Case of the week Details

Focal T2/FLAIR hyperintensity and diffusion restriction in central pons with sparing the periphery.

DIAGNOSIS:

CENTRAL PONTINE MYELINOLYSIS

DISCUSSION:

• Central pontine myelinolysis (CPM) is a syndrome that is characterised by rapid destruction of myelin sheaths of mainly oligodendritic cells, generally caused by a rapid rise in serum osmolality.
• Along with extrapontine myelinolysis, it is part of the osmotic demyelination syndrome (ODS).
• In most cases, ODS occurs in patients with chronic hypotonic hyponatraemia which is corrected too quickly.
• Known risk factors include severe hyponatraemia, alcoholism, thiazide use, hypokalaemia and malnourishment.
• Symptoms include confusion, quadriplegia and pseudobulbar palsy which occur 2-6 days after a rise in serum osmolality.
• The earliest changes are seen on diffusion weighted imaging in the central pons with eventual T2/FLAIR hyperintensity and T1 hypointensity. There is sparing of the periphery (ventrolateral longitudinal fibres and corticospinal tracts) with Trident shaped appearance. The overall appearance on T2/FLAIR axial MR images has also been likened to the face of a pig, referred to as piglet sign.’
• Similar appearances are seen in other parts of the brain: basal ganglia, midbrain and subcortical white matter.
• Differentials include: demyelination; pontine infarction; rhombencephalitis; pontine neoplasms;

Dr. Sriram Patwari
MD, PDCC (Neuroradiology)
Consultant Radiology, Co-lead Neuroradiology
Manipal Hospitals Radiology Group

Dr Vikas H P
DNB resident
Manipal Hospitals Radiology Group