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Retro-odontoid pseudotumor presenting double layer on MRI: A case report
Ryo Kanematsu1, Junya Hanakita1, Toshiyuki Takahashi1
1Spinal Disorders Center, Fujieda Heisei Memorial Hospital, Fujieda, Japan.
Surgical Neurology International
|November 3, 2022
Summary
Retro-odontoid pseudotumors (ROPs) can present with a unique double-layer sign on MRI. This finding, associated with cervical myelopathy, may resolve spontaneously after C1-C2 fusion surgery.
Area of Science:
- Radiology
- Neurosurgery
- Orthopedic Surgery
Background:
- Retro-odontoid pseudotumors (ROPs) are masses posterior to the odontoid process.
- ROPs typically appear isointense to hypointense on T1-weighted MRI.
- The double-layer sign on T1WI MRI is a newly described imaging finding in ROP.
Observation:
- An 84-year-old male presented with cervical myelopathy and atlantoaxial instability.
- The patient's MRI revealed ROP with the double-layer sign and a cystic component.
- Dynamic X-rays confirmed atlantoaxial instability.
Findings:
- The double-layer sign consists of a ventral and a dorsal layer posterior to the odontoid process.
- Following C1-C2 posterior fusion, the patient's myelopathy resolved.
- Follow-up MRI demonstrated spontaneous regression of both pseudotumor layers.
Implications:
- The double-layer sign in ROP may represent reactive hypertrophy of the transverse ligament with cystic changes.
- Spontaneous regression of ROP and symptom resolution can occur after C1-C2 posterior fusion.
- This case highlights a potential imaging biomarker for treatment response in ROP.
