Metrizamide cisternography in the diagnosis of acoustic neurinomas

MR cisternography of the cerebello-pontine angle and internal auditory canal in diagnosis of intracanalicular acoustic neuroma

One hundred and fifteen patients, suffering from sensorineural hearing loss were tested with a 1.5 T superconducting magnet. The authors describe utility of both T1-weighted multiple slice and T2-weighted multiple echo images for the evaluation of cerebello-pontine angle, internal auditory canal and their neurovascular content. In seventy-three cases MR cisternography was normal. The remaining forty-two cases were subdivided into twenty extracanalicular masses, eleven small intra-extracanalicular and nine purely intracanalicular lesions. All the lesions were histologically proven acoustic neuromas, except one intracanalicular mass which was a meningioma. Examination was inconclusive only in two cases and decision was then made to follow the clinical course. Advantages of MR cisternography over CT and air CT cisternography, such as absence of ionizing radiation and contrast material, easy multiplanar evaluation of the region of interest and the possibility to delineate both the cisternal and canalar extremities of the tumor mass are pointed out.

Volume growth rate of acoustic neurinomas

Of 79 acoustic neurinomas seen between June 1980 and June 1984, at least two CT scans were available for each of 23 tumors (21 patients); the scans were performed at intervals of at least 6 months. The volume growth rate of the tumours was either moderate, with a volume doubling time ranging from 205 to 545 days, or slow, with a doubling time ranging from 1090 days to no observable growth. No single clinical, radiological or histological feature correlated with any type of growth rate. However, some conclusions were drawn. If a primary CT scan is negative, at least 1 year should elapse before it is worthwhile taking another scan, even though audiological findings suggest growth; after an apparently radical removal, at least 3 years should elapse before a check CT scan is worthwhile; and if a small acoustic neurinoma is diagnosed, but for some reason not operated upon, a second CT scan should be carried out 1 year later in order to reassess the case.

Metrizamide cisternography of the cerebello-pontine angle by lateral C1-C2 puncture

Cisternography of the cerebello-pontine angle was performed with metrizamide using pluridirectional motion tomography on the Polytome. Lateral puncture between C1-C2 with a low pressure technique was used with the patient in lateral decubitus position. In a series of 20 patients all examinations were conclusive and small acoustic neuromas were seen in three patients. The investigation is easy to perform and sufficient contrast-medium-filling of the cerebello-pontine cistern and the internal auditory canal was obtained with 2 ml metrizamide (300 mg I/ml).