Anterior inferior cerebellar artery

Cerebellar infarcts can be grouped in territorial (superior cerebellar artery, anterior inferior cerebellar artery, posterior inferior cerebellar artery and combined), borderzone and lacunar. They are often combined with brain stem infarcts and with superficial posterior cerebral artery or thalamic infarcts. The most common isolated cerebellar infarcts are located in the superior cerebellar artery and posterior inferior cerebellar artery territories (Amarenco 1993 Amarenco et al. 1993,1994). 

The basilar artery ascends ventral to the pons to the ponto-midbrain junction in the interpeduncular cistern, where it divides into the two posterior cerebral arteries. Numerous small branches penetrate the brainstem and cerebellum. The basilar artery also gives rise to the anterior inferior cerebellar artery, which supplies the rostral cerebellum, brainstem, inner ear, and the superior cerebellar artery, which supplies the brainstem, superior half of the cerebellar hemisphere, vermis and dentate nucleus. 

The posterior cerebral artery supplies the occipital lobe and portions of the medial and inferior temporal lobe. The arterial supply of the spinal cord is derived from the vertebral arteries and the radicular arteries. The brain is supplied by the internal carotid arteries (the anterior circulation) and the vertebral arteries, which join at the pon tomedullary junction to form the basilar artery (collectively termed the posterior circulation). The brainstem is supplied by the posterior system. The medulla receives blood from branches of the vertebral arteries as well as from the spinal arteries and the posterior inferior cerebellar artery (PICA). The pons is supplied by paramedian and short circumferential branches of the basilar artery. Two major long circumferential branches are the anterior inferior cerebellar artery (AICA) and the superior cerebellar artery. The midbrain receives its arterial supply primarily from the posterior cerebral artery as well as from the basilar artery. The venous drainage of the spinal cord drains directly to the systemic circulation. By contrast, veins draining the cerebral hemispheres and brain stem drain into the dural sinuses. Cerebrospinal fluid also drains into the dural sinuses through unidirectional valves termed arachnoid villi. 

Fig. 4.3 (a) 3D time of flight (TOF) MRA there is apparent narrowing and irregularity of the distal right vertebral artery arrow head) and without definite flow in the right anterior inferior cerebellar artery arrow). 

Kaech D, de Tribolet N, Lasjaunias P (1987) Anterior inferior cerebellar artery aneurysm, carotid bifurcation aneurysm, and dural arteriovenous malformation of the tentorium in the same patient. Neurosurgery 21 575-582... 

Fig. 5.5. Distal small aneurysm of the anterior inferior cerebellar artery (AICA) associated with a high-flow arterious-venous malformation...

Most arterial aneurysms arise at the bifurcation of major arteries, and this is also true for the intracranial location. Around 85% of all intracranial aneurysms originate from the anterior circulation. The most common location (30%-35%) is the anterior communicating artery (Acorn). However, many of these so-called Acorn aneurysms do have their origin at the A1/A2 junction of the anterior cerebral artery and do not involve the anterior communicating artery. Internal carotid and posterior communicating artery aneurysms account for 30% and middle cerebral artery (MCA) bifurcation aneurysms for 20%. Around 15% of intracranial aneurysms arise at the vertebrobasilar circulation. Half of them develop at the basilar tip (with various degrees of involvement of the PI segments) and the other 50% from other posterior fossa vessels. Aneurysms of the anterior inferior cerebellar artery (AICA) and vertebral artery (VA) aneurysms without involvement of the VA-PICA junction or the vertebrobasilar site are extremely rare. 

Amarenco P, Hauw JJ (1990) Cerebellar infarction in the territory of the anterior and inferior cerebellar artery. A clinico-pathological study of 20 cases. Brain 113 139-155 Baquis GD, Pessin MS, Scott RM (1985) Limb shaking - a carotid TIA. Stroke 16 444-448 Barth A, Bogousslavsky J, Regli F (1994) Infarcts in the territory of the lateral branch of the posterior inferior cerebellar artery. J Neurol Neurosurg Psychiatry 57 1073-1076 Baumgartner RW, Sidler C, Mosso M et al (2003) Ischemic lacunar stroke in patients with and without potential mechanism other than small-artery disease. Stroke 34 653-659... 

Vertebral arteries vary in size and symmetry, where mostly the left vertebral artery is the dominant one. The coincidence of vertebral fenestrations and aneurysms is well known. The anterior spinal artery receives tiny vessels from the vertebral arteries which are physiologically not depicted by MRA due to their size. The posterior inferior cerebellar artery (PICA) as the largest, most important and most variable cerebellar artery however, under normal conditions it is constantly depictable with TOF and CE-MRA. 

Medullary infarcts can be medial, lateral or combined (Fig. 14.6). The medial territory is supplied by penetrating vessels from the anterior spinal artery and the distal vertebral artery. The lateral territory main arterial supply comes from penetrating arteries from the distal vertebral artery and the posterior inferior cerebellar artery. The small posterior territory is supplied by the posterior spinal artery and the posterior inferior cerebellar artery. Medial... 

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