Chronic Type II Odontoid Fracture With C1-C2 Instability and Severe Spinal Cord Compression

History

This 29-year-old female had a history of an old type II odontoid fracture she sustained after a fall one year ago. Surgical intervention was recommended, but she declined that treatment.

She presented with severe mechanical neck pain, progressive bilateral upper and lower extremity weakness and numbness, and gait and balance difficulties.

Examination

On examination, the patient was awake and responsive, and oriented to person, place and time. The cranial nerves (II-XII) intact, there was no pronator drift, bilateral upper and lower extremities 4/5 throughout, there was diffuse numbness in both arms and legs, hyperreflexia throughout, positive bilateral Hoffman’s sign, and sustained clonus bilaterally.

Pretreatment Imaging

Cervical spine imaging revealed an old sclerotic type II dens fracture with anterolisthesis of C1 over C2, resulting in severe compression of the spinal cord with high T2 cord signal at the cervicomedullary junction. Flexion-extension cervical spine x-rays showed atlanto-dental interval (ADI) of 14mm on flexion that reduced to 4mm on extension.

Figures 1A-1D (below) respectively demonstrate sagittal cervical spine CT showing a chronic sclerotic type II dens fracture with anterolisthesis; cervical spine MRI shows a severely compressed spinal cord at the cervicomedullary junction with high T2 cord signal; flexion-extension cervical spine x-rays shows ADI of 14mm on flexion that reduces to 4mm on extension.

Figure 1A. Sagittal cervical spine CT shows a chronic sclerotic type II dens fracture with anterolisthesis.

Figure 1B. Cervical spine MRI shows a severely compressed spinal cord at the cervicomedullary junction with high T2 cord signal.

Figure 1C. Cervical flexion x-ray.

Figure 1C. Cervical extension x-ray.

Diagnosis

Chronic type II odontoid fracture with C1-C2 instability.

Selected Treatment

Posterior C1 lateral mass screw and C2 pedicle screw with fusion and C1 laminectomy.

Surgical Rationale
Given that C1 reduces on extension view to a relatively normal spinal alignment with ADI of 4mm, we elected for C1-C2 instrumented fusion with C1 laminectomy.

Post-Treatment Imaging

Figures 2A-2C (below) respectively demonstrate C1 lateral mass with C2 pedicle screws with reduction of the C1 anterolisthesis; mid-sagittal cervical spine CT shows reduction of the fractured dens and C1 anterior arch; lateral side image of the cervical spine CT shows the trajectory of the screws.

Figure 2A. C1 lateral mass with C2 pedicle screws with reduction of the C1 anterolisthesis.

Figure 2B. Mid-sagittal cervical spine CT shows reduction of the fractured dens and C1 anterior arch.

Figure 2C. Lateral side image of the cervical spine CT shows the trajectory of the screws.

Outcome

The patient did very well, and at 6 weeks following surgery her mechanical neck pain completely resolved, and her upper and lower extremity weakness and numbness improved significantly, as well as her gait and balance.

Peer Discussion

Vincent Traynelis, MD

Professor of Neurosurgery

Rush University

Dr. Khalil presents a case of instability and myelopathy in a young woman with an untreated odontoid fracture. The management with a C1 laminectomy and posterior C12 fusion is excellent.

There are really no other alternatives at this point. It is outstanding that she is already significantly improved within 6 weeks of surgery. The importance of making the proper diagnosis, formulating the correct surgical plan, and executing the procedure with precision cannot be overstated.

Additionally, this case underscores the importance of treating all odontoid fractures promptly in an appropriate fashion to avoid patients from progressing to such a severe condition.