Microvascular neural blood flow assessment for a chronic nerve compression neuropathy mouse model by fluorescein angiography

Abstract

ABSTRACT Background and aims Intraoperative fluorescence angiography with indocyanine green or fluorescein is used in ophthalmology and neurosurgery. However, there are few reports on the use of fluorescence angiography for peripheral neuropathy. This study aimed to assess the validity of fluorescein angiography (FAG) for peripheral nerve entrapment neuropathy. Methods We used an established model of chronic nerve compression (CNC) neuropathy in C57BL/6 mice by entrapping their left sciatic nerve with a silastic tube. Mice were assigned to the uninjured group (control), two-week CNC neuropathy group, four-week CNC neuropathy group, or six-week CNC neuropathy group. We then performed FAG to assess neural blood flow and quantified the peak of the luminance at the compression site with luminance analysis software. Following FAG, histological examinations using an anti-fluorescein antibody and Masson’s trichrome staining were performed to evaluate the area of fluorescein distribution and epineural fibrosis. Results The luminance in the CNC neuropathy groups was significantly lower than that in the control group. Histological analysis revealed the fluorescein positive areas in the CNC neuropathy groups were significantly smaller than that in the control group, and the epineural fibrosis areas in the CNC neuropathy groups were significantly larger than that in the control group. Conclusion We observed a significant decline of luminance in the CNC neuropathy groups, and the histological assessment was consistent with this result. FAG was found to be a valid method for assessing CNC neuropathy in mice.