Longitudinally extensive transverse myelitis with trident sign and positive AQP4 antibody: a case report

Longitudinally extensive transverse myelitis (LETM) is characterized by spinal cord lesions that affect at least three spinal cord segments. It can be associated with various inflammatory conditions. While imaging characteristics can aid in diagnosis, relying solely on them may lead to misinterpretation. We describe a 35-year-old woman who presented with subacute myelitis. Her cervical MRI (magnetic resonance imaging) revealed an extensive lesion from the area postrema down to the second thoracic level, with a trident sign observed in axial T1-weighted post-gadolinium imaging. The presence of a trident sign in MRI of patients with myelopathy is more commonly associated with sarcoidosis than other conditions. But our patient had positive (rechecked) AQP4 antibody and negative FDG-PET (fluorodeoxyglucose positron emission tomography) scan that shows trident sign could be seen in other inflammatory disorders such as NMO (neuromyelitis optica). Trident sign is not pathognomonic for sarcoidosis, additional investigations are necessary to identify the diagnoses related to the trident sign.