Case Study
A 28-year-old nulliparous woman had labor induced for prolonged preterm rupture of membranes at 35 weeks’ gestation. Apart from obesity, her prebooking body mass index (BMI) being 34 kg/m2, she had no other medical comorbidities. That morning, the insertion of an epidural catheter via a 16-gauge Tuohy needle at the L3–L4 interspace was complicated by an accidental dural puncture (ADP). The epidural catheter was successfully inserted 3 cm into the subarachnoid space, aspiration of cerebrospinal fluid (CSF) was confirmed, and the catheter secured. An initial intrathecal injection of 2 ml of 0.125% plain bupivacaine with fentanyl 5 µg/ml provided good analgesia. This was maintained using a patient-controlled spinal analgesia method of the same drug doses by bolus with a 45 minute lockout interval via an electronic pump. No change was made to her labor management plan, and the patient had a spontaneous vaginal delivery 7 hours later. The epidural catheter was removed within 1 hour. The woman was advised of the complication that had occurred and the risk of headache. She was reassured that she would be reviewed by the pain service next morning but was asked to inform hospital staff prior to this should she develop a headache.
On review the following morning, approximately 24 hours after the ADP, the patient reported having mild nausea and a moderate frontal headache that had developed shortly after sitting up in bed but that resolved when lying flat. After discussing the options of either an epidural blood patch (EBP) or expectant management, a conservative symptomatic treatment approach of bed rest and regular acetaminophen and ibuprofen was started. However, the patient’s headache worsened considerably over the day such that she was unable to sit upright without the onset of severe frontal and occipital headache and neck stiffness. She was confined to bed, making nursing of her baby very difficult, and she requested further review.
In the absence of fever or other relative contraindications, the woman agreed to and provided written consent for an EBP that evening, 36 hours after the ADP. The procedure was performed in the operating room (OR) by two anesthesiologists. An intravenous (IV) cannula was inserted, and the antecubital fossa of the other arm prepped with antiseptic. With the patient in the left lateral position with lumbar flexion and under full aseptic conditions, the epidural space was located without difficulty at L4–L5. The second anesthesiologist, using sterile gloves and an aseptic technique, obtained 20 ml of venous blood that was then injected slowly over 60 seconds via the epidural needle by the other anesthesiologist. The patient complained of lower back pain radiating to the legs after injection of 15 ml, and this limited total injected volume of blood to 18 mL. However, the patient commented on an immediate reduction in the severity of her headache.
After a short period of time in the recovery area to monitor her vital signs, the patient was returned to the postnatal ward, where she was instructed to remain flat in bed for 2 hours. Thereafter, she started ambulatory care of her infant, and on review the following morning, she reported that she had been headache-free since the EBP. She was discharged that day, with written instructions, including contact information, should the headache recur or other concerning symptoms arise. At telephone contact a week later, she remained symptom free.
Key Points
Post–dural puncture headache (PDPH) is one of the most common complications of neuraxial anesthesia. It adversely affects the ability of mothers to self-care and care for their newborns and prolongs hospital stay.
PDPH is uncommon, of mild to severe intensity, and lasts up to several days. It varies in incidence with spinal needle gauge and point design from 0.5 to 2 percent.
ADP in an obstetric patient confers a 50–80 percent risk of subsequent postural headache that is most commonly moderate to severe, of onset within 48 hours, and persistent for at least a week. Pharmacologic therapies are largely ineffective.
Although invasive, a therapeutic EBP is the best way to immediately and completely relieve PDPH. Although very effective against postspinal headache, after ADP most of the obstetric population obtains benefit, but only a third gets complete and sustained relief from a single EBP due to headache recurrence.
Repeat EBP may be appropriate, but other diagnoses need to be considered and possibly excluded through appropriate investigation. Regular care and follow-up should be routine regardless of whether an expectant or interventional approach is taken.
