Miscellaneous Central Vestibular Disorders

Small Cerebellar Infarctions. Such lesions in the territory of either the anterior inferior cerebellar artery (AICA) or the posterior inferior cerebellar artery (PICA) have been repeatedly reported to mimic unilateral peripheral labyrinthine disorder, mostly with a similarly benign course (Duncan et al. 1975; Guiang and Ellington 1977; Rubinstein et al. 1980; Samson et al. 1981; Kömpf 1986). The areas covered by these arteries and the anatomy of the collaterals are both variable, so it is sometimes difficult to decide which artery is responsible for clinical signs or infarcted areas seen on CT scans or MRI. When the PICA is hypoplastic, the AICA takes over the territory usually supplied by the lateral branch of the PICA (Amarenco and Hauw 1989). All reports are entitled “cerebellar infarctions causing vertigo”, which is correct on the basis of the imaging data and concurrent clinical signs, but it is more likely that the vertigo itself results from pontomedullary brainstem ischaemia near the vestibular nuclei. The AICA supplies the rostral part of the vestibular nuclei, the middle cerebellar peduncle, the flocculus and the neighbouring lobules of the cerebellum. The PICA supplies the caudal part of the vestibular nuclei and the dorsal medullary territory, the uvular and the nodulus (Amarenco and Hauw 1989). Occlusion of the PICA causes the typical Wallenberg’s syndrome.