Thus, careful evaluation of HSN may provide clues for diagnosis of AICA infarction in patients with acute audiovestibular loss ( Huh et al., 2013). Therefore, detection of central lesions may require additional tests, such as horizontal head shaking, which detected central patterns of HSN in 3 of the 5 patients with AICA infarction and negative HINTS ( Huh et al., 2013). Indeed, the HINTS failed to detect central lesions in 5 of 18 patients with AICA infarction ( Huh et al., 2013). The HINTS (negative HIT, direction-changing nystagmus, and skew deviation), the most useful bedside tool to detect central vestibulopathy, may not be sufficiently robust to detect central lesions in AICA infarction, since the HIT is mostly positive in this disorder ( Huh et al., 2013 Newman-Toker et al., 2013b Choi et al., 2014a). HSN is also common with both peripheral and central patterns. Asymmetric bidirectional GEN, frequently mimicking Bruns’ nystagmus, is found in 43% of patients ( Lee et al., 2009). In AICA infarction, spontaneous nystagmus is predominantly horizontal and mostly beats away from the lesion side ( Lee et al., 2009). (2015b), with permission from Springer Science and Business Media. A patient with infarction in the territory of right anterior inferior cerebellar artery ( A) shows ipsiversive ocular torsion ( B), contralesional spontaneous nystagmus ( C), gaze-evoked nystagmus ( D), ipsilesional caloric paresis ( E), ipsilesional hearing loss ( F), decreased amplitude of the ipsilesional cervical vestibular-evoked myogenic potentials (VEMPs, G), and absent responses of ocular VEMPs during ipsilesional ear stimulation ( H). Ipsilateral conjugate gaze palsy may reflect infarction of the flocculus (see Table 2-5).įig. 189, 192, 193 Other features include vomiting, ipsilateral facial numbness, facial palsy, Horner syndrome, and contralateral loss of pain and temperature. ![]() Usual symptoms are nausea, vertigo, tinnitus, and hearing loss. The findings reflect involvement of the peripheral nervous system and CNS structures at the cerebellopontine angle. Syndrome of Anterior Inferior Cerebellar Artery Occlusion Comparison of Anterior Inferior Cerebellar Artery and Superior Cerebellar Artery InfarctsĪICA infarcts most consistently involve the lateral pons and the middle cerebellar peduncle, 191 often sparing the cerebellum itself, in contrast to SCA infarction, which predominantly affects the cerebellum, sparing the brainstem. When the PICA is missing, the territory of the AICA includes the territory of the PICA (see Fig. Its cerebellar territory borders on and is reciprocal in size with the territories of the SCA and PICA. 190Īs seen ventrally, the AICA irrigates a triangle with its base toward the midline, where it abuts on the paramedian zone irrigated by perforators from the BA and VA (see Fig. The AICA acts as the artery of the cerebellopontine angle. Typically, the AICA also gives rise to an IAA that enters the internal acoustic meatus (see internal auditory artery (IAA), infra). The AICA runs laterally to irrigate the ventrolateral pons, essentially the caudal part of the middle cerebellar peduncle, which is its core distribution the spinothalamic tract the trigeminal, facial, vestibular, and cochlear nuclei the roots of CN VII and VIII and the ventral parts of the cerebellum, including the flocculus. With a left dominant AICA, the ipsilateral VA and PICA are usually hypoplastic (see Fig. ĪICA dominant on the left and PICA dominant on the right. ![]() Įqual right and left origins from the BA, with a major anastomosis between the AICA and the PICA ( Fig.The AICA runs laterally, just caudal to CN VI. vestibular schwannomas or meningiomas) would displace the vessel whereas intra-axial masses tend not to.The AICA arises from the BA, just rostral to the union of the VAs to form the BA. medial branch supplies the biventral lobuleīefore cross-sectional imaging, the AICA (along with venous displacement) was used to identify posterior fossa intra- or extra-axial masses, especially at the CP angle.lateral branch passes around the flocculus and into the hemispheric fissure (supplying both superior and inferior semilunar lobules).internal auditory branch (80% single, 20% double) passes into the IAM.anteroinferior surface of the cerebellumĩ9% of AICAs arise from the basilar artery, but where along the vessel is variable:.The amount of tissue supplied by the AICA is variable ( AICA-PICA dominance) but usually includes: It has a variable origin, course and supply, with up to 40% of specimens not having an identifiable standard AICA. The anterior inferior cerebellar artery (AICA) is one of three vessels that provides arterial blood supply to the cerebellum.
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