The pathogenesis of cerebral symptoms in colloid cysts of the third ventricle: a clinical and pathoanatomical study.

Abstract

The purpose of the investigation was to elucidate the pathogenesis of the symptoms in cases of colloid cysts of the third ventricle and in this connection to discuss the importance of a previously undescribed stenosis of the aqueduct of Sylvius in this disease. Eleven cases of colloid cysts are described, out of which four fatal cases are described in some detail. The autopsied cases showed a pronounced narrowing of the aqueduct. This is thought to be a secondary stenosis caused by cellular debris from lesions in the walls of the anterior part of the third ventricle due to the colloid cyst. Aqueductal stenosis was found on encephalography in one more case. In seven cases a raised ventricular fluid pressure was recorded. The present study offers an alternative explanation for the typical attacks of cerebral symptoms, previously thought to be caused by a ball-valve action of the cyst. It seems likely that these attacks are the result of acute disorders of the cerebral blood circulation of the plateau wave type, secondary to intracranial hypertension caused by obstruction of the fluid pathways. The stenosis of the aqueduct which may be a not uncommon complication of colloid cyst of the third ventricle might contribute to the rise of the intracranial pressure necessary for the occurrence of plateau waves. The importance of this stenosis from a neurosurgical point of view is discussed.