Tetany

Classification according to ICD-10
R29.0	Tetany
ICD-10 online (WHO version 2019)

Tetany ( Greek τέτανος tétanos , German “tension” ) is the disorder of the motor skills (cramp-like) and sensitivity (tingling) as a sign of over-excitability of the nerves and muscles . In extreme cases, it is a painful muscle cramp .

root cause

The cause is usually hypocalcemia , i.e. a lack of calcium in the blood .

Calcium (II) ions have a membrane potential stabilizing effect that is mediated by interacting with the voltage-regulated sodium channels . This is commonly explained by the fact that the Ca ²⁺ ions “clog” the channel. Correctly, however, there is a change in the conformation of the channel, as a result of which its electrical properties change in such a way that a higher depolarization is necessary to open the channel. Conversely, if the extracellular calcium concentration is reduced by 50%, spontaneous discharges in peripheral nerves and thus tetany occur. The Ca ²⁺ ions bound to the sodium channel are in equilibrium with the “free” (i.e. not bound to plasma proteins) Ca ²⁺ ions.

The cause of the calcium deficiency can e.g. B. Accidental, infrequent (<1%) removal of the parathyroid glands (glandulae parathyroideae) during thyroid surgery ; The result is a so-called parathyroid drive tetany (cf. hypoparathyroidism , parathyroid insufficiency).

Symptoms

In hypocalcemic tetany there are tetanic attacks with anxious restlessness, numbness, abnormal sensations and muscle cramps, etc. a. also blepharospasm .

clinic

Chvostek and Trousseau signs as an expression of increased neuromuscular excitability are positive. The patient usually has a kind of “paw” position on one and / or both hands and arms.

Classification

Hypocalcemic tetany

Here there is a decrease in the total calcium in the plasma ; the ions diffuse away from the sodium channels and an action potential can now be triggered more easily. This leads to cramps in the muscles, even when the patient is resting, for example while sleeping. The excessive excitability of sensitive nerve tracts is perceived as tingling.

Normocalcemic tetany

The total calcium (free plus bound Ca ²⁺ ) in the plasma remains constant; however, there is an increased Ca ²⁺ binding to the plasma proteins. The cause of this can be an alkalosis (for example, in the case of hyperventilation , which is also referred to as hyperventilation tetany).

Psychogenic tetany

In psychiatry, dissociative seizures are also known as psychogenic tetany . In extreme cases, this can lead to epilepsy- like manifestations.

Veterinary medicine

Pasture tetany is a particular disease in ruminants .

Individual evidence

↑ John E. Hall, Arthur C. Guyton (Eds.): Textbook of medical physiology . 11th edition. Elsevier / Saunders, Philadelphia 2006, ISBN 0-7216-0240-1 , pp. 65 (English).
^ Klaus Poeck : Neurology. 8th edition. Springer-Verlag, Berlin 1992, ISBN 3-540-53810-0 , p. 284 f.
↑ Ludwig Weissbecker: The tetany, hypoparathyroidism (parathyroid insufficiency). In: Ludwig Heilmeyer (ed.): Textbook of internal medicine. Springer-Verlag, Berlin / Göttingen / Heidelberg 1955; 2nd edition, ibid. 1961, pp. 1052-1057, here: p. 1055.

[1] John E. Hall, Arthur C. Guyton (Eds.): Textbook of medical physiology . 11th edition. Elsevier / Saunders, Philadelphia 2006, ISBN 0-7216-0240-1 , pp. 65 (English).

[2] Klaus Poeck : Neurology. 8th edition. Springer-Verlag, Berlin 1992, ISBN 3-540-53810-0 , p. 284 f.

[3] Ludwig Weissbecker: The tetany, hypoparathyroidism (parathyroid insufficiency). In: Ludwig Heilmeyer (ed.): Textbook of internal medicine. Springer-Verlag, Berlin / Göttingen / Heidelberg 1955; 2nd edition, ibid. 1961, pp. 1052-1057, here: p. 1055.