A 38-year-old man with a 10-year history of alcohol use disorder presents to the emergency department with acute confusion, ataxia, and bilateral ophthalmoplegia (inability to abduct the eyes). His wife reports he has not eaten properly for 2 weeks. On examination, temperature is 37.2°C, heart rate 102/min, and he is disoriented to time and place. Which water-soluble vitamin deficiency is most likely responsible for this acute neuropsychiatric emergency?

Explanation

## Acute Presentation Recognition The patient presents with the **classic triad of Wernicke encephalopathy**: 1. **Ophthalmoplegia** (bilateral inability to abduct eyes = sixth nerve palsy) 2. **Ataxia** (gait disturbance) 3. **Acute confusion** (disorientation) This is a **medical emergency** caused by **thiamine (B1) deficiency**. ## Pathophysiology of Thiamine Deficiency **Key Point:** Thiamine pyrophosphate (TPP) is a critical coenzyme for: - **Transketolase** (pentose phosphate pathway) - **Pyruvate dehydrogenase** (TCA cycle entry) - **α-ketoglutarate dehydrogenase** (TCA cycle) - **Branched-chain amino acid metabolism** Deficiency impairs energy metabolism in the **brain**, particularly in: - **Mammillary bodies** (memory, confusion) - **Medial thalamus** (eye movement control → ophthalmoplegia) - **Cerebellum** (ataxia) ## Wernicke vs. Korsakoff Syndrome | Feature | Wernicke | Korsakoff | | --- | --- | --- | | **Onset** | Acute (hours to days) | Chronic (weeks to months) | | **Triad** | Ophthalmoplegia, ataxia, confusion | Anterograde amnesia, confabulation, apathy | | **Reversibility** | Partially reversible if treated early | Often irreversible | | **Pathology** | Edema, petechial hemorrhage | Neuronal loss, gliosis | | **Relationship** | Wernicke → untreated → Korsakoff | Korsakoff is chronic sequela | **High-Yield:** Wernicke encephalopathy is a **medical emergency**. If suspected, give thiamine **immediately** (100 mg IV/IM) BEFORE glucose, as glucose administration without thiamine can precipitate or worsen Wernicke. ## Risk Factors in This Patient **Clinical Pearl:** The combination of: - **Chronic alcohol use** (impairs thiamine absorption, increases metabolism) - **Poor nutrition** (2-week history of not eating) - **Acute presentation** (stress, infection, or glucose load can unmask deficiency) ...creates a perfect storm for Wernicke encephalopathy. ## Diagnostic Confirmation - **Serum thiamine level** (low) - **RBC transketolase activity** (↓ baseline, ↑ after TPP addition = diagnostic) - **MRI brain** (mammillary body atrophy, thalamic edema, periaqueductal gray involvement) ## Treatment Algorithm ```mermaid flowchart TD A[Suspected Wernicke encephalopathy]:::urgent --> B[Give thiamine 100 mg IV/IM IMMEDIATELY]:::action B --> C[Then give glucose if needed]:::action C --> D[Continue thiamine 100 mg daily × 3-5 days]:::action D --> E[Then oral thiamine 50-100 mg daily]:::action E --> F{Response?}:::decision F -->|Good| G[Ophthalmoplegia resolves in days]:::outcome F -->|Poor| H[Risk of Korsakoff progression]:::urgent ``` **Mnemonic: WERNICKE** — **W**ernicke encephalopathy, **E**mergency, **R**equires **N**early immediate **I**ntramuscular **C**obalamin... wait, no! **Thiamine**, **K**orsakoff follows, **E**arly treatment prevents progression.