2026 Poster Presentations
P326: DISCOVERY AND IMPROVEMENT OF A CERVICOMEDULLARY SYRINX FOLLOWING ENDOSCOPIC ENDONASAL ONDONTOIDECTOMY AND POSTERIOR FIXATION
Samantha A Omidfar, BS, MS; Stephanie Cheok, MD; Hailey Mattheisen, BS, MS; Sara Saleh, MD; Nathan Zwagerman, MD; Medical College of Wisconsin
Introduction: Odontoid pannus is a rare, usually benign soft tissue growth on the odontoid process of the C2 that can cause significant craniocervical compression. In caudal cases, compression can lead to syrinx formation. Literature demonstrates that surgical decompression can improve syrinxes We present a case of postoperative syringobulbia and syringomelia with subsequent improvement following endoscopic endonasal ondontoidectomy and posterior occipito-cervical-thoracic decompression and fusion
Methods: We performed an IRB-approved retrospective review of a patient at our institution.
Case Presentation: The patient is a 72-year-old left- handed male with diabetes mellitus type 2, degenerative osteoarthritis and a prior C3-C6 anterior cervical discectomy and fusion 30 years ago after trauma. He presented with left hemibody weakness progressing to quadriparesis. Initial CT angiogram for stroke showed a posterior odontoid mass. Cervical spine MRI revealed a soft tissue pannus compressing the craniocervical junction and kinking of the cervical cord at that level with associated cord signal change. He was then transferred to our institution for definitive management.
On neurologic exam, he was alert, oriented, without cranial nerve deficits, but had increased muscle tone and significant weakness in all extremities. This was worse on the left, with near loss of volitional movement in the left arm, summarized in Table 1. At this point, he was >24 hours from symptom onset.
Given the primarily ventral pathology, staged anterior decompression and posterior decompression and fixation was offered. He underwent an endoscopic endonasal approach for odontoid pannus resection with neurosurgery and otolaryngology, followed by posterior decompression and occiput to T3 posterior fusion with a spine specialist.
Immediate postoperative MRI showed a new cystic CSF collection at the ventral cervicomedullary junction consistent with a syrinx. (Figure 2). Recovery was slow and complicated by acute congestive heart failure, acute kidney injury and requirement of a tracheostomy tube. He was discharged on postoperative day 32 with significant neurologic improvement and was ambulatory with a walker (Table 1). MRI obtained 6 weeks postoperatively showed near complete syrinx resolution (Figure 3).
Discussion: We present a rare case of postoperative syrinx discovery following anterior/posterior decompression and stabilization for symptomatic odontoid pannus. This case demonstrates multiple unique facets: first the acuity and progression of quadriparesis is relatively uncommon as a C2 pannus is generally slow growing. Next, decompression revealed a large cervicomedullary syrinx, likely pre-existing but only apparent on post-operative imaging. Finally, decompression and stabilization improved both the syrinx and the patient’s neurologic exam.
Conclusion:
Chronic compression can induce syrinx formation in the lower brainstem and cervical spinal, sometimes uncovered after decompression. While a syrinx may mark spinal cord injury, it does not preclude improvement. Access to the ventral source of compression is feasible with an endoscopic endonasal approach. Decompression and fixation can improve both the syrinx and the patient’s neurologic status.
