Arachnoiditis

December 31, 2014

Synonyms

Overview

Arachnoiditis describes a pain disorder caused by the inflammation of the arachnoid, one of the membranes that surround and protect the nerves of the spinal cord. The arachnoid can become inflamed because of an irritation from chemicals, infection from bacteria or viruses, as the result of direct injury to the spine, chronic compression of spinal nerves, or complications from spinal surgery or other invasive spinal procedures. Inflammation can sometimes lead to the formation of scar tissue and adhesions, which cause the spinal nerves to "stick" together. If arachnoiditis begins to interfere with the function of one or more of these nerves, it can cause a number of symptoms, including numbness, tingling, and a characteristic stinging and burning pain in the lower back or legs. Adhesive arachnoiditis is the most severe form, characterized by debilitating, intractable neurogenic back and limb pain and a range of other neurological problems.[2]Arachnoiditis is difficult to treat and long-term outcomes are unpredictable. A regimen of pain management, physiotheraphy, exercise, and psychotheraphy is often recommended. Surgical treatment seem to offer only short-term relief.

Symptoms

The swollen arachnoid can lead to a host of painful and debilitating symptoms. Chronic pain is common, including neuralgia. Numbness and tingling of the extremities is frequent in patients due to spinal cord involvement. Bowel, bladder, and sexual functioning can be affected if the lower part of the spinal cord is affected. While arachnoiditis has no consistent pattern of symptoms, it frequently affects the nerves that supply the legs and lower back. Many sufferers find themselves unable to sit for long (or even short) periods of time, often due to severe pain as well as efferent neurological symptoms, such as difficulties controlling limbs. This can be particularly problematic for those patients who exhibit difficulties standing or walking for protracted periods, as wheelchairs are not helpful for this group. Some sufferers benefit from relatively new inventions, such as the Segway or the less expensive Stand'n'Ride alternative. Standing wheelchairs are also available, although often quite expensive and limited compared to these alternatives. However, standing endurance and vibration tolerance should be taken into account before a motorized assistance device is selected.

Other symptoms:

Abnormality of the eye
Arthralgia
Hearing impairment
Meningitis
Muscle weakness
Paresthesia
Tinnitus

Causes

In most cases it does not seem to be inherited. In rare cases, arachnoiditis may occur in multiple members of the same family; in these cases, it appears to be inherited in an autosomal dominant manner.

The arachnoid can become inflamed because of an irritation from chemicals, infection from bacteria or viruses such as meningitis, as the result of direct injury to the spine, chronic compression of spinal nerves, or complications from spinal surgery or other invasive spinal procedures such as anesthesia drugs or testing dyes injected into the spine or arachnoid membrane.

It appears to have multiple etiologies, including iatrogenic cause from misplaced epidural steroid injection therapy when accidentally administered intrathecally (inside the dura mater, the sac enveloping the arachnoid mater), or from contrast media used in myelography prior to the introduction of Metrizamide.

Other noninfectious inflammatory processes include surgery, intrathecal hemorrhage, and the administration of anesthetics (e.g. chloroprocaine), and steroids (e.g. prednisolone, triamcinolone acetonide). Prior spinal surgery has been documented as a cause of arachnoiditis ossificans, as well as for the adhesive form. It can also be caused by long term pressure from either a severe disc herniation or spinal stenosis.

Diagnosis

For the ossificans form of the condition, unenhanced CT may better show the presence and extent of arachnoid ossifications, and is complementary to MRI, as MRI can be less specific and findings can be confused with regions of calcification or hemosiderin.

Prognosis

Arachnoiditis is a chronic disorder and there is no known cure at this time. Pain management techniques may provide some relief to patients. Prognosis may be hard to determine because of the lack of correlation between the beginning of the disease and the start of symptoms. For many, arachnoiditis is a disabling disease that causes chronic pain and neurological deficits. It may also lead to other spinal cord conditions, such as syringomyelia.

Treatment

Arachnoiditis is difficult to treat and treatment is generally limited to alleviation of pain and other symptoms.[3] While arachnoiditis may not yet be curable and can be significantly life-altering, management of the condition, including with medication, physical therapy, and if appropriate, psychotherapy, can help patients cope with the difficulties it presents.[3] Surgical intervention generally has a poor outcome and may only provide temporary relief,[3] but some cases of surgical success have been reported.[13] Epidural steroid injections to treat sciatic pain have been linked as a cause of the disease by the U.S. Food and Drug Administration as well as in other research, and are therefore discouraged as a treatment for Arachnoiditis as they will most likely worsen the condition.[2][4][14] Some patients benefit from motorized assistance devices such as the Segway or standing wheelchairs, although these types of devices may be beyond the reach of those with limited means. Standing endurance and vibration tolerance are considered before considering such devices in any case.