Polytetrafluoroethylene for microarterial prosthetic grafts.

Polytetrafluoroethylene (PTFE) grafts can successfully be used as a microvascular prosthetic grafting material in rats with patency results of 90%. There was not a significant difference between patency percentages obtained with the PTFE grafts in comparison with autologous vein grafts. Excellent patency was achieved at 40 days for all of the interposition grafts in this study. Aspirin and dipyridamole did not improve patency.

Staged intracranial and extracranial revascularization.

Twenty patients with a combination of intracranial and extracranial cerebrovascular lesions were identified in a series comprised of 118 candidates for superficial temporal artery to middle cerebral artery (STA-MCA) bypass. Ten patients had internal carotid (ICA) occlusion and contralateral ICA stenosis, seven patients had combinations of ipsilateral lesions, usually ICA occlusion and external carotid (ECA) stenosis, and three patients had multiple lesions. Eighteen patients had a STA-MCA bypass performed; 11 of these had contralateral reconstruction for ICA stenosis, and seven had ECA stenosis corrected. Two additional patients became asymptomatic after ECA endarterectomy only and their proposed STA-MCA bypass has been postponed. There were two deaths, one early and one late. Eleven patients are asymptomatic, five are improved, one is unchanged, and one is neurologically worse.

Endaneurysmal microendarterectomy in the treatment of giant cerebral aneurysms: technical note.

Giant cerebral aneurysms continue to present the surgeon with substantial technical challenges. Operative techniques for managing giant cerebral aneurysms are becoming increasingly sophisticated. We emphasize in this report a technique for direct obliteration of the giant aneurysm with a hard, calcified atheroma at its base that prevents direct clip application without compromise of the parent artery. Temporary trapping of the aneurysm, intramural thrombectomy, and endaneurysmal microendarterectomy allow direct obliteration of the aneurysm neck with preservation of the parent artery.

Clinical manifestation of glioma before computed tomographic appearance: the dilemma of a negative scan.

Eight cases are presented to summarize our experience with patients initially evaluated for the new onset of either seizure activity or focal transient neurological deficits. Each was found to have a normal computed tomographic (CT) scan with and without iodinated contrast infusion. All subsequently returned with a CT scan indicative of a glioma 2 weeks to 39 months later. The apparent reasons for the difficulty in early diagnosis of glioma in certain instances are discussed. A review of the literature with an analysis of the conglomerate data is presented. These cases probably represent a subset of gliomas undergoing anaplastic dedifferentiation from relatively benign to more malignant forms. Recommendations for clinical and radiographic follow-up are outlined.

Photodynamic therapy for intracranial neoplasms: development of an image-based computer-assisted protocol for photodynamic therapy of intracranial neoplasms.

Photodynamic therapy is being studied as an adjuvant therapy for malignant gliomas. Therapeutic efficacy is based on photosensitizer uptake kinetics and the ability to deliver adequate light doses to an appropriate treatment volume at the optimal time. Our laboratory has developed an image-based, computer-assisted treatment-planning protocol to study the treatment variables leading to optimizing photodynamic therapy for intracranial neoplasms. Fifteen patients with recurrent malignant glial tumors underwent 16 treatments in the developmental phase of the project in which light treatment volume was progressively expanded. Group I (n = 4) received postresection intracavitary photoillumination only, Group II (n = 3) received limited interstitial/intracavitary photoillumination, and Group III (n = 9) received multiple interstitial/intracavitary photoillumination. Between 3 and 18 interstitial fiber probes were placed through optically lucent tumor access catheters. Computed three-dimensional image-based treatment planning provided reproducible data-based tumor volumes, treatment volumes, and stereotactic accuracy for tumor volume resection and interstitial light fiber insertion. Initial observations include: 1) treatment failures occur outside of the effective light treatment volumes; 2) effective light volumes can be expanded safely with multiple stereotactically implanted interstitial light fibers; and 3) optimal treatment involves individualized tailoring of light dose volume and geometry. This protocol allows standardized scientific study of the variables affecting the application of photodynamic therapy for intracranial neoplasms.

