Case Report: Nyctalopia Due to Severe Liver Cirrhosis-induced Vitamin A Deficiency.

SIGNIFICANCE: Vitamin A is a micronutrient critical for retinal function. Patients with a deficiency may notice a progressive decline in night vision as rod photoreceptors become unable to regenerate rhodopsin. Although uncommon in developed nations, vitamin A deficiency should be considered in symptomatic patients with chronic, severe liver disease. PURPOSE: This report presents a rare case of night blindness secondary to poor vitamin A metabolism due to severe liver cirrhosis. CASE REPORT: A 62-year-old White woman presented with progressively worsening vision in dim lighting over the past 6 to 8 months. She was asymptomatic in daylight but "blind in the dark" to the extent that she was afraid to go outside at night. She had no personal or family history of night blindness or retinal disorders. Ocular health was unremarkable with dilation. Given her medical history of severe nonalcoholic liver cirrhosis, malabsorption of vitamin A was suspected and subsequently confirmed by the very low vitamin A level in her serum analysis. The patient was sent to endocrinology for evaluation, and appropriate repletion therapy was implemented. Subjective improvement in symptoms, along with better performance on visual field testing, was noted after initiating oral vitamin A supplementation for 5 months. CONCLUSIONS: Although vitamin A deficiency is a relatively rare disorder in the United States, it should be suspected in patients with severe liver disease or other conditions causing malabsorption who experience a loss of night vision.

Case Report: Unilateral Cranial Nerve IV Palsy Secondary to Trochlear Schwannoma.

SIGNIFICANCE: Cranial nerve IV palsy is the most common cranial nerve affected in both pediatric and adult patients with vertical and/or torsional diplopia. The condition has multiple known etiologies, including schwannoma, which is rarely reported in the literature. Schwannoma should be considered when the most common etiologies have been ruled out. PURPOSE: This report documents a rare case of cranial nerve IV palsy secondary to a trochlear schwannoma. Treatment and management considerations will be discussed. CASE REPORT: A 57-year-old man presented to the clinic for evaluation of his recent-onset vertical diplopia. He was diagnosed with left cranial nerve IV palsy. MRI of the brain and orbits revealed the presence of a schwannoma along the course of his left fourth cranial nerve. It did not compress any other cranial nerves or the brainstem. The patient was referred to the neuro-ophthalmology clinic for further evaluation. He was managed conservatively with prismatic spectacle correction to relieve his diplopia. Repeat MRI of the brain and orbits was recommended every 6 months. CONCLUSIONS: Although rare, schwannoma of the fourth cranial nerve should be considered in cases of cranial nerve IV palsies without an obvious etiology. Neuroimaging of the brain and orbits is warranted in cases where more common etiologies have been ruled out or when other cranial nerves and/or the brainstem are involved.