Chvostek Sign

Original Editor - Umamah Ejaz
Top Contributors - Umamah Ejaz, Ewa Jaraczewska and Rachael Lowe

Introduction

Schematic representation of Chvostek points

The Chvostek sign is a clinical test used to assess nerve excitability, often linked to low calcium levels (hypocalcemia). It was first described in 1876 by Dr. Franz Chvostek, a Viennese surgeon, who noticed that tapping the facial nerve caused muscle twitching in patients with latent tetany.

Purpose

The Chvostek sign helps detect increased nerve sensitivity, commonly due to:  

• Hypocalcemia (low calcium levels)  
• Hypoparathyroidism (low parathyroid hormone, which regulates calcium)  
• Other causes: Kidney failure, vitamin D deficiency, low magnesium, or respiratory alkalosis (e.g., from hyperventilation)  

Why Calcium Matters

• Calcium is crucial for: muscle contractions, nerve signaling, and heart function  
• Severe hypocalcemia can lead to seizures, heart rhythm problems, and muscle spasms.  

Technique

Tap the cheek about 2 cm (0.75 inches) in front of the ear, over the facial nerve.  

• Positive sign: Twitching of the mouth, nose, or eye muscles on the same side.  
• Negative sign: No muscle twitching.  

A Positive Chvostek sign suggests possible hypocalcemia or nerve hyperexcitability.  This is common post-thyroid surgery (due to parathyroid gland damage) , in chronic kidney disease , vitamin D deficiency and magnesium deficiency . However it is important to note, a positive sign does not always mean low calcium; some healthy people may also have it.  

A Negative Chvostek sign does not rule out hypocalcemia. Further testing (blood calcium, PTH, magnesium) may still be needed.  

The following video shows how to perform and observe the sign;

Evidence

A 2016 study (Neurology: Clinical Practice) found:

• Sensitivity: 25.6% (misses many true cases of hypocalcemia).  
• Specificity: 96.3% (correctly rules out hypocalcemia in most healthy people).  

Conclusion

•  A negative result is more reliable in ruling out hypocalcemia.  
•  A positive result is less reliable and should be confirmed with blood tests.  

Key Takeaways

• The Chvostek sign is a quick bedside test but not definitive for hypocalcemia.  
• Always confirm with lab tests (calcium, PTH, magnesium, vitamin D).  
• Consider other causes of nerve excitability if calcium levels are normal.