A case report of monoplegia due to vitamin B1 deficiency

Introduction: Thiamine (vitamin B1) is a water-soluble vitamin essential for cellular metabolism, specifically in the tricarboxylic acid cycle (Krebs’s cycle). Neuropathy due to thiamine deficiency is referred to as dry beriberi. Dry beriberi neuropathy is a metabolic disorder making significant left-right disparity or monoplegia relatively rare. Due to the presence of monoplegia, a relationship with vitamin deficiency may not have been considered, leading to delays in treatment. We investigated the clinical characteristics of a patient with monoplegia and vitamin B1 deficiency. The serum vitamin B1 concentration was 22 ng/mL, which is below the normal reference range of 24–66 ng/mL. The patient achieved complete recovery after approximately four months of vitamin B1 supplementation. Case Report: A 53-year-old woman developed left leg weakness and difficulty walking following approximately three months of appetite loss and chronic alcohol use due to depression. She initially consulted an orthopedic surgeon, and pelvic magnetic resonance imaging (MRI) revealed swelling of the left sciatic nerve, and inflammation (or) ischemia was suspected. Laboratory testing showed a low level of serum vitamin B1. Nerve conduction studies demonstrated peroneal and tibial neuropathy on the left side. Although beriberi was initially considered unlikely due to the marked asymmetry between the left and right limbs, the patient’s left leg monoplegia improved immediately after the initiation of thiamine supplementation. She achieved full recovery after approximately four months of continuous treatment. Conclusion: This study evaluated the clinical course of monoplegia caused by vitamin B1 deficiency. The patient was completely cured with thiamine supplementation. This finding suggests the need to consider the possibility of neuropathy due to vitamin deficiency even in patients with monoplegia. Routine vitamin B1 testing should be considered in similar clinical cases to facilitate early diagnosis and treatment.