Disclosures: Richa Lamba, MD: Nothing to disclose

Case Description: Patient reported pain had a sudden onset 10 years ago but was worse in the past year. He reported a motorcycle accident and a fall from a tree, 10 and 9 years ago, respectively. Pain was located in the occipital region, left more than right, 5/10 at best, 8/10 at worst, regional numbness, and exacerbated by lying down. He denied any radiation down upper extremities, numbness/tingling, difficulty with fine motor skills or changes in balance. On physical exam, patient had pain to palpation at the C1 spinous process site. Strength, sensation, and range of motion testing did not elicit any deficits or pain. Plantar stimulus was down-going. Lhermitte’s and Hoffman’s signs were negative.

Setting: Ambulatory clinic

Patient: 28-year-old male with occipital pain.

Assessment/Results: Cervical spine x-ray noted possible congenital os odontoideum versus post traumatic non-united odontoid process with mild anterior displacement on flexion. CT cervical spine noted congenitally separate and dysplastic dens associated with anomalous thick anterior arch of C1. Orthopedic surgery evaluation deemed the abnormality as an unstable anteriorly displaced type II dens fracture with non-union and recommended urgent C1-C2 posterior spinal fusion, but patient elected to delay intervention.

Discussion: Os odontoideum is a rare anomaly that involves separation of the dens from the body of the axis. Etiology is unclear and is thought to be congenital or post traumatic. Treatment varies from conservative management and physical therapy to surgical fusion depending on presentation and determination of spinal instability.

Conclusion: This is a rare case of os odontoideum of unclear etiology with spinal instability in a young patient with a primary complaint of neck pain and no neurological deficits. Cervical spine instability can present in ambulatory setting, even with remote history of trauma; high index of suspicion and independent viewing of radiographic imaging enabled detection of a potentially serious spinal instability condition.

Level of Evidence: Level V

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PM&R Meeting Abstracts - https://pmrjabstracts.org/abstract/presentation-of-os-odontoideum-in-a-young-male-a-case-report/