Experimental pantopaque arachnoiditis in the monkey.

Experiments with large volumes of retained Pantopaque in the subarachnoid space of the rhesus monkey show that retained Pantopaque is always accompanied by some degree of arachnoidal reaction. Radiological and histological evidence of entrapped Pantopaque, especially within the conus and cauda region, may indicate proliferative changes of the arachnoid. The most several arachnoiditis was seen in animals with Pantopaque instilled into bloody cerebrospinal fluid. This was not a one-to-one relationship, however, nor did it always occur. Moreover, while all animals showed histological evidence of arachnoidal reaction, most showed no clinical evidence of arachnoiditis.