A Case of Neural Integrator Failure in Vitamin B1 Deficiency. (P1-9.004)

Abstract

<h3>Objective:</h3> Case Report <h3>Background:</h3> The nucleus prepositus hypoglossi (NPH) and medial vestibular nuclei (MVN) are two closely related neural integrators situated in the brainstem responsible for horizontal conjugate eye movement. Thiamine deficiency, a hallmark of Wernicke’s encephalopathy, affects the MVN to a greater extent. We report a case of impaired horizontal gaze holding post-sleeve gastrectomy secondary to Vitamin B1 deficiency. <h3>Design/Methods:</h3> A 24-year-old female presented with new onset diplopia on lateral gaze, dizziness, and lower limb distal paraesthesia eight weeks post-sleeve gastrectomy. Examination revealed conjugate eye movements and horizontal gaze-holding failure bilaterally, with intact convergence and vertical gaze. Normal discs were observed on fundoscopy with no retinal haemorrhages, and visual acuity preserved. She had a normal mental state with mild sensory ataxia. Reflexes were present and symmetrical. <h3>Results:</h3> Cerebrospinal fluid analysis was normal, and MRI Brain showed no acute infarction, haemorrhage, or brainstem lesions. Folate, Vitamin B6, B12, and HbA1c levels were within normal range, with a negative infective screen. Vitamin B1 level was found to be low at 44.3nmol/L (normal range: 66.5–200nmol/L). She was commenced on high-dose intravenous thiamine for one week with symptomatic improvement in diplopia and subsequently discharged on long-term thiamine supplementation. <h3>Conclusions:</h3> The high metabolic requirements of MVN neurons responsible for high acceleration horizontal vestibulo-ocular reflex (VOR) is postulated to account for the selective vulnerability to thiamine deprivation. This case highlights an unusual presentation of disruption in horizontal gaze-holding mechanisms through failure of neural integrators, particularly the MVN, in the setting of Vitamin B1 deficiency with preservation of vertical gaze. <b>Disclosure:</b> Dr. Chen has nothing to disclose. Dr. Warfield has nothing to disclose. Dr. Nannery has nothing to disclose. Dr. Togher has nothing to disclose. Dr. Yacoob has nothing to disclose.