Post-Dural Puncture Headache (PDPH)

Definition and Basic Concepts

What is Post-Dural Puncture Headache (PDPH)?

According to the International Society of Headache, any headache that occurs within 5 days of a dural puncture or a disruption in the meninges (the covering of the brain) is considered a postural puncture headache. It is associated with a leak of Cerebrospinal Fluid (CSF). However, it is not restricted only to headache but includes a group of symptoms which follow meningeal disruption within 5 days.

What is the incidence of PDPH?

The incidence is quite varying, ranging from 2% to 40%. It depends on the procedure as well as patient factors. PDPH is predominantly described in the obstetric population, where the incidence varies from 1.5% to 3.5%. In the non-obstetric population, it can vary between 2.5% to 47%. Most published studies concern the obstetric population, but there are few studies focusing on the non-obstetric population that have sprung some new interesting factors.

Pathophysiology

What is the traditional understanding of how PDPH occurs?

Whenever there is a dural puncture, there is continuous CSF leakage, which causes a decrease in CSF pressure. This causes the brain to sink, resulting in traction on the various nerve endings and pain-sensitive meningeal structures. Because of this, there is a compensatory increase in cerebral blood flow and venodilation. This is with regards to the Monro-Kellie rule.

What is the newer understanding of PDPH pathophysiology?

A newer concept involves altered craniospinal elasticity. This term talks about the compliance of the meningeal structures in both the cranial and spinal cavity. Puncture of the dural space at the lumbar level disrupts this compliance, causing an increase in compliance of the spinal region due to a change in pressure. The epidural space is normally negative pressure, but this disruption alters the pressure gradient, resulting in continuous leak of CSF. Additionally, work on chemical mediators (vasoactive substances also involved in migraines) suggests they might be released during dural puncture and contribute to vasodilation, causing headache.

Risk Factors

What patient factors predispose someone to PDPH?

Age: Most literature on obstetric populations reports incidence between 18-30 years. However, studies in non-obstetric populations have found an increased risk up to 40-60 years.
Pregnancy: Increases risk due to cerebral vascular dilation from hormonal changes.
CSF Volume: An increased amount of CSF dripping from the spinal needle is associated with a higher chance of PDPH.
Low Body Mass Index (BMI): Some studies found an association, but a large meta-analysis disproves this, making the literature on BMI inconclusive.

What procedural factors increase the risk of PDPH?

Needle Type: Dural cutting needles have a greater incidence of PDPH compared to dural splitting needles (like Sprotte or Whitacre).
Needle Gauge: Larger gauge needles (e.g., 22G and 24G) are known to cause more incidence of PDPH compared to smaller gauge needles. However, using a smaller gauge needle does not totally avoid PDPH.
Needle Orientation: Passing the needle along the long axis of the spinal cord (longitudinal orientation) results in a lower incidence of PDPH compared to a transverse orientation.
Number of Attempts: An increased number of punctures definitely increases the risk of PDPH.
Patient Position: Performing a lumbar puncture in the lateral decubitus position results in a lower incidence of PDPH, possibly due to the effect of gravity on CSF. In the sitting posture, CSF is deposited in the lumbar area and the pressure is high, which can cause more CSF leakage.

Clinical Presentation and Diagnosis

How does PDPH typically present?

Headache is the most common symptom, generally occurring within the first 3 days (and up to 5 days) of puncture. 90-95% of patients report it within 3 days: over 60% present within 24 hours, and 70-80% within 48 hours. Characteristically, the headache is fronto-occipital in nature. It worsens in the upright position and relieves in the lying down position, which is one of the hallmarks of PDPH. Applying pressure on the upper abdomen in an upright position can decrease the pain (Gissane sign), while pressure over the jugular vein can worsen the headache.

What are some atypical or focal neurological findings in PDPH?

Sometimes focal neurological findings can occur, such as nystagmus or diplopia. One example is lateral rectus palsy (affecting the abducens nerve). This nerve, being the longest, can get compressed due to CSF leakage and brain sagging, getting pressed against the temporal petrous part of the bone.

Are any investigations required for diagnosing PDPH?

Most of the time, PDPH is a clinical diagnosis. An MRI might be done to rule out other causes and can show findings like descent of the cerebellar tonsils, thickening of the meninges, subdural fluid accumulation, venous engorgement, or an enlarged pituitary gland (seen in 30-40% of PDPH patients). Ultrasound of the optic nerve sheath diameter (ONSD) does not aid in diagnosis but helps to prognosticate and monitor response to treatment.

What are the differential diagnoses for PDPH?

Differential diagnoses can be infective, vascular, neoplastic, metabolic, or others. PDPH should be suspected when there is an atypical presentation associated with sensorial changes, focal neurological deficits, visual disturbances, seizures, or altered sensorium.

Prevention

Are there any methods to prevent PDPH after an accidental dural puncture?

