Fractionated high-dose rate brachytherapy for intracranial gliomas.

PURPOSE: To develop a catheter system for fractionated high-dose rate (HDR) brachytherapy for intracranial gliomas. METHODS AND MATERIALS: The catheter system for stereotactic placement as well as delivery of the high-dose rate iridium-192 source wire is described. The force of the impulse wave from the source wire entering brain equivalent material was measured. Dose volume histograms for the first 5 patients treated are presented. RESULTS: The catheter system was found to be satisfactory. The maximum force of the impulse wave was less than 1 acceleration of gravity (which is safe). The patients tolerated the treatment well with no significant problems related to the catheters being left in situ for up to 14 days. CONCLUSION: Based on this pilot experience a phase I dose escalating and morbidity study has been initiated.

A comparison of intensity modulated conformal therapy with a conventional external beam stereotactic radiosurgery system for the treatment of single and multiple intracranial lesions.

PURPOSE: To compare the stereotactic radiosurgery treatment plans generated by a conventional radiosurgery treatment system with the plan generated by a system using intensity modulated beams. METHODS AND MATERIALS: Optimized conformal radiation treatment plans were generated for both single and multiple intracranial lesions using a conventional radiosurgery treatment-planning system computer and the Peacock treatment-planning computer. The Peacock system is a conformal therapy system that uses intensity modulated beams, back projection, and the simulated annealing optimization technique. The dose delivered to critical structures and the target volume were compared by means of dose volume histograms between plans generated by the two different systems. The Radiation Therapy Oncology Group (RTOG) stereotactic radiosurgery criteria were also used to evaluate each plan. RESULTS: (a) For a single small target, radiosurgery plans generated by the conventional radiosurgery system and the Peacock system were comparable. (b) For two separate small targets, where nonoverlapping arcs could be used, plans generated by the two systems were also comparable. (c) For a single large (>4 cm) irregular-shaped target, the Peacock system appeared to be able to generate a treatment plan superior to that of the conventional radiosurgery system. CONCLUSIONS: A treatment plan generated using intensity modulated beams appears to be superior to a multiple isocenter plan using a conventional radiosurgery system, for the treatment of a large irregular shaped intracranial target.

Collagen biosynthesis in healing wounds of the spinal cord and surrounding membranes.

Kinetics of collagen synthesis and deposition were studied in the canine spinal cord, pia mater, and dura mater and in wounds of these tissues over the first 8 weeks. Little collagen is present in unwounded spinal cord compared with surrounding mesenchymal membranes. Collagen synthetic potential was found within the spinal cord, a tissue of neurectodermal origin. Rate of collagen synthesis per collagen content in the unwounded spinal cord was high. This synthetic rate was as high as that of wounds at their maximum collagen synthetic rates. Substantial deposition of collagen followed spinal cord wounding. Wounding the spinal cord, pia mater, and dura mater caused substantial elevations in rates of collagen synthesis in each tissue. These synthetic rates remained at maximum levels throughout the 8-week study, a prolonged period when compared with other wounded tissues previously studied. The role of mesenchymal tissue physiology in central nervous system wound healing is discussed. The potential value of these findings for further studies and for experimental manipulation of the healing process in spinal cord and central nervous system wounds is presented. Implications of these findings on the hypothetical relationship of scar to spinal cord and central nervous system regeneration are noted.

Morphine effects on spontaneous, nociceptive, antinociceptive and sensory evoked responses of parafasciculus thalami units in morphine naive and morphine dependent rats.

The present experiments used freely behaving animals previously implanted with permanent recording electrodes within the parafasciculus thalami (PF) and stimulation electrodes in nociceptive and antinociceptive areas. The spontaneous and the evoked activity in PF neurons following nociceptive, antinociceptive and sensory stimulation, as well as the effects of morphine and its antagonist naloxone on these inputs in morphine naive and morphine dependent animals, were investigated. The observations demonstrated that the spontaneous activity of PF neurons exhibits variable spontaneous firing rates which are affected by acute and chronic morphine treatment. The PF neuronal population exhibits neurophysiological activity characteristic of morphine dependence, tolerance and withdrawal from morphine. The PF receives mono-, oligo- and polysynaptic inputs from multiple sources, including regions associated with pain pathways which converge on PF cells, as well as from sites involved in pain suppression mechanisms, which supports the hypothesis of a role of the PF as a modulator of pain input. The nociceptive, antinociceptive and sensory inputs are not modified by chronic morphine treatment, but single doses of morphine have remarkable effects on those inputs in morphine naive and morphine dependent animals; naloxone reversed the morphine effects on the evoked activity.

