decompressive surgery. (Neurosurgery, 5: 570--575, 1979).

Surgical stabilization of traumatic cervical spine dislocation using methyl methacrylate. Long-term results in 26 patients.

Twenty-six patients with traumatic cervical spine fracture-dislocations had spinal stabilization with methyl methacrylate (acrylic) as the primary support. In most cases a 3/4-in. stainless steel screw was inserted into the articular pillars of the fractured vertebra and of the two adjacent vertebrae, followed by application of the acrylic in the form of an oblong mold over the heads of the screws. The follow-up period in these 26 patients ranged from 6 months to 7 years. There were no instances of wound infection or increased neurological impairment. Vertebral elements remained aligned in 25 of the 26 patients. Breakage of the acrylic support was documented in two patients, but in only one was surgical repair required. The results of this study indicate that the procedure is a safe and effective method for both immediate and long-term stabilization of cervical spine fracture-dislocations.

Intrachiasmatic craniopharyngioma. Case report.

A patient with bitemporal hemianopsia was found to have an enlarged optic chiasm. Biopsy of the intrachiasmatic tissue revealed craniopharyngioma.

Surgical stabilization of cervical spinal fractures using methyl methacrylate. Technical considerations and long-term results in 52 patients.

This study analyzes the long-term outcome of 52 consecutively treated patients with acute cervical spinal fracture/dislocation who underwent posterior surgical stabilization using methyl methacrylate in the absence of bone grafting. The patients ranged in age from 15 to 93 years. In 40 patients the injury was located in the lower cervical spine; for these a previously described surgical format was employed. In 12 patients the fracture involved C-1 or C-2, and the modification used for these injuries is presented. The postoperative period of evaluation ranged from 6 months to 12 years. There was one case of infection, which eventually required removal of the acrylic, but there were no instances of new neurological injury or of operative mortality. Failure of stabilization occurred in two previously reported patients treated early in the series. Comparison of the patient outcome in this study with that of certain other reports suggests that at least four technical factors are important for the success of methyl methacrylate stabilization: 1) the acrylic inlay must be provided with an anchor to bone; 2) the anchor must be of a type that does not easily erode through bone; 3) the inclusion of wire must be done in a manner that allows each strand to be completely encased in the acrylic; and 4) the cross-sectional area of the inlay is critical.

Ultrastructural evidence of arterial denervation following experimental subarachnoid hemorrhage.

Loss of catecholamine histofluorescence, increased sensitivity to norepinephrine, and changes in alpha1 receptor binding have led to the proposal that denervation hypersensitivity may play a role in cerebrovascular spasm. Because the significance of these alterations has remained unclear, the present study was undertaken to determine whether there was direct ultrastructural evidence of arterial denervation following experimental subarachnoid hemorrhage. Under general anesthesia, adult cats were subjected to pre-pontine injection of blood or serum (5 to 7 ml) via a transclival approach. The animals were sacrificed 4, 7, or 10 days later and basilar artery segments were prepared for electron microscopy. Control vessels appeared normal, whereas those bathed in blood revealed unequivocal changes in neural and supporting elements, including: 1) disintegration of both clear- and dense-core vesicles; 2) fragmentation of varicosities; 3) loss of Schwann cell cytoplasm; and 4) axonal degeneration. These changes were most pronounced 7 days after instillation of blood, and correlated in time with maximal injury of the media and endothelium. Although the development of smooth-muscle hypersensitivity remains unsettled, this study indicates that prolonged exposure to blood can cause extensive denervation of cerebral arteries.

Bilirubin and the induction of intracranial arterial spasm.

Although a number of substances which participate in the physiological control of vascular caliber have been proposed to play a causative role in cerebral vasospasm, none of these has been shown to induce the profound, sustained degree of constriction or the vasculopathy that characterize this disorder. The present study was undertaken to determine whether bilirubin, a hemoglobin breakdown product with detergent-like activity, accrued in incubated blood or in intracranial hematoma and whether topical application of bilirubin altered the caliber or morphology of cerebral arteries. As a model of blood residing in the subarachnoid space, sterile vials of cat blood and of human blood were incubated in vitro at 37 degrees C. The concentration of bilirubin in the supernatant of cat blood increased from a value of 0.27 +/- 0.3 mg% (mean +/- standard error of the mean) on Day 0 to a value of 9.57 +/- 2.4 mg% on Day 10; the respective values for human blood were 0.53 +/- 0.02 mg% and 13.4 +/- 5.4 mg%. Samples of intracranial hematoma that had been surgically removed from three patients between 4 and 11 days after hemorrhage yielded bilirubin levels from 2.1 to 15.2 mg%. Application of a bilirubin suspension of 5, 10, or 20 mg% in buffered Ringer's solution to cat basilar artery in vivo led to progressive and sustained constriction; at 4 hours the mean decrease in the width of the blood column was 34% +/- 2.1%. Ultrastructural analysis of these vessels showed widespread pathological changes similar to those associated with cerebral vasospasm. Application of a 10-mg% bilirubin suspension to the basilar artery of two baboons produced similar alterations. Minimal changes in diameter or morphology were observed in cat arteries bathed in buffer solution alone. These findings in animal models indicate that bilirubin may play a central role in the development of cerebral vasospasm.

