What causes hand stiffness or finger cramps after repeated vomiting?

Stiff Fingers After Vomiting: Electrolyte-Induced Carpopedal Spasm

Stiff fingers after repeated vomiting are caused by metabolic alkalosis and electrolyte derangements—specifically hypocalcemia (decreased ionized calcium), hypokalemia, and hypomagnesemia—that result from excessive loss of gastric acid and fluid, leading to carpopedal spasm (tetany). 1

Pathophysiology

• Excessive vomiting causes loss of hydrochloric acid from the stomach, producing metabolic alkalosis. 1
• Alkalosis shifts the equilibrium of serum calcium, reducing the ionized (physiologically active) fraction even when total calcium levels appear normal. 1
• Decreased ionized calcium triggers neuromuscular hyperexcitability, manifesting as painful involuntary muscle contractions—carpopedal spasm—affecting the hands and fingers. 1
• Concurrent hypokalemia (potassium loss through vomiting and secondary hyperaldosteronism) and hypomagnesemia further exacerbate neuromuscular irritability. 1

Clinical Presentation

• Patients develop painful, involuntary flexion and stiffness of the fingers and hands (carpopedal spasm) following bouts of vomiting. 1
• Associated symptoms may include perioral numbness, muscle cramps elsewhere, and in severe cases, laryngospasm or seizures. 1
• The spasms are typically bilateral and occur during or shortly after episodes of excessive vomiting. 1

Diagnostic Approach

• Obtain serum electrolytes (sodium, potassium, chloride, bicarbonate), ionized calcium, magnesium, and arterial or venous blood gas to confirm metabolic alkalosis and identify specific deficiencies. 1
• Check for Chvostek sign (facial twitching with tapping over the facial nerve) and Trousseau sign (carpopedal spasm induced by inflating a blood pressure cuff above systolic pressure for 3 minutes) to confirm latent tetany. 1
• If vomiting is recurrent and stereotyped, consider cyclic vomiting syndrome (CVS) as the underlying cause; CVS is defined by stereotypical acute-onset vomiting episodes lasting <7 days, with ≥3 discrete episodes per year separated by ≥1 week of baseline health. 2, 3

Immediate Management

• Administer intravenous fluids with normal saline to correct volume depletion and chloride deficit, which helps reverse metabolic alkalosis. 1
• Replace calcium intravenously (calcium gluconate 1–2 grams IV over 10–20 minutes) if ionized calcium is low or if tetany is severe; monitor cardiac rhythm during infusion. 1
• Correct hypokalemia with potassium chloride supplementation (oral or IV depending on severity); aim for serum potassium >3.5 mEq/L. 1
• Replete magnesium (magnesium sulfate 1–2 grams IV) because hypomagnesemia impairs parathyroid hormone release and worsens hypocalcemia. 1
• Monitor daily fluid balance and serum electrolytes in patients requiring intravenous fluids to recognize and treat hyponatremia and hypokalemia promptly. 4

Addressing the Underlying Cause

• Control nausea and vomiting with antiemetics to prevent further electrolyte loss; ondansetron 8 mg sublingual every 4–6 hours is effective during active vomiting. 3
• If CVS is diagnosed, initiate abortive therapy (sumatriptan 20 mg intranasal or 6 mg subcutaneous plus ondansetron) at the earliest prodromal symptoms to terminate episodes and prevent metabolic complications. 3
• For moderate-severe CVS (≥4 episodes per year lasting >2 days with ED visits), start prophylactic therapy with amitriptyline 25 mg nightly, titrating by 10–25 mg every 2 weeks to a target of 75–150 mg nightly. 3
• Educate patients to identify and avoid personal triggers (stress in 70–80% of CVS patients, sleep deprivation, hormonal fluctuations, infections, prolonged fasting) to reduce episode frequency. 3, 5

Common Pitfalls

• Do not assume normal total calcium excludes hypocalcemia; always measure ionized calcium or calculate corrected calcium in the setting of alkalosis. 1
• Do not overlook magnesium deficiency; hypocalcemia will not correct until magnesium is repleted. 1
• Do not delay electrolyte replacement in patients with carpopedal spasm; untreated severe hypocalcemia can progress to laryngospasm, seizures, or cardiac arrhythmias. 1
• Do not dismiss recurrent vomiting as gastroenteritis; consider CVS in any adult with stereotyped episodic vomiting, especially if episodes begin in the early morning and are preceded by prodromal symptoms (sense of doom, panic, mental fog, autonomic symptoms). 2, 3
• Do not withhold abortive therapy once the emetic phase begins; efficacy declines sharply, but supportive care with IV fluids and antiemetics in the emergency department remains essential. 3