Adhesive arachnoiditis is a chronic inflammatory condition in which the arachnoid membrane, one of the protective layers surrounding the spinal cord and nerve roots, becomes scarred, thickened, and stuck to surrounding structures. The nerve roots that normally float freely in spinal fluid get clumped together or tethered to the walls of the spinal canal, producing pain, numbness, and sometimes loss of bladder or bowel control. It is considered rare but probably underdiagnosed, and once the scarring has set in, the damage is largely irreversible. That combination of severity and limited treatment options makes it one of the more feared complications in spinal medicine.
How the Arachnoid Membrane Gets Damaged
The spinal cord sits inside a fluid-filled sac made up of three membrane layers. The outermost is the dura, the innermost is the pia, and between them sits the arachnoid. In a healthy spine, nerve roots branch off the spinal cord and travel through this fluid-filled space to exit the spine. They move freely, cushioned by cerebrospinal fluid.
Adhesive arachnoiditis begins when something triggers inflammation in or around the arachnoid layer. The body’s repair response lays down scar tissue, and that scar tissue binds nerve roots together, sticks them to the membrane walls, or forms webs and partitions across the spinal canal. Over time, the scarring can block normal fluid flow, compress nerve tissue, and even form fluid-filled cysts that press on the spinal cord. A large systematic review of 510 cases found that the condition progresses through stages: early inflammation gives way to fibrosis, and eventually the scar tissue can calcify and become permanent.
Causes and Risk Factors
Several triggers can set off the inflammatory cascade that leads to adhesive arachnoiditis, and understanding them matters because some are still relevant to procedures done today.
Spinal Procedures and Injected Substances
Historically, the single biggest cause was an oil-based contrast dye called Pantopaque (iophendylate), used for myelography from the 1940s onward. Because the dye was difficult to remove completely from the spinal fluid space, leftover droplets provoked a severe, ongoing inflammatory reaction that led to fibrosis and nerve root entrapment.1PubMed Central. History of myelography with pantopaque contributing to arachnoiditis Modern water-soluble contrast agents have largely replaced Pantopaque, but the condition has not disappeared. Lumbar epidural steroid injections, one of the most common pain procedures performed today, have been linked to adhesive arachnoiditis in case reports, though the overall incidence appears to be very low.2PubMed Central. Adhesive arachnoiditis following lumbar epidural steroid injections: a report of two cases and review of the literature There is also evidence that certain preservatives and vasoconstrictors occasionally included in epidural or spinal medications can damage the arachnoid.3PubMed. Obstetric epidurals and chronic adhesive arachnoiditis
Spinal surgery itself can trigger adhesive arachnoiditis, particularly when the arachnoid membrane is opened or irritated during the procedure. In one reported case, a woman who received spinal anesthesia for a cesarean delivery developed adhesive arachnoiditis that caused progressive cystic compression of the spinal cord, eventually requiring multiple surgeries.4PubMed Central. Neurosurgical Challenges in Recurrent Adhesive Arachnoiditis After Spinal Anesthesia for Cesarean Delivery: Case Report and Literature Review
Infections
Certain infections that reach the membranes around the spinal cord can cause arachnoiditis. Tuberculosis is one of the most recognized culprits worldwide. Tuberculous meningitis can produce spinal arachnoiditis, sometimes paradoxically developing during or after anti-tuberculosis treatment, and elevated protein levels in spinal fluid appear to be a risk factor.5PubMed Central. Spinal cord involvement in tuberculous meningitis Fungal infections, including those caused by Cryptococcus, Candida, Coccidioides, and Histoplasma, along with bacterial pathogens like Listeria and parasitic infections like cysticercosis, have also been documented as causes.6PubMed Central. Spinal Arachnoiditis in Patients with Coccidioidomycosis Meningitis—Analysis of Clinical and Imaging Features
Autoimmune and Inflammatory Disease
Less commonly, the body’s own immune system can attack the arachnoid. A case report documented adhesive arachnoiditis in a young woman with mixed connective tissue disease, an autoimmune condition, causing severe back pain and neurological deficits in her lower limbs after seven years of the underlying disease.7PubMed Central. Adhesive arachnoiditis in mixed connective tissue disease: a rare neurological manifestation This autoimmune route is considered rare but highlights that adhesive arachnoiditis is not always the result of something done to the spine from outside.
