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Robert J. Spinner, Jay U. Howington and David G. Kline

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Jay U. Howington, John J. Kruse and Deepak Awasthi

Object. The goal of this anatomical study was to investigate the surgical and radiographic anatomy of the C-2 pedicle in relation to transpedicular screw placement in occipitocervical stabilization and to establish anatomical guidelines for the placement of C-2 pedicle screws.

Methods. The C-2 pedicles in 10 cadaveric spines were evaluated using both computerized tomography (CT) scanning and manual measurements. The specimens were scanned; the mediolateral and rostrocaudal angulations of each pedicle were measured, with the midline sagittal plane and the inferior endplate of the C-2 facet, respectively, as references, and values were recorded in 1° increments by using a digital goniometer. The height, width, and length of the pedicles were also measured on the CT scans. Based on these measurements in conjunction with direct visualization of the C-2 pedicle through the C1–2 interlaminar space pedicle screws were then placed. The distances from the screw entry point to the midline, C2–3 joint line, and the medial aspect of the vertebral artery were also measured. Repeated CT scanning was then performed to assess screw placement.

The average pedicle height, width, and length measured 9.1 mm, 7.9 mm, and 16.6 mm, respectively, and the medial inclination and rostrocaudal angulation averaged 35.2° and 38.8°, respectively. The cortex of the pedicle was not violated in any of the 20 cadaveric specimens.

Conclusions. Adequate preoperative imaging studies in conjunction with direct visualization of the C-2 pedicle make transpedicular fixation safe and effective.

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Jay U. Howington, Edward S. Connolly and Rand M. Voorhies

Object. Although synovial cysts commonly involve the joints of the extremities, they are also found in the spinal canal. When symptomatic, they produce signs and symptoms consistent with nerve root and spinal cord compression. In this report the authors review the clinical presentations, radiological studies, and operative findings in 28 patients with intraspinal synovial cysts treated surgically at the Ochsner Clinic between 1988 and 1998.

Methods. The medical records and radiological studies obtained in 28 patients (31 intraspinal synovial cysts) were analyzed. Twenty-nine (94%) of the cysts were located in the lumbar, one in the thoracic (T8–9), and one in the cervicothoracic (C7—T1) spine. Sixteen (57%) of the 28 patients presented with radicular pain. The remaining patients presented either with neurogenic claudication (25%) or with radicular pain and an associated neurological deficit (18%). Each cyst was located adjacent to a facet joint in which there was evidence of degenerative disease.

Conclusions. Intraspinal synovial cysts are uncommon lesions most often found in the lumbar spine at the L4–5 level. They are invariably associated with facet degeneration and respond very well to surgical therapy.

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Jay U. Howington, Scott C. Kutz, Gregory E. Wilding and Deepak Awasthi

Object. The goal of this study was to analyze the relationship between cocaine use and outcomes of aneurysmal subarachnoid hemorrhage (SAH).

Methods. A retrospective review was performed of the medical records of patients with intracranial aneurysms treated at a single institution between January 1996 and December 2001. Only patients who presented with SAH were included in the study. The covariates chosen for the statistical analysis included the following: patient age, sex, and race; systolic and mean arterial blood pressure measurements on hospital admission; Hunt and Hess and Fisher grades; preexistent major systemic disease; and history of alcohol, tobacco, or cocaine use. The Glasgow Outcome Scale (GOS) was used to standardize outcome and was dichotomized such that a score between 1 and 3 was considered a poor outcome and a score of 4 or 5 was considered a favorable outcome.

The records of 151 patients were reviewed and 108 of these presented with aneurysmal SAH. Of these 108 patients, 36 (33.3%) had used cocaine within 24 hours before presentation. A Hunt and Hess grade of IV or V was assigned to 20 (55.6%) of 36 patients who used cocaine, compared with eight (11.1%) of 72 patients who did not; this difference was found to be statistically significant (p < 0.0001). Twenty-eight patients (77.8%) in the cocaine user group and 20 patients (27.8%) in the non—cocaine user group experienced clinically significant, angiographically confirmed vasospasm during their hospital course (p < 0.0001). Cocaine use was associated with a 2.8-fold greater risk of developing vasospasm (95% confidence interval [CI] 1.86–4.22). A GOS score of 1, 2, or 3 was assigned to 33 patients (91.7%) in the cocaine user group and to 20 patients (27.8%) in the non—cocaine user group (p < 0.0001). Cocaine use was associated with a 3.3-fold greater risk of poor outcome (95% CI 2.24–4.85). This association was found to be independent of Hunt and Hess grade as well as of vasospasm.

Conclusions. Cocaine adversely affects both the presentation of and outcome in patients with aneurysmal SAH who are undergoing treatment for this disease. The vasoactive properties of the drug appear to aggravate the already tenuous situation of SAH and increase both the occurrence and influence of cerebral vasospasm. Statistical analysis demonstrates that cocaine directly affects both presentation and outcome in a significant manner. It is the authors' interpretation of the results of this retrospective review that cocaine use negatively affects outcome to such an extent that it should be considered equal to the presence of a major systemic illness when determining Hunt and Hess grade.

