A 63-year-old woman with advanced chronic kidney disease, diabetes mellitus, hypertension and peripheral vascular disease presented with three successive tonic–clonic seizures. She was obtunded, with a Glasgow coma scale score of 4/15 but with no lateralising neurological signs. She had marked renal impairment (serum creatinine 606 µmol/L (49–90) and estimated glomerular filtration rate of 6 mL/min/1.73 m² (>60)). There was severe hyperparathyroidism (parathyroid hormone 48.8 pmol/L (1.7–7.6)).

CT scan of the head found widespread infratentorial and supratentorial calcifications, unchanged from a CT scan 2 years before, and subtle acute subdural and subarachnoid haemorrhages (figure …