Proceedings: Differential diagnosis of cerebellopontine angle lesions by vertebral angiography.

LINDSAY SYMON and BRIAN KENDALL (London) had used vertebral angiography for the past five years as a definitive investigation for providing details of the sites and probable natures of cerebellopontine angle lesions. Advantages of angiography were its performance under basal sedation with consequent diminution of the disturbance of intracranial dynamics consequent on anaesthesia, and its potential use as an elective investigation not necessarily urgently followed by surgery. The angiograms of 141 cerebellopontine angle masses were reviewed and plain film changes were mentioned. Erosion of the internal auditory meatus was demonstrated in 63 of 78 patients with acoustic neuromas and in two of the 22 posterior fossa meningiomas. Sclerosis of the petrous bone was evident in five of these posterior fossa meningioma cases. The six trigeminal neuromas were associated with fairly typical apical petrous erosions with smooth edges. These findings were also present in one patient with a chordoma and in one with a meningioma. Plain radiographs of the skull were normal in 15 of the acoustic neuromas, 10 of the meningiomas, and in a variety of other less common conditions. The importance of adequate study of the venous phases in angiography was emphasized. Small masses usually first displaced a complex of veins running towards the petrosal vein which passes from the lateral aspect of the pons to the superior petrosal sinus. The typical arterial displacements associated with acoustic neuroma and trigeminal neuroma were demonstrated. The occurrence of pathological circulation in two-thirds of the acoustic neuroma cases was emphasized, and the importance of adequate visualization of both external carotid and internal carotid circulations in the detection of pathological vessels in meningiomas and acoustic neuromas was emphasized. The common source for the pathological circulation in acoustic neuromas was found to be either the dural distribution of the vertebral supply or the meningeal or ascending pharyngeal branches from the external carotid circulation. The blood supply of the angle meningiomas usually emanated either from the hypophysial branch of the internal carotid artery or the external carotid circulation. The vertebral circulation sometimes, but not invariably, played a part.