Symmetric T2/FLAIR and DWI signal in the medial thalami, mammillary bodies, periaqueductal grey and tectal plate in a malnourished or alcoholic patient — thiamine is given on suspicion, the MRI supports it.
Orient first
- Thiamine deficiency: alcohol, hyperemesis, bariatric surgery, malignancy, prolonged vomiting.
- Non-alcoholic patients more often show atypical cortical and cranial nerve nucleus involvement.
- Related symmetric patterns: osmotic demyelination (central pons, basal ganglia), hypoglycaemia (cortex, hippocampi), methanol (putamina, haemorrhage).
Acquire the study
- MRI brain: FLAIR, DWI/ADC, T2, post-gadolinium T1, SWI.
The manoeuvre
- Axial FLAIR through the third ventricle: symmetric medial thalamic hyperintensity.
- Mammillary bodies: FLAIR signal and enhancement on post-gadolinium T1 (acute).
- Periaqueductal grey and tectal plate on axial FLAIR.
- DWI: restriction in acute lesions.
- Name any symmetric pattern elsewhere (pons, putamina, cortex) and its differential.
What confirms it
- Typical symmetric lesions with a compatible clinical picture, improving with thiamine.
What licenses you to exclude it
- A normal MRI does not exclude Wernicke encephalopathy — sensitivity is moderate; treat on clinical grounds.
The classic misread
- Calling bilateral medial thalamic signal an artery of Percheron infarct without checking the mammillary bodies and periaqueductal grey.