Case of Wernicke's encephalopathy with isolated abducens nucleus lesion

Abstract

A 46-year-old man presented with diplopia and gait instability that had been preceded by diarrhea 4 days before the onset of neurological symptoms. On admission, he was alert, and neurological examinations revealed bilateral abducens nerve palsies (Fig. 1a), decreased tendon reflexes and gait ataxia. Findings of routine laboratory tests and nerve conduction studies were normal. Initially, a diagnosis of Miller–Fisher syndrome was made. However, an isolated high-intensity signal lesion in the bilateral abducens nuclei (Fig. 1b,c) was detected by magnetic resonance imaging. The patient's alcoholism prompted us to consider the possibility of Wernicke's encephalopathy (WE) with immediate parenteral administration of thiamine. After the treatment, his symptoms improved rapidly and he recovered to normal on day 6. On day 8, the lesion completely disappeared on follow-up magnetic resonance imaging (Fig. 1d,e) and a serum thiamine concentration, which had been measured after parenteral thiamine administration, was confirmed to be low (20.8 ng/mL, normal 21.3–81.9 ng/mL). In WE, signal-intensity alterations in the cranial nerve nuclei are less common.1 To our knowledge, this is the first report of WE with an abducens nucleus-confined lesion on magnetic resonance imaging. When Miller–Fisher syndrome-like symptoms are encountered, physicians should consider the possibility of WE and carefully evaluate the presence of signal intensity alterations in the cranial nerve nuclei. We declare that there is no source of financial grants and other funding. We thank Dr Imaharu Nakano for his educational suggestions and engagement. The authors declare no conflict of interest. All human studies have been reviewed by the appropriate ethics committee and have therefore been carried out in accordance with the ethical standards laid down in an appropriate version of the 2000 Declaration of Helsinki as well as the Declaration of Istanbul 2008. Informed consent was obtained from all persons before their inclusion in the study. Details that might disclose the identity of the participants under the study should be omitted.