Reason: evaluate nerve roots and for cord compression History: C1-C2 instability The patient has an os odontoideum. The patient is status post posterior fusion and laminectomies at C1 - C2.There is signal hyperintensity within the spinal cord at the C2 vertebral body level which to some degree was present on the prior exam.Compared to the previous exam the alignment between C1 and C2 has changed. The anterior arch of C1 as well as the os odontoideum have migrated posteriorly relative to the rest of the C2 vertebral body. There is no compromise of the cervical spinal cord at C1-2.At C2-3 there is no significant compromise to the spinal canal or neural foramina.At C3-4 there is no significant compromise to the spinal canal or neural foramina.At C4-5 there is no significant compromise to the spinal canal or neural foramina.At C5-6 there is no significant compromise to the spinal canal or neural foramina.At C6-7 there is no significant compromise to the spinal canal or neural foramina.At C7-T1 there is no significant compromise to the spinal canal or neural foramina.The vertebral artery flow voids appear to be intact. The left vertebral artery is significantly larger than the right vertebral artery. The right vertebral artery appears to be hypoplastic and this finding was also present on the previous exam.
1.The patient has an os odontoideum. The patient has undergone posterior fusion at C1-2. Since the previous examination the alignment between C1 and C2 has changed. The anterior arch of C1 as well as the os and the 20 and are subluxed posteriorly relative to the C2 vertebral body. There is no associated compromise to the cervical spinal canal at this level however. Please note that extension/flexion plain film views may provide more insight on stability.2.There is signal change present within the cervical spinal cord at the the C1-2 level. To some degree this is previously present and may represent a cord myelomalacia. A superimposed new or injury cannot be excluded.3.Please note that this examination is rather limited due to some patient motion as well as the patient's inability to tolerate the exam terminating the exam early.4.Please refer to CT of the cervical spine for further comments.