178 THE DISEASES OF THE PARATHYROID GLANDS 



cessible for the test. For the most part it is present in like intensity in 

 symmetrical nerves, although there are exceptions to this rule. For in- 

 stance v. Frankl-Hochwart found in the right ulnar in a case a C.C.C. of 0.3 

 milliampere, in the left ulnar a C.C.C. of o.i milliampere. Erb's phenom- 

 enon, like all the symptoms of tetany, shows great variations. It is most 

 distinct at the onset or during the acute exacerbations, less distinct, as a 

 rule, during the intervals. In the chronic tetany that extends through many 

 years the galvanic excitability can, during the interval free from attacks, ap- 

 proach the lower limiting values of the normal, and may even show values 

 as high as for normal individuals. As v. Frankl-Hochwart points out, this 

 relation is beautifully shown in the tetany of maternity; here the galvanic 

 hyper excitability is seen only during pregnancy or lactation. Erb's phe- 

 nomenon is the most important symptom of tetany, because we as yet know 

 of no other condition in which it occurs. It is also very frequent, v. Frankl- 

 Hochwart says that he has not seen any acute case of tetany with normal 

 electrical excitability; exceptions do, however, extremely rarely, occur. 

 Kahn and / observed a case of chronic tetany with acute exacerbations, in 

 which all the important symptoms of tetany were present pronouncedly, but 

 Erb's phenomenon, in spite of the presence of severe spasms, was absent 

 during the first days. The condition ameliorated; Erb's phenomenon was 

 positive only on an acute exacerbation of the illness, which occurred after 

 about two weeks. 



A heightened excitability to the electric current is shown by the sensory 

 nerves also (Hoffmann). We usually test the ulnar nerve. Paresthesias 

 occur in its distribution even on very low values of the C.C.C. There occurs 

 too an analogous change in the sensation formula. Finally the nerves of 

 special sense may be hyper excitable. With relatively low current strengths, 

 Chvostek, Jr., found sensory reactions in the acoustic nerve with analogous 

 alterations in the formula of sensation in six out of seven cases of tetany. v. 

 Frankl-Hochwart found a similar relation to the galvanic current of the 

 taste sensations. Occasionally, in testing the electrical excitability, when 

 the electrode is placed over the mastoid process there occur with very low 

 current strength, and often before the occurrence of contraction, ear noises 

 and finally a bitter taste sensation (Falta and Kahn). These symptoms are 

 subject to great variation. 



Another certain symptom of latent as well as manifest tetany is the 

 mechanical hyperexcitability of the motor and sensory nerves. Chvostek, Sr., 

 first pointed out in this regard, that in tetany percussion of the motor nerve 

 trunks and especially the facial trunk leads to lightning-like contractions in 

 the muscles supplied. When the facial trunk is struck, the contractions 

 rarely affect the muscles of the forehead, v. Frankl-Hochwart distinguishes 

 three degrees of the phenomenon depending on the intensity. In Chvostek 

 I on percussion of the vicinity of the auditory meatus contractions occur in 



