20th February 2024

A 34-year-old cachectic woman presents to the acute medical unit with acute confusion.

A 34-year-old cachectic woman presents to the acute medical unit with acute confusion. Her daughter states she is a heavy drinker and was found in her home mumbling to herself. She has been increasingly unsteady for the past two weeks, leading to several falls. Examination of her eyes revealed a bilateral nystagmus on horizontal gaze. Bilateral lateral rectus palsy was noted on examination. She has a broad-based gait at present and remains confused. Sensory neuropathy in a glove-and-stocking distribution was noted. 

Given her likely diagnosis, a deficiency in which of the following vitamins has resulted in her condition?