cxii Journal of Comparative Neurology. 



The Dorsal Roots of the Cranial Nerves in Tabes Dorsalis.i 



The autlior gives an interesting resume of the history of opinion re- 

 garding the dorsal columns. He says that at present there can be no 

 doubt that Goll's columns are the continuation of the dorsal roots chiefly 

 of the lower extremities. Flechsig divides the dorsal columns into ven- 

 tral, middle and dorsal zones and also a median zone near the dorsal sep- 

 tum. The first to develop is the ventral, then a part of the middle and 

 the median zones, then Goll's column and the remainder of the middle 

 and the mesal part of the dorsal zone, and, finally, the dorso-lateral root 

 zone. 



In a moderately severe case of tabes the degeneration is most pro- 

 nounced in the lower dorsal and upper lumbar regions. In the lumbar 

 region the dorsal one-third is wholly degenerate, while the ventral third 

 is almost unaltered. In the middle third there is a zone of degeneration 

 occupying about the middle. At the lowest level of the dorsal cord the 

 degeneration involves about the dorsal half. In the lumbar and sacral 

 cord a ventral portion of the dorsal columns remains undisturbed. This 

 area is broadest at the commissure and passes along the ventral half of the 

 dorsal cornu, diminishing as it goes. According to Singer and Miinzer, 

 this area does not contain root-fibres, but such fibres as arise in the gray 

 substance. 



Frequently there is a small zone adjoining the dorsal fissure, which 

 is slightly degenerated. A portion lying beneath the peripheral half of 

 this region often is unaltered, even in severe cases of tabes. It is this 

 portion which has been found to be affected by descending degeneration 

 like portions of the lateral columns in a case of myelitis due to pressure 

 in dorsal region. 



Fibres arising in the sacral cord enter, not only a part of the dorsal 

 septum but the wliole dorsal periphery of the lumbar region. 



The area of degeneration passes mesad as we pass to the dorsal and 

 cervical region and becomes actually smaller. The relations are very like 

 those resulting from compression of the cauda equina. 



1. Redlich, Emil. Die Ilinteren Wurzeln des Rueckenmarkes und die pattu)- 

 logische Anatomie der Tabes dorsalis. Arbeiten aus dem Inst. f. Anat. u. Pliys. des 

 Centralnervensystems. Vienna, 1892. 



