Trident sign (osmotic demyelination)

The trident sign describes the typical appearances of the pons in osmotic demyelination syndrome, whereby the symmetrical high T2/FLAIR signal abnormality centrally in the pons is shaped like a trident, the three-pronged spear of classical Greece . The predominant involvement of the transverse pontine fibers and relative sparing of the descending corticospinal tracts is responsible for this characteristic ‘trident’ shaped appearance (omega sign) .

History and etymology

The trident is a three-pronged lance employed for spearing fish, and in Classical mythology was the weapon born by sea gods, such as the sea god Poseidon in Ancient Greece (or Neptune, the classical Roman equivalent). Although a similar weapon, the trishoola, with rounded tines, is also seen being carried in images of Hindu gods, e.g. Shiva and Durga .