Double origin of the posterior inferior cerebellar artery

Double origin of the posterior inferior cerebellar artery

The posterior inferior cerebellar artery (PICA) frequently arises from the fenestrated segment of the intracranial vertebral artery (VA), and this common variation can be misinterpreted as or confused with a PICA of double origin. Rarely, a PICA of true double origin occurs when two branches of the PICA arise separately from the intracranial VA and fuse to form an arterial ring.

Uchino et al. discovered this rare variation incidentally while interpreting images of magnetic resonance angiography. This is the first report of MR angiographic findings of this rare variation 1).


For Lesley et al. double origin of the PICA is seen in 4.1% of patients with intracranial aneurysms and on 1.45% of catheter angiograms. The double origin of the PICA has an increased association with intracranial aneurysmal disease and may represent a risk factor for subsequent development of an intracranial aneurysm 2).


Posterior fossa arteriovenous malformations (AVMs), especially cerebellar arteriovenous malformations, are also not common. Consequently, the association of a Double origin of the posterior inferior cerebellar artery (DOPICA) with a cerebellar AVM is even rare.

Rodriguez-Calienes et al. presented a rare case of a pediatric cerebellar AVM supplied by a branch of a DOPICA which was treated endovascularly with NBCA. Total obliteration was achieved in the immediate controls and at 1-year follow-up.

Navigation through tortuous and long branches from a DOPICA is technically feasible. Although NBCA cure rates are relatively low, when the microcatheter can no longer navigate through the feeding artery, a correct dilution of NBCA with lipiodol can provide adequate penetration of this embolic agent, to obliterate the AVM nidus completely 3).


A cadaveric specimen was prepared for dissection. A far lateral craniotomy was performed on the right side. While exploring the right cerebellomedullary cistern, two separate origins of PICA were found from the vertebral artery (VA) as the caudal and rostral trunks that joined to form the distal PICA trunk at the tonsillomedullary segment. Microscopic and endoscopic illustrations are provided.

To the best of the authors’ knowledge, this is the first anatomic report on the DOPICA. Cadaveric illustration of this variant helps with understanding its anatomical relationship with adjacent neurovascular structures of the cerebellomedullary cistern including the perforating arteries and the lower cranial nerves 4).


Cho et al. demonstrated the first case of double origin of the posterior inferior cerebellar artery (PICA) with juxta-proximal fenestration of the caudal component, which was misunderstood as triple origin, combined with an unruptured middle cerebral artery aneurysm. The caudal component of the PICA originated from the atlanto-occipital portion and it was fenestrated shortly after origin. The cranial component originated from the intracranial vertebral artery and converged with the superior branch of the caudal component, and then met the inferior branch of the caudal component distally 5).


Two cases of anatomical variation of the PICA that they have called its double origin, one of which gave rise to an aneurysm. The first patient was a 36-year-old man who presented with a subarachnoid hemorrhage related to the rupture of a PICA aneurysm. The aneurysm was treated by the endovascular route. Selective and super selective studies showed that the PICA origin was low on the fourth segment of the vertebral artery (VA). The aneurysm was located on an anastomosis between the PICA and a small upper arterial branch originating from the VA. Embolization was performed through the small branch with no problem, but a lateral medullary infarct followed, probably due to occlusion of the perforating vessels. The same anatomical variation was incidentally discovered in the second patient. To the authors’ knowledge, neither this anatomical variation of the PICA nor the aneurysm’s topography has been previously described angiographically. This highlights the role of angiography in pretreatment evaluation of aneurysms especially when perforating vessels or small accessory branches that are poorly visualized on angiographic studies are concerned, as in the territory of the PICA. Anatomy is sometimes unpredictable, and the surgeon must be very careful when confronted with these variations because they are potentially dangerous for endovascular treatment 6).


