Arachnoiditis

What is Arachnoiditis?

The meninges are the tissues within your head and spine that protect your nervous system and act as a frame for the blood vessels in your brain and spinal cord. These tissues have three parts: the dura mater, the arachnoid mater, and the pia mater. The fluid that provides nutrients and helps maintain balance of electrolytes and fluids outside cells in the nervous system, known as cerebrospinal fluid (CSF), moves in the space between the arachnoid and pia. This fluid, which is created by structures called the choroid plexuses in your brain’s four ventricles, also acts like a protective cushion.

The dura mater sticks to the inside of your skull and vertebrae and is split into two layers: an outer layer that lines the inside surface and a robust, web-like inner layer that threads through the opening where the brain and spinal cord’s dura layers connect. There’s also a potential space between the bone and dura mater that can fill up with fluid or blood.

The dural venous sinuses are cavities within the dural layer that house CSF, which enters these sinuses via clusters of arachnoid villi, called “arachnoid granulations”. There is another potential space between the dura and arachnoid called the subdural space.

The arachnoid and pia mater tissues are closely connected to each other because they developed from the same layer around the embryonic brain. Small fluid-filled spaces within these layers form the subarachnoid space. Trabeculae (a kind of connective tissue) within these layers gives the arachnoid mater a web-like appearance. The arachnoid mater contains collagen and elastic fibers and fibroblasts. The pia mater is a slim membrane packed with blood vessels that sticks tightly to the brain and spinal cord surfaces.

Unlike the potential spaces mentioned before, the subarachnoid is an actual space holding connective tissues and blood vessels. CSF allows your nervous system to float within this space.

Arachnoiditis is a chronic inflammation of the arachnoid mater and subarachnoid space, primarily in the spinal cord. Its causes are not well understood but it often develops after spinal surgery, infection, subarachnoid hemorrhage, lumbar epidural injections, and chemical irritation, among others. It can even occur without a known reason. This condition can cause the growth of scar tissue, which can trap nerve roots, block CSF flow, and lead to chronic adhesive arachnoiditis. Prolonged inflammation can cause ossification, a condition where calcium deposits form and harden the tissue, and this can lead to advances in neurological health conditions. Swelling of the spinal cord and other complications can arise in severe cases of arachnoiditis.

What Causes Arachnoiditis?

The exact cause of arachnoiditis, a condition that affects the nerves causing pain, is not clear. The time it takes to notice symptoms after being exposed to potential triggers can change. Diagnosing arachnoiditis can also be tricky due to varying imaging results. Yet, there are certain risk factors that make a person more likely to develop this condition. These risk factors are grouped into four categories:

1. Chemical factors, which may involve being exposed to substances that are harmful to the nerves. This could be certain preservatives, blood from a specific type of brain hemorrhage, harmful effects of local anesthesia, certain types of spinal imaging techniques, certain drugs used for spinal anesthesia, or accidental injection of harmful chemicals.

2. Mechanical factors, such as physical trauma, surgical procedures involving the protective layers of the brain and spinal cord, spinal operations, or a condition where a spinal disk slips out of place.

3. Inflammatory factors, like a type of arthritis that affects the spine, Guillain-Barré syndrome, a disorder causing nerve inflammation, or diseases that cause inflammation in your blood vessels.

4. Infectious factors, such as syphilis, tuberculosis, HIV, viral infections, or certain types of fungi.

Sometimes, arachnoiditis can develop without any clear trigger.

When faced with a harmful agent, scar tissue forms in the protective layers of the brain and spinal cord. This scar tissue envelops nerve roots, disrupts blood flow, decreases oxygen and nutrient supply, and leads to waste build-up. These changes cause pain and neurological problems.

Among the most commonly reported causes of arachnoiditis are previous trauma, spinal surgery, or a specific type of brain hemorrhage. People can be exposed to harmful chemicals either on purpose or by accident.

Risk Factors and Frequency for Arachnoiditis

Arachnoiditis is a rare disease that has not been widely studied. Since it was first described as a distinct condition in 1909, less than 1,000 cases have been reported in scientific literature. Precise information on how often arachnoiditis occurs is difficult to determine due to its rarity, the challenges in diagnosing it, and the different names it goes by, such as “chronic spinal meningitis” and “meningitis serosa circumscripta spinalis”. Some people may have arachnoiditis without showing symptoms, which means that it’s likely that the condition is under-diagnosed and under-reported. However, it’s being observed more frequently recently due to increasing need for surgeries on the lower part of the spine.