Symptoms and How They Progress
The symptoms of adhesive arachnoiditis depend on where the scarring forms and how badly the nerve roots are affected, but certain patterns show up consistently.
Pain is central to the experience. In a systematic review of 510 cases, about 38% of patients reported pain at presentation, with lower back pain being the most common location, followed by sciatica and leg pain.8PubMed Central. Spinal Adhesive Arachnoidopathy, the Disorder More Than Simply Adhesive Arachnoiditis: A Comprehensive Systematic Review of 510 Cases The pain is typically described as burning, deep, and difficult to localize precisely. It often does not follow the neat dermatomal patterns that you would expect from a simple pinched nerve, which can make it confusing to both patients and clinicians.
Abnormal sensations are extremely common. In that same review, roughly 48% of patients experienced paresthesia like numbness and tingling early on. As the disease progressed, many developed more distressing sensory changes: about 21% reported dysesthesia such as burning or electrical sensations, roughly 26% developed increased pain sensitivity, and a small group lost sensation entirely.8PubMed Central. Spinal Adhesive Arachnoidopathy, the Disorder More Than Simply Adhesive Arachnoiditis: A Comprehensive Systematic Review of 510 Cases Motor dysfunction was the most frequently noted problem overall, appearing in nearly 79% of patients and ranging from muscle weakness to difficulty walking.
Bladder, bowel, and sexual dysfunction round out the common symptom cluster. These autonomic symptoms tend to appear as the condition worsens and nerve damage accumulates. The progression from tingling to burning pain to motor weakness to autonomic dysfunction represents the typical arc of the disease, though the speed of progression varies enormously from person to person.
How It Is Diagnosed
Adhesive arachnoiditis is primarily diagnosed through MRI, which can reveal the structural changes in the spinal canal without requiring any invasive procedure. The imaging findings are often distinctive once you know what to look for.
A retrospective review of advanced chronic cases identified several characteristic features on imaging: loculated (walled-off) collections of cerebrospinal fluid, nerve roots clumped together or displaced from their normal positions, swelling or shrinkage of the spinal cord, partitions and webs dividing up the spinal fluid space, fluid-filled cavities within the cord called syrinxes, and in long-standing cases, calcification of the scar tissue.9PubMed. Imaging Appearance of Advanced Chronic Adhesive Arachnoiditis: A Retrospective Review Contrast-enhanced MRI can show whether the nerve roots and membranes are actively inflamed, which helps distinguish active disease from old, burned-out scarring.
One challenge in diagnosis is that some patients develop clear imaging abnormalities without corresponding changes in their symptoms. Two patients who developed adhesive arachnoiditis after lumbar epidural steroid injections showed unmistakable MRI evidence of the condition but experienced no worsening of their clinical status.2PubMed Central. Adhesive arachnoiditis following lumbar epidural steroid injections: a report of two cases and review of the literature This disconnect between imaging findings and symptoms means that a diagnosis based on MRI alone can sometimes overstate or understate the clinical picture. Symptoms, imaging, and clinical history all need to line up.
Treatment Options and Their Limits
There is no cure for adhesive arachnoiditis, and managing it honestly involves acknowledging that most treatments aim to reduce pain and maintain function rather than reverse the underlying damage. The scarring itself is generally permanent, and treatment strategies vary depending on whether the disease is caught early or has been present for years.
Medications for Pain Management
The pain of adhesive arachnoiditis is neuropathic, meaning it originates from damaged nerves rather than from tissue injury, so it often responds poorly to standard painkillers. Gabapentin, an anticonvulsant medication widely used for nerve pain, has shown some benefit in reducing the neuropathic pain associated with arachnoiditis, including symptoms like burning sensations and bladder dysfunction.10Regional Anesthesia and Pain Medicine. Gabapentin reduces neuropathic pain in arachnoiditis Opioid medications are sometimes prescribed for severe pain, and animal research has shown that morphine can reduce pain responses in an arachnoiditis model, though only at higher doses.11Spine. Characterization of Pain and Pharmacologic Responses in an Animal Model of Lumbar Adhesive Arachnoiditis The reliance on opioids is problematic for an ongoing chronic condition, and most pain specialists try to minimize their long-term use.
