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Biomedical subjects

Robert F Spetzler

Publications and source records attributed to Robert F Spetzler.

At least 91 records · Page 5Linked to original sources
PubMed2003

Scalp arteriovenous malformation draining into the superior sagittal sinus associated with an intracranial arteriovenous malformation: just a coincidence? Case report.

OBJECTIVE AND IMPORTANCE: Recent experimental and clinical evidence suggests that hemodynamic changes in the venous system can induce the formation of new arteriovenous malformations (AVMs). In a rat model, increased venous pressure induces the formation of soft tissue and dural AVMs. We report a clinical observation that may support these data. CLINICAL PRESENTATION: A 4-year-old boy with a midline scalp AVM draining into the superior sagittal sinus had an associated intracranial/parenchymal AVM. The cerebral AVM increased venous pressure in the superior sagittal sinus as revealed by angiography. INTERVENTION: The scalp AVM was resected, and the intracranial AVM was treated by use of the gamma knife. CONCLUSION: On the basis of reported experimental data and the morphological and hemodynamic characteristics in this patient's two lesions, we suggest that the scalp AVM might have been induced by hypertension in the superior sagittal sinus. This clinical observation supports the notion suggested by experimental studies that hemodynamic changes can induce the formation of associated AVMs.

Angiography, Digital Subtraction↗
PubMed2003

A three-dimensional interactive virtual dissection model to simulate transpetrous surgical avenues.

OBJECTIVE: This project involves the development of a three-dimensional surgical simulator called interactive virtual dissection, which is designed to teach surgeons the visuospatial skills required to navigate through a transpetrosal approach. METHODS: A robotically controlled microscope is used for surgical planning and data collection. The spatial anatomic data are recorded from sequentially deeper cadaveric head dissections as a series of superimposed anatomic pictures in stereoscopic digital format. The sequential series of images are then merged to form the final virtual representation. RESULTS: The current three-dimensional virtual reality simulator allows the user to drill the petrous bone progressively deeper and to identify crucial structures much like an experienced surgeon drilling the petrous bone. The program allows surgeons and trainees to manipulate the virtual "surgical field" by interacting with the surgical anatomy. The interactive system functions on a desktop computer. CONCLUSION: The ability to visualize and understand anatomic spatial relationships is crucial in surgical planning, as is a surgeon's confidence in performing the surgery. The virtual reality simulator does not replace the need for practicing surgery on cadavers. However, it is designed to facilitate, via stereoscopic projection, learning how to manipulate a drill in complicated or unfamiliar surgical approaches (e.g., a transpetrosal approach).

Brain↗
PubMed2003

Surgical management of cavernous malformations involving the cranial nerves.

OBJECTIVE: To analyze the indications and techniques pertinent to the treatment of cranial nerve (CN) cavernous malformations (CMs). METHODS: CN CMs are lesions isolated to the CNs. CMs affecting the optic nerve (CN II), oculomotor nerve (CN III), facial/vestibulocochlear complex (CN VII and CN VIII), and hypoglossal nerve (CN XII) have been described. The records for six patients were reviewed with respect to lesion location, symptoms, surgical approach, and therapeutic considerations. This is the largest series of CMs isolated to CNs reported to date. RESULTS: Three female patients and three male patients (age range, 28-76 yr; mean age, 41 yr) presented with six CN lesions; four lesions involved the optic chiasm and two involved CN VII and CN VIII. The patients with chiasmatic lesions presented with acute visual deterioration. Both patients with CN VII/CN VIII lesions exhibited acute hearing loss. The level of deterioration suggested CM hemorrhage. Orbitozygomatic craniotomies were performed for chiasmatic lesions, and retrosigmoid craniotomies were performed for cerebellopontine angle lesions. All patients experienced symptom improvement after surgery. One chiasmatic lesion recurred after 2 years and required resection. CONCLUSION: CN CMs present with site-specific symptoms and require complex surgical techniques for resection. These lesions are frequently symptomatic, because of the eloquence of the tissue of origin. Therefore, all CN CMs should be resected. Subtotal resection uniformly results in disease and symptom recurrence. CN CMs can be resected safely, with preservation of CN function.

