The "Giraffe Neck" Phenomenon
It is truly difficult for many to comprehend the reasons why the great majority of patients experiencing the disease, adhesive arachnoiditis, (and other slowly advancing neurologic impairments) may be without clinical symptoms even though they have severe and progressive neurologic impairment.

National Geographic, June 1979		  The reason why this can happen is explained by examining the  "Giraffe Neck" phenomenon.  This image honors a Burmese (Padaung Tribe) beauty.  The length of her neck is adorned with silver chains and coins signaling to all her elegance, wealth and position in the community.

This remarkable effect is achieved by beginning to place brass rods around her neck at age 5 and continually adding them throughout childhood.  Because the change is gradual the body, and the nervous system, acclimate and and body and nervous system function remains "normal."  This phenomenon is a matter of promoting bodily deformation and insult slowly, over a period of time so as to allow compensation and not to create impairment of function.  
If nerve roots are slowly impaired in adhesive arachnoiditis they have an opportunity to survive apparently "normal" function.  If the opposite is true and they can not acclimate the evidence of impairment becomes evident.

If the deformation of this woman's neck were sudden she would either be quadriplegic or dead.  In the field of neurosurgery the same situation exists when an individual complains of headache for one week and is found, on an imaging study, to have a benign brain tumor the size of an orange.  Because the tumor enlarged slowly, over many years, the brain acclimated until it reached a point where such acclimation could no longer be maintained without clinical symptoms.  Individuals with underlying pathologic processes such as these can often, following exposure to what would ordinarily be insignificant events or injuries, become severely impaired.

From the above it should be clear why the majority of those afflicted with diffuse lumbo-sacral adhesive arachnoiditis are asymptomatic.  When due to exposure to a toxic chemical agents such as iophendylate or polyethylene glycol there is a progressive inflammatory reaction over a period of weeks to months (perhaps years).  The process is governed by many factors including the individual's immune system.  It is possible for such an inflammation to not be self-limiting and cause death due to this.  In adhesive arachnoiditis the nerve roots of the cauda equina become enmeshed in solid collagenous scar tissue.  The scar tissue impairs nerve nutrition by decreasing blood supply and the "percolating" effect of cerebrospinal fluid as well as limiting venous drainage.  In the same way that the Padaung tribe member's neck is stretched the lumbar nerves progressively atrophy.  It is a remarkable achievement of Mother Nature that nerve function remains "normal" in the great majority of those afflicted.

The reason why some have constant and horrendous pain while others do not appears to be a function of many factors with time being the most important.  Those patients with asymptomatic adhesive arachnoiditis exist, however, in a tenuous state, one which can be readily changed by external impactors such as additional insult or injury.  The release of blood into the subarachnoid space, typically by a motor vehicle accident or a lumbar surgery can be the means of converting a quiescent adhesive arachnoiditis into a disabling affliction.

 Our greatest blessing is not only an intact nervous system but the remarkable amount of redundancy of function and neuronal reserve while can allow effective recovery from what would otherwise be devastating insults.