Other medications commonly tried include other anticonvulsants like pregabalin, antidepressants that act on nerve pain pathways, anti-inflammatory drugs, and muscle relaxants. The evidence base for most of these in adhesive arachnoiditis specifically is thin, largely because the condition is rare enough that large randomized trials have not been conducted. Clinicians typically borrow treatment strategies from the broader chronic neuropathic pain literature and adjust based on individual response.
Immunotherapy and Anti-Inflammatory Approaches
Because inflammation drives the disease process, suppressing the immune response seems like a logical strategy. In practice, the results have been discouraging for chronic cases. A case series examining immunotherapies found that three out of four patients showed no improvement after treatment with corticosteroids, methotrexate, or plasmapheresis. The one patient who did recover fully had been diagnosed less than a month after symptoms began, while the non-responders had all been living with the condition for several years.12PubMed Central. Immunotherapies in chronic adhesive arachnoiditis – A case series and literature review This pattern suggests a narrow window of opportunity: once scar tissue has matured and calcified, anti-inflammatory drugs cannot undo the structural damage. Early and aggressive treatment in the inflammatory phase may be the best shot at halting progression, but catching the disease that early is uncommon because the initial symptoms are often attributed to other, more common spinal problems.
Surgery
Surgical options exist but come with significant caveats. The fundamental problem is that operating on scarred tissue inside the spinal canal risks triggering more scarring. Laminectomy with lysis of adhesions, where a surgeon opens the spinal canal and carefully separates the stuck-together nerve roots and membranes, can provide temporary relief. But the disease has a well-documented tendency to recur. In the cesarean delivery case mentioned earlier, a patient who underwent laminectomy with cyst fenestration showed persistent arachnoiditis, septations, and spinal cord distortion on follow-up imaging four months after surgery.4PubMed Central. Neurosurgical Challenges in Recurrent Adhesive Arachnoiditis After Spinal Anesthesia for Cesarean Delivery: Case Report and Literature Review
The extent of scarring matters a great deal for surgical outcomes. A study on flexible thecoscopy, a minimally invasive approach using a small scope inserted into the spinal fluid space, found that arachnoiditis extending beyond four spinal segments has a much worse prognosis because adhesions are harder to remove completely and the area is more prone to postoperative scarring and retethering.13PubMed Central. Flexible thecoscopy for extensive spinal arachnoiditis In short, surgery is generally reserved for specific complications like cyst formation or severe cord compression, not for the adhesive process itself.
Spinal Cord Stimulation
Spinal cord stimulation, which involves implanting electrodes near the spinal cord that deliver mild electrical impulses to interrupt pain signals, is used for various chronic pain conditions and has been tried in adhesive arachnoiditis. However, outcomes for arachnoiditis patients appear to be worse than for people with simpler nerve injuries. A study comparing spinal cord stimulation results across diagnoses found that patients with arachnoiditis and multiple injured nerve roots had significantly poorer treatment outcomes than those with single nerve root injuries.14PubMed. Outcome of implanted spinal cord stimulation in the treatment of chronic pain: arachnoiditis versus single nerve root injury and mononeuropathy The diffuse nature of the nerve damage in arachnoiditis likely makes it harder for electrical stimulation to cover all affected areas effectively.
Physical Rehabilitation and Self-Management
Given the limitations of medications and surgery, physical rehabilitation plays an important role in maintaining function and managing pain. One approach that has shown promise in individual cases is neural mobilization, a set of gentle exercises designed to help nerves glide more freely through surrounding tissues. In one case report, a woman with postoperative spinal adhesive arachnoiditis was treated with neural mobilization of the sciatic nerve twice a week for three weeks, supplemented by home exercises. Her disability scores dropped by 19%, and her pain intensity fell by two points on an analogue scale.15PubMed Central. Neural Mobilization in a 54-Year-Old Woman With Postoperative Spinal Adhesive Arachnoiditis This is a single case and not a substitute for robust trial evidence, but it illustrates that movement-based therapies done carefully and within tolerance can make a meaningful difference in day-to-day function.
