LAUSR

© Author(s) (or their employer(s)) 2022. No commercial reuse. See rights and permissions. Published by BMJ. CASE REPORT A 33yearold Japanese woman, 13 weeks pregnant, developed progressive nausea and vomiting. The vomiting episodes were accompanied by headache, occasional lowgrade fever and excessive sleepiness with subsequent diplopia. She had developed hyperemesis gravidarum in a previous pregnancy but had been otherwise well. The neurological examination showed confusion, sleepiness and involuntary nonrhythmic eye movements, suggesting opsoclonus. There was no ophthalmoparesis, ataxia, myoclonus or meningism. Blood tests showed hypokalaemia, evidence of renal failure, leucocytosis and abnormal liver function tests. CT scan of head was normal and cerebrospinal fluid examination was normal with negative microbiology, including common viruses and flaviviruses. HIV and hepatotropic viruses were negative. We gave her intravenous fluids and antiemetics along with intravenous thiamine and corticosteroids to treat hyperemesis gravidarum. MR scan of brain (figure 1) showed fluidattenuated inversion recovery (FLAIR) and diffusionweighted imaging (DWI) hyperintensities in area postrema, periaqueductal grey matter, mammillary bodies, mesencephalic tegmentum and both dorsomedial thalami. Serum antiaquaporin4 and antimyelin oligodendrocyte protein(MOG) antibodies were negative. Over the following days, her altered mental status and opsoclonus progressively improved, though slight horizontal nystagmus persisted to the right. Finally, she was diagnosed with hyperemesis gravidarum causing electrolyte disturbances and thiamine deficiency leading to Wernicke’s encephalopathy. Her liver renal function abnormalities were corrected and she was discharged 3 weeks later on a tapering dose of corticosteroids. Two months later, her neurological examination showed no nystagmus, mild gait instability without ataxia and mild anterograde memory loss.