Double origin and early bifurcation of the anterior inferior cerebellar artery diagnosed by CT angiography

Challenges in Using the Posterior Inferior Cerebellar Artery for Revascularization of the Anterior Inferior Cerebellar Artery: A Microsurgical Anatomic Study

BACKGROUND

A bypass is usually required to prevent ischemia during the treatment of anterior inferior cerebellar artery (AICA) aneurysms. The intracranial (IC)-to-IC bypass provides several advantages over the extracranial-to-IC bypass in the posterior fossa. However, there are only 2 case reports about AICA revascularization with the posterior inferior cerebellar artery (PICA). We aimed to investigate the microsurgical anatomical challenges for PICA to AICA anastomosis.

METHODS

Ten cadaveric heads injected with colored silicone were inspected on both sides using a lateral transcondylar approach. After the donor and recipient arteries were examined from the posterior side, neurovascular contents of the posterior fossa were excised and the origin, course, and variations of both arteries were investigated from the anterior view. The diameters of the AICA and PICA segments and the intersegment distance were measured.

RESULTS

PICA variations and posteromedial origins from the vertebral artery were identified in 8 of the 20 right and 6 of the 20 left sides, and the first segment of the PICA was not present in 7 sides. Furthermore, in 18 sides, the PICA was trapped between the lower cranial nerves and dentate ligaments. Therefore the donor artery could not be brought closer than 1 cm to the recipient artery in 19 sides. Moreover, AICA variations were identified in 6 sides, and in 12 sides, the diameter of the recipient artery was <1 mm.

CONCLUSIONS

The mostly PICA-related issues made PICA-to-AICA anastomosis unfeasible in all cadaveric heads included in the study.

Vascular Anomalies of Posterior Fossa and Their Implications

Posterior fossa houses very vital and sensitive structures namely midbrain, pons, medulla, and cerebellum. These structures are irrigated by vertebral, posterior inferior cerebellar, anterior inferior cerebellar, and superior cerebellar arteries. Parts of brain located in posterior fossa control important parts of body so any variation pertaining to stenosis, atresia, hypoplasia, fenestration, agenesis, and duplication in the arteries supplying these parts alter the irrigation pattern culminating into various morbid and mortal neurologic disorders. Therefore, a sound understanding and thorough knowledge of posterior circulation vascular variant anatomy builds the foundation for the accurate diagnosis and appropriate management of neurovascular ischemic and hemorrhagic diseases of posterior fossa. To aid in addressing these complex neurologic disorders and neurosurgical treatment to be carried out successfully, updating and consolidating the knowledge of all the variations/insults of these arteries becomes essential. Therefore, review study has been carried out.Literature search was carried out using databases, including Scielo, Scopmed, Medline, PubMed, and Wiley online library. Papers containing original data were selected and secondary references retrieved from bibliographies. Search terms used were posterior fossa, anomalies of vertebral, posterior inferior cerebellar, anterior inferior cerebellar, and superior cerebellar arteries.The study will be of paramount importance to angiographers in interpreting angiographs, neurologists in diagnosis and treatment of neurologic disorders, and neurosurgeons in performing surgery in posterior fossa and craniovertebral region particularly dealing with tumors and vascular malformations.