Which sign is indicative of hypocalcemia?

Trousseau's sign is indicative of hypocalcemia due to its association with neuromuscular excitability resulting from low serum calcium levels. This sign is demonstrated when a blood pressure cuff is inflated around the upper arm to a pressure greater than the systolic blood pressure. A positive Trousseau's sign is observed when the hand and fingers spasm and flex into the "carpopedal spasm" position. This occurs because low calcium levels lead to increased neuromuscular excitability, causing these involuntary contractions.

In contrast, Cullen's sign indicates the presence of internal bleeding, often seen in cases of ectopic pregnancy or pancreatitis, rather than signifying hypocalcemia. Brudzinski's sign is associated with meningitis and reflects irritation of the meninges, not calcium levels. Babinski's sign assesses neurological function indicating central nervous system dysfunction when an infant's reflex is seen; it's unrelated to calcium status. Therefore, Trousseau's sign specifically points to the calcium deficiency, making it the correct choice for identifying hypocalcemia.