Wernicke's encephalopathy in a non-alcoholic patient with a normal blood thiamine level

A 64-year-old woman who had never consumed alcohol presented to hospital with a several-day history of vomiting and severe diarrhoea, secondary to Clostridium difficile colitis. She had suffered a similar episode 3 months earlier. Her symptoms settled after 7 days’ treatment with vancomycin and metronidazole, but her admission was complicated by nosocomial pneumonia and her oral intake was poor. Fifteen days into her stay, she became drowsy and less communicative and developed generalised weakness. Clinical examination revealed signs of encephalopathy. She had slowed mentation, paucity of facial expression and slow limb movements. She could follow one-stage commands but only slowly and with significant prompting. Her eye movements were normal. She had mild generalised weakness in all four limbs, but her deep tendon reflexes were intact and plantar responses were downgoing. Ataxia could not be assessed reliably due to impaired consciousness. Electroencephalography showed generalised slowing without focal features. Magnetic resonance imaging (MRI) of the patient’s brain revealed symmetrical changes of high signal in the periaqueductal grey matter, superior colliculi and medial thalami, most evident on the fluid-attenuated inversion recovery (FLAIR) sequences (Box 1, A–C). These symmetrical periventricular changes were consistent with typical findings recently described for Wernicke’s encephalopathy. Given the clinical history of dietary deprivation and colitis, together with the typical radiological changes, a diagnosis of Wernicke’s encephalopathy was strongly suspected. Hence, intravenous thiamine 500 mg three times a day was administered, after which the patient made a dramatic clinical and radiological recovery (Box 1, D–F) over a period of about 7 days. Despite this, her pretreatment (Day 15) blood thiamine pyrophosphate level, measured using high-performance liquid chromatography, was eventually reported as being normal (136 nmol/L [reference range, 67–200 nmol/L]). However, given her clinical history, the changes noted on MRI and the dramatic improvement in her condition with thiamine, the diagnosis of Wernicke’s encephalopathy remained the most likely explanation.2 page(s