Chvostek's sign

Chvostek’s sign is a twitch, spasm or tetanic, cramp-like contraction of some or all of the ipsilateral facial muscles on tapping over the pes anserinus anterior to the tragus.(1-4) It is classically a sign of tetany but may also occur with hyperreflexia due to upper motor neuron dysfunction.

Various degrees of response may occur (Video). The sign is minimal if only a slight twitch of the upper lip or the angle of the mouth results; moderate if there is movement of the ala nasi and the entire corner of the mouth; maximal if the muscles of the forehead, eyelid, and cheek also contract. When the response is marked, even muscles supplied by the trigeminal nerve may respond. When very active the response may be elicited merely by stroking the skin in front of the ear. Schultz's sign is the same response elicitied by percussing midway between the zygomatic arch and the angle of the mouth.

Chvostek's sign is the result of hyperexcitability of the motor nerves, in this instance the facial nerve, to mechanical stimulation. The motor Tinel’s sign has been reported as evidence of abnormal mechanosensitivity in entrapment neuropathies but may also occur in normals. Both Chvostek’s sign and the Lust peroneal phenomenon are probably examples of a motor Tinel’s sign.

See Kamalanathan for another video, although it is much less dramatic than this one.(5) The Méneret paper shows multiple videos eliciting Chvostek’s sign in normal individuals.(6) YouTube offers multiple examples. Trousseau's sign is more specific than Chvostek's sign for latent tetany.

Video legend. A patient demonstrating her own Chvostek’s sign, due to transient hypocalcemia that developed post-thyroidectomy. She also had a positive Trousseau’s sign. Modified with permission from original video.

References

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.

3. Athappan G, Ariyamuthu VK. Images in clinical medicine. Chvostek's sign and carpopedal spasm. N Engl J Med. 2009;360:e24.

4. Narayan SK, Sivaprasad P, Sahoo RN, et al. Teaching video NeuroImage: Chvostek sign with Fahr syndrome in a patient with hypoparathyroidism. Neurology 2008;71:e79.

5. Kamalanathan S, Balachandran K, Parthan G, et al. Chvostek's sign: a video demonstration. BMJ Case Rep. 2012;2012.

6. Méneret A, Guey S, Degos B. Chvostek sign, frequently found in healthy subjects, is not a useful clinical sign. Neurology. 2013;80:1067.