Wernicke Encephalopathy Following Severe Hyperemesis Gravidarum: A Missed Opportunity for Timely Thiamine Replacement.

Wernicke's encephalopathy (WE) is a rare but potentially fatal complication of hyperemesis gravidarum (HG) caused by thiamine (vitamin B1) deficiency. WE is a medical emergency with complete recovery occurring in only a few cases associated with HG in pregnancy. Classical clinical features include the triad of ophthalmoplegia, altered mental status, and ataxia.  We report a case of a 42-year-old gravida 2 para 1 female patient at 16 weeks and 3-day period of gestation (POG) who presented to primary care during routine antenatal follow-up with a two-week history of sudden visual loss. She had experienced persistent nausea and vomiting for approximately eight weeks and reported a total weight loss of 15 kg since early pregnancy, including 5 kg in the past two weeks. At presentation, she appeared cachectic and extremely lethargic. She was tachycardic with a heart rate (HR) of 116 beats per minute, though her blood pressure remained normotensive. Eye examination revealed visual acuity of counting fingers with positive horizontal nystagmus, suggesting ophthalmoplegia. Fundoscopy was normal. Urinalysis showed ketonuria and proteinuria, with laboratory findings showing severe acute kidney injury (AKI). She was promptly referred to a tertiary center where she was treated with intravenous thiamine 500mg three times daily along with electrolyte replacement and hydration. Her symptoms improved rapidly, and her visual acuity returned to 6/6 bilaterally within 48 hours. She was discharged on a tapering dose of oral thiamine, which was to be continued until delivery, and remained well throughout the rest of her pregnancy. At 28 weeks' gestation, she underwent an emergency caesarean section due to fetal distress and delivered a premature baby girl weighing 1.3 kg. This case highlights the need for early recognition of WE in pregnant women with severe HG. Although rare, it is a reversible complication. Timely thiamine supplementation is essential for both treatment and prevention, and prophylaxis should be considered in high-risk patients.