. . "A preferred form of the invention can treat a neurodegenerative disorder, such as Parkinson's disease Huntington's or Amyotrophic Lateral Sclerosis (ALS), by means of an implantable pump and a catheter having a proximal end coupled to the pump and having a discharge portion for infusing therapeutic dosages of the one or more drugs capable of altering the level of excitation of neurons of the brain" . .