Potential Etiologic Agents
Non-Foreign Bodies (i.e. air, blood)
Injury, Local (i.e.
Foreign Body Substances
Adhesive arachnoiditis represents the most severe form
of an inflammatory disease process involving the pia-arachnoid membranes of the
brain and spinal canal. The inflammatory process itself represents a disease
spectrum separable as follows:
a very common entity. Frequently present following injury, spine surgery or
infection. It is highly unlikely to be of clinical significance.
Arachnoiditis- a more advanced but uncommon
entity. It may, when focal be associated with significant clinical problems.
Adhesive arachnoiditis- a much less common
entity, but potentially serious in nature due to the possibility of dramatic
anatomic change, disability related to constant and incapacitating pain and
sometimes associated with progressive neurologic impairment.
In the case of specific toxic agents such as iophendylate incidence
level can be quite high. Not all patients with anatomically documented adhesive
arachnoiditis have associated clinical symptoms. The scientific explanation for
this phenomenon has not yet been documented but the most plausible explanation
seems to relate to severity of nutrient nerve vascular impairment and nerve
anoxia produced by the pattern of the encapsulating collagenous scar tissue. It
is well documented that when the scar tissue of adhesive arachnoiditis becomes
calcified it can progressively compress nerve rootlets of the cauda equina
leading to irreversible neurologic impairment such as loss of bowel and bladder
Neural tissue anoxia is known to be associated with a
particularly disabling condition referred to as "causalgia".
Neurologist, Weir Mitchell, during the U.S. Civil War, coined the term "causalgia"
as a attempt to explain the horrible agony suffered by many of the soldiers
experiencing partial peripheral nerve injuries. In causalgia the direct nerve
injury produces a disruption in the normal flow of sensory information passing
from the nerve to the brain. This change in information is confusing to the
brain and interpreted as a uniquely disabling pain state, which is constant, and
of a "agonal" quality. Causalgic pain syndromes are highly resistant
to normal forms of medical therapy.
The most common causes of incapacitating, clinically
significant, adhesive arachnoiditis (over the past 50 years internationally),
based on our ILBNC experience in the U.S. are as follows:
Myelography with iophendylate (i.e. Lipiodol®, Pantopaque®, Myodil®)
04% Trauma, segmental to spine from motor vehicle accidents
01% Trauma, segmental to spine occurring at surgery
01% Inadvertent deposition of foreign body substance into
sub-arachnoid space usually for the purpose of epidural steroid
deposition. The neurotoxic preparation most commonly involved has been
Depo-Medrol® (also known as Depo-Medrone®; and more recently as "methyl
prednisolone suspension" containing the highly neurotoxic agent
01% All other causes
Over the past decade, following the cessation of use of oil-based myelographic
agents in the 1980s, the most common cause of incapacitating, clinically
significant, adhesive arachnoiditis in the world population has now become the
subarachnoid deposition of substances containing polyethylene glycol.
Charles V. Burton, M.D.
Senior Medical Director
The Institute for Low Back and Neck Care
Arachnoiditis Sufferers Action and Monitoring Society (ASAMS)
Dr Charles Burton