PERIPHERAL VASCULAR DISEASES 



1231 



and inhibition of oxygen dissociation from hemo- 

 globin. 



The palms are often sweaty. The hands are usually 

 much colder than normal during exposure to a com- 

 fortable temperature but warm readily in a hot room. 

 The disease varies considerably in degree from very 

 mild to severe. 



In the past, acrocyanosis has been confused with 

 Raynaud's disease but many differentiating features 

 are apparent. In acrocyanosis the color changes are 

 persistent rather than episodic. The changes are not 

 limited to the digits but include the entire hand and 

 foot, though they rarely extend proximally to the 

 wrist or ankle areas. There may be associated livedo 

 reticularis or pernio involving more proximal areas 

 of the extremities. There are usually no episodes of 

 blanching, sclerodactylia does not develop, and areas 

 of ulceration and gangrene are generally absent. 

 Swelling however may occur, particularly in cold 

 weather, and occasionally localized areas may become 

 tender or painful. Although spontaneous ulceration is 

 extremely rare, traumatic lesions in affected areas 

 may become infected and heal slowly. Palmar clammi- 

 ness is a well-known feature of acrocyanosis and 

 differs from the dry skin of Raynaud's disease which 

 appears when the local circulation ceases (94). In 

 true acrocyanosis, examination of peripheral arteries 

 reveals no evidence of occlusive organic arterial dis- 

 ease. The dependent cyanosis frequently present in 

 the feet of patients with occlusive arterial disease 

 should not be classified as acrocyanosis. 



As in early Raynaud's disease, very little is known 

 of the pathology of acrocyanosis. Stern (94) studied 

 sections from the dorsal skin of the hands and feet of 

 of 12 patients with acrocyanosis. It was found that 

 the medial coats of nearlv all arterioles were thick- 

 ened. Local edema and dermal fibrosis frequently 

 were present in association with considerable dilata- 

 tion of the superficial capillaries with formation of 

 new capillaries. Others have described distention of 

 the venules and venous limb of the capillaries and 

 have noted large capillary loops occurring in increased 

 numbers in the nail bed (3, 6, 41). In fact, this tend- 

 ency to dilatation of the venous side of the circulation 

 with a marked decrease in venomotor tone is a char- 

 acteristic feature of acrocyanosis. 



Little work is available on the vascular mechanisms 

 responsible for acrocyanosis. Most evidence points to 

 excessive arteriolar constriction which occurs at 

 ordinary environmental temperatures and which is 

 increased by cooling. The arteriovenous anastomoses 

 are also probably constricted (60). This constriction 



is followed by secondary dilatation of capillaries and 

 venules with stasis in the minute vessels of this skin. 

 There is loss of capillary and venular tone (6, 60), 

 thought to be due in large part to anoxia. Stasis allows 

 increased formation of reduced hemoglobin and the 

 associated deep cyanosis, the blue color being due to 

 increased amounts of reduced hemoglobin and the 

 deep character of the color being due to the engorge- 

 ment of the vessels. That venous obstruction is not a 

 significant factor has been pointed out by Lewis & 

 Landis (50) from the simple observation that cyanosis 

 is abolished by venous drainage produced by eleva- 

 tion of the involved part. The color of the cyanosed 

 '.kin is not uniform, since it frequently contains 

 bright red areas (cinnabar red spots) (94) and occa- 

 sionally changing reticular areas of pink color due 

 probably to temporary relatively normal rate of blood 

 through the perpendicular-arteriole reticuiar-capil- 

 lary network (22). It has been noted that acrocyanosis 

 is less pronounced in the presence of hypertension, 

 since the latter tends to produce more normal circu- 

 lation in spite of the dermal arteriolar spasm (60). 



In acrocyanosis, the white spot produced by ex- 

 ternal pressure on the cyanosed part disappears spon- 

 taneously in a very characteristic fashion (94). The 

 color returns from the periphery and not from below 

 as in normal skin. 



Comments by Lewis concerning the mechanism of 

 acrocyanosis are worth quoting (49) : 



"The minute vessels of the skin are verv dilated, as 

 is evident equally Irom macroscopic and microscopic 

 examination. But the temperature of the hands and 

 other tests show the blood-flow to the skin to be 

 reduced greatly. The veins though contracted l>\ cold 

 are not occluded. The pulses in the main arteries are 

 normal. The constriction is in the small arteries or 

 arterioles of the skin. If the hand at the time is 

 cyanosed and a small part of it is warmed, the latter 

 soon becomes sharply defined as a bright red area; 

 similarly if a little histamine (1 in 3000) is pricked 

 into the skin, the skin reddens locally and its tempera- 

 ture rises. This is in contrast to the cyanosed skin in the 

 attack of Raynaud's disease, where the obstruction 

 lies in the main digital arteries, and in which redden- 

 ing of the skin does not occur in similar tests, but only 

 after these arteries open. In acrocyanosis all the 

 arteries and arterioles are capable of opening widely; 

 gross structural impediment is not present in any of 

 their channels." 



Again, as in Raynaud's disease, whether the basic 

 underlying disorder lies in the sympathetic nervous 

 system or in the vessels themselves is unknown. As 



