Rabbit Elastase Aneurysm: Imaging and Histology Correlates for Inflammation and Healing.

OBJECTIVE: Aneurysmal subarachnoid hemorrhage remains a devastating event with poorly understood pathophysiology. Previous studies have suggested that aneurysm wall inflammation may play a part in the development and potential rupture of aneurysms. The rabbit elastase aneurysm model is a well-established model, which produces aneurysms closely mimicking human cerebral aneurysms in flow dynamics and histopathology. The primary aim of this study was to correlate inflammatory changes after aneurysm formation using sequential vessel wall imaging with histopathologic analysis. A secondary aim was to evaluate the potential effect of gender and anti-inflammatory treatment with aspirin on this inflammatory response. METHODS: Twenty-seven New Zealand rabbits underwent surgery to create an aneurysm using elastase infusion at the right common carotid artery origin. Vessel wall imaging and histopathologic analysis was obtained at different time points after aneurysm creation. The rabbits were also randomized by gender and to treatment groups with or without aspirin. RESULTS: Histopathologic analysis revealed 3 distinct phases after aneurysm formation. These phases were an initial inflammatory phase, followed by a regeneration phase, and finally a connective tissue deposition phase. Vessel wall imaging demonstrated 2 distinct imaging patterns. No appreciable differences were seen in histology or imaging when comparing gender or treatment with aspirin. CONCLUSIONS: Inflammatory changes induced by the rabbit elastase aneurysm model can be correlated with histopathologic findings and observed on noninvasive vessel wall imaging. This may provide a method to study the inflammatory pathway as it pertains to aneurysmal development and subsequent rupture.

Neoplastic Cerebral Aneurysm From Metastatic Nonsmall Cell Lung Carcinoma: Case Report and Literature Review.

BACKGROUND AND IMPORTANCE: Intracranial cerebral aneurysms secondary to neoplastic etiology are a very rare occurrence. There have only been 5 published reports of intracranial cerebral aneurysms secondary to metastatic lung cancer. Four of those five previously published reports have been secondary to nonsmall cell lung carcinoma, and only 1 case caused subarachnoid hemorrhage. To our knowledge, this is the first report of a lung cancer-associated superior cerebellar artery aneurysm. CLINICAL PRESENTATION: A 41-yr old male presented with right-sided cerebellar hemorrhage. Cerebral angiogram was negative, but he was noted to have an underlying nonsmall cell carcinoma. His workup revealed a left upper lobe mass consistent with a diagnosis of metastatic lung carcinoma. A few weeks later, the patient represented with subarachnoid hemorrhage from a left superior cerebellar artery aneurysm that was new in comparison with a magnetic resonance angiography 19 d earlier. The aneurysm was remote to the surgical site, and the patient had a negative infectious workup, making an iatrogenic pseudoaneurysm or mycotic aneurysm unlikely. In the setting of metastatic cancer, a neoplastic cerebral aneurysm was the presumptive diagnosis. CONCLUSION: Intracranial neoplastic cerebral aneurysms are extremely rare entities, and a rare cause of subarachnoid hemorrhage. This diagnosis should be considered in patients who present with concurrent metastatic cancer and cerebral aneurysm or aneurysmal subarachnoid hemorrhage. Early initiation of chemotherapy may be beneficial in reducing the risk of tumor-particle embolization, but more research needs to be conducted to better understand this rare phenomenon.

Factors Affecting the Obliteration Rate of Intracranial Aneurysms Treated with a Single Pipeline Embolization Device.

