What area of the brain atrophies with thiamine deficiency?

Brain Regions Affected by Thiamine Deficiency

Thiamine deficiency primarily causes atrophy in the mammillary bodies, thalamus, and periaqueductal/periventricular gray matter, with the mammillary bodies being the most characteristic site of damage. 1, 2

Primary Affected Brain Regions

Thiamine deficiency leads to selective neuronal loss in specific brain regions:

• Mammillary bodies: Most consistently affected structure showing significant volume loss and atrophy 3, 2, 4
• Thalamus: Shows bilateral volume deficits and signal changes 2
• Periaqueductal and periventricular gray matter: Commonly affected regions 2
• Collicular bodies: Show edema in acute thiamine deficiency 2

Pathophysiological Progression

The brain damage in thiamine deficiency follows a predictable pattern:

1. Acute phase: Characterized by edema and inflammation in affected brain tissue 2
2. Chronic phase: If untreated, progresses to tissue shrinkage and atrophy of selective brain structures 2
3. Resolution phase: With thiamine repletion, some changes may be reversible, particularly in the acute phase 4, 5

Neuroimaging Findings

MRI is the preferred imaging modality for detecting thiamine deficiency-related brain changes:

• Acute changes: Hyperintense signals on T2-weighted images in the mammillary bodies, thalamus, and periaqueductal gray matter 2
• Chronic changes: Bilateral ventricular enlargement, mammillary body atrophy, and cerebellar degeneration 6, 2
• Microstructural changes: Decreased fractional anisotropy in the fornix and other white matter tracts 4

Clinical Correlations

The pattern of brain atrophy explains the clinical manifestations of thiamine deficiency:

• Wernicke's encephalopathy: Acute syndrome with mental status changes, ocular abnormalities, and ataxia 1, 2
• Korsakoff syndrome: Chronic amnestic disorder resulting from damage to mammillary bodies and thalamus 2
• Cerebellar dysfunction: Ataxia related to cerebellar hemisphere and vermis involvement 2

Important Clinical Considerations

• Thiamine deficiency should be suspected in patients with unexplained neurological symptoms, especially in those with risk factors 1
• Prompt thiamine supplementation is critical as early treatment may prevent irreversible brain damage 1
• Neuroimaging changes may serve as biomarkers of thiamine deficiency 4
• Alcohol exposure may exacerbate thiamine deficiency-related brain damage and impair recovery 5

Differential Diagnosis

Thiamine deficiency should be considered in patients presenting with ataxia, especially when associated with:

• Chronic alcohol use 1
• Malnutrition 1
• Chronic liver disease 1, 3
• HIV-AIDS 6
• Gastrointestinal disease 6

Thiamine deficiency is severely underdiagnosed based on clinical criteria alone, making awareness of the characteristic pattern of brain atrophy particularly important for early recognition and treatment 6.