Tetany is a long-term tonic convulsions in violation of calcium-phosphorus metabolism (see Hypoparathyroidism).
Tetany is a symptom complex that occurs in the form of convulsive seizures and is accompanied by severe disorders of the central and peripheral nervous system.
Etiology and pathogenesis . Tetany can occur with gastrointestinal diseases (pyloric stenosis , pancreatitis , colitis, dysentery); in acute infectious diseases (for example, tetanus ) and intoxication; in some endocrine disorders (hypoparathyroidism, Addison's disease, etc.); severe hyperventilation (for example, in hysteria or encephalitis ); after heavy operations; in women during pregnancy and lactation; in children suffering from rickets , etc. There are cases of idiopathic tetany.
The basis of the pathogenesis of tetany is an increase in neuromuscular excitability, resulting from the violation of acid-base balance and a decrease in the content of ionized calcium in the blood. In gastrointestinal diseases, these disorders are associated with the loss of large amounts of chlorides and hydrogen ions (as a result of loss of fluid with vomiting and diarrhea), which leads to increased CO 2 binding, and increased protein breakdown, leading to an accumulation of nitrogenous slags and excessive intake of blood phosphorus , the high content of which contributes to the excretion of ionized calcium. Hyperventilation tetany occurs on the background of alkalosis and hypocapnia, leading to a drop in the content of ionized calcium. Pregnant tetany occurs due to increased calcium intake by the fetus; in endocrine disorders - as a result of disorders of salt metabolism and acid-base balance, parathyroid tetany often occurs during operations on the thyroid gland with complete or partial removal of the parathyroid glands, as well as due to various injuries and chronic infections ( tuberculosis , syphilis ) as a result of lowering the hormone content parathyroid glands. The lack of the hormone of the parathyroid glands leads to hypocalcemia in two ways: primarily due to difficulty in mobilizing calcium from the depot and secondarily due to the accumulation of inorganic phosphorus in the blood.
The clinical picture (signs and symptoms). Tetany proceeds according to the type of hidden and pronounced convulsive seizures. The latent (latent) form of tetany manifests itself only in the form of paresthesia , spasms and cooling of the extremities; sometimes it is not detected for a long time, or under the influence of any provoking factors (anesthesia, infection, pregnancy, etc.) more or less obvious seizures occur.Go
Severe tetanic seizures occur spontaneously and manifest themselves with tonic muscle spasms, which predominantly capture the flexor muscles of the extremities, as well as the muscles of the face, torso, spine , less often the larynx and stomach. Spasms often symmetrically seize both upper limbs, although sometimes they occur only on one side. The hand usually takes the so-called position of the hand of an obstetrician, sometimes clenched into a fist with an extended thumb. Much less often, convulsions seize the legs, and the leg is usually extended, the foot is bent inward, and in the spasms of the adductors, the legs are closely pressed to one another. The convulsions of the muscles of the face are accompanied by a trisism , the lips take on the typical trunk shape. Sometimes, due to cramps in the muscles of the tongue, speech is difficult. Cramps of the cervical muscles and back muscles are accompanied by articulation of the spine. Involvement in the convulsive state of bronchial and intercostal muscles, as well as the diaphragm, can lead to respiratory distress. Spasms of the heart muscle lead to a stenocardial seizure, which can result in death from cardiac arrest in systole. Cramps in the muscles of the stomach and intestines cause vomiting, diarrhea, and constipation, with urinary cramps urinating. As a result of a breach of convergence or temporary strabism, double vision occurs. Muscle cramps are sharply painful. Their duration is extremely diverse: from several minutes to several hours. Attacks of convulsions are sometimes rare, sometimes repeated at short intervals. After the termination of attacks weakness and even paresis are observed.
The Trusso phenomenon is the occurrence of tonic convulsions of the fingers during tetany (the so-called “obstetrician's hand”) under the influence of compression of the shoulder with a tourniquet for several minutes until complete cessation of blood circulation. Appears due to a decrease in neuromuscular tone.
The vegetative nervous system in tetany is over-excited. The appearance of a “dead finger” and a sharp blanching of the limb when Trusso's symptom is called (typical tonic spasms in the hand when pressing on the nerve in the sulcus bicipitalis area) is often observed. Patients react sharply to the introduction of vegetotropnyh substances. For example, the introduction of adrenaline contributes to the resumption of a calmer convulsive seizure, the introduction of pilocarpine in the acute stage of tetany causes a sharp sweat and salivation , tearing, redness of the skin, cardiac disorders, the appearance of vomiting, diarrhea, a significant increase in urination.
Disorders of cardiac activity during tetany seizures are expressed in the amplification of tones, sometimes noise appears. Very common symptoms of tetany are pallor due to a spasm of peripheral vessels and angiospastic edema.
Violations of thermoregulation in tetany are expressed both in an increase in excitability with a change in external temperature, and in a fluctuation of body temperature during convulsive seizures. Trophic disorders are observed: hair becomes thin, falls out, splits; nails brittle, streaked; teeth break, crumble, enamel defects appear. Often, young patients develop cataracts.
During attacks of tetany, leukocytosis appears, the fraction of calcium associated with protein is reduced or completely absent in the blood, while the amount of total calcium is preserved, the amount of potassium and phosphorus is increased. With tetany, alkalosis is noted, the nitrogen content in the blood and urine increases.