Whatever happened to stereotactic surgery?

The field of human stereotactic surgery began when Spiegel and Wycis introduced their stereoencephalotome in 1947, reached its epitome in the early 1960s, and declined sharply after the introduction of L-dopa in 1968. When the development of implantable stimulators provided an abrupt expansion of techniques in nonstereotactic functional neurosurgery, the field became "stereotactic and functional neurosurgery." The marriage of stereotactic surgery with computed tomography has reawakened the use of stereotactic surgery and brought it closer to general neurosurgery than ever before. Stereotactic and functional neurosurgery as a subspecialty has expanded rapidly and will continue to expand at an unprecedented rate, with significant changes reflecting the continuing advances in technology begun 15 years ago. It is becoming an increasingly important part of the field of neurosurgery and has extended its influence in many new clinical areas previously outside the realm of stereotaxis.

New head-positioning system for use with computed tomographic scanning.

A new head-positioning system has been developed to hold the head firmly during the performance of a computed tomograhic scan and to position the head reproducibly during repeat scans. This can be used to maintain the head in position during long scanning sessions, to relate a lesion to landmarks on scout views, to follow lesions in repeated scans over time, and to perform a variety of invasive procedures.

Calculation of stereotactic coordinates from the computed tomographic scan.

A protocol has been developed to use the GE 8800 scanner and its resident programs to calculate stereotactic coordinates, which has made it possible to use any stereotactic apparatus without modifying the apparatus in order to introduce a cannula into any lesion visualized on a computed tomographic (CT) scan to biopsy tumors, drain abscesses, implant radioisotopes, etc. The CT scanning is done in a routine fashion except that a lateral ScoutView, with the planes of each CT slice indicated, is included. Once the CT scan has been completed, resident programs for measuring distances are used to establish a zero point on a reference plane, from which all other coordinates can be defined. The stereotactic procedure is done at a separate time in the operating room, using the coordinates derived from the CT scan. The ScoutView image is compared to the lateral x-ray film taken during the stereotactic procedure to establish the location of the targets. It has been estimated that the accuracy of this system is 3 mm. Abscesses less than 1 cm in diameter deep within the cerebral hemisphere have been accurately aspirated and tumor biopsies have been successfully taken.

General metabolism in patients with acute paraplegia and quadriplegia.

This study measured the nutritional status of eight spine-injured patients during their first 10 to 14 days in the hospital. Initial and follow-up nutritional assessment showed that their nutritional status deteriorated at least partly due to an inadequate supply of protein and calories. Infective complications and prolonged respiratory support were common and may have been caused in part by impaired nutrition. This suggests that a prospective study of aggressive nutritional support for patients with spinal cord transection should be initiated to determine whether this acquired malnutrition and its associated complications can be prevented.

Pallidotomy: a survey of current practice in North America.

Twenty-eight centers completed a survey about their current practice of pallidotomy. This sample represents a non-exhaustive survey of the current practice of pallidotomy in North America and is not a study of outcomes. 1015 patients underwent 1219 pallidotomies: 811 (80%) unilateral, 72 (7%) staged bilateral, and 132 (13%) simultaneous bilateral. Pallidotomy has long been an accepted procedure and the indications for this surgery, in the opinion of the responding centers, were rated on a scale of 1 (poor) to 4 (excellent) and demonstrated dyskinesia as the best indication (median = 4); on-off fluctuations, dystonia, rigidity, and bradykinesia as good indications (median = 3); and freezing, tremor and gait disturbance as fair indications (median = 2). Most centers used MRI alone (50%) or in combination with CT scan (n = 6) or ventriculopathy (n = 5) to localize the target. The median values of pallidal coordinates were: 2 mm anterior to the midcommissural point 21 mm lateral to the midsagittal plane and 5 mm below the intercommissural line. Microrecording was performed by half of the centers (n = 14) and half of the remaining centers were considering starting it (n = 7). Main criteria used to define the target included the firing pattern of spontaneous neuronal discharges (n = 13) and the response to joint movement (n = 10). Most centers performed motor (n = 26) and visual (n = 23) macrostimulation. Twenty four centers performed test lesions using median values of 55 degrees C temperatures for 30 s. Final lesions consisted of 3 permanent lesions placed 2 mm apart, each lesion created with median values of 75 degrees C temperatures for 1 minute. Median hospital stay was 2 days.

