The anterior inferior cerebellar artery (AICA) is one of three pairs of

arteries An artery (plural arteries) () is a blood vessel in humans and most animals that takes blood away from the heart to one or more parts of the body (tissues, lungs, brain etc.). Most arteries carry oxygenated blood; the two exceptions are the pu ...

that supplies blood to the

cerebellum The cerebellum (Latin for "little brain") is a major feature of the hindbrain of all vertebrates. Although usually smaller than the cerebrum, in some animals such as the mormyrid fishes it may be as large as or even larger. In humans, the cerebel ...

. It arises from the

basilar artery The basilar artery () is one of the arteries that supplies the brain with oxygen-rich blood. The two vertebral arteries and the basilar artery are known as the vertebral basilar system, which supplies blood to the posterior part of the circle of W ...

on each side at the level of the junction between the

medulla oblongata The medulla oblongata or simply medulla is a long stem-like structure which makes up the lower part of the brainstem. It is anterior and partially inferior to the cerebellum. It is a cone-shaped neuronal mass responsible for autonomic (involun ...

and the

pons The pons (from Latin , "bridge") is part of the brainstem that in humans and other bipeds lies inferior to the midbrain, superior to the medulla oblongata and anterior to the cerebellum. The pons is also called the pons Varolii ("bridge of Va ...

in the

brainstem The brainstem (or brain stem) is the posterior stalk-like part of the brain that connects the cerebrum with the spinal cord. In the human brain the brainstem is composed of the midbrain, the pons, and the medulla oblongata. The midbrain is cont ...

. It has a variable course, passing backward to be distributed to the anterior part of the undersurface of the cerebellum,

anastomosing An anastomosis (, plural anastomoses) is a connection or opening between two things (especially cavities or passages) that are normally diverging or branching, such as between blood vessels, leaf veins, or streams. Such a connection may be normal ...

with both the posterior inferior cerebellar (PICA) branch of the

vertebral artery The vertebral arteries are major arteries An artery (plural arteries) () is a blood vessel in humans and most animals that takes blood away from the heart to one or more parts of the body (tissues, lungs, brain etc.). Most arteries carry o ...

and the

superior cerebellar artery The superior cerebellar artery (SCA) is an artery of the head. It arises near the end of the basilar artery. It is a branch of the basilar artery. It supplies parts of the cerebellum, the midbrain, and other nearby structures. It is the cause of ...

. It also gives off the internal auditory or

labyrinthine artery The labyrinthine artery (auditory artery, internal auditory artery) is a branch of either the anterior inferior cerebellar artery or the basilar artery. It accompanies the vestibulocochlear nerve (CN VIII) through the internal acoustic meatus. ...

in most cases; however, the labyrinthine artery can less commonly emerge as a branch of the

. The amount of tissue supplied by the AICA is variable, depending upon whether the PICA is more or less dominant, but usually includes the anteroinferior surface of the cerebellum, the flocculus, middle cerebellar peduncle and inferolateral portion of the pons.

Clinical significance

Occlusion of AICA is considered rare, but generally results in a

lateral pontine syndrome A lateral pontine syndrome is a lesion which is similar to the lateral medullary syndrome, but because it occurs in the pons, it also involves the cranial nerve nuclei of the pons. Symptoms Damage to the following areas produces symptoms (from me ...

, also known as AICA syndrome. The symptoms include sudden onset of vertigo and vomiting,

nystagmus Nystagmus is a condition of involuntary (or voluntary, in some cases) eye movement. Infants can be born with it but more commonly acquire it in infancy or later in life. In many cases it may result in reduced or limited vision. Due to the invol ...

dysarthria Dysarthria is a speech sound disorder resulting from neurological injury of the motor component of the motor–speech system and is characterized by poor articulation of phonemes. In other words, it is a condition in which problems effectively ...

, falling to the side of the lesion (due to damage to

vestibular nuclei The vestibular nuclei (VN) are the cranial nuclei for the vestibular nerve located in the brainstem. In Terminologia Anatomica they are grouped in both the pons and the medulla in the brainstem. Structure Path The fibers of the vestibular nerve ...

), and a variety of ipsilateral features including hemiataxia, loss of all modalities of sensation of the face (due to damage to the

principal sensory trigeminal nucleus The principal sensory nucleus of trigeminal nerve (or chief sensory nucleus of V, main trigeminal sensory nucleus) is a group of second-order neurons which have cell bodies in the caudal pons. It receives information about discriminative sensation ...

), facial paralysis (due to damage to the

facial nucleus The facial motor nucleus is a collection of neurons in the brainstem that belong to the facial nerve (cranial nerve VII). These lower motor neurons innervate the muscles of facial expression and the stapedius. Structure The nucleus is situated i ...

), and hearing loss and tinnitus (due to damage to the

cochlear nuclei The cochlear nuclear (CN) complex comprises two cranial nerve nuclei in the human brainstem, the ventral cochlear nucleus (VCN) and the dorsal cochlear nucleus (DCN). The ventral cochlear nucleus is unlayered whereas the dorsal cochlear nucleus ...

). Vertigo may sometimes present as an isolated symptom several weeks or months before acute ischemia and cerebral infarction occurs, probably with the meaning of transient ischemia of the inner ear or the

vestibular nerve The vestibular nerve is one of the two branches of the vestibulocochlear nerve (the cochlear nerve being the other). In humans the vestibular nerve transmits sensory information transmitted by vestibular hair cells located in the two otolith orga ...

. There is also loss of pain and temperature sensation from the contralateral limbs and trunk, which can lead to diagnostic confusion with

lateral medullary syndrome Lateral medullary syndrome is a neurological disorder causing a range of symptoms due to ischemia in the lateral part of the medulla oblongata in the brainstem. The ischemia is a result of a blockage most commonly in the vertebral artery or the p ...

, which also gives rise to "crossed" neurological signs but does not normally cause cochlear symptoms, severe facial palsy or multimodal facial sensory loss.

References

External links

* * http://neuroangio.org/anatomy-and-variants/aica/ * {{Authority control Arteries of the head and neck