The cerebello-pontine angle has always posed a challenge to the neurosurgeon, the otoneurosurgeon, and the neuroradiologist. Angle masses which are very small and difficult to detect frequently produce symptoms, but may remain silent while growing to exceptional size. The neuroradiologist must have firm knowl­ edge of the clinical manifestations of the diverse angle lesions in order to tailor his studies to the patients' needs. The majority of angle lesions are benign; thus successful surgery has the potential for complete cure. Angle lesions typically arise in conjunction with vital neurovascular structures, and often displace these away from their expected positions. Large lesions may attenuate the vestibulocochlear and facial nerves and thin them over their dome. Since the nerves often remain functional, the surgeon then faces the need to separate the tumor from the contiguous nerve, with preservation of neurological function. Depending on the exact location and extension of the lesion, resection may best be attempted via otologic or neurosurgical approaches. The neuroradiologist must determine - precisely -the presence, site, size, and extension( s) of the lesion and the displacement of vital neurovascular structures as a guide to selecting the line of surgical attack. Since the arteries, veins, and nerves that traverse the angle are fine structures, the neuroradiologist must perform studies of the highest quality to do his job effectively.

Historical Overview.- CT Examination: Techniques for Evaluation of the Cerebello-Pontine Angle.- 1 Standard CT Examination.- 2 High Resolution CT.- 3 Physical and Technical Limitations of CT Examination of the Cerebello-Pontine Angle.- 4 Water Soluble Positive-Contrast CT Cisternography.- 5 Gas CT Cisternography.- 6 Dynamic Contrast Enhanced CT.- CT Anatomy of the Cerebello-Pontine Angle.- Axial Sections.- Coronal Sections.- The Anterior Inferior Cerebellar Artery.- The Internal Auditory Canal.- The Jugular Foramen.- The Tentorial Incisura.- General Principles for the CT Diagnosis of Cerebello-Pontine Angle Lesions.- Pathology of the Cerebello-Pontine Angle.- Acoustic Neurinoma.- 1 General Considerations.- 2 Conventional Radiology.- 3 Computed Tomography.- Meningioma of the Posterior Surface of the Petrous Bone.- 1 General Considerations.- 2 Conventional Radiology.- 3 Computed Tomography.- Epidermoid Tumors.- 1 General Considerations.- 2 Conventional Radiology.- 3 Computed Tomography.- 4 Differential Diagnosis.- Arachnoid Cysts of the Cerebello-Pontine Angle.- 1 General Considerations.- 2 Conventional Radiology.- 3 Computed Tomography.- 4 Differential Diagnosis.- Trigeminal Neurinoma.- 1 General Considerations.- 2 Conventional Radiology.- 3 Computed Tomography.- 4 Differential Diagnosis.- Chordoma of the Cerebello-Pontine Angle.- 1 General Considerations.- 2 Conventional Radiology.- 3 Computed Tomography.- 4 Differential Diagnosis.- Chemodectomas of the Petrous Bone.- 1 General Considerations.- 2 Conventional Radiology.- 3 Computed Tomography.- 4 Differential Diagnosis.- Neurinomas of the Caudal Cranial Nerves.- A. Neurinomas of the Hypoglossal Nerve.- B. Jugular Foramen Neurinomas.- Neurinomas of the Facial Nerve.- 1 General Considerations.- 2 Conventional Radiology.-3 Computed Tomography.- 4 Differential Diagnosis.- Vascular Lesions of the Cerebello-Pontine Angle.- A. Berry Aneurysms of the Cerebello-Pontine Angle.- B. Giant Cerebello-Pontine Angle Aneurysms.- C. Megadolichobasilar Anomaly.- D. Vascular Malformations of the Cerebello-Pontine Angle.- Secondary Tumors of the Cerebello-Pontine Angle.- Magnetic Resonance Imaging of the Cerebello-Pontine Angle.- MRI Examination Technique.- MRI Anatomy.- MRI of Acoustic Neurinoma.- MRI of Other Cerebello-Pontine Angle Masses.- References.