What is Cerebrospinal Fluid Leak?
Cerebrospinal fluid (CSF) is a clear, colorless fluid found in the spaces within our brains and around our central nervous system (or CNS, the brain and spinal cord). Most of this fluid is made up of water (99%), and the remaining 1% contains electrolytes, proteins, neurotransmitters (which send signals in the brain), and chemicals like glucose.
According to most theories, this fluid is mainly made in certain parts of the brain, known as the choroid plexuses. From here, it circulates around various parts of the CNS before being reabsorbed back into the bloodstream. However, this process is not fully understood and there is ongoing debate among scientists about exactly how it works.
The amount of CSF in an adult is usually between 125 to 150 mL in the brain and spinal cord, and 25 mL within the brain’s ventricles (basically, fluid-filled cavities in the brain). The volume of this fluid stays constant due to an equal production and absorption rate of about 420 to 530 mL per day in adults.
The CSF plays a crucial role in maintaining the brain’s temperature, cushioning the brain and spinal cord, and providing a finely balanced force that helps the brain retain its shape and circulation. It also helps in removing waste products from the brain through its continuous renewal and forms the barrier between the blood and the brain.
Sometimes, if there is a tear or hole in the outermost layer of the meninges (layers that protect our brains), CSF can leak. This can connect the inside of the brain with the outside, causing symptoms like low-pressure headaches, neck pain, ringing in the ear, and occasional loss of smell or taste. A CSF leak can have serious consequences for the brain’s blood supply and function, and can also make direct damage to the brain more likely due to the loss of fluid cushion. More dangerously, it can also open up a pathway for dangerous brain infections, including meningitis. Therefore, if there are signs and symptoms of a CSF leak, it’s crucial to get further checks and treatment.
What Causes Cerebrospinal Fluid Leak?
Cerebrospinal fluid (CSF) leak happens when the fluid that surrounds the brain and spinal cord escapes. This usually occurs when there is a tear or hole in the dura mater, which is the outer most layer that safeguards the central nervous system. A hole can cause the area inside the dura mater to connect with other spaces and lead to a CSF leak. People who have this leakage often face low pressure headaches, nausea, and neck pain. Other noticeable symptoms can be ringing in the ear and loss of smell or taste.
In most cases, CSF leak happens due to severe head and facial injuries which make up 80% of leaks. Another 16% are caused by medical procedures, while a small 4% are due to various other causes. There are three classifications for a CSF leak: spontaneous or unknown cause, traumatic or injury-related, and iatrogenic or caused by a medical procedure.
Different head and facial traumas can lead to CSF leak. It heavily depends on the location and severity of the injury. Skull fractures often lead to leaks as they cause an unnatural connection between the space inside the dura mater and the air space in the nose, sinuses, middle ear, or mastoid cells, which are small air-filled spaces in ear’s temporal bone. These fractures often result from forceful impacts. The cribriform plate, ethmoid bone, and sphenoid sinuses, which are thin and share a close relationship with the dura, are often associated with these fractures. In rare cases, injuries to the orbit, the cavity or socket of the skull in which the eye sits, can result in CSF leaking from the eye.
CSF leaks caused by medical procedures often occur after sinus surgeries. The cribriform plate and the ethmoid bone, situated at the front of the skull, are usually damaged and this leads to leaks. Brain surgeries can also result in leaks, specifically during pituitary gland surgeries, which are now more common due to the development of less invasive endoscopic procedures.
CSF leaks also occur without a direct cause or traumatic event, usually at the spine. It is believed these leaks are due to conditions leading to decreased pressure inside the skull, which causes severe headaches when standing or sitting up. Such leaks are divided into several types based on their characteristics and have been associated with various complications if they persist.
CSF leaks can also be linked to elevated intracranial pressure or undue pressure inside the skull. Preexisting weaknesses in the dura likely due to a hereditary condition involving the connective tissue, are also described as a significant contributing factor. Furthermore, abnormal skull development, defects caused by tumors, and conditions increasing the pressure inside the skull can also lead to CSF leaks.
Risk Factors and Frequency for Cerebrospinal Fluid Leak
A cerebrospinal fluid leak, or CSF leak, is a condition primarily caused by nonsurgical traumas, accounting for 80% of all cases. Other causes include various medical procedures (16%) and spontaneous leaks (4%). Spontaneous CSF leaks are more often seen in adult women compared to children. The typical age of patients with different types of spontaneous CSF leaks ranges from 33 to 52.4 years. CSF leaks are most common in the upper part of the back (T1 – T6), followed by the lower part of the back (T7 – T12), with the least common areas being the neck and lower back.