1)

Uchino A, Saito N, Ishihara S. Double Origin of the Posterior Inferior Cerebellar Artery Diagnosed by MR Angiography: A Report of Two Cases. Neuroradiol J. 2015 Apr;28(2):187-9. doi: 10.1177/1971400915576659. Epub 2015 Apr 13. PMID: 25923681; PMCID: PMC4757150.
2)

Lesley WS, Rajab MH, Case RS. Double origin of the posterior inferior cerebellar artery: association with intracranial aneurysm on catheter angiography. AJR Am J Roentgenol. 2007 Oct;189(4):893-7. doi: 10.2214/AJR.07.2453. PMID: 17885063.
3)

Rodriguez-Calienes A, Saal-Zapata G, De la Cruz J. Endovascular Treatment of an Arteriovenous Malformation Associated with a Double Origin of the Posterior Inferior Cerebellar Artery. Pediatr Neurosurg. 2021 Jul 8:1-5. doi: 10.1159/000517248. Epub ahead of print. PMID: 34237747.
4)

Meybodi AT, Moreira LB, Zhao X, Lawton MT, Preul MC. Double Origin of the Posterior Inferior Cerebellar Artery: Anatomic Case Report. World Neurosurg. 2019 Jan 3:S1878-8750(18)32950-4. doi: 10.1016/j.wneu.2018.12.127. Epub ahead of print. PMID: 30611945.
5)

Cho YD, Han MH, Lee JY. Double origin of the posterior inferior cerebellar artery with juxta-proximal fenestration of caudal component. Surg Radiol Anat. 2011 Apr;33(3):271-3. doi: 10.1007/s00276-010-0747-9. Epub 2010 Nov 24. PMID: 21107570.
6)

Pasco A, Thouveny F, Papon X, Tanguy JY, Mercier P, Caron-Poitreau C, Herbreteau D. Ruptured aneurysm on a double origin of the posterior inferior cerebellar artery: a pathological entity in an anatomical variation. Report of two cases and review of the literature. J Neurosurg. 2002 Jan;96(1):127-31. doi: 10.3171/jns.2002.96.1.0127. PMID: 11794593.

Anterior Inferior Cerebellar Artery Anomalies

Anterior Inferior Cerebellar Artery Anomalies

The anterior inferior cerebellar arteryposterior inferior cerebellar artery (AICAPICA) common trunk anomaly is reportedly one of the most common vessel variants in the posterior circulation 1).


A healthy 59-year-old male with a unilateral sporadic vestibular schwannoma.

The patient elected to undergo a translabyrinthine approach for resection of a vestibular schwannoma. An aberrant loop of AICA was encountered during the temporal bone dissection within the petrous part of the temporal bone.

The patient suffered a presumed ischemic insult resulting in a fluctuating ipsilateral facial paresis and atypical postoperative nystagmus.

MRI demonstrated an ischemic lesion in the vascular distribution of the right anterior-inferior cerebellar artery, including the lateral portion of the right cerebellar hemisphere, middle cerebellar peduncle, and bordering the right cranial nerve VII nucleus. His functional recovery was excellent, essentially identical to the anticipated course in an otherwise uncomplicated surgery.

This case highlights the irregular anatomy of the AICA as well as the importance of thorough neurological exams in the postsurgical lateral skull base patient 2).


Anomaly in which a segment of the anteroinferior cerebellar artery (AICA) is embedded in the dura or bone surrounding the subarcuate fossa, a small depression in the bone posterior to the internal acoustic meatus (IAM), through which the subarcuate artery enters the bone. This anomaly places the artery at risk in removing the posterior wall of the IAM.

An anomalous AICA having a segment that was embedded in the dura covering on the bone surrounding the subarcuate fossa was found during a microsurgical dissection course. The senior author (ALR) has observed this anomaly in four patients during surgery for acoustic neuromas and in three specimens in microsurgery dissection courses. To define the microsurgical anatomy of the anomalous artery further, the latex-injected specimen was dissected in a stepwise manner using x3 to x40 magnification.

