Anesthesiology

Neurologic Complications of Neuraxial Analgesia/Anesthesia: Postdural Puncture Headache

General Information

A postdural puncture headache (PDPH) can occur following deliberate dural puncture with a spinal needle or after an unintentional dural puncture with an epidural needle.

1. Incidence

The overall incidence of unintentional dural puncture with an epidural needle is considered to be 1.5%. This may be lower or higher, depending on the experience of the person performing the procedure. In these cases, the risk of the patient developing a postdural puncture headache is 52.1% (CI 51.4-52.8%).

Headache after dural puncture with a spinal needle varies according to the type and size of needle used. For example, 11.2% with a 24g short-beveled Quincke, 3.5% with a 24g pencil-point Sprotte, 1.7% with a 27g pencil-point Whitacre.

2. Symptoms

Headache:

Classically postural in nature. Worse when standing or sitting and partially or completely relieved by lying supine. It is usually present in occipital or frontal regions, but can occur in other areas, radiating to the neck and shoulders in less than 50% of patients. The lack of a postural element to the headache makes the diagnosis of PDPH unlikely, but its presence is not pathognomonic for this complication. It can range from mild, with minimal impact on daily living, to severe and incapacitating. Onset varies from immediately after dural puncture to 5 days later, typically occurring in the first 48 hours. Nearly 95% of PDPH last less than a week, but occasionally symptoms may linger for months or even years.

Associated Symptoms:

a. nausea in >50%

b. vomiting in <25%

c. auditory symptoms (tinnitus, hearing loss, hyperacusis) in <15%

d. visual symptoms (diplopia, photophobia, problems accommodating) in <15%

e. seizures are rare

3. Differential Diagnosis

The differential diagnosis of post-partum headache is extensive. About 40% of women complain of head or neck pain after delivery. In most cases, tension or migraine headaches are the cause. Simple musculoskeletal headaches are also fairly common. Postdural puncture headache is responsible in only about 16% of cases.

Other causes of postpartum headache with a postural component include cortical vein thrombosis (3% of postpartum headaches) and spontaneous intracranial hypotension, both of which may present with nausea and vomiting like a PDPH. Cortical vein thrombosis is often associated with focal neurological signs and seizures. There is usually no history of dural trauma with spontaneous intracranial hypotension.

Many causes of postpartum headache present with similar symptoms, with or without focal neurological signs, making diagnosis challenging. A thorough history and physical and appropriate imaging can help pinpoint the underlying pathology. For more details, refer to the references below.

Causes of Postpartum Headache

  • Tension headache

  • Migraine

  • Musculosketal

  • Hypertensive disorders/Preeclampsia

  • Postdural puncture headache

  • Cortical vein thrombosis

  • Subarachnoid hemorrhage

  • Brain tumor

  • Meningitis

  • Subdural hematoma

  • Cerebral infarction

  • Caffeine withdrawal

  • Lactation headache

  • Sinusitis

  • Posterior reversible (leuko)encephalopathy syndrome (PRES)

  • Spontaneous intracranial hypotension

  • Pseudotumor cerebri/benign intracranial hypertension

  • Pneumocephalus

  • Drug-induced, e.g., magnesium therapy

4. Pathophysiology

There are several theories as to the exact cause of a PDPH.

Downward pull on pain-sensitive structures

When CSF volume is low and the patient moves into vertical position, gravity causes the brain to sag, generating downward tension on the meninges and other sensitive structures such as nerves and blood vessels).

Compensatory cerebral vasodilatation.

As the CSF volume decreases due to leakage through the dural puncture, the cerebral blood vessels dilate, increasing cerebral blood volume to maintain total intracranial volume.

Hypersensitivity to substance P.

The risk of postdural puncture headache triples in pregnancy, perhaps due to low levels of substance P.

5. Risk Factors

Nonmodifiable

a. Age. The highest risk is between 20-30 years of age, with incidence decreasing after the age of 40. PDPH is uncommon in people over 60 years old.

b. Gender. Women have twice the risk of developing a PDPH than men, unrelated to age.

c. Pregnancy. An increase in intra-abdominal pressure and reduced density of CSF may predispose women to PDPH during pregnancy due to increased CSF leakage.

d. Vaginal delivery. There is conflicting evidence as to whether the repetitive increase in intra-abdominal pressure during second stage of labor increases the risk of PDPH.

e. Previous PDPH. This is a risk factor for recurrence.

f. History of chronic headache. About 40% of patients with PDPH have a history of chronic headache.

g. Low BMI. Patients who develop PDPH have a significantly lower BMI. Morbid obesity may reduce the risk of PDPH. The reasons for this are not clear.

