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Theodore Kurze, Peter Dyck and Howard S. Barrows

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Howard H. Ginsburg, Andrew G. Shetter and Peter A. Raudzens

✓ Intraoperative somatosensory evoked potentials (SSEP's) are being used with increasing frequency to monitor neurological function during spinal surgery. The authors report a case of postoperative paraplegia that occurred despite preserved intraoperative SSEP's in an achondroplastic dwarf who underwent correction of a congenital kyphoscoliosis. Surgeons and anesthesiologists involved with SSEP monitoring should be aware that false-negative results may occur with this technique.

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M. Peter Heilbrun, O. Howard Reichman, Robert E. Anderson and Theodore S. Roberts

✓ 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.

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M. Sean Grady, Matthew A. Howard III, Ralph G. Dacey Jr., Walter Blume, Michael Lawson, Peter Werp and Rogers C. Ritter

Object. The magnetic stereotaxis system (MSS) is a device designed to direct catheter tips through magnetic forces. In this study the authors tested the safety and performance of the MSS in directing catheters through a nonlinear path to obtain biopsy specimens in pig brains.

Methods. Sixteen pigs underwent biopsy of the frontal brain region with the aid of an MSS (11 pigs) or a standard stereotactic biopsy tool (five pigs). Surgical preparation consisted of placement of six fiducial markers in the skull and the creation of a burr hole for attachment of a cranial bolt and passage of the biopsy catheter. The pigs underwent magnetic resonance (MR) imaging of the head to define a biopsy target and to plan a nonlinear path. Guided by the MSS, which used nearly real-time fluoroscopic imaging fused to the preoperative MR image, the authors advanced a catheter to the biopsy target. A biopsy tool was passed through the catheter and a tissue sample was obtained. The animals were observed for 3 to 5 days postoperatively, when they were assessed for neurological abnormalities or other signs of morbidity. Actual catheter placement was within 1.5 mm of the planned path to the biopsy site, using a minimum path radius of 30 mm. The registration error associated with the use of the MSS x-ray fluoroscopy and MR imaging averaged 1.7 mm. Tissue disruption caused by the MSS was similar to that of standard stereotactic procedures.

Conclusions. The MSS affords accurate and safe guidance of brain catheters in animals. The application tested here, brain biopsy, is one of a number of potential catheter-guided procedures.

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Michael C. Dewan, Justin Onen, Hansen Bow, Peter Ssenyonga, Charles Howard and Benjamin C. Warf

There is inadequate pediatric neurosurgical training to meet the growing burden of disease in low- and middle-income countries (LMIC). Subspecialty expertise in the management of hydrocephalus and spina bifida—two of the most common pediatric neurosurgical conditions—offers a high-yield opportunity to mitigate morbidity and avoid unnecessary death. The CURE Hydrocephalus and Spina Bifida (CHSB) fellowship offers an intensive subspecialty training program designed to equip surgeons from LMIC with the state-of-the-art surgical skills and equipment to most effectively manage common neurosurgical conditions of childhood. Prospective fellows and their home institution undergo a comprehensive evaluation before being accepted for the 8-week training period held at CURE Children’s Hospital of Uganda (CCHU) in Mbale, Uganda. The fellowship combines anatomy review, treatment paradigms, a flexible endoscopic simulation lab, daily ward and ICU rounds, radiology rounds, and clinic exposure. The cornerstone of the fellowship is the unique operative experience that includes a high volume of endoscopic third ventriculostomy with choroid plexus cauterization, myelomeningocele closure, and ventriculoperitoneal shunting, among many other procedures performed at CCHU. Upon completion, fellows return to their home institution to establish or rejuvenate a robust pediatric practice as part of a worldwide network of CHSB trainees committed to the care of underserved children. To date, the fellowship has graduated 33 surgeons from 20 different LMIC who are independently performing thousands of hydrocephalus and spina bifida operations each year.

