A woman with intractable nausea and vomiting

A previously healthy 44 year old Chinese woman was referred by the emergency department to the gastroenterology ward with a seven week history of progressively worsening nausea and vomiting and weight loss of 13 kg. She did not have abdominal pain, distension, or diarrhoea. A general physician and a gastroenterologist had prescribed antidepressants (first flupentixol, then melitracen tablets, and finally olanzapine) for a functional gastrointestinal disorder, and she had been taking these for three weeks, as well as prokinetics (domperidone), and anti-emetics (domperidone and ondansetron), but she had not responded to treatment. Liver, kidney, thyroid function, and basic autoimmune antibodies were within normal ranges. Fasting blood glucose and glycated haemoglobin were normal. Previous gastroscopy and a computed tomography scan of the abdomen (conducted during the seven weeks of symptoms) showed no obvious abnormalities. Previous sagittal magnetic resonance imaging (MRI) of the head and cervical spine (taken three weeks after the first episode of nausea and vomiting) had shown a very small hyperintense lesion in the medulla oblongata, which had been considered normal (fig 1A).

Eight days after admission, the woman experienced metabolic alkalosis (caused by acute vomiting and hypokalaemia) and acute respiratory failure (caused by central hypoventilation and aspiration), and she was transferred to the intensive care unit for mechanical ventilation. Clinical examination found

• paralysis of the right limbs

• horizontal nystagmus

• loss of the pharyngeal reflex

• loss of tendon reflex on …