Gunshot wounds to the head: a perspective.

Craniocerebral gunshot wounds are a significant cause of injury and death in the United States. However, despite reports of occasional unexpectedly favorable outcome in surgically treated patients, these injuries have been viewed pessimistically and indeed have generally been excluded from modern studies of head injuries, which have concentrated on closed head injuries. A review of 143 victims of craniocerebral gunshot wounds admitted to Hermann Hospital, Houston, Texas, during a recent 30-month period confirmed that a few apparently neurologically devastated patients can be saved. A detailed analysis of these patients, including demographic details, general and neurological condition, anatomic injuries, laboratory findings, surgical care, neurological course, and neurological and functional outcome follows. The helpfulness of early resuscitation and appropriate criteria for surgery need to be studied using historic or randomized controls.

Neurobehavioral outcome after gunshot wounds to the head in adult civilians and children.

To assess the quality of long term outcome of civilian gunshot wounds to the head after intensive neurosurgical management, particularly with regard to the possibility of subtle problems due to diffuse injury, we administered neuropsychological tests to six survivors (four adults and two children) at about 1 year after injury. Five patients were moderately disabled, and one patient achieved a good recovery. Residual neurobehavioral sequelae were present in all cases. Defects in long term memory for new information were the most common sequelae, whereas the persistence of linguistic and visuospatial deficits was related to the hemispheric lateralization of injury. In comparison with the outcome reported for patients with closed head injuries who had similar Glasgow coma scale scores, our patients exhibited more severe impairment due to significant focal brain injuries and less evidence of diffuse damage.

The incidence and significance of hemostatic abnormalities in patients with head injuries.

Abnormal coagulation and fibrinolysis is a frequent complication in patients with head injury. This complication can be severe enough to lead to hemorrhage or thrombosis. A study was undertaken to determine if the hemostatic abnormalities are reliable indicators of outcome. Hemostasis in 269 patients with head injuries alone was screened using platelet count (PC), prothrombin time (PT), activated partial thromboplastin time (APTT), thrombin clotting time (TCT), fibrinogen assay (FIB), level of fibrin-fibrinogen degradation products (FDP), and disseminated intravascular coagulation (DIC) score in the first 24 hours after injury. Test results were compared with the outcome (discharged or dead) in the entire group and in subgroups divided on the basis of the severity of injury as determined by the Glasgow coma score (GCS). Increased consumptive coagulopathy at admission, as reflected in the DIC score, predicts the outcome of head-injured patients with a high degree of accuracy. The degree of increase of the initial FDP level and prolongation of TCT also correlated positively with the outcome. Prolongation of the APTT correlated strongly with unfavorable outcome in a large group of patients, and in a small group, markedly accelerated APTT also predicted death. Stepwise logistic regression analysis demonstrated that GCS, FDP level, and DIC score predicted outcome. Other tests did not provide additional predictive value. Abnormal hemostasis frequently complicates the course of patients with head injuries. This study demonstrates that hemostasis tests are predictors of outcome in these patients.

Delayed and recurrent intracranial hematomas related to disseminated intravascular clotting and fibrinolysis in head injury.

Twelve delayed or recurrent intracranial hematomas were seen in 340 patients with head injuries. Eleven of these hematomas were associated with clotting abnormalities suggesting disseminated intravascular clotting and fibrinolysis (DICF). Seven of 8 delayed traumatic intracerebral hematomas were associated with clotting abnormalities. Two of these were at ventriculostomy sites, which suggests an increased risk of bleeding in association with the insertion of ventricular catheters in patients with DICF. There were 2 delayed epidural hematomas, 1 under a fracture and the other on the side opposite a craniotomy that had been made to treat an intracerebral hematoma, and there were 2 postoperative epidural hematomas. No postoperative hematomas occurred in the absence of DICF. DICF is a major factor in the development of delayed and recurrent intracranial hematomas in patients with head injuries.

