The Radiology of Aqueductal Stenosis

The entity, aqueductal stenosis, includes a variety of lesions affecting the aqueduct of Sylvius. It is not surprising, therefore, that the range of clinical and radiologic features within the group is hard to define in simple and precise terms. It was with the aim of understanding the variations in radiologic features within the group of lesions causing aqueductal stenosis that we reviewed the clinical, radiologic, and pathologic (when available) features in 88 patients with aqueductal stenosis hospitalized at the National Hospital for Nervous Diseases, London, England, and at the Atkinson-Morley Hospital, Wimbledon, England. To these cases were added several others collected from the Bronx Municipal Hospital Center and from St. Vincent's Hospital, New York, N. Y. The radiological features of these cases are the subject of this communication. The ages of the patients at the time of presentation are given in Table I. It is obvious that frequently aqueductal stenosis presents relatively late in life. The age distribution is skewed in such a fashion as to emphasize this fact, for most of the cases in this series were drawn from the National Hospital for Nervous Diseases, where there are few pediatric admissions. The presentation of cases of “benign” aqueductal stenosis in adolescence and adult life is well established. Our experience differs from that of Taveras and Wood (22) who state: “Aqueductal stenosis in teen-aged children and adults is often produced by periaqueductal gliomas, which are slowly growing infiltrating tumors.” Not included in this material are cases of aqueductal stenosis caused by a number of interesting inflammatory lesions such as syphilis, tuberculosis, cysticercosis, toxoplasmosis, histoplasmosis, and from ependymitis following the creation of a shunt. Nor are we including cases of obstruction of the aqueduct due to vascular lesions such as “aneurysm of the vein of Galen” and ectasia and aneurysm formation of the terminal basilar artery. The problem of differentiating neoplastic lesions from true aqueductal stenosis will be dealt with further on in this report. The cases presented herein have all been followed for a long time, and, in 26, postmortem examinations were performed. Pathology Dorothy Russell (19) in her monograph described several kinds of “maldevelop-ment” of the aqueduct as well as an entity labelled “gliosis,” and this is the starting point for a discussion of pathology. The first of these subspecies of maldevelopments is stenosis, which is defined “as a state in which the aqueduct is histologically normal, but abnormally small.” At the time of Russell's monograph there was little precise data on the variations in caliber of the aqueduct.