VEGF (vascular endothelial growth factor) is a growth factor that is possibly present in a reduced amount in some ALS patients which contributes to the degeneration of motor nerve cells. This hypothesis derives from a series of animal studies which showed in 2001 that eliminating VEGF in the mouse model by genetic engineering leads to a motor disease that has features in common with ALS. Previous studies in humans have yielded controversial results so that it is currently unclear whether a deficiency of VEGF is of significance in ALS. To answer this question, a pilot study was planned by the Belgian neurologist Wim Robberecht in which the substance VEGF is administered to the spinal canal of ALS patients. Administration of VEGF into the spinal fluid (intrathecal administration of VEGF) represents direct administration of medication into the central nervous system of the ALS patients. This study is intended to investigate the safety and tolerability of intrathecal VEGF administration. Up to now, it has not been shown whether VEGF can lead to slowing of the ALS.