Monitoring of transient central nervous system postirradiation effects by 133Xe inhalation regional cerebral blood flow measurements.

The early transient postirradiation effects in the central nervous system are well known; however, no specific means of objective follow-up have been devised. The xenon (133Xe) inhalation technique for measurement of regional cerebral blood flow (rCBF) is easily reproducible. Serial rCBF measurements corresponding to the clinical presentation and course of the early postirradiation syndrome have not been previously reported. It is our belief that the global decline in rCBF identified in these patients represents a generalized metabolic derangement induced by whole brain irradiation rather than primary vascular changes. A distinction between tumor recurrence and the early transient postirradiation effects can be made utilizing this technique. It also provides a reproducible monitor of the clinical and metabolic impact of radiotherapy for brain tumors. A series of seven such patients is presented with appropriate case histories and graphic representations of the serial rCBF measurements.

Venous drainage of the inferolateral temporal lobe in relationship to transtemporal/transtentorial approaches to the cranial base.

OBJECTIVE: Intimate to the application of lateral transtemporal approaches to the cranial base are the identification, manipulation, and/or the sacrifice of the venous anatomy of the inferolateral temporal lobe and the superior petrosal sinus and the transection of the tentorium. This study demonstrates the relationship and variability of the venous drainage of the lateral and inferior surfaces of the temporal lobe. METHODS: Twenty-one specially prepared, injected cadaver specimens yielded 40 temporal lobes for examination. The venous systems in these specimens were traced from their origins on the temporal lobe (venous drainage complexes) to the transverse/petrosal sinuses, and the geometry of these venous complexes (venous configuration) was noted. The measurements of each complex's entry to the sinuses were noted. RESULTS: Four distinct venous drainage complexes were identified: 1) the lateral complex, 2) the anteroinferior complex, 3) the medial-inferior complex, and 4) the posteroinferior complex. Three basic venous configurations were found: 1) the candelabra of veins uniting to form one large draining vein, 2) multiple independent draining veins, and 3) venous lakes running in the tentorium before entering the sinuses. The lateral complex, incorporating the classic "vein of Labbé," was present in 100% of the specimens. However, in the majority of cases, it did not represent the dominant venous drainage of the lateral and inferior surfaces of the temporal lobe. CONCLUSION: An understanding of the complexity and diversity of the venous drainage complexes and their configurations is necessary to avoid venous complications during lateral cranial base surgery.

Indium-111-Photofrin-II scintillation scan.

Photodynamic therapy is under intense investigation as an adjuvant treatment for malignant glial tumors of the central nervous system. Photofrin-II (HpD-II) is currently the most actively investigated photosensitizing agent. A crucial issue regarding the safe and efficacious usage of HpD-II-based photodynamic therapy is the individual in vivo kinetics of tumor uptake and retention, compared with normal brain clearance. The optimal time for photoactivation of sensitized tumor must be known to ensure a high target-to-nontarget ratio, resulting in the maximal tumor destruction while preserving normal brain. Our laboratory developed a radionuclide scan based on 111indium (111In)-labeled HpD-II to evaluate HpD-II localization and clearance noninvasively within a canine model of intracerebral gliosarcoma. Synthesis of the 111In-HpD-II complex in greater than 90% yield is achieved by a simple, rapid labeling method. Radiochemical purity and stability were verified by high-performance liquid chromatography. Using the canine model of intracerebral gliosarcoma, we followed the uptake of 111In-HpD-II in tumors with serial scintillation scanning. Localization of the tumor by 111In-HpD-II has been verified by contrast-enhanced computed tomographic scan followed by gross and histological examination of the enhancing brain region. Total body biodistribution of 111In-HpD-II at various times after injection has been evaluated. The ratio of uptake in tumor compared with surrounding brain peaked at 72 hours after injection. The knowledge of regional distribution and concentration of a photosensitizing agent within a tumor mass and surrounding brain allows for the most efficacious timing and localization of a photoactivating source.

