This extremely painful condition can result from interventional pain treatments, which are recommended by the CDC instead of opioids.
Arachnoiditis is a progressive neuroinflammatory disease. Although recognized many years ago, heretofore it has been considered a rare disease and is listed in the “Rare Disease Registry.”
Today, we expand our coverage of the condition, which is, for many reasons, increasing in incidence and prevalence.
This increase is probably because the CDC came close to banning opioids, so many doctors are sending their patients for spinal injections or surgery instead.
Although the term arachnoiditis simply implies inflammation of the arachnoid lining of the meninges or thecal sac, the major pathologic abnormality in the majority of cases is neuroinflammation of the nerve roots in the cauda equina.
Once glia cells in nerve roots produce neuroinflammation, they may form adhesions and scars that may cause nerve roots to stick together or clump and adhere to the arachnoid lining.
The term AA is the term historically assigned to the condition when adhesions or scarring between nerve roots and/or the arachnoid lining is visible on magnetic resonance imaging (MRI). AA will be the term used throughout this paper as it is this stage of the disease that usually causes a patient to seek medical and pain treatment.
AA may be a crippling, progressive, painful condition of immense severity.
- It may progress to lower extremity paralysis
- bladder, bowel and gastrointestinal dysfunction
- inability to sit or stand for long periods of time
- deterioration of mental abilities
- and create an autoimmune disorder with symptoms that mimic classic rheumatologic disease.
Over the past 5 years, my clinic has admitted to treatment an increasing number of patients with AA. Today, the practice follows about 65 cases. I have reviewed the MRI’s from over 200 confirmed patients. Some of the cases were accepted as emergencies because they developed severe pain and partial paralysis of the lower extremities and bladder dysfunction immediately after a spinal tap, epidural anesthesia given for childbirth, epidural corticoid injection, or surgery.
Anatomy of the Spinal Cord
Understanding AA requires some knowledge about the anatomy of the cauda equina, or “horse’s tail.” About two dozen nerve roots emanate and hang down from the end of the spinal cord known as the conus medullaris (Figure 1).
The nerve roots within the thecal sac are quite organized. They are primarily in the posterior portion of the thecal sac between L1 to L3 and then move forward or anterior. The nerve roots progressively exit the thecal sac beginning between L1 and L3.
Nerve roots of the cauda equina are constantly bathed and submerged in spinal fluid that acts as a lubricant against friction between nerves, transports waste products, and brings nutrients to the nerve roots.
The spinal fluid turns over about 4 times a day. Therefore, waste products, including inflammatory particles from inflamed nerve roots, are carried upward to drain through channels in the meninges into cervical lymph nodes and general circulation
Although the term cauda equina syndrome has traditionally only referred to the acute compression of the nerve roots, some practitioners have used the term “chronic cauda equina syndrome” when bladder and bowel dysfunction, pain, and some paraparesis coexist
As far as I can determine, the term chronic cauda equine syndrome is not due to nerve root compression but, rather, neuroinflammation of the nerve roots in the cauda equine—in effect, it may be considered an alternate name for AA.
The Inciting Cause: Irritation and Neuroinflammation
Traditionally, the diagnosis of AA has been made on MRI, where nerve roots in the cauda equina can be seen to have formed adhesions between each other, forming clumps, and/or when adherence to the arachnoid lining is caused by adhesions.
Common pathologic conditions of the spine, including herniated discs, spinal stenosis, and degenerative arthritis, may cause enough irritation to produce neuroinflammation in cauda equina nerve roots in the lumbar region.
Despite the lubricating properties of spinal fluid, spine deformities and imbalances produced by scoliosis, cysts, or arthritis may cause enough compression and friction between nerve roots to cause irritation, activation of glia cells, and neuroinflammation.
The trauma of medical procedures, including paraspinal injections and surgeries that are medically indicated, may leave AA behind as a complication.
Although the percentage is unknown, many patients who are now labeled with “failed back surgery syndrome” likely have AA and should be evaluated for this condition.
Pathologic Progression and Diagnosis
Unfortunately, AA may develop, resolve, and become a progressive, debilitating disease
The inflamed nerve roots and arachnoid lining may progressively inflame and add or “capture” additional nearby nerve roots. The progression may go up or down the spine
Some severe patients literally have so much pain, fatigue, and disability that they report to me that they spend 80% to 90% of their time in bed.
Some patients report that pain is so excruciating that high-dose opioids are required for even a modicum of pain control.
It’s ironic that since opioids have been discouraged, more patients are seeking interventional treatment, which then results in increaseing cases of this even more painful condition.
It seems unconscionable to hold back opioids after patients have incurred an additional painful condition specifically because they were trying to avoid opioids.
Although the mechanism is somewhat unclear, patients may apparently develop some interference with spinal fluid flow
In addition to adhesions and scarring, AA patients may develop some interference with spinal fluid flow
Mental impairment and deterioration relative to
- attention span,
- logistical or abstract thinking, and
- even reading and writing may occur.
Some advanced stage AA patients develop such mental and physical debility that they require constant caretaking.