Signs and Symptoms of Arachnoiditis

Arachnoiditis is a condition that can present in very different ways, with its severity ranging from mild to disabling. Its symptoms may not change over time or could gradually worsen. This is a condition that causes painful and uncomfortable symptoms in the back and legs, including sensory, motor, or reflex issues. Identifying what causes arachnoiditis can be difficult. For instance, spinal adhesive arachnoiditis symptoms may start many months after a ruptured aneurysm.

The symptoms of arachnoiditis can differ depending upon the spinal levels it affects, and how severe it is. The most common areas impacted are the lower back and middle back, followed by the region where the spine meets the hips. It’s rare that the entire spine is affected. Severe cases of this condition can cause symptoms such as very strong back pain, numbness, a tingling feeling, and symptoms related to nerve roots and the spinal cord in the lower limbs. It can also cause bowel or bladder problems, sexual dysfunction, difficulty sitting for long periods, and muscle weakness.

• Very strong back pain
• Numbness
• Tingling sensation
• Lower limb nerve and spinal cord-related symptoms
• Bowel or bladder problems
• Sexual dysfunction
• Difficulty sitting for long periods
• Muscle weakness

The most frequently seen symptoms of arachnoiditis include back pain, pain radiating along the nerves, and sensory issues. Other, less common symptoms are muscle weakness, issues with balance whilst walking, and bowel or bladder problems arising from nerve damage. About a quarter of patients with arachnoiditis develop urinary symptoms late in the disease course. These symptoms often present as a pressing need to urinate, needing to urinate more often, and occasionally, loss of bladder control. Paralysis and isolated lower back pain have also been observed in patients.

Symptoms related to the nervous system can differ depending on where they occur and their severity. When arachnoiditis is suspected, it’s crucial for a full neurological examination to be carried out to aid both diagnosis and treatment planning.

Testing for Arachnoiditis

Arachnoiditis is a condition usually identified by examining a patient’s symptoms. Laboratory tests and additional procedures such as examining muscle and nerve electrical activity often provide varied results and are not typically used to diagnose this condition.

When a doctor wants to support the symptoms observed, they may use sophisticated imaging techniques, like MRI and CT scans. These techniques are very sensitive and accurate when looking for chronic adhesive arachnoiditis, a specific type of the disease. However, the signs we see on these scans don’t always match up with a patient’s symptoms or how severe those symptoms are. If MRI results aren’t clear, a method called thecaloscopy, which involves direct visualization, can help detect sac-like structures known as loculated arachnoid cysts.

In some cases where there is swelling of the spinal cord and an increased signal within the cord, a spinal cord biopsy might be undertaken. This is to ensure we are not dealing with tumors instead.

Common findings on an MRI for this condition could be loculated arachnoid cysts. These cysts can affect several spinal sections or potentially the entire spine. Other MRI findings might include swelling of the spinal cord, displacement or shrinking (atrophy) of the cord, clumping of nerve roots, formation of a fluid-filled cyst (syrinx), and transverse barriers (septations) in the arachnoid membrane. On the other hand, typical signs spotted on a CT scan may include blockage of the contrast dye during the scan, nerve roots that are stuck or thickened, uncharacteristic soft tissue masses within the arachnoid space, and intrathecal calcification, a condition where there is calcium buildup in the spaces around the spinal cord.

When making a choice between these two methods, MRI is generally preferred for adhesive arachnoiditis because it can tell the difference between harmless calcification of the meningeal layers and actual ossification, a process where soft tissue transforms to bone in the arachnoid tissue. However, a CT scan without contrast is better than MRI at diagnosing arachnoiditis ossificans, a rare type of arachnoiditis where the arachnoid layer solidifies due to calcification or ossification.

Treatment Options for Arachnoiditis

Arachnoiditis, a condition that can cause intense pain and other symptoms, currently has no definitive cure. Treatment is mostly focused on easing symptoms to improve the patient’s day-to-day life. Medications like pain relievers and anti-inflammatory drugs are often used, along with other medicines like duloxetine, gabapentin, and pregabalin. Muscle relaxants such as baclofen can also be used in conjunction with painkillers.

Several other strategies can also be helpful, such as physical therapy and psychological techniques. Cognitive behavioral therapy, biofeedback, and guided imagery can help shift how a patient perceives their pain, potentially lessening their discomfort. Some individuals, particularly those who find it painful to sit, might greatly benefit from assistive motor devices like standing wheelchairs to enhance mobility and overall quality of life. However, it’s crucial to check if the patient can safely use such devices before moving on.