Head injuries are also a significant concern in the United States, with nearly 2.8 million people seeking emergency department care, hospitalization, or suffering death from 2007 to 2013. Around 4% of these injuries resulted in skull base fractures, which account for 21% of all skull fractures. Male patients make up the majority of these cases (78%), and the average age is 49. While it’s often reported that 10 to 30% of skull base fractures result in CSF leaks, recent studies have found a lower rate of 4%.
CSF leaks can also occur as a complication from various surgical procedures, like skull base surgery, lumbosacral spine surgery, or lumbar puncture. The likelihood of getting a CSF leak after the first spine surgery is between 5.5% to 9%, and 13.2% to 21% for any subsequent surgeries. Some surgeries lead to unidentified openings in the dura mater, occurring in 6.8% of cases. The rate of CSF leaks is lower in minimally invasive surgeries (4.7%) compared to open surgeries (9%). Moreover, a recent review revealed that the post-operative rate of CSF leaks in endoscopic endonasal approaches for tumor removal was 10.1%. The materials used for closure and the technique can also impact this rate.
Signs and Symptoms of Cerebrospinal Fluid Leak
Cerebrospinal fluid (CSF) leak is often due to accidental injuries or complications from a surgical procedure. Patients with a CSF leak may have symptoms like a clear runny nose, headache, neck pain, or stiffness. In some cases, if the brain tissue herniates (gets pushed out of its normal position) through the defects in the skull and covering layers (dura), it could cause rare symptoms like abnormal milk production (galactorrhea), reduced muscle strength (quadriparesis), impaired blood flow to a region in the brain (infarcts), or a comatose state.
Standing-induced headaches are a classic symptom of Spontaneous intracranial hypotension (SIH), which essentially happens due to low spinal fluid pressure. The headaches often worsen when the person stands up, and could potentially become continuous. In rare instances, the headache might improve when the person is upright. Researchers suggest that this might be because lying down increases congestion in the veins of the layers covering the brain (dural venous sinuses), making the headache worse. Common additional symptoms of SIH include nausea, neck discomfort, ringing in the ears (tinnitus), and dizziness.
- Classic CSF leak symptoms:
- Clear runny nose
- Headache
- Neck pain or stiffness
- SIH symptoms:
- Headaches that worsen with standing
- Nausea
- Neck discomfort
- Tinnitus
- Dizziness
CSF leaks can also result in unusual symptoms like confusion, memory loss, a particular type of dementia (frontotemporal brain sagging syndrome), shakiness (parkinsonism), and loss of coordinated movements (ataxia). Recent findings propose that dural tears, which might be the underlying factor for some unexplainable cases of brain surface bleeding (superficial siderosis) predominantly in the back of the brain (posterior fossa), might often be due to these leaks. Nerve root disease (Radiculopathy), arm muscle wasting (brachial amyotrophy), and spinal cord disease (myelopathy) can occur in SIH due to the superficial siderosis of the spinal cord, or compression of the central nervous system.
Testing for Cerebrospinal Fluid Leak
If you might have a cerebrospinal fluid (CSF) leak, it’s essential for your doctor to accurately identify if you have this condition. CSF is a fluid found in your brain and spinal cord that protects these areas. Your doctor may suspect a leak based on certain signs and your medical history, and then uses tests for more information.
One of these tests might be for a substance called beta-2 transferrin. This substance is found only in CSF, making it a reliable indicator of a possible CSF leak. This protein is not usually present in your body except in the CSF. Research has shown it to be a good marker for identifying CSF leaks. If beta-2 transferrin is found in any fluid coming from your nose or ear, it indicates a possible CSF leak. If this test result is negative, it’s doubtful the leak is from the CSF. In the past, doctors often tested fluid from the nose for glucose (a type of sugar), but beta-2 transferrin has proven to be a better test.
Based on the timing of the possible leak after a head injury, your doctor may classify it as the early onset (with a leak occurring within the first two days), delayed (at least a week after the injury), or late onset (within three months). Studies show that half of the leaks start within the first two to three days, most begin within a week, and almost all occur within three months. In some cases, patients might have a condition called meningitis, an infection of the lining of the brain, without apparent leakage. In such cases, a high-resolution CT (including detailed images) can help identify the problem.
Different imaging methods, such as high-resolution CT (HRCT), CT cisternography, and magnetic resonance (MR) cisternography, help provide more detailed information about the suspected leak and its location. If the leak is still active, HRCT is usually the first choice. If the leak is inactive, contrast-enhanced MR cisternography or radionucleotide cisternography might be better choices. Radionucleotide cisternography involves injecting a small amount of radioactive substance into your spinal fluid.
