Although underdiagnosed, arachnoiditis may be one of the most common complications of spine surgery. Hundreds of thousands of back operations are performed yearly yet roughly 25% of these operations fail to help the patients completely. A good portion of this 25% is thought to be related to arachnoiditis. Difficulty in diagnosing this problem is compounded by a lack of awareness by the physician. Understanding the problem begins with understanding the anatomy of the spinal canal.

The spinal cord and the contained nerves travel from the brain to the lower spine region. The nerves exit the spinal cord at the appropriate levels. The nerve roots are encased by membranes which protect and nourish the nerves. The layers are: inner layer - pia matter, middle layer - arachnoid and outside layer - dura. These membranes are very delicate and easily injured. Arachnoiditis is an inflammation/swelling of the arachnoid membranes around the nerve roots. Later stages can cause pain. People who have arachnoiditis describe the pain as a burning type pain. The pain is located in the lower back region and often times radiates into the legs. Frequently it persists while resting. Arachnoiditis can also cause neurologic dysfunction.

The causes of arachnoiditis include tuberculosis , meningitis, syphilis, ankylosing spondylitis, syringomyelelia, epidural anesthesia analgesia, epidural blocks, spine surgery, and myelographic studies. Presently, surgery and myelographic studies are the most common causes. Surgery can injure the roots and/or the arachnoid membrane directly or indirectly. The injury may occur in retracting the nerve root out of the way to allow access to the disk space or due to harsh manipulation and intrathecal bleeding. It also occurs 10-30% with degenerative disc disease and spinal stenosis. Myelographic tests, in which special dyes are placed in the fluid around the membranes and roots followed by an x-ray, can irritate the arachnoid membranes leading to arachnoiditis. Using only the latest water soluble dyes can help prevent this. Epidural injections of depo medrol may cause arachnoiditis, based on one study. About 20% of the patients developed arachnoiditis after epidural injections of depo medrol. There is a belief that the preservative in the vial of anesthesia may have been the causative factor.

Diagnosing the problem can be difficult but sophisticated tests such as the CT scan with myelogram and the MRI scan have helped. The MRI, while less invasive (no dyes injected) and therefore less painful, is a more expensive test to use. It gives us a similar picture to look at.

How is arachnoiditis treated? It is an extremely tough problem to treat. There is no cure. Most patients will continue to have some pain as well as depression. Pain relieving measures are helpful in most instances. Some of these include but are not limited to the use of pain medications, massage treatments, special battery powered stimulation units (Tens units), limited exercise, and specialized self help such as imagery, self-hypnosis, coping skills and support groups. Treatment of subsequent depression using psychiatrists and anti-depressants is extremely important. More elaborate treatments include implantable pain medication units placed under the skin. There is also a surgical option which would free the roots in the arachnoid membranes by removing the scar tissue. This is a limited treatment option for most patients and is surrounded by a great deal of controversy. The new surgical treatment of the implantation of spinal cord leads and stimulator is helping some of the patients.

Because the diagnosis of this problem is poor, it is easy to see why patients with arachnoiditis have trouble with depression and low morale. The majority of patients have improvements in pain but most will not be pain free. Both the patient and the physician understand that the treatment of this problem is less than acceptable. Hopefully with the increased awareness of the problem coupled with our more sophisticated methods of diagnosing arachnoiditis we can better design treatment plans in the future.

Glossary of Terms

CT Scans - Special x-ray created by taking a picture of the portion of the body in cross section Meningitis - Inflammation (swelling) of the meninges (including the pia and arachnoid). MRI scan - (Magnetic Resonance Imaging) Special pictures taken using a magnetic field on tissues of the body. Spinal Canal - Bony tube made up of individual levels corresponding to the vertebra. This bony tube encases the spinal cord and its contained nerves. Spinal Cord - Includes spinal nerves and associated meningial membranes beginning at the base of the brain stem and traveling to L1 level. Syphilis - Infection by the Spirochaeta Treponema pallidum. It affects the cardiovascular system, the cerebral spinal system as well as the skin. Tuberculosis - Infection by the microbacterium tuberculus. Transferred person to person by a respiratory system but can be found anywhere in the body once it is transferred into the lungs.

Bibliography

Bourne IHJ. Lumbo-sacral adhesive arachnoidities: a review. The Royal Society of Medicine. April, 1990: 83(4); 262-265.

Browning M. Helping lumbosacral arachnoiditis patients. Nursing Standard.October 14; Vol. 7, No. 4, 1992; 28-30.

Dolan RA. Spinal adhesive arachnoiditis. Surg Neurol 1993; 39, 479-84.

Fitt GJ, Stevens JM. Postoperative arachnoiditis diagnosed by high resolution fast spine-echo MRI of the lumbar spine. Neurorad 37(2):139-45, 1995, Feb.

Gourie-Devi M, Satishchandra P. Hyaluronidase as an adjuvant in the management of tuberculous spinal arachnoiditis. J Neurol Sci 102(1):105-11, 1991 Mar.

Guyer DW, Wiltse LL, Eskay ML and Guyer BH. The long range prognosis of Arachnoiditis. SPINE, Dec. 1989; 14(12), 1332-1341. Roca J, Moreta D, Ubierna MT, Caceres E and Gomez JC. The results of surgical treatment of lumbar arachnoiditis. International Orthopaedics (SICOT) 1993, 17:77-81.

Klekamp J, Batzdorf U, Smii M, Bothe HW. Treatment of syringomyelia associated with arachnoid scarring caused by arachnoid or trauma. J Neurosurg 86(2):233-40, 1997, Feb.

O'Connor M, Brighouse D, Glynn CJ. Unusual complications of the treatment of chronic spinal arachnoiditis. Clin J Pain 6(3):240-2, 1990 Sept.

Roca J, Moreta D, Ubierna MT, Caceres E and Gomez JC. The results of surgical treatment of lumbar arachnoiditis. International Orthopaedics (SICOT) 1993 17:77-81.

Roeder MB, Bazan C, Jinkins JR. Ruptured spinal dermoid cyst with chemical arachnoiditis and disseminated intracranial lipid droplets. Neurorad 37(2):146-7, 195 Feb.

Rosenberg SK, Stacey BR. Comment. Reg Anesth 1997 Sept-Oct; 22(5):484-5.

Sklar EM, Quencer RM, Green BA, Montalvo BM, Post MJ. Complications of epidural anesthesia: MR appearance of abnormalities. Radiology. 181(2):549-54, 1991 Nov.

Tseng SH, Lin SM. Surgical treatment of thoracic arachnoiditis with multiple subarachnoid cysts caused by epidural anesthesia. Clin Neur & Neurosurg. 99(4): 256-8, 1997 Dec.