Arachnoiditis is an inflammatory condition of the

arachnoid mater The arachnoid mater (or simply arachnoid) is one of the three meninges, the protective membranes that cover the brain and spinal cord. It is so named because of its resemblance to a spider web. The arachnoid mater is a derivative of the neural cr ...

or 'arachnoid', one of the membranes known as

meninges In anatomy, the meninges (, ''singular:'' meninx ( or ), ) are the three membranes that envelop the brain and spinal cord. In mammals, the meninges are the dura mater, the arachnoid mater, and the pia mater. Cerebrospinal fluid is located in ...

that surround and protect the

nerve A nerve is an enclosed, cable-like bundle of nerve fibers (called axons) in the peripheral nervous system. A nerve transmits electrical impulses. It is the basic unit of the peripheral nervous system. A nerve provides a common pathway for the ...

s of the central nervous system, including the brain and

spinal cord The spinal cord is a long, thin, tubular structure made up of nervous tissue, which extends from the medulla oblongata in the brainstem to the lumbar region of the vertebral column (backbone). The backbone encloses the central canal of the spin ...

. The arachnoid can become inflamed because of adverse reactions to chemicals, infection from

bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were am ...

viruses A virus is a submicroscopic infectious agent that replicates only inside the living cells Cell most often refers to: * Cell (biology), the functional basic unit of life Cell may also refer to: Locations * Monastic cell, a small room ...

, as the result of direct injury to the spine, chronic compression of spinal nerves, complications from spinal surgery or other invasive spinal procedures, or the accidental

intrathecal Intrathecal administration is a route of administration for drugs via an injection into the spinal canal, or into the subarachnoid space so that it reaches the cerebrospinal fluid (CSF) and is useful in spinal anesthesia, chemotherapy, or pa ...

injection of steroids intended for the epidural space. Inflammation can sometimes lead to the formation of

scar A scar (or scar tissue) is an area of fibrous tissue that replaces normal skin after an injury. Scars result from the biological process of wound repair in the skin, as well as in other organs, and tissues of the body. Thus, scarring is a n ...

tissue and adhesion that can make the spinal nerves "stick" together,NINDS Arachnoiditis Information Page

National Institute of Neurological Disorders and Stroke The National Institute of Neurological Disorders and Stroke (NINDS) is a part of the U.S. National Institutes of Health (NIH). It conducts and funds research on brain and nervous system disorders and has a budget of just over US$2.03 billion. The ...

National Institutes of Health The National Institutes of Health, commonly referred to as NIH (with each letter pronounced individually), is the primary agency of the United States government The federal government of the United States (U.S. federal government or U ...

. Accessed 2015-10-23. a condition where such tissue develops in and between the leptomeninges. The condition is extremely painful, especially when progressing to ''adhesive arachnoiditis''. Another form of the condition is ''arachnoiditis ossificans'', in which the arachnoid becomes

ossified Ossification (also called osteogenesis or bone mineralization) in bone remodeling is the process of laying down new bone material by cells named osteoblasts. It is synonymous with bone tissue formation. There are two processes resulting in t ...

, or turns to bone, and is thought to be a late-stage complication of the adhesive form of arachnoiditis.

Signs and symptoms

Arachnoid inflammation can lead to many painful and debilitating symptoms which can vary greatly in each case, and not all people experience all symptoms. Chronic pain is common, including

neuralgia Neuralgia (Greek ''neuron'', "nerve" + ''algos'', "pain") is pain in the distribution of one or more nerves, as in intercostal nerve, intercostal neuralgia, trigeminal neuralgia, and glossopharyngeal nerve, glossopharyngeal neuralgia. Classific ...

, while

numbness and tingling Paresthesia is an abnormal sensation of the skin (tingling, pricking, chilling, burning, numbness) with no apparent physical cause. Paresthesia may be transient or chronic, and may have any of dozens of possible underlying causes. Paresthesias ar ...

of the extremities can occur with spinal cord involvement, and bowel, bladder, and sexual functioning can be affected if the lower part of the spinal cord is involved. While arachnoiditis has no consistent pattern of symptoms, it frequently affects the nerves that supply the legs and lower back. Many patients experience difficulty sitting for long (or even short) periods of time due to discomfort or pain, or because of efferent neurological or other motor symptoms, such as difficulties controlling limbs. Difficulty sitting can be problematic for patients who have trouble standing or walking for long periods, as wheelchairs are not always helpful in such cases.

