Trident Sign: The Key Magnetic Resonance Imaging Finding Distinguishing Spinal Cord Sarcoidosis From Multiple Sclerosis and Seropositive Neuromyelitis Optica Spectrum Disorder

Background: Spinal cord sarcoidosis, an uncommon manifestation of neurosarcoidosis, presents diagnostic and therapeutic challenges because the condition is rare and has diverse clinical manifestations that can mimic other conditions such as multiple sclerosis and neuromyelitis optica spectrum disorder. Case Report: A middle-aged African American female with a history of idiopathic intracranial hypertension and hydrocephalus with ventriculoperitoneal shunt presented with progressive, predominantly left-sided gait instability, weakness, and paresthesia. Cerebrospinal fluid showed lymphocytosis, red blood cells, elevated oligoclonal bands, and elevated kappa free light chains, concerning for multiple sclerosis. Neuromyelitis optica spectrum disorder testing was negative. Magnetic resonance imaging (MRI) demyelination protocol revealed normal brain imaging and a longitudinally extensive spinal cord lesion with the distinctive trident sign on contrast-enhanced axial views, consistent with spinal cord sarcoidosis. The patient was treated with intravenous methylprednisolone for 5 days, resulting in improved lower extremity strength, but ataxia and sensory deficits, especially proprioception, persisted. Follow-up imaging and examinations demonstrated continued spinal cord involvement with minimal improvement despite treatment. Conclusion: Current management guidelines for spinal cord sarcoidosis are based on limited evidence, necessitating further research to establish optimal protocols. The trident sign on MRI may distinguish spinal cord sarcoidosis from conditions such as multiple sclerosis and neuromyelitis optica spectrum disorder. Early radiologic detection could improve outcomes and reduce long-term neurologic deficits. A comprehensive multidisciplinary approach is essential for effective, patient-centered care planning.