Do the gaps in the ligamentum flavum in the cervical spine translate into dural punctures? An analysis of 4,396 fluoroscopic interlaminar epidural injections.

BACKGROUND Cervical interlaminar epidural injections are performed frequently in managing chronic neck and upper extremity pain, although less commonly than lumbar interlaminar epidural injections. Recently, the US Food and Drug Administration warnings and safeguards to prevent neurologic complications. These were developed by the Multi-Society Pain Workgroup have taken center stage for all types of epidural injections, including cervical interlaminar epidural injections. The recommendations of safeguards to prevent neurologic complications after epidural steroid injections include that cervical interlaminar epidural injections must be performed utilizing fluoroscopy with anteroposterior, lateral, or oblique views with injection of contrast medium and that entry be limited to the C7-T1 epidural space or occasionally the C6-C7 with requirements for magnetic resonance imaging assessment of the epidural space. OBJECTIVES To assess the incidence of dural puncture associated with fluoroscopically directed cervical interlaminar epidural injections. STUDY DESIGN A retrospective assessment of patients undergoing cervical interlaminar epidural injections from January 2013 through February 2015. SETTING A private interventional pain management practice; a specialty referral center in the United States. METHODS The data were collected for 4,396 consecutive cervical interlaminar epidural injections performed from January 2013 through February 2015. The procedures were all performed under fluoroscopic visualization under posteroanterior view with contrast medium injection with lateral view confirmation when indicated. The procedures were performed by one of 2 physicians; the dural puncture and subsequent postoperative complications with level of epidural entry were determined. OUTCOMES ASSESSMENT The outcome was assessment of dural puncture. RESULTS A review of multiple manuscripts showed that defects in the ligamentum flavum may extend to as much as 100% of the population. However, it also has been shown that among the levels with a gap, the location of a gap in the caudal third of the ligamentum flavum was more frequent than in the middle or cephalic portion of the ligamentum flavum. Among the 4,396 epidural injections performed at C7-T1, C6-C7, and C5-C6, 1,227 were performed at C7-T1; 1,835 were performed at C6-C7; and 1,334 were performed at C5-C6. Dural punctures were observed in 1.8% (24 procedures) at the C5-C6 level entry; 0.87% (16 procedures) at the C6-C7 level entry; and 1.71% (21 procedures) at the C7-T1 level. There was no significant difference among the entry levels. No complications or spinal cord damage or postdural puncture headache were observed. LIMITATIONS The limitations of this report include that it is an assessment by only 2 well experienced physicians, even though it included a relatively large number of patients. CONCLUSION This study illustrates that dural puncture is equally prevalent, though very rare, irrespective of the needle entry level into the epidural space, with an overall dural puncture rate of 1.4%, with 1.8% at the C5-C6 level, 0.87% at the C6-C7 level, and 1.71% at the C7-T1 level. Based on the present literature, it appears that performing the procedure by inserting the needle into the cephalic portion of the intervertebral space rather than the caudal portion may be safer.