Arrhythmia in a 38-year-old man.

Accepted 7 February 1996 A 38-year-old man presenting with progressive blurring of vision was diagnosed to have a pituitary macroadenoma with suprasellar extension. He underwent left frontal craniotomy with subtotal excision of the tumour without a proper pre-operative endocrine work up. He was put on prophylactic anticonvulsant (sodium valproate) after the operation. Dexamethasone and intravenous desmopressin (DDAVP) were also given, the latter being for the control of cranial diabetes insipidus that developed postoperatively. On the eleventh postoperative day, a 15 mg tablet of midazolam was given for insomnia. He developed an unexpected episode of generalised tonic clonic seizure about 12 hours later with an electrocardiogram (ECG) as shown in figure 1. Serum electrolytes showed mild hypokalaemia (3.1 mmol/l) and severe hypercalcaemia (3.37 mmol/l). Hormonal assay revealed a serum prolactin level of 33 507 mIU/l (normal < 500).