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[[File:Trousseau sign.jpg|thumb|Trousseau's sign ]]Trousseau’s sign is a sign of tetany.(1,2) It is most often due to hypocalcemia but can occur with a normal calcium level and in other conditions.(3-7) Ischemia of the peripheral nerve trunks increases nerve excitability and causes spontaneous discharges that produce carpopedal spasm.
Compression of the arm by manual pressure, a tourniquet, or a sphygmomanometer cuff is followed first by distal paresthesias that progress centripetally, then twitching of the fingers, and finally by cramping and contraction of the muscles of the fingers and hand with the thumb strongly adducted and the fingers stiffened, slightly flexed at the MCP joints, and forming a cone clustered about the thumb (obstetrician’s or accoucheur's hand, main d’ accoucheur). (Figure 1) There may be a latent period of ½- 4 min.
Similar pressure around the leg or thigh will cause pedal spasm. A modification is to keep a moderately inflated sphygmomanometer cuff on one arm for about 10 min., then remove it and have the patient hyperventilate; typical tetanic spasm occurs earlier in the previously ischemic arm.
1.Campbell WW. Clinical signs in neurology: a compendium. Philadelphia: Wolters Kluwer Health, 2016.
2. Campbell WW. Barohn RJ. DeJong's the neurologic examination, 8th ed. Philadelphia: Wolters Kluwer, 2020.
