A Case of Sylvian Aqueduct Syndrome Caused by Intra-Fourth Ventricle Tumor

Abstract

We treated a rare case of the intra-fourth ventricle tumor which manifested the Sylvian aqueduct syndrome.A nine-year-old girl was admitted complaining of headache, vomiting and gait disturbance. Neurological examination on admission revealed papilledema, the right cerebellar sign and the truncal ataxia with no other neurological dysfunctions. The vertebral angiography and the Conray-ventriculography disclosed an intra-fourth ventricle tumor extending from the tumor of the cerebellar vermis. The tumor was removed subtotally as it was partially adherent to the outlet of the aqueduct. The histology was seen as astrocytoma of the piloid type. About 17 months after the operation the patient was readmitted complaining of headache and vomiting with the objective signs of convergence nystagmus, retractory nystagmus, upward gaze palsy and pupillary light reflex disturbance (the Sylvian aqueduct syndrome). A recurrence of the tumor was ruled out as a malfunction of the V-P shunt was evident. Conray-ventriculography revealed that the Sylvian aqueduct was remarkably dilated with a filling defect of the fourth ventricle. It might be considered that the outlet of the aqueduct was occluded by the rest of the tumor in addition to the malfunction of the V-P shunt. The ocular signs were gradually recovered after the reconstruction of the shunt; convergence nystagmus disappeared 6 months later, and upward gaze palsy at 12 months.Sylvian aqueduct syndrome is often observed in cases of pineal region tumor or a tumor in the posterior third ventricle; in such cases this syndrome is attributed to external compression of the midbrain.However, a dilated aqueduct caused by the obstructive hydrocephalus was demonstrated. Invasion of the tumor to the midbrain could be ruled out as ocular signs disappeared after the reconstruction of shunt.We conclude that the Sylvian aqueduct syndrome is caused by the cerebrospinal fluid pressure effect to the pretectal area, the posterior commissure and the periaqueductal area of the midbrain.