Neurobiologic effects of radiosurgery: histologic, immunohistochemical and electron-microscopic studies of a rat...

Spinal cords of rats were irradiated with a single fraction of 14-36 Gy (group A) or 55 Gy (group B) and examined by light and electron microscopy. Degeneration and reduced numbers of motor neurons were found even at an early stage in group B animals. Necrosis in the spinal cord was found at a later stage. The ultrastructure of vessels around areas of necrosis showed degeneration of pericytes and vacuolar changes of vascular walls. This study indicates that single, high-dose irradiation causes direct effects on neurons at early stages and degeneration of vascular walls followed by necrosis at a later stage.