OBJECTIVE: To evaluate the clinical and angiographic outcomes of intracranial aneurysm treatment using a single Pipeline embolization device (PED), and to evaluate the factors affecting aneurysm obliteration rate. METHODS: The demographic characteristics and anatomic features of 58 aneurysms in 47 patients treated with a single PED were reviewed retrospectively. All aneurysms treated with a PED at a single center and with follow-up angiograms for at least 6 months were included in this study. RESULTS: The overall rate of complete and near-complete occlusion was 84% (49 of 58) after a mean follow-up period of 18.3 months. The rate of complete aneurysm obliteration was lower in aneurysms with an arterial branch arising from the aneurysm neck compared with aneurysms without an arterial branch (13% [1 of 8] vs. 68% [34 of 50]; P = 0.0075). The overall rate of complete and near-complete aneurysm occlusion was 90% (45 of 50) in aneurysms without an arterial branch arising from its neck. There were no statistically significant associations between obliteration rate and aneurysm neck width, size, or type, or history of previous coil embolization. CONCLUSIONS: Our data suggest that a single PED is sufficient to induce complete or near-complete obliteration of most aneurysms. The presence of a branching artery arising from the aneurysm neck is highly predictive of incomplete occlusion after treatment with a single PED.

Using the Endoscopic Endonasal Transclival Approach to Access Aneurysms Arising from AICA, PICA, and Vertebral Artery: An Anatomical Study.

Objective To explore the use of the endoscopic endonasal transclival approach (EEA) for clipping anterior inferior cerebellar artery (AICA), posterior inferior cerebellar artery (PICA), and vertebral artery (VA) aneurysms. Design Anatomical study. Participants Fifteen adult cadavers. Main Outcome Measures Length of artery exposed and distance from the nasal ala to the arteries. Results The length of the right and left VA exposed were 1.7 ± 0.6 cm and 1.6 ± 0.6 cm, respectively. The distance to the right VA was 11.1 ± 0.9 cm and to the left was 11.1 ± 0.8 cm. Right and left AICA were exposed for an average length of 1.1 ± 0.3 cm and 0.8 ± 0.3 cm, respectively. The distance to the right AICA was 10.3 ± 0.8 cm and to the left was 10.3 ± 0.8 cm. The right PICA was exposed for a length of 0.5 ± 0.2 cm at a distance of 10.9 ± 0.5 cm. The left PICA was exposed for a length of 0.5 ± 0.2 cm at a distance of 11.1 ± 0.9 cm. Conclusion The EEA can provide direct access to AICA, PICA, and VA, making it a potential alternative to the traditional approaches for the clipping of aneurysms arising from those arteries.

The Expanded Endoscopic Endonasal Approach to Anterior Communicating Artery Aneurysms: A Cadaveric Morphometric Study.

OBJECTIVE: The purpose of this study was to explore the endoscopic endonasal approach to the anterior communicating artery complex. DESIGN: Anatomic, morphometric analysis of human cadaver heads. SUBJECTS: Fifteen latex-injected adult cadaver heads. MAIN OUTCOME MEASURES: The anatomic boundaries of the operative field and the dimensions of exposure of the anterior communicating artery (ACoA) complex were measured and clip placement feasibility was assessed. RESULTS: Exposure of the ACoA and bilateral A1 and A2 segments was accomplished in all 15 cadaver heads. Average length of the exposed ACoA was 3 ± 1 mm, the left A1 was 5 ± 3 mm and right A1 was 5 ± 1 mm, while the A2 segment was 5 ± 2 mm bilaterally. The average distance from the alar floor to the ACoA was 95 mm, while proximal lateral limit measured between the alar floor margins was 36 mm. The distal lateral limit as defined by the distance between the lateral most exposed margins of the chiasm was 19 mm. Clip placement was accomplished for the ACoA and the A1 and A2 segments bilaterally in all specimens. CONCLUSION: The endoscopic, endonasal transtuberculum, transplanum approach is an anatomically feasible alternative to treating select aneurysms of the ACoA complex.

Endoscopic endonasal transclival approaches: case series and outcomes for different clival regions.

