Case of the Month

Reduced conciousness and seizures

Diagnosis

Wernickes encephalopathy / thiamine deficiency

Investigation

Left Image: Axial T2 weighted sequence demonstrating increased signal in the periaqueductal grey matter of the midbrain surrounding the cerebral aqueduct and increased signal in the mamillary bodies.

Centre Image: Axial T2 weighted image at a slightly higher level showing increased signal in the structures surrounding the third ventricles, including the medial thalamus and hypothalamus.

Right Image: Coronal FLAIR sequence showing increased signal adjacent to the third ventricle.

Discussion

Thiamine deficiency can result in Wernickes encephalopathy, a serious neurological condition. In the Western world this typically occurs in the setting of chronic alcoholism, however it is increasing being recognised in nonalcoholic nutritional deficiencies.

MRI is between 50% and 60% sensitive in demonstrating changes typical of thiamine deficiency and so cannot exclude the diagnosis.

Typical changes include increased signal in the periaqueductal grey matter of the midbrain surrounding the cerebral aqueduct and in the structures adjacent to the third ventricle including the medial thalamus, hypothalamus and mamillary bodies. These regions may show abnormal enhancement and diffusion restriction. The mamillary bodies may also be atrophic.

MRI may also demonstate other features of chronic alcoholism. These include atrophy of the cerebral hemispheres and disproportionate atrophy of the cerebellar superior vermis.