The apparent predilection of lead and its salts for the extensor muscles of the wrist, or the musculospiral nerve which supplies them, has for a long time remained unexplained.
This peculiar localization, as well as changes in the muscles themselves, has formed subject matter for numerous hypotheses. One of the oldest views, which is now almost obsolete, held that the paralysis was due to intramuscular changes. The spinal view was held by Remak and Erb, but the preponderance of opinion at present points to the peripheral nerves as the most likely origin, and even Remak himself admits the lack of convincing testimony in favor of the spinal origin. "The constancy of peripheral changes and the infrequency of noteworthy changes in the cord make the peripheral the more probable theory; but if it is correct, there is yet no explanation of the almost regular escape of certain muscles from the