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Trousseau sign of latent tetany

Trousseau’s sign presents as carpopedal spasm occurring after a few minutes of inflation of a sphygmomanometer cuff above systolic blood pressure "about 3 minutes inflate of cuff >SBP". Occlusion of the brachial artery causes flexion of the wrist and metacarpophalangeal joints, hyperextension of the fingers, and flexion of the thumb on the palm, producing the characteristic posture called main d’accoucheur (The Figure). Trousseau’s sign is
thought to be both sensitive and specific for hypocalcemic tetany. In addition to the obvious visual manifestations, patients with a positive Trousseau’s sign may also experience paresthesia of the fingers, muscular fasciculations or twitches of the fingers, and a sensation of muscular cramping or stiffness.

The proposed mechanism for Trousseau’s sign is increased excitability of the nerves in the arm and forearm, ostensibly caused by hypocalcemia, which, in turn, causes the muscular contractions. These conditions are exacerbated by ischemia produced by the sphygmomanometer, resulting in the twitching that defines the sign.

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