Chvostek sign is abnormal contracture of the ipsilateral facial muscles that can occur in patients with hypocalcemia. The test is performed by gently tapping over the facial nerve region just anterior to the ear, at the zygomatic arch (~2 cm in front of the earlobe). Twitching of the facial muscles on the same side as the tapping indicates a positive test result. Illustration courtesy of Dr Shannon Zhang.
