A Critical Re-Examination of the Intraluminal Filament MCAO Model: Impact of External Carotid Artery Transection.

The intraluminal filament procedure is the most common model of middle cerebral artery occlusion (MCAO). However, consequences of subtle variations in surgical technique on behavioral outcome measures have not been sufficiently explored, which is the aim of this study. Rats randomly received one of three types of transient MCAO (60 min) surgeries. The first transected the external carotid artery (ECA) for filament insertion. The other two inserted the filament in the carotid artery (CA), and after reperfusion, the CA was either ligated or blood flow restored. All animals, including shams and naïve controls, were monitored with behavioral tests for 90 days. Lesion size and NeuN + cells in the striatum were comparable among MCAO groups. However, rats with ECA transection were consistently lighter than rats with permanent CA ligation, which were lighter than rats with CA reperfusion. Furthermore, rats with ECA transection exhibited the poorest lick efficiency and the greatest impairments in sensorimotor tasks. This study is the first to systematically evaluate the role of ECA transection on functional and morbidity outcomes. Behavioral impairments attributable to the surgical procedure were observed. This confounds studies and is an important issue that needs to be considered when using the intraluminal filament model.