Aquatic therapy is another approach frequently recommended because water buoyancy reduces the load on the spine while allowing movement. Stretching programs, core stabilization, and pacing strategies, where you learn to alternate activity and rest to avoid pain flares, are standard components of rehabilitation plans. The goal is not to fix the underlying scarring but to keep the body as functional and as comfortable as possible around it.
The Impact on Daily Life
Adhesive arachnoiditis affects far more than just the spine. Fatigue is a pervasive issue for people living with the condition, contributing to both physical and mental exhaustion that interferes with work, social participation, and overall quality of life.16Archives of Physical Medicine and Rehabilitation. Understanding How Adhesive Arachnoiditis Impacts Adults’ Daily Occupational Performance The combination of chronic pain, sleep disruption, medication side effects, and the psychological toll of living with a poorly understood condition creates a cycle that can be difficult to break.
Many people with adhesive arachnoiditis find that their condition is poorly recognized by healthcare providers outside of specialized pain or neurosurgery clinics. Because the disease is rare and symptoms overlap with more common spinal conditions like disc herniations and spinal stenosis, years of misdiagnosis are not unusual. Patients frequently describe a frustrating journey through multiple specialists, repeated imaging studies, and failed treatments before arriving at the correct diagnosis. This delay matters because, as the immunotherapy evidence suggests, the disease may be more responsive to treatment in its early inflammatory phase than after scar tissue has become established.
Why the Condition Is Probably Underrecognized
The true prevalence of adhesive arachnoiditis is unknown, and there are good reasons to think official numbers undercount it. Part of the problem is diagnostic overlap: a patient with chronic low back pain, leg pain, and nerve dysfunction will often receive diagnoses like “failed back surgery syndrome” or “chronic radiculopathy” without anyone specifically looking for the imaging hallmarks of arachnoiditis. Another factor is that mild cases, where imaging changes exist but symptoms are minimal, may never come to clinical attention at all. The observation that some patients develop clear MRI signs of arachnoiditis after epidural injections without any change in symptoms underscores how silently the process can begin.2PubMed Central. Adhesive arachnoiditis following lumbar epidural steroid injections: a report of two cases and review of the literature
Epidural steroid injections are performed millions of times per year worldwide, and while the absolute risk of developing clinically significant arachnoiditis from any single injection is very small, even a tiny percentage of a very large number produces real patients. The fact that the pathogenesis remains uncertain makes it hard to identify who is most at risk or to modify techniques to eliminate the danger entirely. For now, the medical community treats it as a rare but recognized complication and generally considers the benefits of epidural injections to outweigh the risks for most patients with appropriate indications.
Emerging Approaches and Open Questions
Research into adhesive arachnoiditis is hampered by the same rarity that makes it hard to diagnose. No large randomized controlled trials exist for any treatment, and most of the published literature consists of case reports and small case series. This means that nearly every treatment decision is based on limited evidence combined with clinical judgment.
Thecoscopy, the minimally invasive spinal endoscopy technique mentioned earlier, represents one of the more promising surgical avenues because it avoids the wide-open surgical exposure of traditional laminectomy, potentially reducing the risk of further scarring.13PubMed Central. Flexible thecoscopy for extensive spinal arachnoiditis Even so, its use is limited to specialized centers, and the evidence remains preliminary. Anti-fibrotic agents, drugs designed to prevent or reverse scar tissue formation used in other areas of medicine like pulmonary fibrosis, are a theoretical avenue that has not yet been rigorously tested in spinal arachnoiditis.
One of the most important unanswered questions is whether routine follow-up imaging after spinal procedures could catch early arachnoiditis before it becomes symptomatic and irreversible. If immunotherapy works best within the first weeks, as the case series data hints, then early detection could change outcomes dramatically. But screening asymptomatic patients after every epidural injection is not currently practical or cost-effective. Whether targeted surveillance of higher-risk patients, such as those who have had multiple spinal procedures or those with autoimmune disease, would pay off remains an open research question.