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Elad I. Levy, Ricardo A. Hanel, Jay U. Howington, Balazs Nemes, Alan S. Boulos, Fermin O. Tio, Ann Marie Paciorek, Shoaib Amlani, Kathleen S. Kagan-Hallett, Mary Duffy Fronckowiak, Lee R. Guterman and L. Nelson Hopkins

Object. Use of the sirolimus-eluting stent has led to a reduction of in-stent stenosis following treatment of coronary atherosclerosis, whereas treatment of intracranial atherosclerosis with bare-metal stents results in excessive restenosis rates of approximately 40%. Neurotoxicity effects and vessel injury are unknown in the cerebral vasculature. To assess the safety profile and vascular effects of sirolimus-coated stents, the authors conducted a prospective comparative study in which drug-eluting and bare-metal stents were implanted in the canine basilar artery (BA).

Methods. Sixteen mongrel dogs were randomized (eight animals per group) to receive either bare-metal 1.5 × 8—mm (six-cell) stents or sirolimus-eluting stents of the same dimensions. Interventionists, histopathologists, and histopathology technicians who participated in the study were blinded to the stent characteristics. Stents were implanted in the canine BA. Serial peripheral blood samples were obtained during the 1st week after implantation to determine the time-dependent serum concentration of sirolimus. Follow-up angiographic studies were performed 30 days after stent implantation to assess the effects of stent placement on the BA and brainstem perforating vessels. Explantation of the stent and BA was performed immediately after angiography by using a pressurized formalin fixation procedure. Histological and computer-assisted morphometric analyses of specimens obtained in each animal were performed.

Sirolimus could not be detected in peripheral blood samples obtained later than 24 hours posttreatment. On follow-up angiography, all perforating vessels observed on initial angiograms remained patent, and no evidence of parent vessel damage or pseudoaneurysm formation was observed. Explanted vessels and brainstem sections did not demonstrate evidence of histological neurotoxicity, such as gliosis or infarction. No significant differences were found in the time to endothelialization of bare-metal and sirolimus-coated stents. Smooth-muscle cell (SMC) proliferation, the putative agent for restenosis, was lower in animals receiving sirolimus-coated stents (p = 0.003). Additionally, intimal fibrin density was increased in the dogs treated with sirolimus-coated stents (p < 0.0001). Histological evidence of an inflammatory response demonstrated a trend toward a reduced response in the sirolimus group (mean 0.58) compared with the bare-metal group (mean 0.83, p = 0.33).

Conclusions. No neurotoxic effects were observed in the intracranial vessel walls or brainstem tissue in which sirolimus-coated stents were implanted. Compared with bare-metal stents, the sirolimus-coated devices did not impair endothelialization and, furthermore, tended to reduce the proliferation of SMCs. These findings indicate that sirolimus-coated devices may inhibit in-stent stenosis. Further studies with longer-term follow up are required to assess the restenosis rates of sirolimus-coated stents implanted in the intracranial vasculature.

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J Mocco, Kenneth V. Snyder, Felipe C. Albuquerque, Bernard R. Bendok, Alan S. Boulos, Jeffrey S. Carpenter, David J. Fiorella, Brian L. Hoh, Jay U. Howington, Brian T. Jankowitz, Kenneth M. Liebma N, Ansaar T. Rai, Rafael Rodriguez-Mercado, Adnan H. Siddiqui, Erol Veznedaroglu, L. Nelson Hopkins and Elad I. Levy

Object

The development of self-expanding stents dedicated to intracranial use has significantly widened the applicability of endovascular therapy to many intracranial aneurysms that would otherwise have been untreatable by endovascular techniques. Recent Food and Drug Administration approval of the Enterprise Vascular Reconstruction Device and Delivery System (Cordis) has added a new option for self-expanding stent-assisted intracranial aneurysm coiling.

Methods

The authors established a collaborative registry across multiple institutions to rapidly provide largevolume results regarding initial experience in using the Enterprise in real-world practice. Ten institutions (University at Buffalo, Thomas Jefferson University, University of Florida, Cleveland Clinic, Northwestern University, West Virginia University, University of Puerto Rico, Albany Medical Center Hospital, the Neurological Institute of Savannah, and the Barrow Neurological Institute) have provided consecutive data regarding their initial experience with the Enterprise.

Results

In total, 141 patients (119 women) with 142 aneurysms underwent 143 attempted stent deployments. The use of Enterprise assistance with aneurysm coiling was associated with a 76% rate of ≥ 90% occlusion. An inability to navigate or deploy the stent was experienced in 3% of cases, as well as a 2% occurrence of inaccurate deployment. Procedural data demonstrated a 6% temporary morbidity, 2.8% permanent morbidity, and 2% mortality (0.8% unruptured, 12% ruptured).

Conclusions

The authors report initial results of the largest series to date in using the Enterprise for intracranial aneurysm treatment. The Enterprise is associated with a high rate of successful navigation and low occurrence of inaccurate stent deployment. The overall morbidity and mortality rates were low; however, caution should be exercised when considering Enterprise deployment in patients with subarachnoid hemorrhage as the authors' experience demonstrated a high rate of associated hemorrhagic complications leading to death.