Abstract
A 33-year-old woman developed generalised muscle twitching and cramps 4 months following a minimally invasive parathyroidectomy for a parathyroid adenoma. Neurological examination was normal apart from intermittent lip twitching, carpopedal spasm and positive Chvostek and Trousseau’s signs. Parathyroid hormone level remained within normal range post-operatively. Calcium (2.3–2.5 mmol/L; normal range 2.1–2.6 mmol/L), magnesium (0.7–0.9 mmol/L: normal range 0.7–1.1 mmol/L) and 25-hydroxycholecalciferol (86 nmol/L; normal range >50 nmol/L) levels were persistently normal post-operatively. Nerve conduction studies were unremarkable. Concentric needle electromyography identified cramp potentials in abductor digiti minimi, abductor pollicis brevis and flexor carpi ulnaris following application of a pressure cuff to the upper limb. Serological investigations for peripheral nerve hyperexcitability syndromes including voltage-gated potassium channel complex and GAD antibodies were negative. Treatment in the form of calcium, magnesium and Vitamin D replacement provided temporary symptomatic relief for the patient. Symptomatic therapy with carbamazepine and/or recombinant parathyroid hormone are being entertained. Normocalcaemic, normomagnesemic tetany following parathyroidectomy is a rarely reported phenomenon that is hypothesised to occur due to neuromuscular irritability resulting from relative hypocalcemia following muscle membrane adaption to long-standing hypercalcemia