Discussion
Accidental dural puncture is a not uncommon complication of a labor epidural, the reported incidence varying from 0.5 to 2 percent.1–3 The leak of CSF through the arachnoid and dura mater (meninges) is the precipitating event for PDPH, which is characterized by its postural nature – being worse when erect and relieved by lying flat. Low intracranial pressure in the upright position is thought to cause traction on the meninges, meningeal veins, and cranial nerves. Intracranial hypotension due to caudad redistribution of CSF when upright results in compensatory cerebral vasodilation, similar to that of migrainous headache, and this may also contribute.3, 4
PDPH is typically described as a frontal-occipital headache associated with neck stiffness, nausea, tinnitus, and occasionally hearing loss or visual disturbance.2 Rarely, cranial nerve palsies, seizures, or other neurologic pathologies and events are associated, so if symptoms are atypical or neurologic evaluation is suggestive, it is essential to exclude other serious pathologies (see Table 42.1).2
Following an ADP in pregnancy, the incidence of PDPH varies between 50 and 80 percent depending mainly on the size and type of epidural needle used as well as various patient factors.1–3, 5 The obstetric population appears particularly susceptible, with observational studies identifying adults younger than age 40 and female gender as independent risk factors for PDPH.3, 6 Obesity may have an impact on the incidence of PDPH, with lower rates of headache observed among morbidly obese women.1 Compared with an incidence of PDPH of less than 2 percent when using atraumatic spinal needles, the larger size of an epidural needle is a major factor contributing to morbidity.2, 3, 5 Accidental dural puncture with a 16-gauge epidural needle appears almost twice as likely to result in PDPH as ADP with an 18-gauge needle.7, 8 With conservative management, the median duration of PDPH from large spinal needles may be longer than 7 days,9 and 10 percent of women who experience ADP are still symptomatic after 1 month.1, 2 It is possible that those who develop PDPH will be more likely to suffer from chronic headaches subsequently.10
The onset of headache within 5 days of dural puncture is required to meet the diagnostic criteria for PDPH set forth in the International Classification of Headache Disorders (3rd edn; ICHD-3), but 90 percent of women with an ADP are likely to be symptomatic within 48 hours.1 Debilitating headache can prolong hospital stay due to compromise of a mother’s ability to care for both herself and her newborn baby. Daily follow-up should be instituted because the diagnosis of PDPH is clinical. Although typical changes occur in the presence of low intracranial pressure (Figure 42.1), neuroimaging is normally reserved for when other pathologies are suspected or headache fails to respond to multiple blood patches. The woman needs to be monitored to ensure that she does not develop a rare but serious complication, for example, a subdural hematoma, cranial nerve palsy, or cerebral vein thrombosis.
Figure 42.1 Brain MRI scans showing typical findings in intracranial hypotension with coronal and axial fluid attenuated inversion recover-weighted images. A, B Thickening of the pachymeninges. C. Coronal gadolinium-enhanced T1-weighted image.
Following an ADP, women are often advised to limit ambulation, maintain hydration, and drink coffee or take caffeine (caffeine is a cerebral vasoconstrictor) and are prescribed regular oral analgesia (opioid and nonopioid) in an attempt to prevent PDPH or minimize its severity. Unfortunately, the drug therapies lack good supporting evidence and are at best of limited efficacy. Restricting ambulation and providing supplemental fluid are of no benefit.11 Evidence that oral or IV caffeine and other cerebral vasoconstrictors are of benefit is equivocal and compliance problematic due to the high incidence of side effects and insomnia.1, 5, 12 Low levels of evidence suggest a possible therapeutic benefit from analgesia with IV cosyntropin (a synthetic adrenocorticotropic hormone analogue), epidural morphine, occipital nerve blocks, or oral gabapentin or pregabalin, but without further validation, neither these nor other pharmacologic therapies can be recommended for routine use.11
The invasive procedure of EBP is the best supported treatment of PDPH.11, 13 Expansion of the epidural space with blood usually produces an immediate and sustained increase in epidural and subarachnoid space pressure, with shift of CSF relieving intracranial hypotension and inducing cerebral vasoconstriction. This may rapidly relieve headache. Additionally, further CSF loss may be prevented by sealing the meningeal hole with a hemostatic plug that also stimulates collagen repair of the defect.4 A therapeutic EBP provides complete or partial relief in up to 95 percent of women with PDPH, but recurrence of headache is common, especially when the CSF leak is greater through a larger meningeal perforation after an ADP.14 Given the poor initial efficacy or recurrence of PDPH (usually within 48 hours), 15–30 percent of these women may request a repeat EBP.5, 14, 15 Hence, only a third of women receiving a single EBP obtain complete and sustained relief from headache after ADP.6, 14, 15 This contrasts with the efficacy of EBP for PDPH subsequent to use of an atraumatic or small-gauge spinal needle, where permanent resolution of PDPH is much more likely.11
A prophylactic EBP, in which blood is administered through a reinserted epidural catheter before the onset of PDPH, has been used to try to reduce the incidence, severity, and/or duration of symptoms. Research has been limited by small sample sizes and bias due to the inability to blind study subjects, and the two largest randomized trials have produced conflicting results.16, 17 One reported excellent outcomes,16 but the other study, which included a sham procedure, found no difference in the incidence of PDPH or need for therapeutic EBP.17 Concern about bacteremia immediately postpartum and the risk of injecting a growth medium such as blood, possibly through a colonized catheter, have led to a major decline in the popularity of this approach.18 A consensus recommendation to defer the conduct of a therapeutic EBP until at least 24–48 hours after ADP is based on observational studies indicating a higher success rate, although this may be attributable in part to selection bias, given that the natural history of PDPH is to improve with time.6, 14 On balance, EBP tends to be offered early for women with severe headache (one that prevents normal ambulation and care of the neonate) and late for those with persisting moderate headache.
