Computed tomography-guided cervical selective transforaminal epidural block for a patient with bilateral anatomical variations of vertebral artery -a case report-
A 56-year-old female patient presented with neck and left shoulder pain radiating to the left upper extremity. However, no objective loss of sensory or motor function was observed. Her pain had been aggravated for 10 days. Her visual analogue scale (VAS) score was 7 of 10. Although conservative treatments, including as resting, traction, non-steroidal anti-inflammatory drug and muscle relaxant were properly done for two weeks, her pain was not improved. The neurosurgeon requested a selective left C6 nerve root block. A cervical spine plain film radiograph showed degenerative cervical spondylosis (). The radiologist reported that the cervical magnetic resonance image (MRI) revealed a left-sided foraminal stenosis at the C5-6 level. Before performing the procedure, the author re-examined the MRI meticulously. Although the radiologist did not mention the VA, the author detected a tortuous anatomical variation in the VA at the left C5-6 level on the MRI (). The author ordered a CT angiogram to show the anatomical variations in the VA more precisely. The CT angiogram clearly showed bilateral tortuous anatomical variations in the VA (). In particular, the 3D reconstruction image showed a unilateral atypical entrance into the foramen transversarium (FT) of the fifth cervical vertebra and a hypoplastic abnormality of the right VA (). The diameters of the left and right VA were 4.86 mm and 2.47 mm at the lower endplate level of C5, respectively. The diameter of the left VA was 2.39 mm greater than that of the right at the C5 lower endplate. The maximum diameters of the tortuous component of the left and right VA were 9.80 mm and 6.64 mm, respectively. The maximum diameter of the tortuous component of the left VA was 3.16 mm greater than that of the right. The left VA entered the FT of the sixth cervical vertebra, whereas right entered the fifth. To minimize adverse events, the procedure was performed with dexamethasone (non-particulated steroid) and under CT guidance. The patient was placed in the supine position on a CT table with her head tilted slightly to the right. Before scanning, a wire was placed on the lateral side of her neck to use as a marker. The patient was scanned to identify a suitable approach point for the 23 G spinal needle. A path that avoided contact with the periosteum and deep cervical plexus was chosen to minimize patient discomfort. The scanning level for the CT fluoroscopy (CTF) image was selected and the target lesion was scanned to a thickness of 1 mm from the middle of the C5 body to the middle of the C6 body. The skin entry point and target point for the spinal needle was determined on the CT scan view () and marked on the neck. Before the CSTE was performed, 2% lidocaine was aseptically infiltrated into the skin and subcutaneous tissue. The needle was then advanced toward the target point using intermittent CTF guidance. The needle was advanced slowly into the left C5-6 foraminal area while avoiding the large tortuous VA. It was confirmed that the 23 G spinal needle was located exactly within the left-sided C5-6 foraminal area using 0.3 ml of radio-contrast dye (). After confirmation of appropriate needle placement, the author injected a mixture of 0.5% lidocaine 2 ml and dexamethasone 5 mg. Pain was relieved immediately after completion of the procedure and two weeks later, VAS score was decreased to 1 or 0 of 10. The patient's symptoms were relieved almost completely and did not recur in the following 3 months.