It was with great pleasure that I accepted Professor Wackenheim's invitation to write the preface of this most interesting monograph. During the international course on neuroradiology in Obernai, organized by Professor Wackenheim in 1978, an entire day was devoted to discussions about various aspects of stenosis of the lumbar vertebral canal. As Professor Wackenheim and his group, in particular Dr. E. Babin, had thorough· ly studied this field, it was an excellent occasion for the exchange of views through personal contact. Their support of basic views such as attributing the cause of stenosis to a developmental disturbance of growth of the neural element - the vertebral arc- and spontaneous agreement about essentials in classification and nomenclature facili­ tated this exchange. Reading the present monograph made me think back to 1949 when I wrote my first publication on stenosis of the lumbar vertebral canal in a French volume that com­ memorated my teacher in neurosurgery, Professor Clovis Vincent. During the following years it was impossible to publish a more detailed paper on the subject in international journals since their editorial boards did not believe in its occurrence. My first English papers were published in the Journal of Bone and Joint Surgery (1954, 1955), but it was only during the 1970s that this form of stenosis became more universally recog­ nized.