Spontaneous CSF leaks can occur due to a condition called intracranial hypertension, which creates excessive pressure inside your skull. If this is the case, the doctors will likely recommend imaging tests and a fundoscopic examination, which involves examining the back of your eye to check for signs of this pressure. If the leak occurred due to intracranial hypotension, where there’s reduced pressure inside your skull, an MRI of your spine and brain can show signs such as thickening of the membranes covering the brain and spinal cord (pachymeningeal), fluid collections beneath the protective layers of the brain (subdural), and the downward movement of the brain.
A study showed that MRI findings were present in 79% of patients with spontaneous CSF leaks, with a sensitivity rate of 85.7% for these leaks. Detailed analyses suggested that enhancement of the pachymeninges was the most sensitive sign, followed by subdural fluid accumulation and a sagging brain. Less common indicators included the swelling of blood vessels and an overactive pituitary gland.
Treatment Options for Cerebrospinal Fluid Leak
The appropriate medical response to a cerebrospinal fluid (CSF) leak depends on details such as what caused it, its size and where it’s located. If it’s a minor leak, it’s possible that it will self-resolve, whereas larger leaks may need surgical treatment. Standard treatment for a CSF leak often includes bed rest and increased fluid intake. If the leakage continues, medical practitioners might suggest a procedure called a lumbar epidural blood patch, where some of the patient’s own blood is injected into the area surrounding the spinal cord. This helps seal the leak and alleviate symptoms. There are also other procedures such as nasal packing, endoscopic repair and surgical repair.
In circumstances where the CSF leak resulted from a craniofacial injury, doctors may choose to observe progress and take a more conservative approach, because some of these injuries heal without any medical interference. However, there’s a 29% chance of patients developing an infection of the brain membranes (meningitis), so this approach should be taken with caution. Other strategies include lumbar shunts or repeat lumbar punctures, using an endoscope for repair or even ventriculoperitoneal (VP) shunts, though these carry a high risk of complications.
Even when managing CSF leaks in a conservative way, things like bed rest can help lower pressure on the affected area and allow healing. Over-the-counter pain medications like ibuprofen or acetaminophen can help with headaches and neck pain. Hydrating by drinking a lot of fluids helps maintain fluid levels in the body, reducing symptoms. Limiting caffeine intake may also be beneficial since caffeine can exacerbate symptoms. Avoiding activities that raise pressure on the affected area like coughing, sneezing or straining also tends to aid in managing symptoms. Acetazolamide, a type of medication, can sometimes be recommended because it reduces the production of CSF, and it’s been found to work well for certain patients.
Initial treatments may yield favourable outcomes in mild occurrences of a CSF leak, letting the leak heal naturally, although severe cases or persistent symptoms may necessitate more invasive treatments such as surgery. Working closely with competent medical professionals is instrumental in deciding the best treatment based on each unique situation.
The epidural blood patch (EBP) is frequently used in treating CSF leaks. In this procedure, the patient lies on their belly while under local anesthesia. The doctor numbs the skin and tissues over the lower back, then uses a needle to insert a catheter into the space around the spinal cord (epidural space). A small amount of the patient’s own blood is slowly applied via the catheter into the epidural space, putting pressure on the leak, and sealing it. EBP is generally safe and effective, with high symptom resolution success rate, more so for individuals who did not respond well to initial treatments, or have had recurrent leaks.
Other procedures that can be done to treat CSF leaks include the lumbar drain procedure and endoscopic nasal packing. The lumbar drain procedure involves a catheter inserted into the lumbar (lower back) area of the spinal canal to drain accumulated CSF fluid and relieve symptoms. This also provides time for the leak to mend. How long the catheter remains in place depends on the exact size and location of the leak, as well as the patient’s unique healing process.
Endoscopic nasal packing involves placing small, absorbent material into the nasal passages to plug the leak and prevent further loss of CSF fluid. This is typically done under general anesthetic and has become a popular chosen procedure for patients looking to sidestep more invasive surgical options.
One other medical intervention for CSF leaks is the External Ventricular Drainage (EVD) procedure. Here, a drain is placed in the brain’s ventricles to remove cerebrospinal fluid, thereby reducing pressure and allowing for better healing of the CSF leak region. This procedure also usually requires the patient to be under general anesthesia.
Lastly, surgical correction becomes an option when the leak site has been identified, and severe symptoms persist or hasn’t responded well to less invasive procedures which includes those aforementioned.
What else can Cerebrospinal Fluid Leak be?