Improved cerebral blood flow and CO2 reactivity after microvascular anastomosis in patients at high risk for recurrent stroke.

The medical community has not yet identified cerebrovascular pathophysiological factors that distinguish patients at high risk for stroke or aid in selecting patients for microvascular cerebral bypass. In this study, we describe the courses of 13 patients, all of whom suffered recurrent episodes of transient cerebral ischemia after previous cerebral infarction. These patients underwent regional cerebral blood flow studies using xenon inhalation with a CO2 challenge before and at various times after extracerebral-to-intracerebral microvascular anastomosis. Collateral circulation was assessed in all patients before surgery using four-vessel cerebral angiography. Patients were followed for a mean of 30 months (range, 1-7 yr) after the anastomosis. Measurements of mean cortical cerebral blood flow, as measured using the initial Slope Index, and CO2 cerebrovascular reactivity of these 13 patients were compared with those in a group of 20 patients designed as controls. Hemispheric cortical blood flow was significantly depressed in these patients before surgery compared with those in the control group (P less than 0.05). After the bypass, the mean resting Initial Slope Index in these patients increased 14% (P = 0.0005). Cerebral blood flow both before and after CO2 inhalation improved significantly in these patients after surgery (P = 0.001). Detectors bordering computed tomographic or magnetic resonance image documented infarctions, identified as peri-infarct regions, and demonstrated significant mean increases in both cerebral blood flow (38.8-43.2 ml/min/100 g, P = 0.05) and CO2 cerebrovascular reactivity in these patients after bypass (1.71 + 1.91% to 4.00 + 2.38% change Initial Slope Index/mm Hg CO2, P = 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Sustained increased cerebral blood flow with prophylactic hypertensive hypervolemic hemodilution ("triple-H" therapy) after subarachnoid hemorrhage.

Delayed cerebral ischemia is the major cause of death and disability in patients who initially survive an aneurysmal subarachnoid hemorrhage (SAH). In the present study, a protocol for prophylactic hypertensive hypervolemic hemodilution ("triple-H" therapy) was utilized in the treatment of SAH, and the response of cerebral blood flow (CBF) was evaluated. Serial CBF measurements, f1 and CBF15, were performed using the xenon-133 inhalation technique to maximize therapy. Surgery within 24 hours of subarachnoid hemorrhage was preferred. In 43 patients with SAH, mean hemoglobin and hematocrit were lowered 3.0 +/- 0.3 g/dL and 8.9 +/- 0.5%, respectively, over the first 24 hours. Mean f1 and mean CBF15 over the same period increased 34.2 +/- 5.8% and 21.2 +/- 3.6%, respectively. The maximum mean increase in CBF was 47.2 +/- 4.7% for f1 and 30.1 +/- 3.2% for CBF15. Cerebral blood flow remained elevated during the 21 days after SAH, irrespective of neurological grade on admission, age, sex, or angiographic arterial narrowing. This is the first report of a consistent method for establishing sustained improvement in CBF after SAH. All patients managed in total compliance with the protocol remained neurologically stable or improved. Two patients developed delayed ischemia and infarction because of the inability to sustain protocol requirements. Thirty-six of the 43 patients (84%) were discharged capable of an independent lifestyle. Triple-H therapy is a safe and effective modality for elevating and sustaining CBF after SAH. In combination with early aneurysm surgery, it can minimize delayed cerebral ischemia and lead to an improved overall outcome.

Photodynamic therapy for intracranial neoplasms: investigations of photosensitizer uptake and distribution using indium-111 Photofrin-II single photon emission computed tomography scans in humans with intracranial neoplasms.

