Vascular permeability changes associated with experimentally induced facial nerve lesions in the rabbit

Changes in vascular permeability to sodium fluorescein following experimentally induced nerve lesions were examined in the rabbit facial nerve. Sodium fluorescein was injected intravenously as a permeability tracer and then localized by fluorescence microscopy. In control nerves, endoneurium showed only slight fluorescence while intense fluorescence was observed in the epineurium and perineurium. In nerves demonstrating edema and Wallerian degeneration, endoneurium was found to have an increased accumulation of tracer. This increased endoneurial vascular permeability in facial nerve lesions may explain nerve enhancement seen in gadolinium-enhanced magnetic resonance imaging in patients with facial nerve paralysis.