Several interventions have been tried to prevent PDPH after accidental dural puncture, including the use of combined spinal-epidural technique, placement of an intrathecal catheter, prophylactic blood patch, prophylactic bed rest, and prophylactic drug therapy with corticosteroids or morphine. However, none of these have been found to be effective, and there is insufficient evidence to support their routine use.

Management

Conservative and Pharmacological Management

How is mild PDPH managed?

Mild PDPH is when the patient is able to carry out day-to-day activities but is bothered by the headache. It is managed with plenty of oral fluids, bed rest, and simple analgesics like paracetamol and ibuprofen.

How is severe or debilitating PDPH managed?

If the pain is debilitating, unbearable, and the patient is restricted to bed, there is a need for pharmacological or invasive therapy.

First-line: Paracetamol and NSAIDs, but they are limited by side effects like gastritis, fluid retention, and renal dysfunction.
Drug of Choice: Caffeine is the drug of choice, advocated at a dose of 75mg to 300mg (max 900mg per day). It acts by causing cerebral vasoconstriction. A 2015 meta-analysis found it has a short-term beneficial effect until the dural hole gets repaired. Side effects include cardiac arrhythmias and seizures.
Other drugs tried (limited evidence): Corticotropin analogues (increase ICP), gabapentinoids (alter pain sensitivity), sumatriptan (releases inflammatory mediators), desmopressin, hydrocortisone, theophylline, and dexamethasone. These are only from case reports and can be used in resistant cases.

Invasive Procedures: Epidural Blood Patch (EBP)

What is a therapeutic epidural blood patch and how does it work?

It is the definitive invasive treatment for PDPH. It works by causing an immediate increase in intracranial pressure through direct pressure. As the clot resolves, it results in closing of the dural hole.

How is an epidural blood patch performed?

It typically requires two anesthesiologists. One seeks the epidural space. The other draws around 20 ml of blood from the antecubital vein. The optimal volume is around 15-20 ml, with meta-analysis reporting a mean ideal volume between 13-15 ml. The best practice is to inject until the patient gets relief of symptoms or complains of heaviness in the legs or back.

Where and when should an epidural blood patch be performed?

It can be done at the same level as the prior dural puncture, preferably 24 to 48 hours after the onset of symptoms. Doing it before this window increases the possibility of needing a repeat blood patch.

What are the complications of an epidural blood patch?

Complications include:

Accidental dural puncture: Can occur in 5-6% of cases. In such a situation, the blood patch can be performed at a level higher than the first attempt.
Other rare complications: Backache, infection, subdural abscess, facial nerve paralysis, and cauda equina syndrome.

Alternative Invasive Techniques

What is a Sphenopalatine Ganglion (SPG) block and how is it done?

It is a recently discussed topic for PDPH management. It is thought to act by blocking the parasympathetic supply of the SPG, which prevents cerebral vasodilation. The technique involves placing a local anesthetic-soaked cotton-tipped applicator into the patient's posterior nasopharynx at the level of the middle concha for about 10-15 minutes. Adverse effects include nausea, bitter taste, discomfort, and nasal/throat pain.

What is the evidence for the SPG block?

An early meta-analysis showed a benefit, but it was very short-lived (only for the first hour). A 2023 meta-analysis found it effective only during the first 6 hours after application, with no significant difference in the need for rescue treatment beyond that.

What is a Greater Occipital Nerve (GON) block?

It is performed for various headaches, including PDPH. Using a landmark technique, you mark a point 3-3.5 cm from the occipital protuberance and 1.5 cm laterally to infiltrate local anesthetic. It can also be done under ultrasound guidance.

What is the evidence for the GON block?

A 2021 meta-analysis favored the use of GON block for PDPH. It was associated with lower mean pain scores at 1, 6, and 24 hours and also reduced the risk of intervention failure (lack of pain relief).

What is the role of intranasal or nebulized lignocaine?

Intranasal lignocaine (10% spray) or nebulized lignocaine can provide some early relief. It is associated with significant pain reduction in the first 6 hours after intervention but is not as effective beyond that.

Is there a role for intrathecal or epidural morphine?

It has been tried as both a prophylactic and therapeutic measure but has not been found to be effective in reducing the incidence or severity of PDPH. While it can provide good surgical pain relief, it does not result in a reduction of headache scores.

Summary and Key Takeaways

What are the key take-home points about PDPH?

The diagnosis of PDPH is clinical.
Simple analgesics and caffeine are effective in relieving symptoms in most patients.
The definitive therapy tried and tested is the epidural blood patch, which shows benefit in 80-90% of patients.
Newer techniques like SPG block and GON block are being advocated, but more evidence is needed to recommend them for routine use.
Importance of Communication: Counseling patients about the possibility of PDPH during the pre-anesthetic visit is crucial. Explaining what is expected and what might happen helps patients accept complications better and cooperate during post-operative management, leading to better outcomes.