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5 Articles in Volume 4, Issue #2
Adhesive Arachnoiditis:A Continuing Challenge
Cardiovascular Consequences of Severe Acute Pain
Dramatically Disturbed Patients in Interdisciplinary Pain Programs
Persistent Spine-centered Chronic Pain Scenarios and Treatment Options
Provider-patient Interactions

Adhesive Arachnoiditis:A Continuing Challenge

Poorly understood and often misdiagnosed, adhesive arachnoiditis continues to be a cause of severe, unremitting pain.

This little known and poorly understood condition has a reputation amongst medical personnel as a rare entity, or maybe even a non-existent one.1 However, far from being a medical dinosaur, adhesive arachnoiditis, the clinically significant form of the disease, is a ‘clear and present danger’ that practitioners need to be aware of since it remains a life sentence of unremitting pain and disability imposed, in some cases, very early in life.

Historically, adhesive arachnoiditis was first recognized over a hundred years ago and was originally principally linked with spinal infections such as TB and thoracic involvement was the typical presentation. However, iatrogenic arachnoiditis, involving the lumbar region, has since been associated with the use of oil-based myelogram dyes such as iophendylate (Pantopaque/Myodil).2

Many doctors, if aware of the condition at all, tend to link it with Pantopaque/Myodil and thus to consider it a past threat rather than a continuing one. This is sadly not the case. First, one must bear in mind the prolonged usage of the oil-based dyes up until the late 1980s, and the possibility of considerably delayed onset of symptoms, maybe some 15-20 years later. In fact the delayed onset can lead to a lack of recognition of the true cause of the symptoms, which may be triggered by a relatively minor event such as a fall or slight car accident. The ensuing deterioration appears completely out of proportion, but may in fact be a result of disruption of cysts releasing residual dye to act as a potent nerve irritant, especially if there is also blood within the subarachnoid space.

It is important to note that the current practice of placing a number of different chemotherapeutic agents in or near the cerebrospinal fluid space is relatively commonplace, despite this area being highly vulnerable to damage. In some cases, the treatment is lifesaving (leukemia) but in others, such as intraspinal steroid injections for low back pain, the true risks may often be underestimated and preclude an accurate assessment of risk-benefit.

Confounding Aspects

One of the major difficulties with this condition is the lack of accurate data on incidence and prevalence.3 The known cases are likely to constitute the proverbial tip of the iceberg. In addition, we remain ignorant of the number of people currently going about their lives, symptom free, but carrying a ‘time bomb’ within them that could be triggered by some relatively mild initiating event, and lead to a major and enduring impact on their quality of life.

A common myth about arachnoiditis is that it is simply a spinal condition. During the author’s research over the past six years, it has become clear that adhesive arachnoiditis is syndromic in nature. One of the problems encountered in diagnosing many patients is the multifactorial nature of the disease’s etiology together with a complex clinical picture comprising the effects of pathological damage, secondary features, and the progression of any underlying condition such as degenerative disc disease.

Furthermore, we are constrained by difficulties identifying the condition because medical evidence may be lacking or fails to correlate with the clinical picture, and much of the medical literature on the subject tends to deal only with the most severe end of the spectrum.4 Clinicians may often fail to recognize the disease5 and this can reinforce the notion that this this disease is rare.

Medically this disease appears to remain in something of a ‘fog’ of imprecise information, but there is an urgent need for co-ordinated research. Unfortunately, the iatrogenic aspect of the majority of cases further muddies the waters and perhaps complicates initiation of medical research that this disease warrants. At this time, the way forward remains unclear.3

Typical Disease Progression

Arachnoiditis is inflammation of the arachnoid layer of the meninges. Generally medical use of the term refers to a chronic inflammation, because acute arachnoiditis is virtually indistinguishable from meningitis clinically. When the arachnoid membrane is damaged, whether by trauma (accidental or surgical), chemical injection or infection, there is an inflammatory reaction much as there is in any part of the body. In adhesive arachnoiditis, however, the healing process, which involves deposition of scar tissue, is inefficient or may be repeatedly impaired when the insult/damage is ongoing. This means that excess scar tissue forms.

Effectively there are three main stages of arachnoiditis as follows:

  • First Stage — Radiculitis: The spinal nerve roots are inflamed in response to an event such as surgery in the area and the adjacent blood vessels distended (hyperaemia). The subarachnoid space is encroached upon by the swollen nerve roots and practically disappears. Deposition of collagen fibrils begins. Substances in the body involved with inflammation can sensitize nerves, and these nerves begin to fire abnormally.
  • Second Stage — Arachnoiditis: The scar tissue increases, and the nerves begin to adhere to each other and the dura. At this stage they begin to resemble strands of overcooked spaghetti sticking to each other and local tissue.
  • Third Stage — Adhesive Arachnoiditis: This involves complete encapsulation of the nerve roots by scar tissue with the subsequent smothering causing them to atrophy. The scarring prevents contact with surrounding spinal fluid and severe adhesive arachnoiditis may be obliterative, causing completely impeded CSF flow within the affected area. The isolated nerve roots are therefore starved of oxygen and nutrients and waste products of metabolism accumulate. There may be cysts containing CSF or oil-based myelogram dye. There may also be calcification or ossification of the affected tissues.

