Causalgia pathogenesis and treatment

Gross and microscopic anatomical evidence indicates that pain fibers involved in causalgia are those distributed to blood vessels-possibly to the arterioles-and that, for the greater part, these fibers constitute part of the general visceral afferent system. Several investigators have reported evidence that injury to a peripheral nerve of such a type as to cause damage to the vasomotor control of any area produces the initial pain in an extremity, and it is predicated that the arteriolar constriction causing the pain is then prolonged by the sensitization of arteriolar smooth muscle to the amount of epinephrine normally in the blood. If the condition is not treated, tissue anoxia occurs to such an extent that irreversible changes take place in the affected area.Treatment of causalgia in the lower extremities is directed toward interruption of either the vasomotor or afferent supply of blood vessels by blocking or excision of the second to fourth lumbar ganglia inclusive with the intervening chains. For the upper extremities, the blocking or disconnection of the second and third thoracic ganglia with interruption of the sympathetic chain between the third and fourth ganglia is considered a feasible method of treatment which does not produce the concomitant disability of Horner's syndrome.     

Studies on the ecology of the vegetation at Mawson Statio Antarctica

The flora of Mawson Rock is fairly depauperate; the two commonest lichens are Buellia frigida and Caloplaca elegans and the only two mosses are Bryum algens and Grimmia lawiana. The lichens form open colonies on exposed rock, and closed patches on sheltered aspects. The mossfields are small and confined chiefly to gravels on northerly aspects receiving snow-bank melt waters. The moss colonies form cushions, turfs or hummocks and may be contorted by cryoturbic processes. Larger colonies thus contain greater cores of sand and gravel. Mature cushions of Bryum algens are up to 25 years old, but the deepest peats are certainly much older. The small biomass of green moss in the most sheltered sites at Mawson is similar to comparable mossfields on the exposed plateau of subantarctic Macquarie Island.