When experiencing symptoms like a runny nose or a headache, several medical conditions might be the cause. These could include:
- Allergies causing a runny nose
- Low pressure in the brain
- Damaged arteries leading to the brain or spine
- Common cold or other infections
- Meningitis, an infection of the brain and spinal cord
- Headache following an injury
- Decreased brain pressure that isn’t caused by an injury
- Bleeding in the area between the brain and its protective covering
- Runny nose without an allergic cause
- Sinus disease
- Issues with the spine
- Migraine
- Brain tumor
What to expect with Cerebrospinal Fluid Leak
The overall outlook for a person with a cerebrospinal fluid (CSF) leak is generally positive. This is a condition where the fluid that cushions your brain and spinal cord leaks out, potentially causing a range of symptoms. One study found that the first attempt to fix this leak, using a type of nose surgery known as endoscopic repair, was successful 90% of the time. Another study found an overall success rate of 98% across different causes of CSF leaks, including those caused by injury, medical procedures, or birth defects.
A recent study suggested that a treatment called an Epidural Blood Patch (EBP), which is when a small amount of the patient’s blood is used to plug the leak, works best for individuals with smaller abnormalities in the dura, which is the outermost layer that surrounds the brain and spinal cord. However, larger abnormalities in the dura may be why other treatments like surgery and lumbar drains (a tube used to remove fluid from around the spine) sometimes fail. Of the patients in the study, 97% saw their initial EBP treatment fail, while 21.1% experienced failure with a lumbar drain, and 13.5% with surgery. Overall, the failure rate was 10.9%.
The success rate for nose surgeries to repair CSF leaks ranges from 87% to 100% on the first try. However, those with serious abnormalities at the base of their skull, leaks in the side of the sphenoid bone in the skull, a condition where a person’s nasal fluid leaks (spontaneous CSF rhinorrhea), being overweight, and middle-aged, are more likely to experience a recurrence of CSF leaks. Recurrence of the leak might also occur more often in those with high intracranial pressure (ICP), which is pressure inside the brain, diabetes, and a body mass index (BMI) over 30. Repeated CSF leaks may be associated with higher treatment failure rates.
Possible Complications When Diagnosed with Cerebrospinal Fluid Leak
A leaky brain blood supply can be harmful because it might raise the risk of direct brain tissue damage due to the loss of protective fluid. If this brain fluid leak is chronic and untreated, it can result in symptoms like headaches, neck pain, ear ringing, and, sometimes, a loss of smell or taste. Another serious risk of this condition is a severe brain infection, including meningitis, because this fluid leak creates a way for harmful germs to enter into the brain.
Meningitis, a potential risk of brain fluid leak, is particularly a greater concern before surgery in those confirmed with brain fluid leakage. People who suffered from traumatic injuries have the highest risk, approximately 30%. In fact, meningitis was found in about 18.2% of trauma patients and a third of patients undergoing specific types of skull surgeries. Even those with persistent brain fluid leaks have a 19% risk of contracting meningitis. This risk will remain until the leak is successfully closed through surgery.
Moreover, a recent study has pointed out that palsy is a potential complication of skull-base surgery aimed at treating a brain fluid leak. Surgery in the calvaria, the upper part of the skull, can present more challenging symptoms, like headaches, fever alongside meningitis, and disturbances in consciousness.
Interestingly, patients who experienced spinal taps or spinal surgeries haven’t reported having meningitis. While certain surgeries, spinal taps, and traumatic injuries resulted in more observable brain fluid accumulations on scans, all treatment options, including less invasive ones, had similar success rates and time periods.
However, people with brain fluid leaks due to surgery or trauma usually preferred surgical treatment. In contrast, leaks related to spinal taps typically utilized patches made of the patient’s own blood as the most advanced repair therapy. Also, there can be complications like brain abscess, subset of blood vessels under the dura mater in the brain, and smell disorders.
Potential Issues:
- Direct brain tissue damage
- Headaches
- Neck pain
- Ear ringing
- Loss of smell or taste
- Severe brain infection, including meningitis
- Palsy
- Fever alongside meningitis
- Disturbances in consciousness
- Brain abscess
- Subset of blood vessels under the outermost layer of the brain
- Smell disorders
Preventing Cerebrospinal Fluid Leak
To avoid cerebrospinal fluid (CSF) leaks, which happens when the fluid around your brain and spinal cord leaks out, you should steer clear of situations or activities that might harm the brain or spinal cord. This includes high-impact sports, roller coasters, or other activities that could lead to jostling movements or falls. If you have connective tissue diseases, or if you’ve previously had spinal or brain surgery, you may be more likely to experience CSF leaks so you need to be particularly cautious.
It’s equally important that you understand the signs of a CSF leak. These can include a headache, feeling nauseous, and a clear or salty fluid coming from your nose or ear. These symptoms should never be ignored, and you should reach out to a doctor immediately if you experience them.
It’s also critical that you follow any treatment recommendations from your doctor, such as resting in bed, ensuring you stay hydrated, and avoiding activities that could increase pressure inside your skull. Furthermore, be careful not to blow your nose forcefully as this can increase the chance of a CSF leak occurring.
