ABSTRACT
BACKGROUND AND PURPOSE: Rabbit models of intracranial aneurysms are frequently used in pre-clinical settings. This study aimed to demonstrate an alternative, extravascular method for creating elastase-induced aneurysms, and how ligation of the right common carotid arteries (RCCA) can impact flow redistribution into left CCA (LCCA). METHODS: Elastase-induced aneurysms in 18 New Zealand rabbits (4.14 ± 0.314 kg) were created by applying 3-5 U of concentrated elastase solution to the exterior of the right and left CCA roots (RCCA and LCCA). After the induction of the aneurysm, the aneurysm was either kept intact to the rest of the corresponding CCA, severed from the rest of the CCA to allow for a free standing aneurysm, or was anchored to nearby tissue to influence the angle and orientation of the aneurysm with respect to the parent vessel. Ultrasound studies were performed before and after creation of aneurysms to collect blood flow measurements inside the aneurysm pouch and surrounding arteries. Prior to sacrificing the animals, computed tomography angiography studies were performed. Harvested aneurysmal tissues were used for histological analysis. RESULTS: Elastase-induced aneurysms were successfully created by the extravascular approach. Histological studies showed that the biological response was similar to human cerebral aneurysms and previously published elastase-induced rabbit aneurysm models. Ultrasound measurements indicated that after the RCCA was ligated, blood flow significantly increased in the LCCA at one-month follow-up. CONCLUSION: An alternate method for creating elastase-induced aneurysms has been demonstrated. The novel aspects of our method allow for ligation of one or both common carotid arteries to create a single or bilateral aneurysm with an ability to control the orientation of the induced aneurysm.
ABSTRACT
BACKGROUND AND PURPOSE: Chronic traumatic encephalopathy (CTE) is a neurodegenerative disease occurring most commonly in athletes and is caused by repeated concussive or subconcussive blows to the head. The main purpose of this review is to evaluate the published literature on chronic traumatic encephalopathy (CTE) in athletes participating in high-impact sports. In particular, we highlight the significance of concussive and subconcussive impacts in multiple sports, elucidate the differences between clinical/pathological features of CTE and related neurodegenerative diseases, and provide an explanation for the variation in clinical presentation between athletes of different sports. METHODS: A review targeting relevant publications to CTE was performed. The PubMed/MEDLINE index was searched for keywords such as "chronic traumatic encephalopathy," "repetitive traumatic brain injury," "mild traumatic brain injury," and "concussion" from year 1924 through March 1, 2016. RESULTS: A consensus panel's recent identification of a pathognomonic pathology in CTE, characterized by an irregular distribution of phosphorylated tau deposits, is an important step in developing consensus diagnostic criteria and clinicopathological studies. After review of major clinical studies, evidence suggests that there are clear differences in neuropathological features, clinical progression, and manifestation of symptoms between CTE and other neurodegenerative diseases. The literature suggests boxers tend to have more severe symptoms than other athletes due to more frequent rotational and shearing impacts. Data regarding genetic predispositions of CTE have been inconsistent in part due to low subject populations. Positron emission tomography imaging involving tau-binding ligands has recently proven effective in differentiating CTE from control groups and other neurodegenerative diseases. CONCLUSIONS: Further longitudinal studies should be conducted to correlate the number of suffered concussive/subconcussive forces to the likelihood of developing chronic traumatic brain injury symptoms. Research striving for a reliable antemortem CTE diagnosis would be immensely beneficial, leading to more accurate estimates of prevalence, allowing clinicians to assess future risk of athletes' continued participation in sports, and enabling clinicians to make appropriate preventive recommendations.
