Trident sign (neurosarcoidosis)

Last revised by Jeremy Jones on 10 Feb 2024

Citation, DOI, disclosures and article data

Citation:

Sharma R, Jones J, Garnham J, et al. Trident sign (neurosarcoidosis). Reference article, Radiopaedia.org (Accessed on 27 Apr 2024) https://doi.org/10.53347/rID-172832

DOI:

https://doi.org/10.53347/rID-172832

Permalink:

https://radiopaedia.org/articles/172832

rID:

172832

Article created:

31 Jul 2023, Rohit Sharma ◉

Disclosures:

At the time the article was created Rohit Sharma had no financial relationships to ineligible companies to disclose.

View Rohit Sharma's current disclosures

Last revised:

10 Feb 2024, Jeremy Jones ◉

Disclosures:

At the time the article was last revised Jeremy Jones had no financial relationships to ineligible companies to disclose.

View Jeremy Jones's current disclosures

Revisions:

8 times, by 4 contributors - see full revision history and disclosures

Systems:

Central Nervous System, Spine

Sections:

Signs

Tags:

cases

Synonyms:

Trident sign (spinal cord)

The trident sign is a radiological (MRI) sign described in spinal cord neurosarcoidosis.

The sign is formed by the axial appearance of a longitudinally extensive transverse myelitis due to spinal cord neurosarcoidosis, whereby on a T1 post-contrast (gadolinium) MRI sequence, there is central canal enhancement accompanying crescent-shaped posterior subpial enhancement ^1-3. This gives the appearance of a trident, a three-pronged spear ^1-3.

It has been suggested that this is a useful sign in differentiating neurosarcoidosis from other causes of longitudinally extensive transverse myelitis, such as neuromyelitis optica spectrum disorder (NMOSD) ³. However, it should be noted that while it may be characteristic, the trident sign may not be commonly present in cases of spinal cord neurosarcoidosis; for example, it was not found in any cases in one large case series of patients with the condition ⁴. It is also not specific for neurosarcoidosis and can be seen in other pathologies (e.g. HTLV-1-associated myelopathy, spinal cord primary CNS lymphoma) ^6,7.

History and etymology

The trident is a three-pronged lance used for spear fishing. In classical mythology, it was the weapon born by sea gods (Poseidon in Ancient Greece or Neptune in Roman mythology) ⁵. Although a similar weapon, the trishoola, with rounded tines, is also seen being carried in images of Hindu gods (Shiva and Durga) ⁵. The trident sign was first employed in the context of neurosarcoidosis in 2016 ¹.