Photodynamic therapy is being investigated as an adjuvant treatment for intracranial neoplasms. The efficacy of this therapy is based on the uptake of photosensitizer by neoplastic tissue, its clearance from surrounding brain tissue, and the timing and placement of photoactivating sources. Photofrin-II is the photosensitizer most actively being investigated. We labeled Photofrin-II with Indium-111 and studied the uptake and distribution of this agent in 20 patients with intracranial neoplasms, using single photon emission computed tomography (SPECT) with volume rendering in three dimensions. Of these patients, 16 had malignant glial tumors, 2 had metastatic deposits, 1 had a chordoma, and 1 had a meningioma. Anatomical-spatial data correlated well between the SPECT images and contrast-enhanced computed tomography or magnetic resonance images. Regions of focal uptake on SPECT images correlated with the surgical histopathological findings of the neoplasm. The kinetics of photosensitizer uptake varied according to the tumor's histological findings, the patient's use of steroids, and among patients with similar types of tumor histology. Peak ratios of target-to-nontarget tissue varied from 24 to 72 hours after injection. The study data show that, to be most effective, photodynamic therapy may need to be tailored for each patient by correlating SPECT images with anatomical data produced by computed tomography or magnetic resonance images. Photoactivating sources then can be placed, using computer-assisted stereotactics, to activate a prescribed volume of photosensitized tumor at the optimal time for treatment.

Vascular considerations and complications in cranial base surgery.

The technical evolution of cranial base surgery has resulted in approaches that allow more radical surgical extirpation of complex cranial base lesions. Our service has extensively applied these cranial base approaches for lesions of the cranial base. A subgroup of 100 patients who had cranial base tumors involving potential manipulation or sacrifice of carotid arteries underwent 20-minute balloon test occlusions coordinated with vascular assessments consisting of a combination of the following: 1) four-vessel cerebral angiogram with compression studies; 2) occlusion transcranial Doppler ultrasonography; 3) occlusion single-photon emission computed tomography perfusion studies; and 4) xenon-133 cerebral blood flow studies. Transient neurological deficits associated with balloon test occlusion occurred in 7 of 100 patients (7%). Subsequently, 18 patients underwent permanent carotid occlusion by endovascular detachable balloons. Delayed ischemic complications (> 72 h) occurred in 4 of 18 (22%) patients. Additionally, a number of vascular complications not predicted by the balloon occlusion tests and vascular assessments were experienced. Repeat vascular assessments defined the causes and guided treatment of ischemic patients. Ischemic complications were caused by hemodynamic insufficiency, embolization, vasospasm, radiation vasculopathy, and venous anomaly. Our experience leads us to believe that no vascular assessment exists today that can predict the occurrence of vascular complications accurately. The current enthusiasm for cranial base surgery must be tempered with the sober reality that management of cerebrovascular anatomy and physiology remain significant limitations. Consideration of potential cerebrovascular complications is paramount to successful outcome and implementation of cranial base surgery.

Use of vascularized fat from the rectus abdominis myocutaneous free flap territory to seal the dura of basicranial tumor resections.

Resection of large skull base tumors may sometimes result in extirpation defects that are not amenable to local tissue closure. Patients with these tumors require free tissue transfer for closure of the intracranial space after basicranial tumor extirpation. The deep inferior epigastric artery supplies the rectus abdominis muscle and the skin and subcutaneous tissue of the lower abdomen. The closure of massive, central defects can be performed with a free flap designed from the ample rectus abdominis vascular territory. This free tissue donor site has abundant and reliable well-vascularized skin and subcutaneous tissue that can be customized to seal these tenuous areas and provide three-dimensional reconstruction. We have modified the rectus abdominis myocutaneous free flap in seven patients for reconstruction of the skull base. The subcutaneous fat was sculptured to form a soft, vascularized "cork" and was used for obliteration of the irregular deep portions of defects at the midcranial base against the repaired or unrepaired dura. All patients who had the vascularized fat used to obliterate the deep space had successful closure of the defect without cerebral spinal fluid leak. There were two wound infections and one donor-site hernia in this group. The judicious use of the vascular territory of the deep inferior epigastric vessels can accomplish secure three-dimensional reconstruction of the skull base. The flap can be reliably transferred, and the vascularized subcutaneous fat can be used to sequester and seal the dura repair.(ABSTRACT TRUNCATED AT 250 WORDS)

Inhibition of in vitro meningioma proliferation after growth factor stimulation by calcium channel antagonists: Part II--Additional growth factors, growth factor receptor immunohistochemistry, and intracellular calcium measurements.

