{"id":"d1ef6261-bfb4-42a2-92db-178423a1d55d","slug":"retro-odontoid-pseudotumor-presenting-double-layer-on-mri-a-case-report","title":"Retro-odontoid pseudotumor presenting double layer on MRI: A case report","authors":["Ryo Kanematsu","Junya Hanakita","Toshiyuki Takahashi","Manabu Minami","Izumi Suda","Sho Nakamura","Shu Takeuchi","Yoshitaka Tsujimoto"],"abstract":"Background: Retro-odontoid pseudotumors (ROPs) typically present as a single mass posterior to the odontoid ranging from isointense to hypointense relative on T1-weighted magnetic resonance (MR) imaging (MRI T1WI). Here, a patient with ROP exhibited the double-layer sign on the MRI T1WI characterized by an initial ventral layer posterior to the odontoid process followed by a secondary dorsal layer. Case Description: An 84-year-old male presented with cervical myelopathy attributed to ROP resulting in atlantoaxial instability on dynamic X-ray studies, and the double-layer sign on the T1 MR accompanied by a cystic component. MR following C1–C2 posterior fusion, the patient’s myelopathy resolved and both layers spontaneously regressed on the follow-up MR studies. Conclusion: The MR-documented double layer sign with ROP, likely attributable to reactive hypertrophy of the transverse ligament with cystic components, may demonstrate spontaneous MR regression with symptom resolution following a C1–C2 posterior fusion.","thumbnailUrl":"https://sni-digital-videos.s3.amazonaws.com/articles/d1ef6261-bfb4-42a2-92db-178423a1d55d/featured/hero-1781560903507.png","publishDate":"2022-09-30T00:00:00.000Z","doi":"10.25259/SNI_756_2022","categories":["Spine","Case Report"],"fullTextUrl":"https://surgicalneurologyint.com/api/articles/d1ef6261-bfb4-42a2-92db-178423a1d55d/pdf"}