Tetany free essay sample

Tetany is a medical sign, the involuntary contraction of muscles, caused by diseases and other conditions that increase the action potential frequency. The muscle cramps caused by the disease tetanus are not classified as tetany; rather, they are due to a blocking of the inhibition to the neurons that supply muscles. Contents [hide] 1 Mechanism 2 Causes 3 Diagnosis 4 References 5 External links [edit]Mechanism Low plasma calcium increases the permeability of neuronal membranes to sodium ions, causing a progressive depolarization. This increases the ease with which action potentials can be initiated. If the plasma Ca2+ decreases to less than 50% of the normal value of 9. 4mg/dl; action potentials may be spontaneously generated, causing contraction of peripheral skeletal muscles. [1] [edit]Causes The usual cause of tetany is lack of calcium, but excess of phosphate (high phosphate-to-calcium ratio) can also trigger the spasms. Milk-and-alkali tetany is an example of this imbalance. Underfunction of the parathyroid gland can lead to tetany. We will write a custom essay sample on Tetany or any similar topic specifically for you Do Not WasteYour Time HIRE WRITER Only 13.90 / page Low levels of carbon dioxide cause tetany by altering the albumin binding of calcium such that the ionised (physiologically influencing) fraction of calcium is reduced; the most common reason for low carbon dioxide levels is hyperventilation. Low levels of magnesium can also lead to tetany symptoms. Clostridium tetani toxin, via inhibition of glycine-mediated and GABA-ergic neurotransmission. Rebirthing-Breathwork, purposeful rapid breathing for one two hours at a time; first causing hyperventilation, can sometimes lead to tetany. Cow grazing on rapidly grown pasture with tetany of the neck suggesting Grass Tetany An excess of potassium in grass hay or pasture can trigger winter tetany or grass tetany, respectively, in ruminants. [edit]Diagnosis The nineteenth-century clinician Professor Armand Trousseau devised the trick of occluding the brachial artery by squeezing to trigger the cramps in the fingers (Trousseau sign). Also, tetany can be demonstrated by tapping anterior to the ear, at the emergence of the facial nerve, also known as Chvostek sign. Tetany is characterized by contraction of distal muscles of the hands (carpal spasm with extension of interphalangeal joints and adduction and flexion of the metacarpophalangeal joints)and feet (pedal spasm) and is associated with tingling around the mouth and distally in the limbs. EMG studies reveal single or often grouped motor unit discharges at low discharge frequency.