596 LEWELLYS F. BAKKEK 



If death occur, the tonic spasm of the muscles may persist until post- 

 mortem rigidity sets in. 



2. The Increased Mechanical Excitability of the 

 Motor Nerves in Tetany 



In nearly all cases of tetany, both manifest and latent, there is 

 increased mechanical excitability of the motor nerves, whether the stimu- 

 lus be compression by a ligature (Trousseau phenomenon), tapping on a 

 peripheral nerve trunk (Chvostek's phenomenon), or making tension on 

 thb large nerves innervating an extremity (arm and leg phenomena of 

 Ferenczi, Pool, and Schlesinger (a) (&)). 



Trousseau's Phenomenon 



Trousseau, in 1864, pointed out that if, in the intervals between 

 attacks of manifest tetany, a ligature be applied firmly about the upper 

 arm so as to suppress the flow of blood through th brachial artery, the 

 typical attitude of obstetrical hand can be produced within a few minutes. 

 The more severe the tetany, the quicker will the abnormal attitude be 

 assumed after the ligature is applied. When the nerves are very hyper- 

 sensitive to mechanical stimuli, firm pressure with a finger in the bicipital 

 groove will call forth such an attack of spa sin. The sign, described by 

 Trousseau, is exceedingly characteristic and has been regarded. by many 

 as pathognomonic of tetany. The test is a very simple one to apply, and 

 it should always be performed, if the existence of tetany be suspected. 

 Even in latent tetany the Trousseau phenomenon will usually appear, if 

 pressure be exerted on the nerves of the upper arm. 



In performing the test, one may apply an Esmarch bandage at the 

 middle of the upper arm, making the pressure strong enough to interrupt 

 the arterial flow. I myself prefer to make use of the cuff of the ordinary 

 blood pressure apparatus, since it is practically always in one's consulta- 

 tion bag. One puts on the cuff, raises the pressure in the manometer to 

 about 200 millimeters of mercury, and waits for at least five minutes, 

 in case the contra.ct.ure does not earlier occur. The obstetrical hand atti- 

 tude will as a rule become evident in tetany in from two to three minutes 

 after the pressure is applied. In a case of postoperative tetany, which I 

 recently had opportunity to observe, the surgeon told me that he had 

 made pressure in the bicipital groove, but that Trousseau's phenomenon 

 had not appeared. On applying the blood pressure cuff, the typical 

 obstetrical hand became- evident in about three minutes. The surgeon 

 then stated that he had not kept up the pressure quite so long. This 

 matter of the time required to elicit the sign should be kept in mind. If 



