Case Report: Vibratory Sensation Loss A Sign of Nutritional Deficient Optic Neuropathy

Longstanding neuropathy may be a precursor to the development of a nutritional deficit optic neuropathy, according to a case study presented at the North American Neuro-Ophthalmology Society (NANOS) 2021 Annual Meeting, held virtually February 20 to 23, 2021.

Although multiple case reports have highlighted the relationship between nutritional optic neuropathy and folic acid deficiency, none of these case reports have explored the natural history of the disease process prior to patient referral to a neuro-ophthalmologist. 

Researchers at NANOS presented the case of a 63-year-old woman with a history of chronic alcohol use who had been referred to a neuro-ophthalmology service with bilateral vision loss. The patient had experienced a 1-year long history of numbness and tingling in her feet and hands, as well as recent vision loss in both eyes. 

Her alcohol intake included 6 to 8 ounces of hard liquor daily, and the patient had a 15 pack-year smoking history. 

On evaluation, the patient’s corrected visual acuity was 20/50 in both eyes; color vision was one-eighth in the right eye and three-eighths in the left eye. Both eyes had moderate depression of the foveal threshold, while the right eye also had a mild depression of the central threshold. No afferent pupillary defects were noted, optical computed tomography of the macula was grossly normal and the patient had no vibration sensation in the peripheral lower extremities. 

The patient had hemoglobin levels above 12, mean corpuscular volume of 90, vitamin B12 levels greater than 350, and folate levels of lower than 3. On magnetic resonance imaging, no retro-orbital pathology was noted. 

Because of the current limitations of diagnostic capabilities, folic acid deficiency neuropathic is, per researchers, largely a diagnosis of exclusion. In this case, the patient did not experience optic nerve involvement until systemic disease became extensive and involved the upper extremities and caused a complete loss of both deep tendon reflexes and proprioception peripherally. 

“Optic neuropathy secondary to folic acid deficiency is uncommon yet important as early recognition can prevent further visual decline,” the research explains. “The pathophysiology of the disease process is not yet fully understood…Complete loss of vibratory sensation and proprioception are postulated to be temporally related to folic acid deficient optic neuropathy.” 

Reference

Rizk M, Kay M, Oramas S. Early natural history of folic acid deficient optic neuropathy: A case report. Presented at: North American Neuro-Ophthalmology Society Annual Meeting; February 20-23, 2021; Poster 5.