A 47-year-old Caucasian woman with a history of migraine was referred to the hospital with fever, headache and bilateral periorbital oedema. The symptoms started nine days earlier. Physical examination revealed a temperature of 38.5 °C, heart rate of 101 beats/min and a normal blood pressure. On neurological examination, there were signs of photophobia, normal light reactive pupil reflexes and neck stiffness. Kernig and Brudzinski signs were negative. There were no signs of muscle weakness in the upper or lower limbs. She had bilateral proptosis with chemosis and eyelid oedema without scleral injection. Laboratory investigations showed leukocytes of 10.9 x 109/l with 18.1% eosinophils (absolute eosinophil count 1.98 x 109/l), C-reactive protein 34 mg/l, creatine kinase levels of 239 U/l (normal < 145 U/l) and mildly elevated transaminases. Cerebral spinal fluid examination yielded 3 leukocytes/µl and normal protein and glucose levels. Contrast-enhanced computed tomography of the brain confirmed the absence of central neurological lesions but showed bilateral oedema of the ocular muscles, most pronounced in the lateral and medial rectus muscle with diameters of 7 to 8 mm (figure 1, arrows). Four days later, her 22-year-old son and 19-year-old daughter were hospitalised as well with similar complaints and findings.