# Thiamine Deficiency After Bariatric Surgery: Early Neurological Complications and Nutritional Monitoring

## TL;DR

A young woman developed neurological issues after bariatric surgery due to thiamine deficiency, which was successfully treated with vitamin supplementation.

## Contribution

This case highlights the importance of early detection and treatment of thiamine deficiency to prevent irreversible neurological damage after bariatric surgery.

## Key findings

- A 23-year-old woman presented with isolated sixth cranial nerve palsy after bariatric surgery.
- Thiamine and folic acid deficiencies were identified through laboratory tests.
- Symptoms resolved completely after vitamin supplementation.

## Abstract

Thiamine (vitamin B1) deficiency is a recognized complication after bariatric surgery (BS) that can lead to severe neurological manifestations. Early identification is critical to prevent irreversible complications. We report a 23‑year‑old woman who presented two months after BS-Roux-en-Y gastric bypass (RYGB) with diplopia and limitation of ocular abduction in the right eye, consistent with isolated sixth cranial nerve palsy. She had no history of head trauma, infection, or prior neurological disease. Cranial CT angiography and brain MRI excluded ischemic, hemorrhagic, vascular, or demyelinating lesions. Laboratory tests revealed thiamine deficiency (20 ng/mL) and folic acid deficiency (1.7 ng/mL). The patient was treated with thiamine 600 mg/day, folic acid 5 mg/day, and cyanocobalamin 1 mg/day, resulting in complete resolution of symptoms.