The Trident Sign in Patients with Neurosarcoidosis: A Systematic Review

Document Type

Conference Proceeding - Restricted Access

Publication Date

5-8-2026

Abstract

Neurosarcoidosis, a manifestation of systemic sarcoidosis that affects the central nervous system, occurs in approximately 5-15% of patients with sarcoidosis. Myelopathy is observed in 10-27% of neurosarcoidosis cases. A highly pathognomonic imaging feature of neurosarcoidosis is the "trident sign," characterized by a distinctive pattern of contrast enhancement on spinal MRI, resembling a trident due to involvement of the central canal and dorsal subpial regions. In this study, we conducted a systematic review to assess the prevalence of the trident sign among patients with neurosarcoidosis. Additionally, we explore the underlying pathophysiology of the trident sign, which is thought to arise from granulomatous inflammation preferentially affecting the meninges and spinal cord parenchyma.

This systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines to evaluate the prevalence of the trident sign in patients with neurosarcoidosis presenting with transverse myelitis or myelopathy. The review focused exclusively on original research articles published in PubMed over the last 20 years (January 1, 2006, to February 8, 2026). A comprehensive literature search was performed in PubMed using the following search terms: ("neurosarcoidosis" OR "spinal sarcoidosis" OR "sarcoid myelopathy") AND ("trident sign" OR "dorsal subpial enhancement" OR "central canal enhancement") AND ("myelitis" OR "myelopathy" OR "spinal cord involvement"). The search was limited to articles published in English, involving human subjects, and within the specified time frame. Only articles with more than 5 cases were included. The quality of included studies was assessed using the Newcastle-Ottawa Scale.

Across the 102 patients, the prevalence of the trident sign varied widely (10%-89%) depending on study population and myelopathy phenotype. In subgroups with subacute or longitudinally extensive myelitis (Zalewski and Flanagan studies, n=40), the trident sign was highly prevalent (70% overall; 28/40). In the broader myelopathy cohort (Murphy study), it was less common (10%), suggesting the sign is more specific to certain presentations like longitudinally extensive transverse myelitis. No meta-analysis was performed due to heterogeneity in patient selection and definitions, but qualitatively, the trident sign appears pathognomonic in appropriate clinical contexts, aiding differentiation from mimics like NMOSD or multiple sclerosis. The most characteristic MRI enhancement pattern is dorsal subpial (up to ~65%), often linear/crescentic and multi-segmental (classic trident sign on axial).Ventral subpial: ~19% ,Meningeal/radicular: ~37%, Patchy/nodular parenchymal: ~23-45% , AND Leptomeningeal: ~23% (range 20-40).

The Trident sign is highly prevalent in neurosarcoidosis, is very specific sign, that most point out doctors, residents that the most likely diagnosis is neurosarcoidosis, but they need to be aware of others patterns of enhancement in neurosarcoidosis.

Comments

2026 Research Day Corewell Health West, Grand Rapids, MI, May 8, 2026. Abstract 2051

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