Patients develop a high prevalence of arthralgia, myalgia, and such autoimmune phenomenon as Hashimoto’s thyroiditis and carpal tunnel syndrome.
A major treatment goal is to stop the progression, disability, and deterioration that is characteristic of AA patients.
Diagnosis: Symptoms and Signs
AA patients have typical symptoms and signs that allow a practitioner to differentiate an AA patient from other back pain patients (Table 1).
In addition to constant pain, in my experience over 90% of patients complain of
- bladder dysfunction;
- inability to stand more than a few minutes;
- burning soles of feet;
- episodes of blurred vision;
- lacerating or stabbing pain in the legs; and
- bizarre feelings on the skin (eg, bug crawling, water dropping, pins sticking).
In my experience, the inability to stand very long is so dominant in these patients that they may even ask to lie on your exam table or on the floor of your office.
Some physical signs of AA include lower extremity weakness, hyporeflexia, and abnormal gait.
Patients may not be able to do straight leg raises or flex one or both feet.
Range of motion of both upper and lower extremities may be restricted.
When their gait is observed, look for short steps, leaning, wide base, and unsteadiness.
In my experience, 30% to 40% of AA patients demonstrate elevated erythrocyte sedimentation rates (ESR) or high sensitivity C-reactive protein (CRP) levels.
Other less known inflammatory markers such as the interleukins, myeloperoxidase (MPO), a1-antitrypsin, and tumor necrosis factor may also be elevated.
Whether neuroinflammation can ever be totally arrested or “cured” is unknown. Considering that AA patients have constant pain and intermittent flares suggests that patients continually carry both neuroinflammatory and neuropathic components to their pain.
Magnetic Resonance Imaging (MRI)
The best MRI image to confirm a diagnosis of AA is usually the axial view of a contrast MRI (Figure 2) at the L3,L4,L5 and S1 levels of the lumbar spine.
My clinic has developed treatment protocols for both acute and chronic cases. The protocol comprises 4 components:
- control and suppression of neuroinflammation;
- exercises to prevent adhesions;
- pain relief; and
- neuroprotection and neurogenesis (nerve growth) (Table 2).
The most critical component of treatment is suppression and control of neuroinflammation; otherwise, AA may progress and worsen.
It is my personal observation that stable pain relief is difficult to attain in AA patients until a potent and aggressive neuroinflammation regimen is in place.
The neuroinflammation regimen recommended here may first appear to have undue risks, but less potent attempts by my team have not been successful
Studies in rats have shown that the corticosteroid, methylprednisolone, and the anti-inflammatory agent indomethacin suppress cauda equina inflammation and adhesion formation.
Microglial activation and neuroinflammation formation has, in rats, been shown to be suppressed by: acetazolamide; minocycline; and pentoxifylline
Pain control in AA is essentially the same as for any patient with severe, intractable pain.
These days, the CDC and many other rules stipulate “no opioids” for anyone, a ridiculous concept desperately needing revision.
The goal of pain relief, particularly opioids, is to provide enough pain relief for the patient to exercise and walk daily, carry out activities of daily living, and escape a bed-couch bound state. Severe cases may require high-dose opioid therapy.
Exercises are essential to prevent spinal nerve roots from clumping, scarring, and forming adhesions that can lead to lower extremity paraparesis and/or paralysis.
The message is simple, keep exercising or become paralyzed.
We teach patients to stretch both upper and lower extremities several times a day. Straight leg raising and foot flexing will put some stretch on nerve roots. Knee bending and raising the leg toward the abdomen while either lying down or standing is necessary.
Walking outside the house each day is mandatory.
Once inflammation involves some of the nerve roots, it clinically appears to be capable of spread as AA patients recurrently claim that they may worsen following additional trauma, medical procedures (including physical manipulation and paraspinal injections), and even infections.
Emergency Treatment for Acute AA
Arachnoiditis may acutely appear after a single spinal tap, epidural anesthesia, epidural corticosteroid injection, surgery, trauma, or viral infection.
Patients who develop acute arachnoiditis complain of severe back pain, leg weakness or radiculopathy, and possibly bladder impairment within 24 hours (sometimes within minutes to an hour) after the inciting event
If the patient presents within the first 90 days after the event, emergency treatment is recommended (Table 3).
Nerve roots in the cauda equina can become inflamed if they are irritated for any reason, including toxins, infections, trauma, or friction between roots.
Medical procedures required to treat spinal pathologic abnormalities may accelerate or possibly initiate a neuroinflammatory process in cauda equina nerve roots.
AA appears to be increasing in prevalence and cases are now being seen throughout the United States. Patients who are labeled “failed back surgery syndrome” undoubtedly have a very high prevalence of AA.
Pain produced by AA may be profound, and any back pain patient who voices severe pain complaints, requires analgesia above the norm, and complains of paraparesis, inability to stand, blurred vision, burning feet, or bowel/bladder dysfunction should be suspected of having AA.
Aggressive treatment should be started as soon as arachnoiditis is suspected to stop or slow its progressive, debilitating nature.
Aggressive treatment of ALL pain is necessary to keep it from turning into chronic pain. (See When does acute pain become chronic?)