Chvostek Sign

The Chvostek sign is a clinical indicator of neuromuscular excitability, typically associated with hypocalcemia (low calcium in the blood). It can also be used to determine whether there is pathology involving the seventh cranial (facial) nerve.

The Chvostek Sign was first described in the late 1800s by Austrian neurologist František Chvostek, he noticed that mechanical stimulation of the facial nerve (as with the examiner’s fingertip, for example) could lead to twitching of the ipsilateral facial muscles.

A calcium level of less than 8.8 mg/dl is considered deficient. Calcium is an essential electrolyte in the body. It is associated with many functions and of greatest significance, muscle contractions and propagation of nerve impulses. Deficiencies in calcium may lead to seizures, cardiomyopathy, QT prolongation, and congestive heart failure. Secondary to this, patients often receive replacement therapy in the hospital setting. One common cause of hypocalcemia is a complication during thyroidectomies.

The sign is elicited by tapping the facial nerve at a specific point on the cheek, just anterior to the ear and below the zygomatic arch.

See Also: Tinel Test for Nerves Evaluation

How to Perform the Chvostek Sign Test?

The test is relatively simple to perform:

1. Position the Patient: Have the patient sit comfortably, facing the examiner.
2. Locate the Facial Nerve: Identify the area just anterior to the ear and below the zygomatic arch.
3. Tap the Area: Using a reflex hammer or your finger, gently tap the area over the facial nerve.
4. Observe the Response: Watch for any twitching of the facial muscles, particularly around the mouth, nose, or eye.

A positive Chvostek sign is indicated by the twitching of the facial muscles, particularly around the mouth, nose, or eye, in response to the tap.

A positive Chvostek sign is an important diagnostic tool. It is often one of the first signs that suggest hypocalcemia, although it can also be present in other conditions that increase neuromuscular excitability. These conditions include:

1. Hypocalcemia: Low calcium levels are the most common cause of a positive Chvostek sign. Hypocalcemia can result from a variety of causes, including hypoparathyroidism, vitamin D deficiency, and chronic kidney disease.
2. Hypomagnesemia: Low magnesium levels can also trigger a positive Chvostek sign. Magnesium is critical for the regulation of calcium, and its deficiency can lead to similar neuromuscular symptoms.
3. Respiratory Alkalosis: Conditions that lead to an increase in blood pH, such as hyperventilation, can cause calcium to bind to albumin more readily, lowering the free calcium available in the bloodstream and potentially leading to a positive Chvostek sign.

Studies suggest that a positive Chvostek sign may be present in a significant number of healthy individuals without any underlying pathology. This underscores the importance of using the Chvostek sign in conjunction with other diagnostic tests, such as serum calcium levels, to confirm hypocalcemia or other related conditions.

Additionally, a negative Chvostek sign does not necessarily rule out hypocalcemia, especially in chronic cases where neuromuscular excitability may be less pronounced.

References & More

1. Orthopedic Physical Assessment by David J. Magee, 7th Edition.
2. Omerovic S, Das JM. Chvostek Sign. [Updated 2023 May 1]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: Pubmed