Prior to performing an EBP, it is important to ensure that the timing falls within a recommended “safe” window with respect to any anticoagulant therapy (e.g., low-molecular-weight heparin thromboprophylaxis) and that there are no relative contraindications, for example, systemic or local infection. Maintenance of procedural sterility is best achieved by two physicians – one performing venesection and the other the epidural needle placement. The postural nature of PDPH means that most women are more comfortable in the lateral position, but the anesthesiologist should select his or her preferred patient position for insertion to minimize the risk of a repeat ADP. Performing the EBP at the same vertebral level or a nearby interspace is recommended, although success may still occur after distant injection because magnetic resonance imaging (MRI) has shown blood to spread at least three to five vertebral levels within the epidural space, and spontaneous low-intracranial-pressure headache can be relieved irrespective of the location of the dural leak. The optimal volume of autologous blood for EBP is unclear. Two randomized trials have compared 7.5 ml versus 15 ml or 15 ml versus 20 ml versus 30 ml, and an attempt to slowly inject at least 20 ml appears a reasonable strategy, recognizing that back pain during the procedure may limit the total volume able to be administered.6, 19
Best practice after an EBP is also uncertain, with weak evidence supporting the advice to remain lying supine for 2 hours.20 It is postulated that remaining supine allows time for CSF production and cerebral vasoconstriction, which correct intracranial hypotension and allow a more stable hemostatic plug of the meningeal perforation to form. Valsalva maneuvers have been linked to recurrence of headache, presumably through disruption of the hemostatic plug, so attempts to prevent sudden increases in lumbar subarachnoid pressure include advice against heavy lifting or coughing and prescription of stool softeners. In the event that PDPH does recur, a repeat EBP can be offered, but again, the optimal timing is unknown – the authors suggest delaying for at least 24 hours after recurrence. A third EBP should not be performed without considering alternative causes for symptoms, seeking neurologic advice, and considering neuroimaging to exclude other causes of postpartum headache.
Back pain can occur during the administration of blood and is also the most common subsequent complication of an EBP. It typically lasts up to 5 days but is not usually distressing.6 Pain is thought to be due to a direct irritant effect of blood on the nerve roots or nerve root compression caused by the substantial increase in spinal canal pressure.6 Daily review of women with PDPH is important to monitor symptoms and for early detection of potentially serious complications such as epidural abscess or lumbovertebral syndrome, in which back pain occurs in association with neurologic deficits of the lower limbs. Other rare neurologic complications include arachnoiditis, subdural hematoma, seizures, cranial nerve palsies, and worsening headache due to raised intracranial pressure following the EBP.
Strategies to minimize the incidence and/or severity of PDPH are difficult to investigate because of the infrequency and unpredictability of ADP. Promising results are often not confirmed in larger and better-controlled studies. The insertion of an epidural catheter intrathecally to prevent PDPH following ADP is one such approach that became popular because of encouraging observational studies. However, meta-analysis shows limited efficacy, with the requirement for EBP reduced but no significant difference in the incidence of PDPH.21
Regardless of whether an expectant or interventional approach is taken to the management of PDPH, mothers should be reviewed daily while in hospital, with phone follow-up and notification of their general practitioner after discharge. Providing written information about “red flag” symptoms (see Table 42.2) is recommended, as well as contact instructions for questions or concerns. Local protocols should be in place, ideally offering ongoing counseling and the opportunity for anesthetic outpatient review during a subsequent pregnancy.
