Trousseau sign of latent tetany in a patient with Crohn's Disease

A 72-year-old male veteran with Crohn's Disease presented to our emergency department with complaints of worsening diarrhea, difficulty walking, and intermittent paresthesia of his arms and legs after starting a new immunomodulator (ustekinumab) one-month prior for the management of his Crohn's Disease. The patient denied recent confusion, circumoral paresthesia, and muscle cramps. A sphygmomanometer cuff was placed on his arm to obtain an initial blood pressure reading and within a minute he began to verbalize that his arm was in severe pain. Physical examination revealed flexion of his wrist and metacarpophalangeal (MCP) joints with concurrent hyperextension of his proximal (PIP) and distal (DIP) interphalangeal joints (Figure 1). These findings, along with resistance to external force, were consistent with a positive Trousseau Sign of Latent Tetany. Chvostek's sign, described as facial muscle twitching in response to tapping on the facial nerve as it traverses anterior to the ear and inferior to the zygomatic arch, was found to be negative. Biochemical testing revealed a calcium of 4.7 mg/dL (normal 8.4-10.2 mg/dL), magnesium of <0.6 mg/dL (normal 1.4-2.4 mg/dL), and a potassium of 3.2 mmol/L (normal 3.5-5.1 mmol/L). He was admitted to the ICU for close monitoring given his severe electrolyte derangement and underwent aggressive electrolyte repletion .