Re: Postepidural Headache: How Late Can It Occur?

To the Editor: I applaud the author's enthusiasm to contribute to the medical literature; however, a number of issues detract from the validity of the published data and any conclusions that may be drawn from it.¹ Although Dr. Reamy suggests that this is the first case to demonstrate the onset of postdural puncture headache (PDPH) beyond the well-accepted normal range of 1 to 7 days after epidural puncture, a range of 1 to 12 days has previously been reported in at least one case series as well as in editorials and review articles.^2–4

According to the cited meta-analysis, the incidence of PDPH in an obstetric population is roughly 0.75% and occurs when there is an accidental entry into the intrathecal space while attempting epidural placement.⁵ In this case, epidural placement was uneventful—ie, without dural puncture—and thus a mechanism for entry into the intrathecal space is unclear. Furthermore, it is impossible to place an epidural catheter through a 25-gauge needle; this is the instrument most often used to provide intrathecal analgesia.³ It is unlikely that the patient received analgesia through this route because the duration of action (>4 hours) is beyond the abilities of intrathecal medications at conventional doses. Epidural catheters are typically placed through 16- to 18-gauge Tuohey needles.

Another major issue that is not adequately addressed in this report is the fact that the patient underwent a diagnostic lumbar puncture in the emergency department. Most emergency department lumbar puncture kits include a 20-gauge spinal needle, which carries a 40% risk of PDPH in the obstetric population.³ Moreover, in the setting of an existing symptomatic dural puncture, further drainage of cerebrospinal fluid exacerbates symptoms. The patient's symptoms were apparently improved with intravenous analgesics, antiemetics, and fluid to the point that she was discharged from the hospital after the diagnostic procedure. Interestingly, the patient's symptoms worsened significantly the day after intervention in the emergency department. This may suggest that the epidural blood patch served as an effective therapeutic modality because of a PDPH from the lumbar puncture in the emergency department.

In addition to these issues, some of the technical jargon is used in a very confusing manner. For example, “high or spinal anesthesia” is listed as a potential complication of epidural placement. This is very ambiguous because the terms “high” and “spinal” are not synonymous. It is possible to have a high epidural level, but only accidental or unrecognized dural puncture can lead to a “spinal” (which may progress to a high spinal). Patient management in each of these situations may be markedly different. Nonetheless, it is crucial to note that Dr. Reamy's central message of not allowing patient care to be negatively influenced by the findings of a single, nonauthoritative, pooled analysis remains extremely important.