Phase II trial of interferon-beta for treatment of recurrent glioblastoma multiforme.

Twelve patients were admitted to a Phase II study on the treatment of recurrent glioblastoma multiforme with interferon-beta (IFN-beta). All patients had previously undergone craniotomy and received a standard course of radiation therapy. Recurrence was inferred from enlargement of the lesion on computerized tomography (CT) scanning and in each case was confirmed by CT-guided stereotaxic biopsy. Treatment consisted of combined intravenous (10 X 10(6) IU/day) and intratumoral (1 X 10(6) IU every other day) administration of IFN-beta over three 10-day cycles. This regimen was well tolerated, with toxicity requiring temporary dose modifications in five patients. As judged from data from historical cases, however, the patients admitted to this study demonstrated no clear improvement in mean survival time. The findings of this study also emphasize the importance of distinguishing between radiation necrosis and tumor recurrence.

Hemin: levels in experimental subarachnoid hematoma and effects on dissociated vascular smooth-muscle cells.

Although hemin is known to exert toxic effects on a variety of cell types, its possible participation in the genesis of cerebral vasospasm has received little attention. The authors measured the concentration of hemin in experimental subarachnoid clot and studied its effects on the morphology and 45Ca++ uptake of vascular smooth-muscle cells dissociated from canine carotid artery. Craniectomies were performed in five dogs under general anesthesia, and 3 to 5 ml of autologous whole blood was deposited in the supraclinoid subarachnoid compartment. The concentration of hemin recovered by Folch extraction from clotted material removed 7 days after surgery was 390 +/- 247 microM (mean +/- standard error of the mean). Mean vascular smooth-muscle cell length after 40 minutes of exposure to 50 microM hemin was 37.3 +/- 1.2 microns (control 51.6 +/- 1.6 microns) (p < 0.01). The mean percent permeation of 45Ca++, measured by a dual label technique, of cells exposed to hemin was 200.9% +/- 23% (control 102.9% +/- 4.3%) (p < 0.01). These findings indicate that hemin accrues in subarachnoid hematoma, that it exerts a constrictive effect on vascular smooth-muscle cells, and that this effect is associated with an increased uptake of Ca++. This study demonstrates that hemin should be included in the list of potential agents that participate in the development of cerebral vasospasm.

The effect of hemoglobin and its metabolites on energy metabolism in cultured cerebrovascular smooth-muscle cells.

Cerebral arteries in spasm have been found to contain low levels of adenosine triphosphate (ATP), and it has been postulated that this change in levels results from hypoxia produced by arterial encasement in clotted material. This study was undertaken to determine whether any of four blood-derived agents, ferrous hemoglobin, methemoglobin, hemin, or bilirubin, is capable of reducing energy levels in cerebral artery smooth-muscle cells. Twenty-four-hour exposure of cultured canine basilar artery cells to ferrous hemoglobin and bilirubin led to a significant decline in ATP levels (to 8.9 nmol/mg protein and 2.8 nmol/mg protein, respectively) versus control (16.6 nmol/mg protein); methemoglobin and hemin showed no effect. Bilirubin but not hemoglobin was found to interfere with electron transport and with creatine phosphokinase activity in intact cells; however, bilirubin showed no inhibitory effect on this enzyme in cell-free conditions. The findings indicate that hemoglobin and bilirubin may be responsible for diminished energy levels in cerebral arteries. These observations also suggest that bilirubin may exert its effect on ATP by impairing mitochondrial function.

Optic glioma associated with Beckwith-Wiedemann syndrome.

A 6-year-old boy with decreased vision was found to have Beckwith-Wiedemann syndrome with an associated glioma involving the intracranial optic nerves, chiasm, and optic tracts. The association of this syndrome with visceral and central nervous system neoplasms is discussed.