COMPLICATIONS OF ADHESIVE ARACHNOIDITIS

1.Subarachnoid cysts

2.Syringomyelia

3.Communicating hydrocephalus

1. Subarachnoid cysts: These are a recognised complication of arachnoiditis, in particular that caused by myelographic dyes or epidural anaesthesia. ([51]) They tend to be more

common in the thoracic region than cervical or lumbar. Kendall et al ([52]) stated that incidence of cysts at myelography, as incidental findings, is relatively common, but rarely of clinical significance. In symptomatic cases, clinical presentation is generally non-specific, although there may be a sensory level, unlike in uncomplicated arachnoiditis. Surgical excision or drainage is often successful, provided that there is early intervention.

2.Whilst an uncommon sequela to arachnoiditis, syringomyelia should nevertheless be considered as a possible complication. Indeed, Kamada et al ([53]) recommend follow-up serial MRI imaging for patients with adhesive arachnoiditis in order to detect syringomyelia as early as possible.

In 1990, Caplan et al ([54]) proposed that arachnoiditis causes syrinx formation by obliterating spinal blood vessels, thereby causing ischaemia. Small cystic areas may form, and these tend to coalesce to form cavities. Alteration of spinal fluid dynamics due to scar tissue creating spinal block contributes to this process.

This was borne out by an animal study in 1992([55]), which concluded from the data that “cavitation within the cord would be induced by the ischemia, and hydromyelia would be produced by the pressure dislocation between the spinal subarachnoid space and the central canal.”

Syrinx formation tends to occur in the segment of spinal cord adjacent to the area affected by arachnoiditis. It then starts to expand, due to pressure differences along the spine causing the fluid to move within the cavity. This is sometimes referred to as noncommunicating syringomyelia.

The primary symptom of syringomyelia is pain, which may spread upward from the site of original pathology (arachnoiditis lesion). Neurological deficit tends to be in a “cape-like” distribution in the upper part of the body. Increased levels of pain, increased spasticity and decreased physical function are often early indicators of syrinx development.

See Appendix II for clinical features, diagnosis and treatment.

3.Hydrocephalus: This is a rare complication, details of which are beyond the scope of this article. It is of the communicating type. Medical literature on hydrocephalus secondary to arachnoiditis is scant, but there are isolated reports. One of these ([56])

describes a case in which a combination of aseptic meningitis, arachnoiditis, communicating hydrocephalus and Guillain-Barre syndrome followed metrizamide myelography.

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
PROGNOSIS
THE SYNDROMIC NATURE OF SYMPTOMS IN ADHESIVE ARACHNOIDITIS (Warning: LONG)
COMPLICATIONS OF ADHESIVE ARACHNOIDITIS
NEXT: 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