Modifiable

Equipment

i. Epidural needle size and design. There is conflicting evidence if this has any effect on the incidence of PDPH.

ii.Spinal needle size/design/shape/type. There is conclusive evidence that the incidence of PDPH decreases as needle size decreases, particularly with "pencil point" or atraumatic needles (Pencan, Whitacre, Sprotte, Gertie Marx) compared to beveled, cutting-tip needles (Quincke). Pencil-point needles may separate rather than cut the dural fibers, reducing the rate of CSF leak.

Technique

i. Needle orientation. It is controversial whether rotating the bevel of the epidural needle once in the epidural space increases the incidence of PDPH. Despite the dura being comprised of multidirectional fibers, inserting the bevel of a cutting-tip needle parallel with the longitudinal axis of the spine significantly reduces the incidence of headache.

ii.Multiple dural punctures. This significantly increases the risk of PDPH.

iv.Experience. The greater the experience of the operator, the lower the likelihood of dural puncture with epidural placement, and thus the lower the incidence of PDPH.

v. CSE. Current evidence shows no difference in the incidence of PDPH with CSE, compared to epidural techniques.

6. Complications

Minor and Temporary

The initial complaint of most women with a postdural puncture headache is inability to care for their baby, even though they may also be having problems carrying out other daily activities due to the severity of the headache and other symptoms. Use of less effective measures (rather than epidural blood patch) to treat the headache often delays discharge, and recurrence of headache frequently brings patients back to the hospital for further assessment and treatment.

Major and Serious/Permanent

Subdural hematoma has been reported following postdural puncture. Downward drag of the brain with decreased CSF volume is thought to cause tearing of fragile subdural bridging veins. Treatment with an epidural blood patch has previously been thought to be preventive, but this has not been true in some case reports. Presentation can be subtle, with minimal focal neurological signs even when there is significant midline shift. Close follow-up is essential after patients with PDPH have been discharged to ensure prompt diagnosis of this rare complication.

Cranial nerve palsy causing hearing loss and diplopia can occur. Most cases resolve over time, but the condition may last for up to 8 months. They should correct after an epidural blood patch.

7. Prevention and Treatment

Conservative Measures

i. Supine bed rest. Although lying supine relieves the symptoms of a PDPH, there is no evidence that supine bed rest reduces the incidence or the duration of a headache compared with early mobilization. Bed rest is not an option for a new mother taking care of her infant, and it may increase the risk of venous thromboembolism.

ii. Hydration. Maintaining normal hydration and euvolemia is important for milk and CSF production, but excessive hydration (for example with intravenous fluid boluses) does not reduce the incidence or provide relief from a PDPH.

Pharmacological Measures

i. Caffeine is a popular treatment for PDPH, especially in patients who have a high caffeine intake normally and who may also be suffering from a caffeine withdrawal headache. Caffeine is a cerebral vasoconstrictor which may counteract the cerebral vasodilatation that occurs when CSF volume decreases, and by that mechanism it can produce temporary relief. Due to CNS stimulant effects, a maximum of 600 mg of oral caffeine in 24 hours, divided into at least 3 doses, is recommended. Drip coffee contains about 1 mg/mL of caffeine. Caffeine has no benefit when used prophylactically.

ii. Oral theophylline, another cerebral vasoconstrictor, can be extremely effective in treating PDPH, but side effects, such as seizures and gastric irritation, limit its use.

iii. Epidural saline is often administered in the belief that increasing the volume and, hence, the pressure in the epidural space will decrease CSF leakage and either prevent or treat a PDPH. Unfortunately, despite transient relief with an epidural saline bolus, or relief for the duration of an infusion, this has not been shown to be any more effective than conservative measures in the long-term.