The anomalous AICA described in this report bifurcated into a rostral trunk and a caudal trunk near the facial-vestibulocochlear nerve complex. The caudal trunk formed a sharp lateral loop that was embedded in the dura covering the subarcuate fossa. The involved trunk continued to supply the suboccipital area normally supplied by the posteroinferior cerebellar artery, which was hypoplastic. The dura surrounding the anomalous loop was opened, and the adjacent bone was removed to free the anomalous loop from the subarcuate fossa so that the artery could be displaced medially to remove the posterior wall of the IAM. Although it has been reported that the AICA may occasionally be adherent to the dura over the subarcuate fossa, this study is the first to demonstrate an AICA that is embedded in the dura and bone of the subarcuate fossa.

Mobilizing the AICA loop that is embedded in the subarcuate fossa posterior to the IAM places the involved AICA at significant risk in exposing the contents of the IAM 3).


Reports of hemifacial spasm (HFS) associated with AICA-PICA common trunk are very rare. In the present study, we describe methods of microvascular decompression (MVD) for HFS caused by AICA-PICA common trunk compression.

Among 159 patients who underwent MVD for HFS, 16 patients had compression of the root exit zone by the AICA-PICA common trunk anomaly. The types of compression were classified into 2 groups: common trunk artery compression group and branching vessel compression group.

The common trunk artery compression group consisted of 11 patients (69%), and the branching vessel compression group consisted of 5 patients (31%). The rostral branch (feeding the original AICA territory) coursed between the seventh and eighth cranial nerves in 5 patients, and in 13 patients (81%), the offending vessel harbored perforators around the root exit zone. Among 16 patients, 14 (87.5%) required interposition of the common trunk or the branching vessel, and in 2 patients, decompression was completed by the transposition method. Fifteen patients experienced sufficient results, and 1 had severe residual spasm. Transient facial palsy developed in 2 patients. No patients encountered recurrence.

Reports concerning decompression methods of AICA-PICA common trunk anomaly are very rare. The tortuosity of the common trunk and perforators from the offending vessel make the usual repositioning of the offending artery much more difficult, and adequate decompression techniques are required for successful MVD 4).

References

1)

Shimano H, Kondo A, Yasuda S, Inoue H, Morioka J, Miwa H, Kawakami O, Murao K. Significance of Anomalous Anterior Inferior Cerebellar Artery-Posterior Inferior Cerebellar Artery Common Trunk Compression in Microvascular Decompression for Hemifacial Spasm. World Neurosurg. 2016 Aug;92:15-22. doi: 10.1016/j.wneu.2016.04.100. Epub 2016 May 4. PMID: 27155382.
2)

Bauer AM, Angster K, Schuman AD, Thompson BG, Telian SA. Aberrant AICA Injury During Translabyrinthine Approach. Otol Neurotol. 2020 Sep 28. doi: 10.1097/MAO.0000000000002826. Epub ahead of print. PMID: 33003181.
3)

Tanriover N, Rhoton AL Jr. The anteroinferior cerebellar artery embedded in the subarcuate fossa: a rare anomaly and its clinical significance. Neurosurgery. 2005 Aug;57(2):314-9; discussion 314-9. PubMed PMID: 16094161.
4)

Shimano H, Kondo A, Yasuda S, Inoue H, Morioka J, Miwa H, Kawakami O, Murao K. Significance of Anomalous Anterior Inferior Cerebellar Artery-Posterior Inferior Cerebellar Artery Common Trunk Compression in Microvascular Decompression for Hemifacial Spasm. World Neurosurg. 2016 Aug;92:15-22. doi: 10.1016/j.wneu.2016.04.100. PubMed PMID: 27155382.

Anterior inferior cerebellar artery aneurysm treatment

Anterior inferior cerebellar artery aneurysm treatment

The management strategies for treatment differ according to the location and configuration of the aneurysm. The existing body of neurosurgical literature contains articles published on aneurysms arising from the AICA near the basilar artery (BA), intracanalicular/meatal aneurysms, and distal AICA. Several therapeutic options exist, encompassing microsurgical and endovascular techniques.

Anterior inferior cerebellar artery aneurysms are rare lesions with a predisposition for distal location and non-saccular morphology. These aneurysms are less amenable to clipping and may instead require aneurysm trapping with bypass.

Anterior inferior cerebellar artery aneurysm endovascular treatment

Anterior inferior cerebellar artery aneurysm surgery

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