There are some invasive techniques that could alleviate symptoms as well. Thecaloscopy, which involves the removal of cysts and adhesions and neurostimulation to manage pain, is one option. Another is intrathecal therapy, although this can sometimes worsen the condition.

The role of surgery in managing arachnoiditis is still unclear. Certain surgical procedures can unstick a cord that’s trapped or improve the flow of cerebrospinal fluid (CSF). These interventions include shunting, myelotomy, duraplasty, cyst fenestration, adhesiolysis, and laminectomy. But it’s important to note that while such surgeries can provide initial relief, the long-term outlook is generally poor. Symptoms can often reemerge and even worsen overtime after surgery.

When it comes to arachnoiditis ossificans, a specific form of the condition, temporary relief could be achieved via surgical removal of hardened plaques. Similarly, severe cases of arachnoiditis with blocked CSF flow could benefit from surgical interventions, but these procedures can’t prevent recurrence.

There’s one scenario where early surgical intervention might be helpful: in preventing arachnoiditis from epidural infection. By treating the infection early, inflammation could be prevented from penetrating the protective dural sac and causing severe arachnoiditis.

While some people have reported improvements after getting epidural steroid injections, this method is generally discouraged as it can worsen the condition. Similarly, oral corticosteroids haven’t demonstrated any therapeutic benefits.

What else can Arachnoiditis be?

When a doctor is trying to diagnose arachnoiditis, they need to keep in mind other medical conditions that cause similar symptoms. Some of these conditions that affect the spinal cord may include:

• Spinal cord tumors
• Herniated disks
• Post-surgery pain in the spine
• Multiple sclerosis
• Cauda equina syndrome (a severe nerve issue in the lower spine)
• Syringomyelia (a rare disorder in which a fluid-filled cyst forms within your spinal cord)
• Spinal cord abscess
• Blood clot in the spine
• Infections that affect the central nervous system

A combination of detailed medical exams and imaging tests can help doctors decide if it’s arachnoiditis or one of these other conditions causing the symptoms.

What to expect with Arachnoiditis

Arachnoiditis, a condition where the thin film around your brain and spinal cord is inflamed, can vary a lot in its progression. Some people may experience stability, while for others, it may worsen over time. Many patients with arachnoiditis have a relatively stable level of disability, with their symptoms neither getting dramatically worse nor better from the time they are diagnosed. However, how severe these symptoms are can change from time to time.

Some people might see the condition get worse over time, experiencing significant pain, disability, and a reduced quality of life as the condition advances. Surgery often doesn’t improve the situation and can sometimes even make the condition worse.

While arachnoiditis can cause permanent disability, it’s usually not directly life-threatening. But, the severe symptoms can take a toll on the mental health of the people it affects. A long-term study of 50 individuals with arachnoiditis found that two patients had committed suicide, and others had died from causes unrelated to arachnoiditis. On average, the condition seemed to reduce the individuals’ lifespan by about 12 years.

Possible Complications When Diagnosed with Arachnoiditis

Arachnoiditis can cause a range of complications including:

• Long-term pain
• Severe problems with nerve function
• Syringomyelia (a fluid-filled cyst in the spinal cord)
• Hydrocephalus (a build-up of fluid in the brain)
• Arachnoid cysts (fluid-filled sacs located between your brain or spinal cord and the arachnoid membrane)
• Sexual dysfunction
• Loss of bladder and bowel control

Treatments including supportive measures, physical therapy, and psychological support can help manage the symptoms of the condition and improve quality of life for patients.

Preventing Arachnoiditis

The prevention of arachnoiditis, a condition affecting the spine, mainly involves reducing the factors that might increase its risk. Although not all cases of arachnoiditis can be prevented, particularly when it happens unexpectedly as a side effect of a medical procedure or condition, there are certain steps you can take to lower its chance of development. Here are some common prevention methods:

• Try to avoid unnecessary spine-related procedures
• Take steps to protect against infections
• Stay away from injections directly into the spinal fluid
• Exercise caution when using spinal medications and dyes used in spinal imaging
• Regularly check on people who have undergone multiple spine-related procedures
• Seek specialist care for spine issues
• Educate patients about maintaining a healthy lifestyle to avoid spine problems associated with obesity, such as spinal artery hemorrhage (SAH) and slipped discs

While these steps can help lower the risk of arachnoiditis, they don’t guarantee that it won’t occur. Many arachnoiditis cases are actually caused by unintended results of medical treatments. Hence, it’s necessary for healthcare professionals to clearly explain the potential risks and benefits of spinal procedures to patients to help them make well-informed decisions before giving their consent.