Roentgen therapy in chronic spinal arachnoiditis.

Abstract

–Chronic arachnoiditis implies adhesive thickening of the leptomeninges, with adherence to the adjacent brain or spinal cord. The process may be localized or disseminated but usually is confined either to the brain or to the cord. Arachnoiditis is a poorly understood clinical entity, of vague etiology, presenting progressive neurologic impairment of both motor and sensory pathways. The purpose of this paper is to call attention to the possible beneficial effects of irradiation in this condition, particularly in more extensive cases not amenable to surgery. Seventeen examples treated by irradiation will be presented. Pathology The primary finding in arachnoiditis is a diffuse, pearly white thickening of the leptomeninges (Fig. 2), which may be localized to a single segment or may involve the entire length of the spinal cord. The spinal roots may be compressed and show definite demyelinization, destruction of nerve fibers, and even replacement of nerve fibers by fibrous tissue. The cord itself is not usually involved, unless it is compressed by cyst formation or an essential blood vessel is occluded. In such cases, there is softening of the cord or even cystic degeneration, resembling syringomyelia. Microscopically, there is a diffuse but patchy thickening of the leptomeninges, which vary in thickness from 85 to 215 microns, i.e., two to five times the normal. There are foci of fusion of the pia and arachnoid by fibrosis, foci of obliteration of the subarachnoid space, and foci of encroachment on the subdural space. The thickened pia arachnoid is composed of dense, focally hyalinized, acellular, collagenous tissue in which are scattered small aggregates of infiltrating mononuclear cells. The spinal vessels are constricted, and many are occluded by collagenous thickening of the surrounding leptomeninges. The usual vascularity of the pia is decreased, and in some cases it is completely devoid of vessels. If a major spinal artery is occluded and there is insufficient collateral circulation, a focus of softening or even cystic degeneration occurs within the cord. Usually, the smaller paracentral arteries escape damage. Cinical Manifestations In the series upon which this paper is based, a typical case gives a history of back trauma followed by an asymptomatic period of months or years. The presenting symptom is usually a burning type of pain occurring over one or more spinal segments and influenced by motion, cough, etc. In most cases, the pain is accompanied by either a hyperesthesia or a paresthesia in the distribution of the involved segments. Occasionally, hypesthesia occurs. Usually the clinical course assumes a subacute pattern of gradual progression without fever or systemic manifestations. The sensory changes may occur over widely separated areas or may be localized to a single segment or to segments that are contiguous. Cystic changes of the arachnoid produce a clinical picture identical with those of a space-occupying lesion in the spinal canal