Adult↗
PubMed2003

A reappraisal of angioplasty and stenting for the treatment of vertebral origin stenosis.

OBJECTIVE: To assess the rate of restenosis after vertebral origin angioplasty and stenting (VOAS). METHODS: We reviewed the records of 33 patients (24 men, 9 women; age range, 49-81 yr; mean, 64.5 yr) who underwent VOAS during a period of 5 years and followed each for the development of adverse sequelae through a prospectively maintained database. A neuroradiologist not involved in the stenting procedures assessed original and follow-up angiograms for evidence of restenosis. Restenosis was quantified as insignificant (0-24%), mild (25-49%), moderate (50-74%), or severe (75-100%). RESULTS: Of the 33 patients, 30 presented with transient ischemic attacks or stroke. Most (31 of 33 patients) manifested other brachiocephalic stenoses, including 27 patients with occlusion, hypoplasia, or stenosis of the contralateral vertebral artery. Angiographic follow-up (mean, 16.2 mo) was obtained in 30 patients (2 patients died before follow-up, and 1 refused). Restenosis was mild in seven patients, moderate in eight, and severe in five. The combined rate of moderate-to-severe restenosis was 43.3%. No complications resulted in permanent morbidity. One patient died as a result of a stroke in a different vascular distribution 4 months after VOAS. Another patient died as a result of basilar thrombosis in which emergent stenting had been undertaken in an effort to perform thrombolysis. CONCLUSION: Despite a technical success rate of 97% and a low incidence of complications, VOAS is associated with a high rate of moderate-to-severe restenosis.

Aged↗
PubMed2003

Toward optimal tissue sealants for neurosurgery: use of a novel hydrogel sealant in a canine durotomy repair model.

OBJECTIVE: Watertight dural repairs are difficult to achieve, and cerebrospinal fluid leakage causes complications and extends hospital stays. Therefore, a novel synthetic hydrogel film was evaluated as an adjunct to dural closure in a canine model. METHODS: The self-polymerizing, absorbable, and biocompatible hydrogel was sprayed onto tissue and formed a flexible, adherent sealant. A 2-cm incision of cranial dura and arachnoid was created in 26 adult dogs and loosely repaired. Hydrogel was applied over the 2-mm dural gap in 13 dogs; 13 control dogs received no hydrogel application. RESULTS: All dogs remained neurologically intact. Valsalva tests conducted at 1, 4, 7, and 56 days were associated with mean leakage pressures (+/- standard error of the mean) of 5 +/- 0, 5 +/- 0, 7 +/- 2, and 13 +/- 8 cm H(2)O in the controls and of 53 +/- 2, 37 +/- 11, 42 +/- 6, and 48 +/- 4 in the treated animals (P = 0.001, 0.053, 0.010, 0.035, respectively, at each time point; one-tailed t test). Histopathological analysis revealed minimal changes. CONCLUSION: The hydrogel-treated animals exhibited normal progression of dural healing, no dural adhesions, and no underlying effects on the brain. Although dural healing progressed normally, the control animals displayed marked peridural adhesions. The results of this in vivo study suggest that hydrogels, such as that used here, may significantly decrease cerebrospinal fluid leakage, thereby increasing the safety and effectiveness of dural closure in patients and facilitating surgical reexploration.

Animals↗
PubMed2003

Intention-to-treat analysis of Spetzler-Martin grades IV and V arteriovenous malformations: natural history and treatment paradigm.

