A Problem-Based Learning Discussion

A 26-year-old patient who is gravida 2, para 1, presents to labor and delivery triage at 30 weeks, 4 days, with significant headaches. She reports no medical history but has had some elevated blood pressures during her obstetric (OB) visits. She also reports a recent neurology workup for her headaches during pregnancy. The OB pages you for a possible epidural blood patch.

Vitals: blood pressure = 144/78 mmHg, heart rate = 100 bpm, respiratory rate = 18, and temperature = 98.6°F
Labs: creatinine = 0.6 mg/dL, hemoglobin = 10 g/dL, platelets = 210 × 10⁹/L

Questions

What is the differential diagnosis for intrapartum headache?

• Primary headache disorders (tension, cluster, migraines)
• Preeclampsia or eclampsia
• Posterior reversible encephalopathy syndrome
• Idiopathic intracranial hypertension (IIH)
• Postdural puncture headache (PDPH) after recent lumbar puncture (LP)
• Brain tumor
• Meningitis
• Central venous thrombosis and ischemic stroke because of increased risk during pregnancy
• Medication overuse headache from over-the-counter analgesics or parturient medications
  

How can you differentiate the clinical presentation of headaches caused by PDPH, preeclampsia with severe features, or IIH?

Table 1. Presentation of headaches caused by PDPH, preeclampsia, and IIH

What tests do neurologists typically perform for patients with presumed IIH?

• IIH is an increase in intracranial pressure with unknown cause, but neurologists typically test opening pressure, cytology for cancers, and white blood cell count for infection.²
• Lumbar punctures may demonstrate high intracranial pressure and rule out other causes of increased intracranial pressure.
• Opening pressures are a surrogate for intracranial pressure.
• Infections or tumors may cause increased intracranial pressure.

What needle gauge is typically used for a LP, and what is the associated risk of PDPH?

• 20- to 25-gauge needles are commonly used for lumbar punctures to obtain an adequate volume of cerebrospinal fluid and measure opening pressures.

Table 2. Factors that influence PDPH incidence³

You diagnose the patient with PDPH and proceed with an epidural blood patch (EBP). Upon examining her back, you notice a small puncture site at the L4–L5 interspace.

Where would you plan your EBP entry point?

• For postdural punctures, target the level of prior LP, in this case L4–L5.
• For patients with suspected spontaneous intracranial hypotension, L2–L3 is often the initial target level, but it is typically inferior to the conus for accidental dural puncture, usually less affected by impeding degenerative changes, and a relatively superior starting point given that most cases of spontaneous intracranial hypotension are associated with upper spine leaks.⁴

What is the suspected spread of injected blood?

• Studies have shown that the mean spread of 15 ml of blood is six spinal segments cephalad and three segments caudad with a mean volume per segment of 1.6 ml.⁵

During the procedure, the patient asks why they did not perform an EBP immediately after their LP. How would you answer their question?

• “When PDPH is less severe, which may reflect a smaller dural tear with less cerebrospinal fluid leak, we prefer to use conservative therapy in the hope that your headache resolves without EBP. We usually consider EBP once your headache is more significant and makes it difficult for you to perform activities of daily life and care for your baby.”⁶
• “Although some studies conflict, we believe that most studies support that prophylactic EBPs do not significantly decrease the incidence of PDPH after inadvertent dural puncture, nor does it decrease the need for a therapeutic EBP.⁷

After you inject 15 mL of blood into the epidural space, the patient cannot tolerate any more. 

Should you attempt to inject more blood? Would you increase your chance of a successful EBP?

