Low Pressure Headaches - Causes, Evaluation and Epidural Blood Patch
- Christopher Liu
- 20 hours ago
- 5 min read
Low pressure headaches can be severe and distressing for many people. These headaches often start suddenly and can significantly affect daily life. In this article, we will discuss what causes low pressure headache, how it is diagnosed and what are the treatments available for this condition - including epidural blood patch.
Common Causes of Low Pressure Headaches
Low pressure headaches arise when the pressure inside the skull / cranium drops below normal levels. This drop can happen for different reasons, broadly categorized into medically-related and spontaneous causes.
Medically-related Causes
The most common cause of low pressure headaches is post-dural puncture headache (PDPH). This occurs after procedures like:
Epidural analgesia, often used during childbirth
Lumbar puncture (also known as a spinal tap) for diagnostic or therapeutic reasons
The spinal nerves and cerebrospinal fluid (CSF) are enclosed within a tough outer membrane called the dura mater. During spinal injections, the needle may intentionally or accidentally puncture the dura mater, creating a small hole. This allows CSF to leak out.
Because the dura mater and the CSF-filled space are continuous from the brain down through the spine, a CSF leak in the spine reduces the amount of CSF surrounding the brain. This lowers the pressure within the brain, leading to headaches.
Spontaneous Causes
Spontaneous intracranial hypotension (SIH) occurs when cerebrospinal fluid (CSF) leaks from the spinal dura without any obvious trigger, such as a medical procedure or significant trauma. It usually results from a spontaneous tear or weakness in the dura mater, allowing CSF to escape.
This can occur when the dura is inherently fragile, such as in people with inherited connective tissue disorders like Ehlers-Danlos syndrome or Marfan syndrome, where the supporting tissues are weaker than normal. In other cases, the dura may become weakened over time due to age-related degeneration or bony abnormalities such as calcified disc spurs or osteophytes that gradually erode or puncture the dura. Occasionally, outpuchings of the dura (also known as spinal meningeal diverticula) may also rupture and cause a leak.
Unlike headaches caused by an accidental dural puncture during a spinal procedure, SIH develops spontaneously, without an identifiable external cause. As with other CSF leaks, the loss of CSF reduces the volume and pressure of fluid surrounding the brain, resulting in low brain pressure (intracranial hypotension). The most characteristic symptom is an orthostatic headache, which worsens when sitting or standing and improves on lying flat.
How Low Intracranial Pressure Causes Headaches
The brain and spinal cord float in CSF, which cushions and supports them. When there is low intracranial pressure, the brain loses some of its buoyancy and can sag slightly inside the skull. This sagging stretches pain-sensitive structures such as the meninges and blood vessels, causing headaches.
A key characteristic of low pressure headaches is a positional headache. Patients commonly report minimal headaches in the lying position and headaches after sitting or standing for a period of time. The headaches are typically worse towards the end of the day and is improved once one assumes the lying position. This happens because standing increases the downward pull on the brain when CSF volume is low, intensifying the pain.
However, not all patients with low pressure headaches have positional headaches. Over time, some patients develop headaches that no longer depend on posture. This change may result from the brain adapting to the low pressure or from ongoing irritation of pain-sensitive tissues.
Clinical Evaluation of Low Pressure Headaches
Doctors use a combination of history, physical examination, and imaging to diagnose low pressure headaches. The key feature of low pressure headaches include headaches that are worse when upright and improves with lying down. Patients often describe having concomitant neck stiffness / pain, nausea, vomiting, hearing changes (muffled hearing), ringing in the ears (tinnitus) and occasionally, visual changes. A history of a recent lu
A history of recent lumbar puncture or epidural analgesia raises suspicion of PDPH.
In cases where the cause is clear - recent lumbar puncture or epidural analgesia, further radiological evaluation is not routinely required to make the diagnosis of low pressure headache or Post-dural puncture headache. However, your doctor might order further tests (such as Magnetic Resonance Imaging or Computed Tomography of the brain) if your symptoms are atypical, to rule out other headache disorders.
Radiological Evaluation
Medical imaging plays an important role in confirming the diagnosis of intracranial hypotension and identifying the site of cerebrospinal fluid (CSF) leakage. While imaging findings can strongly support the diagnosis, a normal scan does not completely exclude a CSF leak, particularly if the leak is small or intermittent
MRI of the brain with gadolinium contrast is usually the first imaging test performed. It can demonstrate characteristic changes caused by low CSF pressure. However, they do not identify the exact location of the leak.
MRI of the spine is often performed to look for evidence of CSF leaking outside the dura. It may reveal extradural fluid collections, meningeal diverticula, or structural abnormalities such as disc protrusions or bony spurs that may be responsible for the leak. In some patients, the approximate leak site can be identified on MRI, although this is not always possible.
CT myelography is a more specialised investigation that is used when the leak cannot be localised on MRI or when targeted treatment is being planned. During the procedure, contrast material is injected into the CSF through a lumbar puncture, followed by CT imaging to track the flow of contrast and identify the precise site of leakage.
Digital subtraction myelography involves injecting contrast into the spine under continuous x-ray imaging. This allows your doctor to visualize how and where the spinal fluid is flowing out of the dura in real time, allowing for targeted procedures to seal up the leak.
Treatment Options for Low Pressure Headaches
The goals of treatment are to restore normal CSF pressure by sealing up the leak. The treatment depends on the cause, severity and duration of the CSF leak.
Conservative Measures
Many patients, particularly those with a recent or small CSF leak, improve with conservative treatment. These measures may allow the leak to heal naturally and can also help relieve symptoms while awaiting definitive treatment.
Conservative treatment includes bed rest, hydration, the administration of pain killers (such as paracetamol or NSAIDS) and caffeine. Caffeine is thought to relieve low pressure headache by constricting the blood vessels in the brain. However, it should be noted that these measures can provide symptom relief and healing takes place only when the dural leak has been sealed - either naturally or with definitive treatment.
Epidural Blood Patch
An epidural blood patch (EBP) is the an effective treatment for low pressure headaches, It is considered for patients with either a medically-related or spontaneous low pressure headache.
During the procedure, a small amount of the patient's own blood is injected into the epidural space, usually close to the suspected site of the leak. The blood forms a clot that seals the hole in the dura, preventing further CSF leakage. In addition, the injected blood temporarily increases pressure within the spinal canal, often providing rapid headache relief even before a permanent seal forms. Many patients experience significant improvement within hours, although some require up to 2 weeks to have resolution of symptoms.
An Epidural Blood Patch is a very safe procedure, especially when done under image guidance (usually X-rays or CT scan). However, no procedure is risk-free. The risks of this procedure includes:
Temporary back pain at the injection site
Mild nerve irritation or transient leg discomfort
Infection (rare)
Bleeding (rare)
Failure to completely seal the leak, requiring repeat treatment
Other Treatment Options
If symptoms persist despite one or more blood patches, or if imaging identifies a persistent spontaneous CSF leak, additional treatments may be recommended. These include targeted epidural blood patching, fibrin glue injection or surgical repair.
If you experience symptoms suggestive of low pressure headaches, make an appointment to see Dr Christopher Liu at Alleviate Pain Clinic, Singapore. Dr Christopher Liu is a headache specialist who also offers interventional treatments for refractory headaches.
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