OBJECT: In this study the authors quantified a subgroup of patients with Spetzler-Martin Grades IV and V arteriovenous malformations (AVMs) recommended for complete, partial, or no treatment, and calculated the retrospective hemorrhage rate for these lesions. METHODS: Between July 1997 and May 2000, 73 consecutive patients with Grades IV and V AVMs were evaluated prospectively by the cerebrovascular team at Barrow Neurological Institute. Treatment recommendations given to the patients or referring physicians were classified as complete treatment, partial treatment, and no treatment. Retrospectively, the hemorrhage rates associated with these treatment groups were also calculated. In the prospective portion of the study (the intention-to-treat analysis), no treatment of the AVM, was recommended for 55 patients (75%) and partial treatment was recommended for seven patients (10%). Aneurysms associated with an AVM were obliterated by surgical or endovascular treatment in seven patients (10%), and complete surgical removal was recommended for four patients (5%). The overall hemorrhage rate for Grades IV and V AVMs was 1.5% per year. The annual risk of hemorrhage was 10.4% among patients who previously had received incomplete treatment, compared with patients without previous treatment. CONCLUSIONS: The hemorrhage risk of 1.5% per year, which was associated with Grades IV and V AVMs appears to be lower than that reported for Grades I through III AVMs. The authors recommend that no treatment be given for most Grades IV and V AVMs. No evidence indicates that partial treatment of an AVM reduces a patient's risk of hemorrhage. In fact, partial treatment may worsen the natural history of an AVM. The authors do not support palliative treatment of AVMs, except in the specific circumstances of arterial or intranidal aneurysms or progressive neurological deficits related to vascular steal. Complete treatment is warranted for patients with progressive neurological deficits caused by hemorrhage of the AVM. This selection process plays a significant role in the relatively low combined morbidity and mortality rates for Grade IV and Grade V AVMs (17 and 22%, respectively) reported by the cerebrovascular group in both retrospective and prospective studies.

Adolescent↗
PubMed2003

Percutaneous intracranial stent placement for aneurysms.

OBJECT: Intracranial stent placement combined with coil embolization is an emerging procedure for the treatment of intracranial aneurysms. The authors report their results using intracranial stents for the treatment of intracranial aneurysms. METHODS: A prospectively maintained database was reviewed to identify all patients with intracranial aneurysms that were treated with intracranial stents. Ten lesions, including eight broad-based aneurysms and two dissecting aneurysms, were treated in 10 patients. Four lesions were located in the cavernous segment of the internal carotid artery, two at the vertebrobasilar junction, two at the basilar trunk, one at the basilar apex, and one in the intracranial vertebral artery. Attempts were made to place stents in 13 patients, but in three the stents could not be delivered. Altogether, intracranial stents were placed in 10 patients for 10 lesions. Results that were determined to be satisfactory angiographically were achieved in all 10 lesions. Two patients suffered permanent neurological deterioration related to stent placement. In two patients, the aneurysm recurred after stent-assisted coil embolization. In one case of recurrence a second attempt at coil embolization was successful, whereas in the second case of recurrence parent vessel occlusion was required and well tolerated. CONCLUSIONS: Intracranial stents can be a useful addition to coil embolization by providing mechanical, hemodynamic, and visual benefits in the treatment of complex, broad-based aneurysms.

Adult↗
PubMed2003

Modifications to the orbitozygomatic approach. Technical note.

The orbitozygomatic craniotomy is one of the workhorse approaches of skull base surgery, providing wide, multidirectional access to the anterior and middle cranial fossae as well as the basilar apex. Complete removal of the orbitozygomatic bar increases the angles of exposure, decreases the working depth of the surgical field, and minimizes brain retraction. In many cases, however, only a portion of the exposure provided by the full orbitozygomatic approach is needed. Tailoring the extent of the bone resection to the specific lesion being treated can help lower approach-related morbidity while maintaining its advantages. The authors describe the technical details of the supraorbital and subtemporal modified orbitozygomatic approaches and discuss the surgical indications for their use. Modifications to the orbitozygomatic approach are an example of the ongoing adaptation of skull base procedures to general neurosurgical practice.

Brain Diseases↗
PubMed2003

Distinction between paraclinoid and cavernous sinus aneurysms with computed tomographic angiography.

