Answer: Hypoparathyroidism (Option A)
The cause of numbness around the mouth and peripheral limbs after total thyroidectomy is hypoparathyroidism resulting in hypocalcemia, not recurrent laryngeal nerve injury. These are classic symptoms of acute hypocalcemia from parathyroid gland injury or devascularization during surgery 1, 2.
Clinical Presentation Distinguishes These Complications
Perioral numbness and peripheral tingling are pathognomonic for hypocalcemia, not nerve injury:
- Hypocalcemia presents with perioral numbness, tingling in extremities, muscle cramps, and carpopedal spasm 1, 2
- These symptoms arise from decreased serum calcium affecting neuromuscular excitability 2
- Recurrent laryngeal nerve injury causes voice changes, hoarseness, and vocal fold immobility—not perioral or limb numbness 3
Mechanism and Incidence
Hypoparathyroidism occurs through parathyroid gland injury during thyroidectomy:
- Temporary hypoparathyroidism affects 5.4-12% of patients; permanent hypoparathyroidism occurs in 1.1-2.6% 1
- Injury mechanisms include devascularization, inadvertent removal, or direct trauma to parathyroid glands 4, 5
- Symptoms typically arise acutely within hours after surgery as calcium levels drop 6, 2
Diagnostic Confirmation
Immediate serum calcium measurement confirms the diagnosis:
- Check serum calcium and ionized calcium levels immediately 1, 2
- Monitor calcium levels every 6-8 hours until stable 1
- Serum calcium <7.5 mg/dL or ionized calcium <1.0 mmol/L indicates significant hypocalcemia requiring treatment 7, 4
- PTH levels ≤12 pg/ml predict high risk for permanent hypoparathyroidism 7
Why Not Recurrent Laryngeal Nerve Injury
Recurrent laryngeal nerve injury produces entirely different symptoms:
- Voice changes, hoarseness, and dysphonia are the hallmark presentations 3
- Vocal fold immobility occurs in approximately 9.8% of cases temporarily 3
- No sensory symptoms occur with RLN injury—it is a motor nerve affecting vocal fold movement 3
Immediate Management
Symptomatic hypocalcemia requires urgent treatment:
- Oral calcium supplementation for mild symptoms 1, 4
- Intravenous calcium infusion for severe symptoms (corrected calcium <7.5 mg/dL or symptomatic) 4, 5
- Add calcitriol (vitamin D) for confirmed hypoparathyroidism 4, 5
- Goal is to maintain calcium in low-normal range to prevent complications 4
Common Pitfall
Do not confuse sensory symptoms (hypocalcemia) with motor symptoms (nerve injury). The distribution of perioral and peripheral numbness is characteristic of systemic hypocalcemia affecting neuromuscular function, not a focal nerve injury pattern 2, 5.