Invasive Measures

i. Intrathecal catheter placement after unintentional dural puncture is frequently performed to provide good analgesia while preventing a PDPH. This is only effective as a preventive measure if left in place for at least 24 hours after delivery, but this technique potentially increases the risk of neuraxial infection.

ii. Studies of prophylactic epidural blood patch have shown conflicting results regarding efficacy in reducing PDPH. With an estimated incidence of PDPH being 52.1% after unintentional dural puncture with an epidural needle, this would mean inappropriate treatment in nearly half the patients, with the attendant risk of complications associated with the procedure. There are also concerns about injecting blood into a potentially contaminated epidural catheter that could increase the risk of neuraxial infection compared with injecting into a newly placed needle.

iii. Therapeutic epidural blood patch (EBP) can be an extremely effective treatment for PDPH. Initial success after the procedure is only about 50-60%, but often there is improvement over the next few days. Some patients require a second blood patch, which increases the overall success rate. Performing the procedure 24 to 48 hours after the dural puncture is associated with higher rates of symptomatic relief. The optimal amount of blood is unknown; usually, 15-20 mL of autologus blood is sufficient, but some providers inject up to 30 mL.

There are several proposed mechanisms by which an epidural blood patch provides relief. Increasing the pressure in the epidural space with the volume of blood increases the CSF pressure, thus reducing symptoms. Injected blood spreads throughout the epidural space, particularly in a cephalad direction, with some blood acting as physical patch over the dural tear. It is also possible that the presence of the blood sets off an inflammatory reaction in the area of the dural tear encouraging healing, even though the blood is generally reabsorbed or dissipated within 24 hours.

Contraindications to an EBP include patient refusal, coagulopathy, untreated systemic infection or localized infection at the site, and raised ICP. HIV is not a contraindication (see the section on "other complications of neuraxial anesthesia"). The patient should be informed of the risks and benefits. The need for a written consent form is debatable.

The technique requires the same level of sterility as placing an epidural for analgesia. The supine position is usually more comfortable for the patient with a positional headache. Once loss of resistance has been established, 20 mL (or more) blood should be withdrawn from the patient in an equally sterile manner. This is then injected slowly into the epidural needle until completed or stopped due to unpleasant pressure or pain in the low back, buttocks, or legs.

It is a matter of opinion whether the patient should remain supine for a short time after the procedure or immediately mobilize. The patient should be warned that they may experience some low back or leg discomfort for a day or so after the procedure. Follow-up is essential, and any fever, severe back pain, or radicular lower extremity pain should be investigated immediately. Complete lack of symptomatic relief or worsening of headache symptoms after 2 EBPs is suspicious for a different etiology, necessitating further investigation.

Possible but uncommon complications include meningitis, arachnoiditis, temporary back pain, and subdural hematoma. Epidural blood patch has not been shown to decrease the effectiveness of epidural anesthesia provided at a later time.

What's the Evidence?

Macarthur, A. Postpartum Headache. Chestnut's Obstetric Anesthesia: Principles and Practice. Mosby Elsevier. 2009.

(A textbook chapter providing an overview of the subject.)

Bezov, D, Lipton, RB, Ashina, S. "Post-dural puncture headache: Part 1 - Diagnosis, epidemiology, etiology, and pathophysiology". Headache . vol. 50. 2010. pp. 1144-1152.

(A review article covering differential diagnosis and case of PDPH.)

Bezov, D, Ashina, S, Lipton, R. "Post-dural puncture headache: Part II - Prevention, management, and prognosis". Headache . vol. 50. 2010. pp. 1482-1498.

(A review article covering management of PDPH.)

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 . vol. 113. 2011. pp. 126-33.

(This is an RCT to determine the optimal volume of blood in an epidural blood patch to treat PDPH.)

Darvish, B, Gupta, A, Alahuhta, S. "Management of accidental dural puncture and post-dural puncture headache after labour: a Nordic survey". Acta Anaesthesiol Scand . vol. 55. 2011. pp. 46-53.

(Many different methods are used in Scandinavia to manage wet tap and PDPH - many of which are not evidence based.)

Baysinger, CL, Pope, JE, Lockhart, EM, Mercaldo, ND. "The management of accidental dural puncture and postdural puncture headache: a North American survey". J Clin Anesth . vol. 23. 2011. pp. 349-60.

(Many different methods are used in North America to manage wet tap and PDPH - many of which are not evidence based.)
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