Objective Transclival endoscopic endonasal approaches to the skull base are novel with few published cases. We report our institution's experience with this technique and discuss outcomes according to the clival region involved. Design Retrospective case series. Setting Tertiary care academic medical center Participants All patients who underwent endoscopic endonasal transclival approaches for skull base lesions from 2008 to 2012. Main Outcome Measures Pathologies encountered, mean intraoperative time, intraoperative complications, gross total resection, intraoperative cerebrospinal fluid (CSF) leak, postoperative CSF leak, postoperative complications, and postoperative clinical course. Results A total of 49 patients underwent 55 endoscopic endonasal transclival approaches. Pathology included 43 benign and 12 malignant lesions. Mean follow-up was 15.4 months. Mean operative time was 167.9 minutes, with one patient experiencing an intraoperative internal carotid artery injury. Of the 15 cases with intraoperative cerebrospinal fluid (CSF) leaks, 1 developed postoperative CSF leak (6.7%). There were six other postoperative complications: four systemic complications, one case of meningitis, and one retropharyngeal abscess. Gross total resection was achieved for all malignancies approached with curative intent. Conclusions This study provides evidence that endoscopic endonasal transclival approaches are a safe and effective strategy for the surgical management of a variety of benign and malignant lesions. Level of Evidence 4.

Level of the conus in pediatric patients with skeletal dysplasia.

OBJECT: Skeletal dysplasias are a heterogeneous group of disorders that affect bone development and can result in reduced vertebral body growth and short stature. The level of the conus medullaris is unknown in this population. The purpose of this review was to determine the level of the conus in a population of pediatric patients with skeletal dysplasia. METHODS: A retrospective chart review of a 7-year period was undertaken at a tertiary care pediatric hospital to identify patients in whom skeletal dysplasia had been diagnosed. Radiographs and MR imaging studies were evaluated to discern the level of the conus with respect to the bony vertebral column. RESULTS: Four hundred sixty-seven patients with skeletal dysplasia were identified. One hundred eleven patients had quality MR images. Forty-seven different skeletal dysplasias were observed. The mean conus level was found at the L-1 vertebral body. No difference was noted with respect to the age of the patients or the type of skeletal dysplasia. Two patients (1.7%) had a conus level lower than L-2. CONCLUSIONS: Skeletal dysplasia leads to abnormal bone formation and can result in short stature. The location of the conus with respect to the vertebral bodies appears to be stable at the L-1 level regardless of patient age or the type of skeletal dysplasia involved. However, the appearance of a low-level conus and associated tethered cord syndrome may be slightly increased in this population.

NMDA-induced seizures in developing rats cause long-term learning impairment and increased seizure susceptibility.

N-methyl-D-aspartate (NMDA) receptors play a prominent role in the pathogenesis of epilepsy, yet few studies have used NMDA as a convulsant in whole animals. In developing rats, systemic NMDA induces seizures with a unique seizure phenotype ("emprosthotonic" or hyperflexion seizures) and electrographic pattern (electrodecrement). These features are not seen in kainic acid-induced seizures, suggesting that seizures activated by NMDA might cause different long-term consequences. Therefore, we investigated the effects of NMDA seizures during development on cognitive function and susceptibility to seizures in adulthood. Rat pups (P12-20) were injected with saline (n=36) or NMDA (n=64) at convulsant doses (15-30mg/kg, i.p.). After NMDA injection, a characteristic sequence of seizure activity was seen: initial behavioral arrest, followed by hyperactivity, agitation, and then emprosthotonus and generalized tonic-clonic seizures. Seizures were terminated 30min later by ketamine (50mg/kg, i.p.). On P85, rats underwent behavioral testing in the water maze. Rats that had experienced NMDA seizures as pups took significantly longer to learn the platform location over 5 days of testing, compared to controls. On P90, rats were injected with pentylenetetrazol (PTZ, 50mg/kg, i.p.) to assess their susceptibility to generalized seizures. NMDA-treated rats had decreased latency and increased duration of class V PTZ seizures. Cresyl violet-stained sections of cortex and hippocampus had no obvious cell loss or gliosis. In summary, NMDA causes a unique seizure phenotype in the developing brain, with subsequent deficits in spatial learning and an increased susceptibility to PTZ seizures in adulthood. This study provides additional evidence for long-term alterations of neuronal excitability and cognitive capacity associated with seizures during development.