Monday, October 31, 2016

Q: Which clinical sign can be graded according to the severity of hypocalcemia? (Select one)

A) Chvostek sign
B) Trousseau sign

Answer: A

Chvostek sign can be demonstrated by briskly tapping the facial nerve at about 2 cm anterior to the external auditory meatus. Depending on the level of hypocalcemia, a response can be graded from mild to severe. Twitching occurs first at the angle of the mouth, then by the nose, the eye, and then the facial muscles. Chvostek sign has high sensitivity but less specificity for hypocalcemia. It can occur without calcium deficiency. 

In contrast, Trousseau sign is less sensitive but highly specific for hypocalcemia. It can be demonstrated by inflating the blood pressure cuff to 20 mm Hg above systolic blood pressure for 3-4 minutes. In hypocalcemia, it will cause a flexion of the wrist and metacarpal phalangeal joints with the extension of the interphalangeal joints and adduction of the thumb, known as carpal spasm. 

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