Erb Symptom

Erb Symptom consists of increased excitability of motor nerves, mainly when tested with galvanic current. In this case, contraction in response to cathode closure occurs and easily passes into tetanus even with very minimal current strength - 1-3 mA instead of 8-10 in normal conditions. Contraction in response to anode opening and cathode opening also occurs with a current strength much lower than usual (up to 5 mA). Mann and Thiemich, Pirquet consider this last one particularly characteristic of the state of increased excitability. Increased excitability to faradic current also occurs, but is less constant and less pronounced compared to increased excitability to galvanic current. It is considered one of the most characteristic symptoms in tetany, in the diagnosis of which, according to some authors, it has decisive importance. It is also found in other diseases accompanied by increased excitability of nerve trunks, such as in rickets (tetany). As for the immediate cause of the Erb symptom, it should be considered as depletion of calcium in the body and its decreased content in the blood (hypocalcemia), occurring along with other disorders of the internal secretory and metabolic activity of the body, mainly as a result of insufficient activity of the parathyroid glands (for more details, see Hyperparathyroidism, Hypoparathyroidism).