We have previously reported that calcium channel antagonists can block both the growth of meningiomas in culture and the potent growth stimulation of meningioma cells by epidermal growth factor (EGF) and platelet-derived growth factor (PDGF). This study further defines the nature of this growth inhibition. Primary meningioma cultures were established, and cells were characterized. Fibroblast growth factor or insulin-like growth factor-I growth stimulation in the presence of calcium channel antagonists was examined. In addition, the effects of ethylene glycol-bis-(aminoethylether) N,N,N',N"-tetraacetic acid and Bay K 8644, a calcium channel agonist, on the growth factors were analyzed. Growth factor receptor immunohistochemistry was performed on the original tumors and the in vitro meningioma cells. Twelve of 17 (71%) meningiomas in this study were positive for the EGF receptor, and 14 of 17 (82%) were positive for the PDGF receptor. Five of six (83%) of the culture cells were positive for the EGF receptor, and four of five (80%) were positive for the PDGF receptor. Intracellular calcium changes were quantified using the intracellular calcium-chelating, fluorescent dye, Fura-2. The growth stimulation of fibroblast growth factor and insulin-like growth factor-I on meningioma cells in culture was decreased in a dose-dependent manner by calcium channel antagonists. The growth stimulation of fibroblast growth factor and insulin-like growth factor-I was not affected by a reduction of extracellular calcium, whereas the growth stimulation of EGF and PDGF was. Interestingly, intracellular calcium was not increased after exposure to growth factors but was increased after serum stimulation. This increase could be blocked by preincubation with verapamil. Calcium channel antagonists can inhibit proliferation of meningioma cells in culture after stimulation with a number of growth factors. These drugs might disrupt intracellular calcium homeostasis or interfere with key elements of the growth factor signal transduction pathways. These mechanisms as well as the potential clinical relevance of these findings are discussed.

Microsurgical treatment of neurovascular disease. Part I. Personnel, equipment, extracranial-intracranial anastomosis.

This study was prepared with the objective of directing the attention of the medical community to advances during the last decade in the operative treatment of cerebral ischemia, intracranial aneurysms, and cerebral and spinal vascular malformations. The requirements for specialized personnel, facilities, and instrumentation are detailed for those who are unfamiliar with the complexities of microneurosurgery. The importance of adequate training in the intricacies of extracranial-intracranial anastomotic procedures is stressed. Reported results of this operation are discussed. It is anticipated that a recently organized cooperative study will provide the data necessary for evaluation of long term benefits. Attention is given to grading the clinical status of patients with intracranial aneurysms in advance of surgery and the importance of operating upon good risk patients. How to manage the relatively large numbers of poor risk patients with aneurysms unsuitable for immediate operation is discussed. Sophisticated radiological procedures utilized in the diagnosis, management, and evaluation of therapy are described. The role and significance of properly administered anesthesia are discussed in relation to the performance of complicated and time-consuming microsurgery on the brain and spinal cord. The study group has tried to present this material objectively and to urge those individuals working in this difficult field to acquire the special skills and instrumentation of microneurosurgery, to implement the "team-of-experts" concept in the operating room, and to enlist the support of related disciplines.

Reevaluation of an experimental streptococcal canine brain abscess model.

An experimental cerebral abscess model in which alpha-hemolytic Streptococci were inoculated into the brain parenchyma of dogs was evaluated for assessment of antimicrobial therapy. Intracerebral ring-enhancing lesions were visualized by computerized tomography, but they resolved after time without therapeutic intervention. Histopathological study demonstrated evolution of the lesions into sterile granulomas. Quantitative cultures were performed and uniformly became sterile in the early cerebritis stage, approximately 3 days after bacterial inoculation. Therefore, this brain abscess model should not be utilized for the evaluation of new antimicrobial treatment regimens. Rather, other models which document persistent viable organisms within cerebral abscesses need to be developed.

