Anterior Inferior Cerebellar ArteryEdit
The anterior inferior cerebellar artery (AICA) is one of the key arteries in the posterior circulation of the brain. It typically arises from the basilar artery and travels laterally around the pons toward the cerebellum, supplying portions of the cerebellar hemisphere and nearby brainstem structures. In many people, AICA also gives off the labyrinthine (internal auditory) artery, which provides the blood supply to parts of the inner ear. Because of its position and connections, the AICA plays an important role in coordinating balance, hearing, and facial function. anterior inferior cerebellar artery basilar artery pons cerebellum labyrinthine artery internal auditory artery
When AICA is occluded or becomes narrowed, the resulting ischemia can produce a distinct clinical picture, often referred to as a lateral pontine syndrome. This syndrome reflects the artery’s territory, which includes elements of the cerebellum, brainstem nuclei, cranial nerves, and the inner ear. Presentations vary with individual vascular anatomy and the degree of collateral blood flow. Clinicians use this pattern recognition, along with imaging, to distinguish AICA-related events from other posterior circulation strokes. AICA syndrome lateral pontine syndrome ischemic stroke
Anatomy and origin
Origin and course: The AICA most commonly branches from the basilar artery near its cisternal segment and then courses laterally around the ventral aspect of the pons toward the cerebellar surface. It supplies the inferior surface of the cerebellum and parts of the caudal pons. Variations exist where the artery originates slightly above or below its usual point, or shares a trunk with adjacent vessels. basilar artery anterior inferior cerebellar artery
Branches and territory: Key branches include perforating vessels to the caudal brainstem, cerebellar branches that reach the inferior cerebellar surface, and often the labyrinthine (internal auditory) artery that supplies the inner ear. In many individuals, the labyrinthine artery arises from the AICA, though it can originate directly from the basilar artery or from other nearby arteries. These branches collectively irrigate the CNCs (cranial nerve nuclei) and structures involved in balance and hearing. labyrinthine artery internal auditory artery facial nerve vestibulocochlear nerve
Relationship to other arteries: The AICA lies in proximity to the other major posterior circulation arteries, including the posterior inferior cerebellar artery and the superior cerebellar artery, and participates in the broader basilar system that sustains the brainstem and cerebellum. Understanding these relationships helps explain why specific deficits occur when the AICA territory is affected. PICA SCA basilar artery
Clinical significance
AICA territory and lateral pontine syndrome: Occlusion or severe stenosis of the AICA can produce a constellation of signs that reflect dysfunction of the cerebellum, facial nerve, vestibulocochlear apparatus, and sensory pathways. Common features include ipsilateral facial weakness from facial nerve involvement, ipsilateral loss or diminished taste from the anterior two-thirds of the tongue, ipsilateral hearing loss or vertigo from involvement of the labyrinthine system, ipsilateral facial hypoesthesia, vomiting, nystagmus, and ataxia with dysmetria. Contralateral loss of pain and temperature from the body may also occur due to spinothalamic tract involvement. AICA syndrome lateral pontine syndrome facial nerve vestibulocochlear nerve taste cochlear nerve
Variability and overlap with other syndromes: Because vascular territories in the brainstem and cerebellum can overlap, some patients with AICA involvement may present with atypical or partial symptom sets. Distinguishing AICA-related events from PICA-related (lateral medullary) or SCA-related syndromes relies on the precise combination of cranial nerve findings, hearing status, cerebellar signs, and imaging. PICA lateral medullary syndrome ischemic stroke
Diagnosis and imaging: Magnetic resonance imaging (MRI) with diffusion weighting is a primary tool for identifying AICA territory infarction, while vascular imaging (such as MR angiography or CT angiography) helps confirm occlusion or stenosis of the AICA. Endovascular or medical management decisions depend on the extent of infarction, collateral supply, and patient-specific factors. ischemic stroke MRI MR angiography CT angiography
Variants and implications for care: Anatomical variations in the origin and branches of the AICA can influence both presentation and the risks associated with surgical or endovascular interventions in the posterior circulation. Clinicians must account for individual anatomy when planning procedures that may affect the basilar system. anatomical variation cerebellum basilar artery
Variants and controversies
Anatomical variability: The precise origin and branching pattern of the AICA can differ between individuals, and the presence or absence of the labyrinthine artery within the AICA’s territory is a notable variation. These differences can alter which functions are most at risk during ischemic events and can complicate imaging interpretation. anterior inferior cerebellar artery labyrinthine artery
Diagnostic challenges: Because symptoms may overlap with those of other posterior circulation strokes, some clinicians debate the best imaging or clinical criteria to clearly diagnose an AICA infarct, particularly in the early phase when diffusion changes are subtle. This has implications for acute stroke protocols and decisions about reperfusion therapy. ischemic stroke lateral pontine syndrome
Therapeutic considerations: Management of AICA-related stroke, including decisions about antithrombotic therapy, thrombolysis, or mechanical thrombectomy, reflects broader debates in stroke care about balancing rapid reperfusion with risk of hemorrhage and about optimizing outcomes given the unique neural structures in the brainstem. AICA syndrome ischemic stroke