Imaging of the cerebellopontine angle

Disease involving the cerebellopontine angle (CPA) may arise from structures located within the cistern or from extension of lesions located primarily outside the cistern—from the brainstem, fourth ventricle, choroid plexus and bony skull base. The symptoms and signs of CPA disease are non-specific, relating either to compression of the neural structures found within it or from compression of the fourth ventricle with resulting obstructive hydrocephalus. Imaging is vital for diagnosis and management planning. The main features to note are the site of origin, shape, density, signal intensity and pattern of enhancement of the lesion.⇓⇓⇓⇓⇓⇓⇓⇓⇓⇓⇓⇓⇓⇓⇓⇓⇓⇓⇓ Figure 1 Normal anatomy: axial (A, B, D) and coronal (C) constructive interference in the steady state MRIs of the cerebellopontine angle. CPA, cerebellopontine angle; IAC, internal auditory canal. Figure 2 Left cerebellopontine angle (CPA) metastasis from a lung primary. T1W gadolinium enhanced axial (A) and T2W (B) axial MRIs. It is sometimes difficult to distinguish intra-axial from extra-axial CPA lesions when the CPA is obliterated. This inhomogenously enhancing left CPA mass is a metastasis. The lack of cerebellar oedema suggests an extra-axial location. Figure 3 Axial constructive interference in the steady state MRIs show a small right intracanalicular vestibular schwannoma, located at the fundus of the internal auditory canal and extending up to the cochlear aperture. Serial scans showed no growth over 3 years. AICA, anterior inferior cerebellar artery; CPA, cerebellopontine angle; IAC, internal auditory canal. Figure 4 Coronal (A) and axial (B) constructive interference in the steady state MRIs show a left-sided T2 hypointense …