Regional cerebral blood flow studies following superficial temporal-middle cerebral artery anastomosis.

Regional cerebral blood flow (rCBF) studies were performed during the postoperative period on 16 patients with internal carotid occlusions and inaccessible stenoses, and middle cerebral artery occlusion and stenoses, who underwent superficial temporal artery-middle cerebral artery (STA-MCA) anastomoses. The intra-arterial xenon method with selective application of the xenon bolus through the internal carotid and the newly established superficial temporal channel has allowed comparison of the flow provided by the pathological input with flow through the new input. The results show that initial rCBF (rCBF1) was globally reduced in all patients to a mean of 28.4 +/- 11.9 ml/100 gm/min at a mean pCO2 of 29.6 +/- 9.55 mm Hg. Patients with transient ischemic attacks (TIA) and minor strokes with minimal residua (RIND) had a mean rCBF1 of 30.4 +/- 11.6 ml/100 gm/min at a mean pCO2 of 30 +/- 10 mm Hg, while patients with completed strokes had a mean rCBF1 of 25.0 +/- 12.4 ml/100 gm/min at a mean pCO2 of 29.1 +/- 8.8 mm Hg. There was no significant difference between these two groups. This finding suggests that in this small group of patients with TIA's and RIND's, the cause of the stroke is probably related more to decreased perfusion than embolus, and may explain why these patients' symptoms improve after STA-MCA anastomosis. The results of this study suggest that in addition to an inaccessible lesion, global or focal decreased rCBF is a necessary criterion in the definition of indications for intracranial revascularization procedures.

Berry aneurysm.

Aneurysmal subarachnoid hemorrhage in a pregnant woman is a rare catastrophic situation that places both the mother and the fetus at high risk. When this situation arises, numerous relevant issues must be individualized in the effort to reduce hazards threatening both the mother and the fetus. These issues have been addressed in terms of the published experience and in terms of modern obstetric, anesthetic, and neurologic surgery technology.

Rhinorrhea associated with intracranial cholesteatomas and an "empty sella.".

Three related disorders in the same patient, namely bilateral primary intracranial cholesteatomas, an "empty sella" syndrome, and a cerebrospinal rhinorrhea are reported. No previous report of bilateral symmetrical cholesteatomas has been made, though single intracranial cholesteatomas have frequently been recorded in medical literature. The "empty sella" syndrome is generally considered to be from a herniation of the subarachnoid into the sella through a deficient diaphragma sella, and was first defined by Ommaya in 1968. Non-traumatic (spontaneous) rhinorrhea remains an uncommon disease initially described in 1826. Experience of the individual otolaryngologist is limited in this region because of infrequent occurrence and because definitive treatment is directed to other specialties. On the other hand, the ear, nose and throat physician may be the first to interpret a drainage from the nose. With this in mind, the etiologic, clinical and management factors in the present case are discussed.

Neurotologic considerations in the treatment of advanced clival tumors.

Head and neck manifestations of advanced clival tumors result from subtle, yet progressive mass effect or direct involvement of multiple cranial nerves. Misinterpretation of clinical or radiographic findings in these patients may result in inappropriate treatment planning, increased patient morbidity, and probable tumor recurrence. Our combined experience in managing 21 patients with advanced clival tumors has shown that preoperative loss of vision, diplopia, or facial hypesthesia suggests superior parasellar disease. Facial twitching or neurotologic symptoms result from posterior central tumor growth, while inferior extension of disease leads to basal cranial nerve deficits with associated speech, voice, and swallowing dysfunctions. The purpose of this article is to correlate the complex anatomy of the clivus, brainstem, and cranial base and the various neurotologic findings associated with neoplasms in this region. Lateral skull base surgical procedures, based on preoperative clinicoradiographic assessment, will be detailed with particular emphasis on preservation of critical neurovascular structures.