Signs of Hypocalcemia: Chvostek's and Trousseau's Signs Size：30.22 K | View：541 | Page：3ypocalcemia is a common condition charac-terized by a net loss of calcium from extra-cellular fluid in greater quantities than can bereplaced by the intestine or bone.1Hypocal-cemia is caused by a number of clinical entities andoften presents with signs of generalized neuromuscularirritab...
ypocalcemia is a common condition charac-terized by a net loss of calcium from extra-cellular fluid in greater quantities than can bereplaced by the intestine or bone.1Hypocal-cemia is caused by a number of clinical entities andoften presents with signs of generalized neuromuscularirritability including paresthesia, muscle cramps, laryn-gospasm, tetany, and seizures. This neuromuscularinstability can also be displayed through the elicitationof Chvostek’s sign and Trousseau’s sign (Sidebars).Both Chvostek’s sign and Trousseau’s sign are time-honored physical predictors that are well- chronicled inmedical history and frequently associated with hypocal-cemia.HISTORIC PERSPECTIVEFrantisek ChvostekFrantisek Chvostek (1835–1884) was an Austrian sur-geon who was born in Moravia, Czech Republic.2Chvo-stek investigated the pathology and treatment of neuro-logic illnesses, including the use of electrotherapy, anddescribed the sign that was to bear his name in 1876.2Armand TrousseauArmand Trousseau was a French physician wholived from 1801 to 1867.2Trousseau was educated inParis, graduated in 1825, and soon became a notablefigure in Parisian medicine, both as an expert clinicianand a superb teacher.2Trousseau was the first person inFrance to perform a tracheotomy, and he introducedthoracentesis as a medical procedure in 1843.2In addi-tion to his description of Trousseau’s sign, this physi-cian is also credited with describing Trousseau’s syn-drome, or thrombophlebitis caused by visceral cancer.3CHVOSTEK’S SIGNElicitationThe definition of Chvostek’s sign varies in the med-ical literature, as does the sign’s interpretation.4In fact,two clearly described methods to elicit Chvostek’s signhave been reported. The most well-known version ofthe sign, or the Chvostek I phenomenon, is describedas twitching and/or contracture of the facial musclesproduced by tapping on the facial nerve at a specificpoint on the face. This point is located 0.5 to 1 cmbelow the zygomatic process of the temporal bone, 2 cm anterior to the ear lobe, and on a line with theangle of the mandible (Figure 1).4A similarly describedresponse, the lesser-known Chvostek II phenomenon,can be produced by tapping on a different location ofthe face. This point is located on the line joining thezygomatic prominence and the corner of the mouth,one third of the distance from the zygoma (Figure 1).4HDr. Urbano is in general internal medicine, Partners in Primary Care,Medford, NJ.Hospital Physician March 2000 43Review of Clinical SignsSigns of Hypocalcemia:Chvostek’s and Trousseau’s SignsSeries Editor and Author: Frank L. Urbano, MDCHVOSTEK’S SIGNElicitation: Tapping on the face at a point just anteriorto the ear and just below the zygomatic bonePostitive response: Twitching of the ipsilateral facialmuscles, suggestive of neuromuscular excitabilitycaused by hypocalcemiaTROUSSEAU’S SIGNElicitation: Inflating a sphygmomanometer cuff abovesystolic blood pressure for several minutesPostitive response: Muscular contraction including flex-ion of the wrist and metacarpophalangeal joints,hyperextension of the fingers, and flexion of the thumbon the palm, suggestive of neuromuscular excitabilitycaused by hypocalcemiaIn both instances, the common feature is the twitchingresponse, which may involve any or all of the musclessupplied by the facial nerve on that side, including thecircumoral muscles and the orbicularis oculi.5,6PathophysiologyThe proposed mechanism for Chvostek’s sign isthought to involve direct mechanical stimulation of themotor fibers in the facial nerve.7Previously, Chvostek’ssign was thought to be a reflex. However, this reflex isnow believed to occur only occasionally; further, the re-flex is believed to only be involved with the Chvostek IIversion of the sign. Another purported explanation forthe mechanism was direct stimulation of the facialmuscles, which subsequently contracted and twitched,but this theory has been disproven as well.Differential DiagnosisAs previously mentioned, Chvostek’s sign is a classicsignification of hypocalcemia. However, some studieshave demonstrated that hypocalcemia is not the onlycondition in which a positive Chvostek’s sign may beseen. Other conditions that have produced Chvostek’ssign include rickets, diphtheria, measles, scarlet fever,whooping cough, and myxedema. The sign has alsobeen positive in persons without any known disease.One study demonstrated a positive Chvostek’s sign innearly 25% of healthy individuals.4Another studyshowed that 29% of patients with laboratory- confirmedhypocalcemia had a negative Chvostek’s sign.8In turn,the medical community considers Chvostek’s sign asonly a crude indicator of neuromuscular irritability andan unreliable indicator of hypocalcemia.9TROUSSEAU’S SIGN ElicitationTrousseau’s sign is more consistently defined in themedical literature than Chvostek’s sign. Most simplydescribed, Trousseau’s sign presents as carpopedalspasm occurring after a few minutes of inflation of asphygmomanometer cuff above systolic bloodpressure.5Occlusion of the brachial artery causes flex-ion