OBJECTIVE: To examine the reliability of using the optic strut as a landmark in computed tomographic (CT) angiography, to differentiate between intradural and extradural (cavernous sinus) aneurysms involving the paraclinoid segment of the internal carotid artery (ICA). METHODS: Microanatomic dissections were performed with five cadaveric heads (10 sides), to establish the relationships of the optic strut to the cavernous sinus and the ICA. Results from these anatomic studies were compared with intraoperative and CT angiographic findings for four patients with nine intracranial aneurysms involving the paraclinoid segment of the ICA. RESULTS: The inferior boundary of the optic strut accurately localized the point at which the ICA pierced the oculomotor membrane (proximal dural ring) and exited the cavernous sinus. The optic strut and its relationship to the ICA could be well observed on CT angiograms. During surgery, six of six aneurysms that arose distal to the optic strut were identified intradurally and were successfully clipped. Conversely, all aneurysms that arose proximal to the optic strut were observed to lie within the cavernous sinus. An aneurysm at the optic strut was within the clinoid segment or interdural, between the proximal and distal rings. CONCLUSION: The optic strut, as identified with CT angiography, provided a reliable anatomic landmark for accurate discrimination between intradural and extradural (cavernous sinus) aneurysms.

Adult↗
PubMed2003

Discovering the novel surgical approach.

Discovering the novel surgical approach requires surgeons to look beyond the dogma of current practices. By applying simple principles and concepts, such as the two-point method, working depth, working area, and angle of attack, novel approaches can evolve from existing approaches to improve exposure and decrease patient morbidity. The EOZ and ELSI are two examples in which these principles have been applied to generate novel surgical approaches by modifying existing ones. Compared to the previously used approaches, both of these novel approaches afford superior access to their respective regions of the brain stem with decreased rates of morbidity.

Brain Diseases↗
PubMed2002

Physiology and pathophysiology of cortico-basal ganglia-thalamocortical loops: theoretical and practical aspects.

A new theoretical framework is used to analyze functions and pathophysiological processes of cortico-basal ganglia-thalamocortical loops and to demonstrate the hierarchical relationships between various loops. All hierarchical levels are built according to the same functional principle: Each loop is a neural optimal control system (NOCS) and includes a model of object behavior and an error distribution system. The latter includes dopaminergic neurons and is necessary to tune the model to a controlled object (CO). The regularities of pathophysiological processes in NOCSs are analyzed. Mechanisms of current functional neurosurgical procedures like lesioning and deep brain stimulation (DBS) of various basal ganglia structures and neurotransplantation are described based on proposed theoretical ideas. Parkinson's disease (PD) is used to exemplify clinical applications of the proposed theory. Within the proposed theoretical framework, PD must be considered as a disease of the error distribution system. The proposed theoretical views have broad fundamental and clinical applications.

Animals↗
PubMed2002

Carotid dissection: technical factors affecting endovascular therapy.

BACKGROUND AND PURPOSE: To delineate factors associated with the successful endovascular treatment of extracranial carotid dissections, the authors review their management of 13 cases. METHODS: The records of 12 patients with 13 dissections were assessed with reference to mechanism of dissection, preoperative symptoms, presence of a pseudoaneurysm, treatment success, and etiology of treatment failure. Patients were followed prospectively and included six men and six women, ranging in age from 27 to 62 years. RESULTS: Angioplasty and stenting were performed successfully in 11 of 13 procedures (10 of 12 patients). Follow-up in these 10 patients demonstrated excellent patency through the stented segment in nine of the 11 treated vessels. Two patients, both of whom suffered their original dissection as a result of endarterectomy, required further angioplasty and stenting for stenosis outside the previously treated arterial segment. Regarding the treatment failures, a stent deployment device could not navigate a tortuous loop in one, while a microwire could not be advanced beyond a pseudoaneurysm in the second. Six patients had pseudoaneurysms, four of which were treated only with stenting across the dissected arterial segment. All pseudoaneurysms treated in this fashion resolved. No permanent complications occurred as a result of endovascular therapy. CONCLUSIONS: Angioplasty and stenting can be performed safely to manage carotid dissection. A pseudoaneurysm or tortuous anatomy can preclude therapy although the former typically resolves if angioplasty and stenting are feasible. Dissections secondary to endarterectomy may be associated with a higher rate of restenosis after stenting and may require further treatment.

