Vitamin B12 Deficiency as a First Sign of Acquired Horizontal Pandular Nystagmus

Abstract

Eye movement disorders are rarely reported in vitamin B12 deficiency. Reported eye movement disorders in vitamin B12 deficiency were downbeat nystagmus and INO in 3 cases each, upward gaze palsy in 2 cases, bilateral abducens palsy, total ophthalmoplegia, bilateral horizontal gaze evoked nystagmus in 1 case each. We describe a case with recently developed horizontal penduler constant nystagmus due to vitamin B12 deficiency. He received replacement therapy but his eye movement disorder did not respond to treatment. The early diagnosis of vitamin B12 deficiency is vital because when axonal damage is started recovery might not occur. To the best of our knowledge, this is the first reported case with acquired horizontal pendulernystagmus caused by vitamin B12 deficiency.