Case 6
Anterior Cervical Approach
John D. Barr and John M. Mathis
Clinical Presentation
A 43-year-old man was referred with severe neck pain and imaging findings consistent with diffuse metastatic disease to bone. The onset of pain had been gradual over several months, and there were no other neurologic symptoms at the time of presentation. The patient had no known primary cancer. An image-guided biopsy was requested.
Imaging Findings
Magnetic resonance imaging (MRI) demonstrated diffusely abnormal signal in the cervical spine with the largest lesion in C4 (Case Figure 6.1A,B). A computed tomography (CT) scan showed that the central portion of C4 was destroyed and the vertebra partially collapsed (Case Figure 6.1C,D). There was no extension of tumor into the spinal canal.
Procedure
A C4 biopsy was planned, which would be followed by vertebroplasty.
There is no contraindication to percutaneous vertebroplasty (PV) in conjunction with biopsy before the cell type of a metastatic or primary tumor of bone is known. The approach to C4 used was anterior oblique with a small guide needle to first ensure that no critical structures (i.e., carotid artery) were punctured. A right side approach is always pre- ferred to avoid the esophagus, found centrally or to the left behind the trachea.
The vascular structures on the right are manually pushed aside during the insertion of a 20-gauge guide needle (Case Figure 6.2A,B;
see also Figure 2.3). After introduction, the guide needle position can be confirmed with CT scanning. As opposed to fluoroscopy, CT scan- ning can show the internal structures of the neck and help ensure that the guide needle adequately misses critical structures. Subsequently, a 272
Case Figure 6.1. (A)Lateral T2 sagittal MRI shows diffuse abnormal signal in cervical vertebra with a large area of marrow replacement within C4 (white arrow). (B) A postcontrast T1 sagittal MRI demon- strates diffuse metastatic disease to bone, with the largest area of enhancement at C4. (C) A sagittal CT reconstruction reveals the loss of height at C4 consistent with a compression fracture. (D) The axial CT image of C4 also shows destruction and replacement of the osseous structure of this vertebral body.
A
C
B
D
Anterior Cervical Approach
Esophagus Sternocleidomastoid
Jugular vein
Carotid artery
Case Figure 6.2. (A)An artist’s sketch of the cervical approach used for guide needle introduction to C4. Note that the approach is on the right, with the vascular structures manually pushed laterally during needle introduction. This technique is commonly used for cervical discography. (B) A lateral radiograph shows the guide needle (black arrow) in place, with the tip touching the anterior lateral margin of C4. (C) The cannula has been coaxially introduced over the guide needle. (D) A biopsy device has been inserted through the guide cannula to allow a core of tissue to be extracted. The cannula can remain in place for the subsequent PV.
A
C
B
D
larger cannula is placed coaxially over the 20-gauge guide needle to the surface of C4 (Case Figure 6.2C). The 20-gauge needle is removed and the trocar replaced into the cannula and advanced into the body of C4. The trocar can now be removed and a biopsy device placed through the cannula to obtain a bone core (Case Figure 6.2D).
A B
C D
Case Figure 6.3. (A,B)Two adjacent level axial CT scans of C4 post-PV. Note good filling of the ver- tebra and no significant leak of cement. (C,D) Lateral and anteroposterior radiographs post-PV demon- strate the appearance of C4 following cement injection. The vertebral margins and exact location of the cement are harder to confirm than with CT.
After the biopsy material is obtained, bone cement (polymethyl- methacrylate) is mixed and injected in small aliquots (i.e., 0.1–0.2 mL) with CT images obtained between injections. Computed tomography gives excellent visualization of the cement location, and small injec- tions ensure that any potential leaks will be detected before becoming large enough to create clinical symptoms (Case Figure 6.3A,B). Radi- ographs of C4 give poorer definition of cement position by compari- son (Case Figure 6.3C,D).
Results
The patient tolerated the procedure well. There were no clinical com- plications, and substantial pain relief was noted within hours of the procedure. The biopsy material revealed a homogenous infiltration of cells consistent with myeloma.
Discussion
This case illustrates an acceptable approach to cervical and high tho- racic vertebrae for both biopsy and PV therapy. An alternate route for the clivus and C1–2 region is transoral. However, the needle must pass through oral mucosa for this approach, and seeding of bacteria is always a concern. Computed tomography offers good visualization and surpasses that obtained with fluoroscopy. Also, the placement of a guide needle allows a small-gauge needle introduction and confirma- tion of location before the large bone cannula is placed.
The cervical spine is rarely involved by a compression fracture unless there is underlying tumor invasion and vertebral destruction. Pure osteoporotic fractures are essentially never seen in this region.
The amount of bone cement needed is usually only 1–2 mL. There is no contraindication to PV before radiation or chemotherapy, so PV can follow immediately after the biopsy, as was done in this case.