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Jan-Karl Burkhardt, Omar Tanweer, Peter Kim Nelson and Howard A. Riina

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Jan-Karl Burkhardt, Howard A. Riina, Omar Tanweer, Peyman Shirani, Eytan Raz, Maksim Shapiro and Peter Kim Nelson

The authors present the unusual case of a complex unruptured basilar artery terminus (BAT) aneurysm in a 42-year-old symptomatic female patient presenting with symptoms of mass effect. Due to the fusiform incorporation of both the BAT and left superior cerebellar artery (SCA) origin, simple surgical or endovascular treatment options were not feasible in this case. A 2-staged (combined deconstructive/reconstructive) procedure was successfully performed: first occluding the left SCA with a Pipeline embolization device (PED) coupled to a microvascular plug (MVP) in the absence of antiplatelet coverage, followed by reconstruction of the BAT by deploying a second PED from the right SCA into the basilar trunk. Six-month follow-up angiography confirmed uneventful aneurysm occlusion. The patient recovered well from her neurological symptoms. This case report illustrates the successful use of a combined staged deconstructive/reconstructive endovascular approach utilizing 2 endoluminal tools, PED and MVP, to reconstruct the BAT and occlude a complex aneurysm.

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Matthew B. Potts, Daniel W. Zumofen, Eytan Raz, Peter K. Nelson and Howard A. Riina

Endovascular embolization is typically reserved as an adjuvant therapy in the management of cerebral arteriovenous malformations (AVMs), either for preoperative devascularization or preradiosurgical volume reduction. Curative embolization plays a limited role in AVM treatment but several studies have shown that it is possible, especially with later-generation liquid embolic agents. Given the complexity of AVM anatomy and the recent controversies over the role of any intervention in AVM management, it is critical that the cerebrovascular community better define the indications of each treatment modality to provide quality AVM management. In this review, the authors evaluate the role of curative AVM embolization. Important considerations in the feasibility of curative AVM embolization include whether it can be performed reliably and safely, and whether it is a durable cure. Studies over the past 20 years have begun to define the anatomical factors that are amenable to complete endovascular occlusion, including size, feeding artery anatomy, AVM morphology, and endovascular accessibility. More recent studies have shown that highly selected patients with AVMs can be treated with curative intent, leading to occlusion rates as high as 100% of such prospectively identified lesions with minimal morbidity. Advances in endovascular technology and techniques that support the efficacy and safety of curative embolization are discussed, as is the importance of superselective diagnostic angiography. Finally, the durability of curative embolization is analyzed. Overall, while still unproven, endovascular embolization has the potential to be a safe, effective, and durable curative treatment for select AVMs, broadening the armamentarium with which one can treat this disease.

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Dennis C. Shrieve, Eben Alexander III, Peter McL. Black, Patrick Y. Wen, Howard A. Fine, Hanne M. Kooy and Jay S. Loeffler

Object. To assess the value of stereotactic radiosurgery (SRS) as adjunct therapy in patients suffering from glioblastoma multiforme (GBM), the authors analyzed their experience with 78 patients.

Methods. Between June 1988 and January 1995, 78 patients underwent SRS as part of their initial treatment for GBM. All patients had undergone initial surgery or biopsy confirming the diagnosis of GBM and received conventional external beam radiotherapy. Stereotactic radiosurgery was performed using a dedicated 6-MV stereotactic linear accelerator. Thirteen patients were alive at the time of analysis with a median follow-up period of 40.8 months. The median length of actuarial survival for all patients was 19.9 months. Twelve- and 24-month survival rates were 88.5% and 35.9%, respectively. Patient age and Radiation Therapy Oncology Group (RTOG) class were significant prognostic indicators according to univariate analysis (p < 0.05). Twenty-three patients aged younger than 40 years had a median survival time of 48.6 months compared with 55 older patients who had 18.2 months (p < 0.001). Patients in this series fell into RTOG Classes III (27 patients), IV (29 patients), or V (22 patients). Class III patients had a median survival time of 29.5 months following diagnosis; this was significantly longer than median survival times for Classes IV and V, which were 19.2 and 18.2 months, respectively (p = 0.001). Only patient age (< 40 years) was a significant prognostic factor according to multivariate analysis. Acute complications were unusual and limited to exacerbation of existing symptoms. There were no new neuropathies secondary to SRS. Thirty-nine patients (50%) underwent reoperation for symptomatic necrosis or recurrent tumor. The rate of reoperation at 24 months following SRS was 54.8%.

Conclusions. The addition of a radiosurgery boost appears to confer a survival advantage to selected patients.