Causes

The root cause of the condition is not entirely clear, and it appears to have multiple causes, including

iatrogenic Iatrogenesis is the causation of a disease, a harmful complication, or other ill effect by any medical activity, including diagnosis, intervention, error, or negligence. "Iatrogenic", ''Merriam-Webster.com'', Merriam-Webster, Inc., accessed 27 ...

cause from misplaced epidural steroid injection therapy when accidentally administered intrathecally (inside the

dura mater In neuroanatomy, dura mater is a thick membrane made of dense irregular connective tissue that surrounds the brain and spinal cord. It is the outermost of the three layers of membrane called the meninges that protect the central nervous syste ...

, the sac enveloping the arachnoid mater), or from contrast media used in

myelography Myelography is a type of radiographic examination that uses a contrast medium to detect pathology of the spinal cord, including the location of a spinal cord injury, cysts, and tumors. Historically the procedure involved the injection of a radi ...

prior to the development of metrizamide and other water-soluble contrast agents. Other noninfectious inflammatory processes include surgery, intrathecal hemorrhage, and the administration of anesthetics (e.g.

chloroprocaine Chloroprocaine (trade name Nesacaine, Nesacaine-MPF) (often in the hydrochloride salt form as the aforementioned trade names) is a local anesthetic given by injection during surgical procedures and labor and delivery. Chloroprocaine vasodilates ...

), and steroids (e.g.

prednisolone Prednisolone is a steroid medication used to treat certain types of allergies, inflammatory conditions, autoimmune disorders, and cancers. Some of these conditions include adrenocortical insufficiency, high blood calcium, rheumatoid arthrit ...

triamcinolone acetonide Triamcinolone acetonide, sold under the brand name Kenalog among others, is a synthetic corticosteroid medication used topically to treat various skin conditions, to relieve the discomfort of mouth sores, and by injection into joints to treat ...

). A variety of other causes exist, including infectious, inflammatory, and neoplastic processes. Infectious causes include bacterial, viral, fungal, and parasitic agents. 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 Calcification is the accumulation of calcium salts in a body tissue. It normally occurs in the formation of bone, but calcium can be deposited abnormally in soft tissue,Miller, J. D. Cardiovascular calcification: Orbicular origins. ''Nature M ...

or hemosiderin.

Treatment

Arachnoiditis is difficult to treat and treatment is generally limited to alleviation of pain and other symptoms. While arachnoiditis may not yet be curable and can be significantly life-altering, management of the condition, including with medication,

physical therapy Physical therapy (PT), also known as physiotherapy, is one of the allied health professions. It is provided by physical therapists who promote, maintain, or restore health through physical examination, diagnosis, management, prognosis, patie ...

, and if appropriate, psychotherapy, can help patients cope with the difficulties it presents. Surgical intervention generally has a poor outcome and may only provide temporary relief, but some cases of surgical success have been reported. Epidural steroid injections to treat sciatic pain have been linked as a ''cause'' of the disease by the U.S.

Food and Drug Administration The United States Food and Drug Administration (FDA or US FDA) is a federal agency of the Department of Health and Human Services. The FDA is responsible for protecting and promoting public health through the control and supervision of food ...

as well as in other research, and are therefore discouraged as a treatment for Arachnoiditis as they will most likely worsen the condition. 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.

Prognosis

Arachnoiditis is a chronic disorder with no known cure, and prognosis may be hard to determine because of an unclear correlation between the beginning of the disease and the appearance of symptoms. For many, arachnoiditis is a disabling disease that causes chronic pain and neurological deficits, and may also lead to other spinal cord conditions, such as

syringomyelia Syringomyelia is a generic term referring to a disorder in which a cyst or cavity forms within the spinal cord. Often, syringomyelia is used as a generic term before an etiology is determined. This cyst, called a syrinx, can expand and elongate o ...

References

External links

* * * {{OMIM, 182950, Spinal arachnoiditis Inflammatory diseases of the central nervous system