Low pressure headaches are caused by low volume or pressure of the cerebrospinal fluid (CSF) surrounding the brain and spinal cord. While often severely debilitating, these headaches can sometimes lead to serious complications. Although many cases resolve with conservative management, fluid loss can signal a danger requiring immediate medical intervention. Understanding the cause and warning signs is important for anyone experiencing this unusual pattern of head pain.
Understanding Intracranial Hypotension
A low pressure headache is the primary symptom of Intracranial Hypotension, a condition describing abnormally low fluid pressure within the skull. The brain and spinal cord are suspended in Cerebrospinal Fluid (CSF), which acts as a cushion and shock absorber. When CSF volume drops, the brain loses buoyancy and shifts downward, often called “brain sag.” This displacement stretches pain-sensitive structures and nerves, generating intense pain.
The defining characteristic of this headache is its orthostatic nature, meaning the pain depends on body position. Symptoms worsen significantly when a person sits or stands upright, as gravity pulls the brain further down. Conversely, the pain often improves or disappears within minutes of lying flat. Other associated symptoms include neck stiffness, nausea, changes in hearing, and dizziness.
Sources of Cerebrospinal Fluid Leakage
Intracranial Hypotension almost always stems from a Cerebrospinal Fluid (CSF) leak, involving a tear or defect in the dura mater, the tough membrane encasing the spinal cord and brain. Leaks are classified into two main categories based on origin. The first type is iatrogenic, meaning it is caused by a medical procedure. This commonly occurs following a lumbar puncture, epidural anesthesia, or spinal surgery, where the needle or incision creates a dural puncture that fails to seal completely.
The second type is a spontaneous CSF leak, arising without obvious preceding trauma or procedure. These leaks are often due to underlying weaknesses in the dura mater, sometimes associated with heritable connective tissue disorders such as Marfan syndrome or Ehlers-Danlos syndromes. Spinal bone spurs or calcified discs can also erode the dura, leading to a tear. The core problem is the rate of CSF loss exceeding the body’s ability to produce new fluid, causing the low pressure state.
When Low Pressure Headaches Become Dangerous
While the headache is the most prominent symptom, the danger of Intracranial Hypotension lies in its potential to cause serious neurological complications. Prolonged low pressure causes brain displacement, which can stretch and rupture small blood vessels, particularly the bridging veins. This stretching can result in the accumulation of blood outside the brain, known as a Subdural Hematoma (SDH). An SDH is a life-threatening complication that may require emergency neurosurgical intervention to drain the blood and relieve pressure.
The risk of developing an SDH is a primary reason why a persistent low pressure headache should be medically evaluated. Individuals must seek immediate emergency care if the headache suddenly changes or if new neurological symptoms develop. Warning signs include a sudden, severe worsening of the headache, altered mental status, or confusion. Other concerning symptoms are weakness on one side of the body, seizures, or double vision. A less common complication is superficial siderosis, where iron deposits from chronic bleeds coat the brain’s surface, potentially leading to balance issues and hearing loss.
Confirming Diagnosis and Treatment Approaches
Confirming a low pressure headache begins with a detailed medical history, focusing on the characteristic positional nature of the pain. Diagnostic imaging is used to support the diagnosis and locate the leak source. A brain Magnetic Resonance Imaging (MRI) scan with contrast is often the first step. This scan reveals signs of low fluid volume, such as thickening and enhancement of the dura mater, called pachymeningeal enhancement. The MRI may also show evidence of brain sagging or a developing subdural fluid collection or hematoma.
If the diagnosis is confirmed but the leak site is unknown, specialized spinal imaging is performed to pinpoint the location. Techniques such as a CT myelogram or dynamic digital subtraction myelography involve injecting a contrast dye into the spinal fluid to visualize where it is escaping. Treatment follows a tiered approach, starting with conservative management. This includes strict bed rest, increased fluid intake, and sometimes caffeine to temporarily boost CSF production.
If conservative measures fail, interventional procedures are initiated. The most common and effective treatment is the Epidural Blood Patch (EBP). This involves injecting a small amount of the patient’s own blood into the epidural space near the suspected leak. The blood clots and forms a temporary seal over the dural defect, allowing natural healing to occur. If the leak is precisely located, a targeted EBP or a fibrin glue patch can be applied directly to the site for a definitive repair.