• An optimal volume is not known. Many providers inject as much blood as the patient can tolerate. Some studies show higher rates of success with higher volumes, but it has not always been reproducible.
• Crawford reported a 70% success rate using 6–15 mL of blood compared to 96% with 20 mL.⁸
• Paech et al. studied 121 obstetric patients and found no statistical difference in 15 mL, 20 mL, or 30mL in permanent or partial relief of PDPH.⁸
• In a retrospective study, Booth et al. reported the outcome of 466 EBPs performed on 394 obstetric patients. The unit policy was to inject up to 30 mL of blood, although 91% did not receive the full amount. The mean (± standard deviation) volume injected was 20.5 ± 5.4 mL. Increasing the volume of blood injected did not reduce the need for a repeat EBP.⁶ 

The patient achieves full symptom relief after the EBP. However, she returns two days later with the same presentation. 

Can you offer a second epidural blood patch?   

• A second EBP may be performed after excluding other causes of headache.⁶
• There is no evidence for an optimal time interval between the first and second EBP.
• Involvement of other specialties should be considered before performing a third EBP.

The most experienced provider performed the patient’s previous EBP but had tremendous difficulty. The patient’s uncle had a similar procedure years ago where the blood patch was performed under x-ray, and she asks if the same can be done for her. What would you tell her?

• Efficacy of fluoroscopy-guided epidural blood patch (FGEBP) is 85% for complete resolution and 95% with partial resolution⁹
• FGEBP are typically performed in the prone position, which may be difficult to achieve for this patient due to pregnancy and gravid uterus
• FGEBP also exposes the fetus to radiation. Radiation is least harmful during the third trimester, but the parents will have to weigh the potential harm of radiation against the severity of the PDPH.
• There are other methods to assist with the EBP.
  • Ultrasound guidance
  • Devices that continuously monitor pressure through the Tuohy and signal when pressure changes occur after crossing the ligamentum flavum

References

1. Mol BWJ, Roberts CT, Thangaratinam S, et al. Pre-eclampsia. Lancet. 2016;387(10022):999–1011. https://doi.org/10.1016/S0140-6736(15)00070-7
2. Moss HE, Margolin EA, Lee AG, Van Stavern GP. Should lumbar puncture be required to diagnose every patient with idiopathic intracranial hypertension? J Neuroophthalmol. 2021;41(3):379–384. https://doi.org/10.1097/WNO.0000000000001373
3. Evans RW, Armon C, Frohman EM, Goodin DS. Assessment: prevention of post-lumbar puncture headaches: report of the therapeutics and technology assessment subcommittee of the American Academy of Neurology. Neurology. 2000;55(7):909–914. https://doi.org/10.1212/wnl.55.7.909
4. White B, Lopez V, Chason D, Scott D, Stehel E, Moore W. The lumbar epidural blood patch: a primer. Applied Radiology. 2019. https://appliedradiology.com/articles/the-lumbar-epidural-blood-patch-a-primer
5. Shin HA. Recent update on epidural blood patch. Anesth Pain Med. 2022;17(1):12–23. https://doi.org/10.17085/apm.21113
6. Russell R, Laxton C, Lucas DN, Niewiarowski J, Scrutton M, Stocks G. Treatment of obstetric post-dural puncture headache. Part 2: epidural blood patch. Int J Obstet Anesth. 2019;38:104–118. https://doi.org/10.1016/j.ijoa.2018.12.005
7. Scavone BM, Wong CA, Sullivan JT, et al. Efficacy of a prophylactic epidural blood patch in preventing post dural puncture headache in parturients after inadvertent dural puncture. Anesthesiology. 2004;101(6):1422–1427. https://doi.org/10.1097/00000542-200412000-00024
8. Paech MJ, Doherty DA, Christmas T, Wong CA. The volume of blood for epidural blood patch in obstetrics: a randomized, blinded clinical trial. Anesth Analg. 2011;113(1):126-133. https://doi.org/10.1213/ANE.0b013e318218204d
9. Özütemiz C, Köksel YK, Huang H, Rubin N, Rykken JB. The efficacy of fluoroscopy-guided epidural blood patch in the treatment of spontaneous and iatrogenic cerebrospinal fluid leakage. Eur Radiol. 2019;29(8):4088–4095. https://doi.org/0.1007/s00330-018-5828-x