What is the Chvostek's sign?

From the Guidelines

Chvostek's sign is a clinical indicator of hypocalcemia, characterized by twitching of the facial muscles in response to tapping the facial nerve, and is used to detect low calcium levels in the blood, as mentioned in the context of managing hypocalcemia in CKD patients 1. The sign is elicited by gently tapping the patient's face about 2 cm anterior to the earlobe, just below the zygomatic arch where the facial nerve passes.

• A positive result is indicated by facial muscle contractions, particularly around the corner of the mouth, nose, or eye.
• The physiological basis for this response is that hypocalcemia increases nerve excitability, making nerves more sensitive to mechanical stimulation.
• While Chvostek's sign is useful for screening, it's not perfectly reliable - it can be positive in 10-25% of people without hypocalcemia and negative in some patients with true hypocalcemia.
• Confirmation of hypocalcemia requires blood tests measuring serum calcium levels, and management may involve therapy to increase serum calcium levels, such as calcium salts and/or oral vitamin D sterols, as outlined in guidelines for managing bone metabolism and disease in chronic kidney disease 1. Key points to consider when interpreting Chvostek's sign include:
• Clinical symptoms of hypocalcemia, such as paresthesia, Chvostek’s and Trousseau’s signs, bronchospasm, laryngospasm, tetany, and/or seizures.
• Plasma intact PTH level above the target range for the CKD Stage.
• The need to maintain the serum calcium-phosphorus product at <55 mg2/dL to prevent complications associated with abnormal calcium and phosphorus levels 1.

From the Research

Definition of Chvostek Sign

• The Chvostek sign is a clinical indicator characterized by a contraction of ipsilateral facial muscles subsequent to percussion over the facial nerve 2.
• It is often associated with hypocalcemia, although research suggests that a positive Chvostek sign may be informative of normal to increased serum calcium levels rather than hypocalcemia 2.

Relationship with Hypocalcemia

• Hypocalcemia is a condition where serum calcium levels are low, and it can be life-threatening if severe 3.
• Symptoms of acute hypocalcemia include neuromuscular irritability, tetany, and seizures, which can be rapidly resolved with intravenous administration of calcium gluconate 3.
• However, the Chvostek sign is not a reliable indicator of hypocalcemia, as increasing serum calcium levels have been associated with an increased odds for a positive Chvostek sign 2.

Diagnosis and Management of Hypocalcemia

• Diagnosis of hypocalcemia involves measuring serum calcium levels, and management options vary depending on the underlying disorder 4.
• Treatment for acute hypocalcemia typically involves intravenous calcium infusion, while oral calcium and/or vitamin D supplementation is used for chronic hypocalcemia 4.
• In cases of hypoparathyroidism, recombinant human parathyroid hormone (rhPTH) therapy may be used to correct serum calcium levels and reduce the need for calcium and vitamin D supplements 4.