General metabolism in head injury.

Seventy-six patients with closed head injuries alone were studied to define the relation between the severity of the head injury and secondary alterations of general metabolism. The effect of metabolic changes on neurological outcome and the importance of nutritional support on nutritional status and neurological outcome were also evaluated. Using a powerful statistical tool, convergence analysis, it was possible to take into consideration the effects of a number of confounding factors that obviously affected general metabolism. Most of the patients were hypermetabolic for prolonged periods. In addition, many did not receive even basal requirements of calories or protein for many days. Despite this, their outcomes were determined by their initial neurological status and the amounts that they were fed, admittedly relatively modest, did not influence their courses. Despite such feedings, their visceral protein levels, which often dropped initially, rose toward normal levels, indicating effective adaptation. Indeed, it could not be shown that these patients developed complications of malnutrition such as infections. However, it will require a sophisticated randomized clinical trial of vigorous intravenous hyperalimentation to determine whether this complex, dangerous, and expensive therapy is helpful for severely head-injured patients.

Angle-meter to indicate the proper angle of insertion in anterior percutaneous cervical cordotomy. Technical note.

An angle meter has been devised to facilitate the anterior approach to lower cervical percutaneous cordotomy and to afford the operator increased accuracy in placing the needle electrode. A method is described which allows the operator to set the trajectory of the needle electrode accurately at the stage when only the tip of the needle is inserted into the disc. The procedure requires no mathematical calculations and has proved accurate in 40 cases.

The efficacy of Doppler monitoring for the detection of venous air embolism.

Venous air embolism can usually be detected by the use of a precordial Doppler ultrasound monitor at an air infusion rate as low as 0.015 ml/kg/min, and consistently at a rate of 0.021 ml/kg/min. This is in contrast to previously reported thresholds wherein the first physiological change, a gasp, occurs at 0.36 ml/kg/min, electrocardiographic changes first take place at 0.60 ml/kg/min, drop in blood pressure at 0.69 ml/kg/min, increased central venous pressure at 0.40 ml/kg/min, and end-tidal CO2 decreases at 0.42 ml/kg/min. The first change in heart sounds monitored through an esophageal stethoscope is not detectable until an air infusion rate of 1.70 ml/kg/min, and the classical mill-wheel murmur does not occur until 1.96 ml/kg/min. This demonstrates that Doppler ultrasound can detect venous air embolism before the earliest physiological changes, in contrast to most other methods which do not detect venous air embolism until after cardiopulmonary changes have become well established.

The history of stereotactic neurosurgery.

Until the work of Horsley and Clarke in 1908, attempts to guide electrodes to parts of the nervous system had not used a three-dimensional targeting technique. Later, from the 1930s into the 1950s, the collaboration of Spiegel and Wycis led to advances in almost every area of functional neurosurgery. Great progress occurred through the accomplishments of other neurosurgeons throughout the world. This article describes the work of many of these pioneers and the evolution of stereotactic apparatus, including the current developments that indicate even more exciting accomplishments ahead.

Management of movement disorders. An overview.

Functional neurosurgery has been involved with management of movement disorders since the first days of stereotactic surgery. Those movement disorders that can be managed surgically are reviewed, along with general criteria for patient selection. A flow sheet of surgically managed movement disorders is supplemented by descriptions of how patients are assigned to various treatment categories and the various treatments available.

The history of surgery for movement disorders.

Treatment of movement disorders by interruption of pathways within the nervous system has been a goal of neurosurgeons for the past century. When human stereotactic surgery was introduced 50 years ago, a major advance was made in surgical treatment of Parkinson's disease and other disorders of the motor system. Since then, the field has experienced a period of progressive growth, then abrupt decline, and now is more active than ever before and continuing to grow rapidly. Recent progress in computer science, imaging techniques, neurophysiology, and stereotactic targeting has provided the fuel for future progress.