PRESERVATIVES IN SPINAL INJECTIONS

In 1975, Kelly et al ([33]) wrote a paper describing the neuropathological effects of intrathecal water. They concluded that infusion of distilled water intrathecally could cause distinctive lesions of spinal roots and cord.

It follows therefore, that if a substance as inert as water can cause damage, that more complex preparations are likely to carry some risk also.

As early as 1954, Moore ([34]) advised that local anaesthetic administered epidurally should be free of preservatives.

Malinovsky ([35]) suggests that “neurotoxicity can result from decrease in neuronal blood supply, elicited by high concentrations of the solutions, long duration exposure to local anaesthetics, and the use of adjuvants.”

Some authors suggest that arachnoiditis occurs as a result of the vasoconstrictive component of the anaesthetic, whilst others say that contaminants ([36]) or preservative agents are responsible.

It must be stressed that ANY drug preparation injected in to the spine, may contain preservatives such as benzyl alcohol, polyethylene glycol, and chlorobutanol (a derivative of chloroform) and that these carry a risk of neurotoxic effects. Another preservative that can cause reaction is sodium bisulfate, which may trigger a severe allergic reaction if the patient is susceptible (and it is unclear how many of the general population may be susceptible).

Burm ([37]) states that epidural anaesthesia results from the interactions of local anaesthetics with nerve structure within the subarachnoid space, which they reach by uptake into the epidural fat and via systemic absorption, and that consequently, epidural doses need to be much higher than spinal doses.

Bearing this in mind, it is unsurprising that there is evidence that epidural anaesthetic agents such as those used in childbirth also carry a risk of neurological damage.

It is vital that patients be FULLY informed of the risks for these procedures outlined above, so that they can give an informed consent. Unfortunately, it is commonplace for this not to be the case. Many doctors feel that it would be confusing to the patient to be given a detailed breakdown of the relative risk of each adverse effect. In addition, arachnoiditis continues to be viewed by the medical profession as a RARE complication and as such, does not warrant mentioning.

As regards therapeutic techniques, it is essential that the potential benefit be weighed against the risk of the procedure causing serious adverse effects. Regrettably there is an under-reporting of adverse effects, so that clinicians may not have access to accurate information to pass on to the patient.

Table of Contents

Introduction
THE SCALE OF THE PROBLEM
ARACHNOIDITIS OR EPIDURAL FIBROSIS?
NOMENCLATURE
THE INFLAMMATORY NATURE OF ADHESIVE ARACHNOIDITIS
PATHOLOGY
CLASSIFICATION
CAUSES
THE IATROGENIC ASPECT OF ADHESIVE ARACHNOIDITIS
PRESERVATIVES IN SPINAL INJECTIONS
NEXT: PROGNOSIS
THE SYNDROMIC NATURE OF SYMPTOMS IN ADHESIVE ARACHNOIDITIS (Warning: LONG)
COMPLICATIONS OF ADHESIVE ARACHNOIDITIS
DIFFERENTIAL DIAGNOSIS
CLINICAL ASSESSMENT
DIAGNOSTIC TESTS
TREATMENT OPTIONS (Warning: LONG)
MULTIPLE CHEMICAL SENSITIVITY
LOOKING TO THE FUTURE
APPENDIX I: AUTOIMMUNE ASPECTS
APPENDIX II: SYRINGOMYELIA
ADDENDUM - May 2000
REFERENCES