MedPix Medical Image Database COW - Case of the Week Case Contributor: Neuroradiology Learning File - © ACR Affiliation: ACR Learning File®

MedPix No: History Pt Demographics: Age = 28 y.o. Gender = man 28-year-old male complained of right arm paresthesias after hurting his neck playing football. He underwent surgery and returns now, 2 years later, with recurrent symptoms. Downloaded by (-1)

MedPix No: EXAM & LABS

Film 1 The initial examination from 2 years ago (Film 1) demonstrates an extradural lesion at C5-6 compressing the anterior dural sac and cord. T2W sagittal sequence fails to demonstrate abnormal cord signal which would suggest myelomalacia from cord compression. Downloaded by (-1)

Film 2 The initial examination from 2 years ago (Film 1) demonstrates an extradural lesion at C5-6 compressing the anterior dural sac and cord. T2W sagittal sequence fails to demonstrate abnormal cord signal which would suggest myelomalacia from cord compression. Downloaded by (-1)

Film 3 The T1-weighted axial image (Film 3) demonstrates the lesion to be eccentric to right. Downloaded by (-1)

Film 4 The second examination done 2 years later (Films 4,5,6) demonstrates surgical fusion at C5-6 and a new extradural lesion at C6-7. As before, the lesion at C6-7 is isointense to disc and projects to the right with no abnormal cord signal on T2. Post-surgical changes include increased signal on the T1 sequence (Film 4) that is uniformly low signal on T2 (Film 5) in the vertebral bodies of C5 and C6. Further, no disc is identified on the central sagittal images at the C5-6 disc level. Downloaded by (-1)

Film 5 The second examination done 2 years later (Films 4,5,6) demonstrates surgical fusion at C5-6 and a new extradural lesion at C6-7. As before, the lesion at C6-7 is isointense to disc and projects to the right with no abnormal cord signal on T2. Post-surgical changes include increased signal on the T1 sequence (Film 4) that is uniformly low signal on T2 (Film 5) in the vertebral bodies of C5 and C6. Further, no disc is identified on the central sagittal images at the C5-6 disc level. Downloaded by (-1)

Film 6 The second examination done 2 years later (Films 4,5,6) demonstrates surgical fusion at C5-6 and a new extradural lesion at C6-7. As before, the lesion at C6-7 is isointense to disc and projects to the right with no abnormal cord signal on T2. Post-surgical changes include increased signal on the T1 sequence (Film 4) that is uniformly low signal on T2 (Film 5) in the vertebral bodies of C5 and C6. Further, no disc is identified on the central sagittal images at the C5-6 disc level. Downloaded by (-1)

FINDINGS The initial examination from 2 years ago (Film 1) demonstrates an extradural lesion at C5-6 compressing the anterior dural sac and cord. T2W sagittal sequence fails to demonstrate abnormal cord signal which would suggest myelomalacia from cord compression. The T1- weighted axial image (Film 3) demonstrates the lesion to be eccentric to right. The second examination done 2 years later (Films 4, 5, 6) demonstrates surgical fusion at C5-6 and a new extradural lesion at C6-7. As before, the lesion at C6-7 is isointense to disc and projects to the right with no abnormal cord signal on T2. Post-surgical changes include increased signal on the T1 sequence (Film 4) that is uniformly low signal on T2 (Film 5) in the vertebral bodies of C5 and C6. Further, no disc is identified on the central sagittal images at the C5-6 disc level.

DIFFERENTIAL DIAGNOSIS What is your Differential Diagnosis?

Diagnosis: Post-traumatic right C5-6 HNP that underwent anterior resection and fusion, with a new right C6-7 HNP. Dx Confirmed by:

DISCUSSION This case demonstrates three significant points. The first is the MR appearance of a post- traumatic cervical disc herniation. Second, it demonstrates the value of MR in the post- surgical patient with recurrent symptoms. Third, this case demonstrates one of the typical post-surgical anterior discectomy/fusion appearances on MR. The MR appearance of a herniated disc is discussed elsewhere. In this case, the MR findings in a post-surgical anterior fusion/discectomy will be discussed. - - In those patients imaged within the first 10 days after discectomy and fusion, there will be seen a characteristic appearance (1). The bone grafts are distinct but of variable signal intensity, depending upon the marrow composition of the graft. Patients that are examined from several months to two years will show a wide variety of signal changes in the graft and adjacent vertebral bodies. For the majority, the bone grafts tend to remain well defined low signal cortical bone. The adjacent bodies will show a wide latitude of signal changes for reasons that are not yet clear. It probably is the summation of effects depending upon the initial status of body and graft, the amount of trauma caused by the surgery, postoperative stresses on the fusion, and the degree of graft revascularization. In areas of vertebral body resection, there will be decreased signal relative to the normal body marrow. However, the most important postoperative changes that have been identified by MR are bony stenosis and new disc herniations (2). The stenosis is most often due to hypertrophic bone from the anterior fusion mass encroaching on the canal or foramen. Following anterior fusion/discectomy, instability can develop above or below the site of fusion due to excess stress. Disc degeneration can occur at the adjacent level in up to 81% of cases (3).