[Clinical reasoning and decision making in practice. A man with unilateral attacks of muscular rigidity following neck surgery for a malignant tumor].

A 54-year-old man with a history of generalised tonic clonic seizures presented with complaints of daily unilateral stiffening of the limbs, preceded by paraesthesia. Two years before he had been treated with surgery and radiotherapy for a laryngo-pharyngeal carcinoma. Therefore, epilepsy due to intracerebral metastasis was suggested. However, neither CT nor MRI of the brain (with intravenous contrast) showed any abnormalities and the EEG showed no epileptiform discharges. Laboratory tests revealed elevated levels of thyroid-stimulating hormone in the blood, hypocalcaemia, hyperphosphataemia and hypomagnesaemia. In combination with the medical history, tetany was found to be the correct diagnosis. In this patient, tetany was caused by hypoparathyroidism secondary to surgery and radiotherapy in the neck region. He was treated with levothyroxine, magnesium, calcium, and vitamin D and recovered in a few weeks' time. Hypothyroidism and hypoparathyroidism are common complications after treatment (surgery, radiotherapy and/or chemotherapy) for laryngo-pharyngeal carcinoma and other malignancies in the neck region.