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Complications of Fluoroscopically Guided Extraforaminal Cervical Nerve Blocks: An analysis of 1036 injections 2005

Interventional Spine

Louis A Gilula, M.D.
Daniel J Ma , Medical Student - he is the main author of this paper, Non ASSR Member
Daniel K Riew , M.D.; Orthopedic surgeon, Non ASSR Member

Purpose

Purpose and Introduction: Despite the popularity of cervical nerve blocks for both therapeutic and diagnostic purposes, the complications related to the procedure are not well-established. Although there are recent case reports of fatal spinal cord infarction, injection into an anterior radicular artery and puncture of the epidural sac of the nerve root sleeve, to our knowledge, there are no studies that have critically examined the true incidence and severity of the complications associated with the procedure. We investigated our experience with fluoroscopically guided cervical nerve blocks (FCNB) to determine the incidence of complications in a large series of FCNB's performed at one institution.

Methods & Materials

Methods: All patients who had received a FCNB in the musculoskeletal section of the radiology department at our institution between 10/1999 & 6/2003 were included. A database of complications associated with the procedure and an early outcomes questionnaire was prospectively kept on all of these patients. An independent observer uninvolved with the procedures reviewed this database. The incidence of death, paralysis, stroke, spinal cord injury, vertebral artery injury, dizziness, numbness, transient weakness, pain, and memory loss following the procedure was noted. For the procedure, the patients were placed in a lateral decubitus position, prepped with alcohol and betadine, and locally anesthetized. A 25 gauge needle was placed into the extraforaminal area under fluoroscopic control, sliding along the anterior surface of the articular pillar, to avoid the vertebral artery. To ascertain that the needle tip was not in a vascular structure, contrast material was injected prior to injecting the anesthetic/medication mixture. Fluoroscopic spot-film radiographs documenting the procedure were taken in frontal, lateral, and oblique positions as a standard protocol. These were analyzed by the independent observer. Needle tip position was considered shallow if it was overlying the lateral half, and deep if overlying the medial half of the articular pillar. Needle tip position was identified as to needle tip widths anterior to the pillar in the true lateral view. Zone A was considered "ideal" when the needle tip lay directly on the anterior surface of the pillar. Zone B was within 2 needle widths anterior to the pillar. Zone C was more than 2 needle tip widths anterior to the pillar.

Results

Results: During the study period we performed 1036 FCNBs. There were no deaths, paralyses, strokes, spinal cord injuries, or vertebral artery injuries. Overall, 17 incidences of minor complications (dizziness, numbness, transient weakness, some pain, and one case of transient global amnesia) were associated with the procedure (1.64%). There was no statistically significant difference between a deep injection (n = 798) and a shallow injection (n = 238) (2.15%, 0.84%, p = 0.31). A statistically significant difference did exist, however, between the incidence of complications associated with a near-perfect posterior placement of the needle tip (Zones A and B; n = 904) and a more anterior placement (Zone C; n = 33) (1.44%, 6.06%, p = 0.04.).

Conclusion

Conclusions: As with any invasive procedure, cervical nerve blocks are associated with potential complications, including the catastrophic ones described in isolated case reports. Case reports, however, can be unnecessarily alarming in that they most often do not provide the incidence of such complications. In this large series of FCNBs, we found no instances of catastrophic complications and a small incidence (1.64%) of minor complications. The medial/lateral needle depth in the frontal view during the procedure does not seem to correlate with complications, though improper needle tip positioning in the lateral view does seem to contribute towards minor complications. We believe that with our technique, FCNBs are safe procedures with a low rate of minor complications.

References

There are no financial involvements in this work from any commercial concern.

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