Spinal adhesive arachnoiditis may be either localized or diffuse. Generally speaking, arachnoiditis from mechanical causes such as surgery tends to be more localized, whereas that caused by chemical insult may be more diffuse and widespread.

As the blood supply to the nerve roots is increasingly impaired, neurophysiological compromise results in pain and other neurological symptoms

Cerebral arachnoiditis affecting the brain is relatively uncommon and is usually related to infections (meningitis), trauma, tumor, intracranial haemorrhage and chemical insult (myelogram dyes). It was reported by Horrax6 as early as 1924 when symptoms suggestive of a tumor turned out to be arachnoiditis in the cisterns.

The most common cause of cerebral arachnoiditis is infection, whether local (within the central nervous system) or in other parts of the body, particularly the sinuses and the middle ear. Tuberculous cerebral arachnoiditis has been shown to arise in the absence of pulmonary infection. The parasite cystercicosis can also cause this type of arachnoiditis.

Complications of arachnoiditis include arachnoid cysts, syringomyelia and hydrocephalus.

Precipitating Factors

There are a number of causes of the inflammatory process that may trigger arachnoiditis and can be roughly divided into three categories — chemical, mechanical, and infection.

Children may be affected — in particular those born with spina bifida who often develop arachnoiditis after surgery to correct myelomeningocele. Arachnoiditis has also been noted in children with congenital spinal dermal cysts. Within this category, bleeding into the spinal fluid, such as following a subarachnoid hemorrhage should also be included; blood is highly irritant to nerve roots.

  • Chemical
    These include injections of various types, into the spinal area, whether intended for the epidural space such as epidural anaesthesia, or steroid injection, or into the subarachnoid space, such as myelogram dye, spinal anaesthesia, or cancer chemotherapy agents. It must be stressed that any drug preparation injected in to the spine, may contain preservatives such as benzyl alcohol, polyethylene glycol, and chlorobutanol (a derivative of chloroform) and that these carry a risk of neurotoxic effects. Currently, the steroid preparation Depo-Medrol® is the common cause of new cases of iatrogenic chemically-induced arachnoiditis.
  • Mechanical
    Mechanical trauma — whether accidental or surgical. This includes lumbar punctures performed to investigate meningitis or multiple sclerosis etc., especially if multiple procedures are performed. Arachnoiditis is the third most common cause of failed back syndrome. There may be some months’ delay between the operation and the onset of symptoms, while the scar tissue develops to a clinically significant degree. Indeed, one might expect as much as 18 months of remission before recurrence of symptoms. Gradually increasing symptoms, beginning a year or so after operation, may represent scar radiculopathy. As the blood supply to the nerve roots is increasingly impaired, neurophysiological compromise results in pain and other neurological symptoms.
  • Infection
    Infections such as meningitis, AIDS, cystercicosis and tuberculosis. There are also a number of miscellaneous, uncommon causes, including sarcoidosis.

    Most individuals with arachnoiditis have a variety of precipitating factors in their history.7 For instance, an ongoing mechanical problem such as prolapsed disc may have been investigated using a myelogram, then a spinal operation performed to correct the defect and, if the patient is one of the 20-40% of patients who have failed back surgery syndrome, repeat investigations and possibly a series of epidural steroid injections attempting to treat the intractable pain.

Diagnostic Considerations

The presenting symptoms are varied and although there is no consensus as to the exact features of the condition,7 the symptoms tend to follow common trends.

Primary symptoms — attributable directly to adhesive arachnoiditis — are dominated by the neuropathic effects of the arachnoiditis pathology and are mainly sensory, with the most debilitating being neuropathic pain. This carries with it the usual burden of dysaesthesia, allodynia, hyperpathia etc. as seen in patients with other conditions causing neuropathic pain. Autonomic features are also common. Typically, arachnoiditis patients report poorly localized, diffuse pain which is often burning in nature and may be felt in numb areas. The pain tends to be worse at night and may include pain evoked by normally non-painful stimulus, or indeed, ‘spontaneous’ pain which arises in the absence of any stimulus. They may also experience a variety of strange sensations affecting various parts of the body, such as feeling as if they are walking on broken glass, water running down the leg, sensation of insects crawling on the skin etc. Pain is often accompanied by paraesthesiae.

Pain associated with arachnoiditis tends to increase with activity. There may be a delay after onset of activity, with a slow summation, to a point where the pain suddenly becomes unbearable and then persists once the activity has ceased. Quite often, there is no immediate effect of activity, and it is only on the following day that the symptoms are exacerbated, and they may well remain more severe than normal for days or even weeks.

This typical pattern of flare-ups and relative remissions may well reflect intermittent inflammatory episodes and certainly, there could be a link with autoimmune conditions, as well as similarity to neurological disorders such as multiple sclerosis.

