952 7. MERCURIALS 



Hg++ (Hanzlik, 1923 c) and mersalyl (Jackson, 1926 b) has been noted, 

 this being attributed to a direct medullary effect at low mercurial concen- 

 tration, but lethal doses of both HgClg and PM cause dyspnea and depres- 

 sion of the respiration (Wien, 1939). The injection of certain mercurials can 

 produce a very rapid fulminant type of reaction characterized by dyspnea, 

 convulsions, and death, and this was also attributed to a central effect on 

 the respiratory centers (Fourneau and Melville, 1931). Direct effects on the 

 central nervous system were observed by Pentschew and Kassowitz (1932) 

 following suboccipital injections of HgClj at the minimal lethal dose (around 

 0.2 mg); tremors, convulsions, and other motor disturbances occur after 

 16 hr and last for several days. It would be interesting to know the form, 

 or forms, in which Hg++ penetrates into the nervous system, whether mainly 

 as the uncharged HgClg or in combination with thiols and other substances 

 in the blood. 



The most characteristic symptoms of mercurialism, regardless of the type 

 of mercurial responsible, may be summarized as follows (Hunter et al., 1940; 

 Cumings, 1959, p. 78; Noe, 1960; Kantarjian, 1961). (1) A fine intention 

 tremor, starting in the fingers and hands, and progressing to the feet, eye- 

 lids, cheeks, tongue, and neck. The motor activity is primarily affected and 

 usually there is little if any disturbance in sensation. (2) Insomnia, anorexia, 

 and various emotional alterations, such as mood depression and timidity. 

 There is generally little effect on intelligence or memory. (3) Erethism, or 

 blushing, is often common, but whether it is due to emotional disturbances 

 or alteration of the autonomic vascular control is unknown. Sometimes, 

 especially in infants, the skin may become red; such erythema is most likely 

 vascular in origin. (4) Stomatitis, salivation, and gingival swelling are fre- 

 quent and possibly due to the secretion of mercurials in the saliva. Of these 

 symptoms, and others less common, only the nervous system changes lend 

 themselves to an analysis of the mechanisms which may be involved, but we 

 shall see that regrettably little can be concluded. 



Urinary mercury excretion in normal individuals is usually between 1 

 and 15 //g/day, but may be so low as to be imdetectable or considerably 

 higher without obvious symptoms. In patients with evident mercurialism, 

 the urinary mercury may vary widely — excretions between 3 and 8000 

 //g/day have been reported — but it is generally above 250 //g/day. The 

 level will depend on the daily uptake and whether the individual is in com- 

 plete balance or not. The fact that the same degree of severity of symp- 

 toms may be observed in patients with very different urinary levels sug- 

 gests that the susceptibility to mercury varies widely, but possibly the 

 tissue concentrations of mercury are much more uniform than the urinary 

 concentrations. 



In view of the selective effect of iodoacetate on the retina and visual 

 function, it is interesting to inquire as to whether other SH reagents, such 