of the wrist and metacarpophalangeal joints, hyper-extension of the fingers, and flexion of the thumb onthe palm, producing the characteristic posture calledmain d’accoucheur (Figure 2).9Trousseau’s sign isthought to be both sensitive and specific for hypocal-cemic tetany.1,9In addition to the obvious visual mani-festations, patients with a positive Trousseau’s sign mayalso experience paresthesia of the fingers, muscular fas-ciculations or twitches of the fingers, and a sensation ofmuscular cramping or stiffness.10PathophysiologyThe proposed mechanism for Trousseau’s sign isincreased excitability of the nerves in the arm and fore-arm, ostensibly caused by hypocalcemia, which, inturn, causes the muscular contractions. These condi-tions are exacerbated by ischemia produced by thesphygmomanometer, resulting in the twitching thatdefines the sign.544 Hospital Physician March 2000Urbano : Signs of Hypocalcemia : pp. 43–45Figure 1. Illustration of the facial points where A) the ChvostekI phenomenon and B) the Chvostek II phenomenon can be elicit-ed. Hoffman E:The Chvostek sign: a clinical study. Adapted withpermission from Am J Surg 1958;96:33–37.Figure 2. Illustration of the elicitation of Trousseau’s sign.Adapted with permission from Netter FH: Clinical manifestationsof acute hypocalcemia. In The Ciba Collection of Medical Illustrations,vol 4. Summit, NJ: Ciba Pharmaceutical Company, 1965:185.ABTrousseau-von Bonsdorff TestThe Trousseau-von Bonsdorff test has been correlat-ed with the presence of Trousseau’s sign.10TheTrousseau-von Bonsdorff test is performed immediatelyafter deflating the sphygmomanometer. The patient isinstructed to breathe deeply at a rate of 40 breaths/minand is then observed for the previously described car-popedal spasm. One study found the Trousseau-vonBonsdorff test to be a useful adjunct to Trousseau’s signwhen evaluating for the presence of hypocalcemia.10Differential DiagnosisAs with Chvostek’s sign, hypocalcemia is not theonly condition that can produce a positive Trousseau’ssign. Another common clinical entity that has beenknown to cause a positive Trousseau’s sign is hypo-magnesemia.9Because this condition often occurs con-comitantly with hypocalcemia, determination of theelectrolyte abnormality responsible for causing the twoseparate positive responses is difficult. COMPARISON OF CHVOSTEK’S SIGN AND TROUSSEAU’SSIGN Although the two signs have never been directly com-pared, Trousseau’s sign is believed to be more specificfor hypocalcemia than Chvostek’s sign. In one study,94% of patients with confirmed hypocalcemia had a pos-itive Trousseau’s sign, whereas only 1% of healthy pa-tients demonstrated a positive Trousseau’s sign.10Inaddition, only 9% of normal patients had a positiveTrousseau-von Bonsdorff test.10HYPOCALCEMIAClinical entities that may commonly result in hypo-calcemia include hypoparathyroidism (especially of thepostsurgical variety), chronic renal failure, rhabdomyoly-sis, pancreatitis, tumor lysis syndrome, nephrotic syn-drome, and dietary deficiency.9Both Chvostek’s signand Trousseau’s sign may be present in patients with allconditions that cause hypocalcemia; however, absence ofthe signs does not preclude the diagnosis. Modernblood chemistry analyzers have the ability to measureboth total and free serum calcium, which has greatlyassisted in the diagnosis of hypocalcemia. The treatmentof hypocalcemia consists of correcting the underlyingpathologic problem (if possible) and replacing the lostcalcium through pharmacologic means.SUMMARYIn the current age of medicine, the utility of Chvo-stek’s sign and Trousseau’s sign has diminished withthe development of technology that is able to assessserum calcium values. However, the signs may still behelpful as crude determinations of the neuromuscularexcitability that occurs in patients with hypocalcemia.Trousseau’s sign is likely to be a more specific indicatorof hypocalcemia than Chvostek’s sign, but both signsare diagnostically useful, and attempts to both performand interpret the signs are an interesting challenge tophysicians and students of medicine. HPACKNOWLEDGMENTThe author wishes to thank Margaret M. Franger,MD, for her assistance in reviewing this manuscript.REFERENCES1. Bushinsky DA, Monk RD: Calcium. Lancet 1998;352:306–311.2. Firkin BG, Whitworth JA: Dictionary of Medical Eponyms,2nd ed. New York: The Parthenon Publishing Group,1996;68:401.3. Stedman’s Medical Dictionary, 25th ed. Baltimore: Williamsand Wilkins, 1990:1539.4. Hoffman E: The Chvostek sign: a clinical study. Am JSurg 1958;96:33–37.5. Netter FH: Clinical manifestations of acute hypocal-cemia. In The Ciba Collection of Medical Illustrations, vol 4.Summit, NJ: Ciba Pharmaceutical Company, 1965:185.6. Noble J: Textbook of Primary Care Medicine, 2nd ed. St.Louis: Mosby, 1996:550 –554.7. Kugelberg E: The mechanism of Chvostek’s sign. Archivesof Neurology and Psychiatry. 1951;65:511–517.8. Fonseca OA, Calverly JR: Neurological manifesta-tions of hypoparathyroidism. Arch Intern Med 1967;120:202–206.9. Becker KL, ed: Principles and Practice of Endocrinology andMetabolism, 2nd ed. Philadelphia: J.B. Lippincott Com-pany, 1995;618:1766–1767.10. Schaaf M, Payne CA: Effect of diphenylhydantoin andphenobarbital on overt and latent tetany. N Engl J Med1966;274:1228–1233.Urbano : Signs of Hypocalcemia : pp. 43–45Hospital Physician March 2000 45Copyright 2000 by Turner White Communications Inc., Wayne, PA. All rights reserved.