Presenting pain may also be due to other factors besides nerve damage. These include musculoskeletal sources secondary to disuse, overuse or compensatory use of muscle groups, due to alteration of spine dynamics. There may also be muscle tension due to being in pain, or increased muscle tone (spasticity) caused by nerve damage. This can be accompanied by pains in the joints. Headaches are another common feature, and these may, in some patients, resemble those in raised intracranial pressure. It is possible that the latter may be the result of altered CSF circulation due to arachnoid scarring. Needless to say, functional disability as a result of weakness, severe muscle spasms, problems with balance and bladder/bowel dysfunction can lead to a severely reduced quality of life.

The clinical picture may be further complicated by symptoms suggestive of an autoimmune type condition and indeed a number of patients have dual diagnoses, with conditions such as rheumatoid arthritis, systemic lupus erythematosus, Sjogren’s syndrome etc. being diagnosed. In those who have undergone myelography, there seems to be an increased risk of thyroid disease, probably as a result of the high iodine content of the myelography dyes.

Multiple diagnoses seem to be accrued in some cases on a background of non-specific clinical presentation, perhaps as a result of the input of a number of different specialists and imprecise test results. For example, complex regional pain syndrome is also diagnosed in some patients, and is likely to be part of the arachnoiditis syndrome rather than a separate condition. Some patients may also receive a diagnosis of fibromyalgia, chronic fatigue syndrome, or myofascial pain syndrome, but again, this is likely to represent an aspect of arachnoiditis.

Investigation of adhesive arachnoiditis should primarily revolve around a full history taking, which may uncover associated risk factors. Often symptoms are not necessarily disease specific although there are typical features consistent with this disease. However, because of the possibility of coexisting, underlying pathology, it is important to exclude treatable conditions, especially in failed back syndrome. The ‘gold standard’ test is the MRI scan, which does not have to be contrast enhanced, but should be high resolution and include axial views to assess the contents of the thecal sac. A stir cycle may pick up evidence of ongoing inflammation. It is important to bear in mind that the MRI results may well not correlate with the clinical picture and a negative MRI does not preclude the possibility of arachnoiditis. A German group performing thecaloscopy found evidence of arachnoiditis in a number of patients in whom MRI was negative.8

Neurophysiological tests (EMG, NCV) are unlikely to contribute to diagnosis if pain is the predominant symptom without marked sensory deficit. Arachnoiditis is associated primarily with a sensory neuropathy, although in more severe cases, motor damage may be demonstrated.

It is worth noting that, as with other chronic pain conditions, there are also secondary and tertiary effects of this disease — namely, musculoskeletal, autonomic, insomnia, side-effect of medication, depression, anxiety, etc.

Treatment Modalities

Treatment of this complex condition remains palliative rather than curative. Most patients require polypharmacy including high doses of opioid medication. Typical regimes also include antidepressants (tricyclics being much more effective than SSRIs) and membrane stabilizers such as gabapentin. Muscle relaxants such as baclofen may also be necessary. NSAIDs are generally ineffective for the neuropathic pain but may attenuate the musculoskeletal pain and perhaps reduce the impact of inflammatory flare-ups. The necessity for high doses of medication, of course, carries its own risk of morbidity and a significant burden of adverse effects.

The author advocates a multimodal approach with physical therapies alongside pharmacotherapy, and a cognitive-behavioural strategy for the inevitable psychological impact. Unfortunately, central nervous system sensitization may render the patient’s pain resistant to medication while also causing significant impediment to physical therapy and exercise. Gentle hydrotherapy may be a helpful strategy alongside adequate pharmacotherapy to encourage as much mobilization as possible to reduce the impact of deconditioning.

Sadly, many patients experience ongoing intractable pain. Some require invasive procedures such as Intraspinal narcotic analgesia (INA), despite the risks attached (which include exacerbating the condition). While the majority will ‘plateau out’ after the initial inflammatory phases, the condition may advance in those who suffer further trauma or require invasive medical procedures. In addition, over time the detrimental effects of intractable pain tend to accumulate and cause a variety of secondary problems. Hence the condition may appear to be progressive even if the actual spinal pathology remains unchanged.

Conclusion

What does the future hold? The single word that sums up the situation remains ‘uncertain.’ The patient remains uncertain as to the ongoing impact of the condition on all aspects of life; the clinician remains armed with a very limited arsenal to tackle the severe pain his patient experiences; and there is no funding for research into this condition. Practitioners will need to think laterally and look for progress in similar neuropathic pain conditions.

Above all, if one contemplates the maxim “prevention is better than cure” and remembering that there is no cure for adhesive arachnoiditis, one must conclude that prevention is the best option. In order to reduce the impact of avoidable, iatrogenic cases, it remains imperative to raise medical awareness of the risks attached to the procedures that can cause arachnoiditis. Admittedly, it may be that some patients carry a predisposition to developing the condition, but until or unless we can identify this group, practitioners are left with a need to be as stringent as possible in implementing elective invasive procedures and aware of this debilitating disease when posing the question “does the proposed benefit really outweigh the potential risks?”

Last updated on: January 6, 2012
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