Adult↗
PubMed2002

Anterior communicating artery aneurysms.

ANTERIOR COMMUNICATING ARTERY aneurysms are complex lesions for which surgical success requires extensive preoperative and intraoperative planning. Adherence to the tenets of aneurysm surgery, including vascular control and preservation of perforating arteries, is essential for their exclusion from the circulation.

Brain↗
PubMed2002

Extradural thoracic arteriovenous malformation in a patient with Klippel-Trenaunay-Weber syndrome: case report.

OBJECTIVE AND IMPORTANCE: Spinal cord involvement in Klippel-Trenaunay-Weber (KTW) syndrome is rare. Cases of intradural spinal cord arteriovenous malformations (AVMs) have been associated with this syndrome. Likewise, cases of epidural hemangioma and angiomyolipoma have been reported to occur at the same segmental level as cutaneous hemangioma in KTW syndrome. This report details a rare case of an extradural thoracic AVM in a patient with KTW syndrome. CLINICAL PRESENTATION: A 30-year-old man presented with a 10-month history of progressive myelopathy, bilateral lower-extremity weakness, and numbness, with the right side affected more than the left. His symptoms had progressed to the point that he was unable to walk. The patient had the characteristic manifestations of KTW syndrome, including numerous cutaneous angiomas and cavernomas, limb hypertrophy and syndactyly, and limb venous malformations. A magnetic resonance imaging scan and subsequent angiogram demonstrated a large extradural AVM causing cord compression at the T3-T4 levels. INTERVENTION: The patient underwent two separate endovascular procedures, including embolization of upper thoracic and thyrocervical trunk feeders. Subsequently, he underwent T1-T4 laminectomy and microsurgical excision of the AVM. Clinically, the patient improved such that he could walk without assistance. CONCLUSION: KTW syndrome represents a spectrum of clinical presentations. Although involvement of the spinal cord is uncommon, the manifestations of this syndrome may include both intradural and extradural AVMs in addition to various tumors.

Adult↗
PubMed2002

Interactive stereoscopic virtual reality: a new tool for neurosurgical education. Technical note.

The goal of this study was to develop a new method for neurosurgical education based on interactive stereoscopic virtual reality (ISVR). Interactive stereoscopic virtual reality can be used to recreate the three-dimensional (3D) experience of neurosurgical approaches much more realistically than standard educational methods. The demonstration of complex 3D relationships is unrivaled and easily combined with interactive learning and multimedia capabilities. Interactive stereoscopic virtual reality permits the accurate recreation of neurosurgical approaches through integration of several forms of stereoscopic multimedia (video, interactive anatomy, and computer-rendered animations). The content explored using ISVR is obtained through a combination of approach-based cadaver dissections, live surgical images and videos, and computer-rendered animations. These media are combined through an interactive software interface to demonstrate key aspects of a neurosurgical approach (for example, patient positioning, draping, incision, individual surgical steps, alternative steps, relevant anatomy). The ISVR platform is designed for use on a desktop personal computer with newly developed, inexpensive, platform-independent shutter glasses. Interactive stereoscopic virtual reality has been used to capture the anatomy and methods of several neurosurgical approaches. In this paper the authors report their experience with ISVR and describe its potential advantages. The success of a neurosurgical approach is contingent on the mastery of complex, 3D anatomy. A new technology for neurosurgical education, ISVR can improve understanding and speed the learning process. It is an effective tool for neurosurgical education, bridging the substantial gap between textbooks and intraoperative training.

Computer-Assisted Instruction↗