Headache rate and cost of care following lumbar puncture at a single tertiary care hospital

DISCUSSION

We found that the rate of PLPH was significantly higher in our patient population with the use of a cutting needle (13%) as compared to what the expected rate would have been with a noncutting needle (4%). The rate of PLPH observed in this study is less than what has been previously reported in the literature but may have been due to underreporting of events. Patients may have stayed at home without seeking medical attention, may have consulted their own primary care physician, or may have gone to another hospital for emergency care. Further, we found that the costs associated with the use of a cutting needle (approximately $20,000 per year) were also significantly higher than what would have been expected with the use of a noncutting needle, despite higher initial costs associated with the purchase of a noncutting needle system.

This study highlights the potential importance of switching from a cutting to noncutting needle not only from the standpoint of patient care but also from the standpoint of cost. The costs estimated in this study were direct only, i.e., to patients and insurers. Indirect costs, e.g., the time spent by hospital personnel triaging patient phone calls (which was generated by 6% of all patients undergoing lumbar puncture in this study), time off work resulting in reduced productivity and wages, and time lost by family members transporting patients to the emergency department of office for headache treatment were beyond the scope of this study. Therefore, the costs estimated in this study are likely an underestimate of the true cost of an increased PLPH rate. Arendt et al.⁷ report that for every 6 patients having lumbar puncture with a noncutting needle, one will be spared a PLPH as compared with a cutting needle. A common misperception is that noncutting needles are more difficult to use. In fact, operator difficulty and failure rate are higher with cutting needles.⁸ Examples of noncutting needles include the Sprotte and Whitacre needles.⁹ These needles are readily available through various manufacturers. The technique of insertion differs from that of a cutting needle in that an introducer needle is used at the start of the procedure in order to puncture the skin.

In this cohort of patients, only younger age was an independent predictor of PLPH. Previous studies have identified younger age, female gender, and headache before or at the time of lumbar puncture as risk factors for headache.⁵ Lower body mass index and prior PLPH have been identified as possible additional risk factors. Class I and Class II data have not demonstrated that the duration of recumbency following a diagnostic LP influences the occurrence of PLPH. Further, there is no evidence that postprocedural hydration prevents PLPH. Despite its frequent use (and substantial cost), the practice of using IV caffeine for PLPH is not supported by well-designed clinical trials.¹⁰ In this study, aspirin use was not an independent predictor of absence of PLPH; however, the relatively few patients using antithrombotic agents may have obscured a true effect. Alternatively, aspirin use may have obscured mild PLPH. Further studies examining a possible relationship should be pursued.

The exact mechanism of PLPH is unknown. Possible explanations include persistent leakage of CSF from the puncture site, dilation of intracranial vessels, and psychological factors. Marshall¹¹ performed lumbar punctures on 43 patients initially and 24 hours later. He found that although there was a tendency for PLPH to be associated with low CSF pressure, the relationship was not invariable nor was a low CSF pressure always associated with a headache. He suggested that a drop in a CSF pressure was not causal of the headache. Göbel et al.¹² showed that patients with PLPH had higher right middle cerebral artery mean systolic flow velocities on TCD prior to lumbar puncture and lower mean systolic flow velocities in the right middle cerebral artery after lumbar puncture. They suggested that dilation of intracranial vessels may play a role in PLPH. Finally, Daniels and Sallie¹³ found that 46% of patients who were warned about PLPH developed one as compared to 6% who were not warned. They suggested that psychological factors may play a role. Noncutting needles offer the advantage of causing less CSF leakage than cutting needles¹⁴ although the precise mechanism of reduced PLPH is not completely known.

The limitations of this study include its retrospective design, the lack of an actual comparison group of patients undergoing lumbar puncture with a noncutting needle, and lack of information on indirect costs.

Further studies evaluating the adverse event rate and costs associated with switching to the noncutting system are warranted. In addition, further studies regarding the roles of aspirin around the time of lumbar puncture are warranted.