Arachnoiditis is a rare, but extremely debilitating, chronic pain condition caused by injury to the arachnoid layer of the spinal cord, of which adhesive arachnoiditis is the most severe form, characterized by debilitating, intractable neurogenic back and limb pain and a range of other neurological problems.

It ranks at the top of the list of “worst pain conditions,” along with metastatic bone cancer, renal colic, chronic regional pain syndrome, and migraine.

Causes of Arachnoiditis:

Arachnoiditis, unfortunately, has become more common in recent years. It is caused by any rupture, trauma, or infection that penetrates the dural lining of the spinal cord. It can occur with epidural steroid injections to the spine, pregnancy epidurals, trauma including that from war injuries and auto accidents, spinal leak and blood patch, lumbar myelogram, and spine surgery.

Arachnoiditis effects women more than men due to epidurals during pregnancy.

The Spinal Cord:

The protective covering of the spinal cord consists of 3 meninges: the dura (outer layer), arachnoid, and pia (inner layer).

Under the microscope, the fibers and filaments that make up the arachnoid layer resemble a spider web, hence the derivation of the name. If this layer becomes inflamed, it is called arachnoiditis.

Arachnoiditis Effects on the Brain and Nervous System:

Between the arachnoid and the inner layer is the subarachnoid space, in which flows the cerebrospinal fluid (CSF) that is secreted within the ventricles of the brain (fluid-filled spaces deep inside the brain) and the ependymal cells lining the cerebral subarachnoid space.

CSF circulates in the subarachnoid space, being absorbed into the venous sinuses via the arachnoid granulations and into the lymphatic system through spinal nerve-root pockets. The fluid provides a protective cushion between the brain and the skull, bathing the nervous system with nutrients and removing waste products.

Impaired CSF flow prevents this natural exchange from taking place, to the detriment of the affected nerve roots. The entire volume of CSF is produced, absorbed, and replaced about 3 times per day in a continuous manner.

If flow is impeded, fluid can build up, causing increased pressure and pain.

Adhesive Arachnoiditis:

Additionally, an inflamed arachnoid lining may entrap nerve roots, scarring them and other neural elements inside and around the spinal canal. When this occurs, the term Adhesive Arachnoiditis is used. Such adhesions within the spinal canal can disrupt many functions of nerves that lead to the extremities, bladder, bowel, and sex organs. Unbearable, suicide-provoking pain can result.