The fast advance of modern brain surgery since the beginning of the current century has brought solution to many a difficult problem, and yet all the efforts of many workers in this field have failed to arrive at definitive answer on many points. One of these unsolved questions is the question of hyperthermia often experienced after brain surgery. In reviewing the past workers on this question, we find there are not a few reports on experimental hyperthermia
6)16)-41) induced by puncture or injury, in various parts of the brain since the days of Ott
16) and Aronsohn & Sachs,
17)-19) but in most of these studies, rabbits were used as the experimental animals, but rabbits are so labile in their body temperature and the experiments were carried out with so little attention to the change in temperatures, (which by the way amounted only a rise of 0.2°C_??_1.0°C) induced merely by the restraint and the surgical interference on the animals, we feel justified in discounting the value of such works. Under such a circumstance, it is natural that there has been no generally acceptable solution on the problem of the exact localization of thermal center.
Since many cases have been reported in which no hyperthermia was induced following unerring introduction of the puncture needle into sites described as the location of the thermal center,
46) there have a considerable number of authors who have expressed doubt on the presence of a “ thermal center ” at all.
42)-49) Now, for the study of a method for treating postoperative hyperthermia, it is indispensable first of all to succeed in inducing central hyperthermia in experimental animals. It is, however, a very difficult proposition to produce such animals with central hyperthermia, seeing that the problem where the pyrogenetic center is exactly located remains yet unsolved, and in the copious literature on the subject, I could not find a single report of 100% success in producing such animals, most of the authors merely confessing the difficulty of the experimental production.
6)49) So, the present author was induced to make the attempt of producing central-hyperthermal cats by application of a variety of surgical methods.
As the sites pointed to as the possible pyrogenetic center, we may enumerate the pons,
17) the upper part of the corpora quadrigemina,
20) the thalamus,
21)-24) the corpus striatum,
19)21)23)-31) the periphery of the third ventricle etc.,
32)-35) but more recently, the hypothalamus
5)6)32)36)-39) and the tuber cinereum
16)40)41) have come more into attention in this connection, the former being said to contain the heat-radiation center in its aterior portion and the pyrogenetic center in its posterior portion.
38) Therefore, I first tried puncture, electrical stimulation and electrocoagulation in these parts, but hyperthermia over 40°C followed in only 2 of the total 85 cases, and I was convinced that mere simple stimulation or destruction of these parts cannot induce hyperthermia. During this series of experiments, however, I found hyperthermia induced in 2 cases, in either of which a rather large hematoma was found spreading from the third ventricle into its surrounding tissue, in contradistinction to all the other non-hyperthermic cases.
Accordingly, I concluded that a wide-scoped stimulation of the periphery of the third ventricle is effective in causing hyperthermia and proceeded to the experiment of introducing sodium citrate-added blood directly into the third ventricle and found hyperthermia induced in nearly all the cases.
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