Fenestration of the posteroinferior cerebellar artery: case report

Multiple Rare Anatomic Variations in Anterior and Posterior Cerebral Circulation: A Case Report

Anatomic variations of intracranial arteries are of paramount importance in neurosurgery and interventional radiology. Three extremely rare arterial variants were found by observing the intracranial vascular anatomy on the magnetic resonance angiography files of a 56-year-old female patient. Firstly, on the left side of the vertebrobasilar axis, a persistent primitive lateral basilovertebral anastomosis was found uniting the left anterior inferior and posterior inferior cerebellar arteries; further, the left anterior inferior cerebellar artery looped above the nerves of the internal auditory canal. Secondly, the right posterior inferior cerebellar artery was shown to be leaving the vertebral artery and had a distal fenestration of the telovelotonsillar segment. Such cases of distal fenestrated posterior inferior cerebellar artery are rare. Thirdly, a partly duplicated anterior communicating artery was also found in the anterior circulation. In conclusion, magnetic resonance angiography helps distinguish and detail discrete and delicate rare arterial variants.

Endovascular management of a ruptured aneurysm associated with distal PICA fenestration

Fenestrations are rare but well-known arterial anatomic variations in which a segment of artery divides into two parallel channels that reunite distally. Although fenestrations as such are asymptomatic, they have gained clinical significance because of their association with aneurysms and other intracranial vascular pathologies. Here we present a 35-year-old woman with history of sudden severe occipital headache and vomiting. Imaging revealed a ruptured aneurysm in the distal posterior inferior cerebellar artery arising from one of the limbs of the fenestration. The aneurysm was successfully managed by coiling, and the patient made complete recovery without neurological sequelae.

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.

Intracranial Arterial Fenestration and Risk of Aneurysm: A Systematic Review and Meta-Analysis

BACKGROUND

Previous studies have been inconsistent regarding risk for intracranial aneurysm related to intracranial arterial fenestration. We conducted a meta-analysis to examine the association between intracranial arterial fenestration and risk of aneurysm.

METHODS

We performed a systematic review of PubMed and Embase through August 2017 for potentially relevant articles. Summary odds ratios with 95% confidence intervals were pooled using a random-effects model.

RESULTS

Of 446 articles found, 7 were selected for meta-analysis. Pooled odds ratios revealed an increased risk of aneurysm owing to fenestration of 1.50 (95% confidence interval, 0.61-3.71; P = 0.38). Subgroup analyses based on the population presenting with various indications suggested that pooled odds ratios indicated a significant increase in risk for aneurysm of 2.43 (95% confidence interval, 1.04-5.69; P = 0.04).

CONCLUSIONS

Our findings indicate that intracranial arterial fenestration may be associated with increased risk for aneurysm formation.

A case with coil embolization for ruptured aneurysm associated with fenestration of the posterior inferior cerebellar artery

An 87-year-old man hospitalized for subarachnoid hemorrhage showed a ruptured aneurysm arising from fenestration of the posterior inferior cerebellar artery. Endovascular treatment was selected and the aneurysm and superior limb were embolized completely using three coils. Fenestration of the posterior cerebellar artery is exceedingly rare. In addition, we present a first case of aneurysm as fenestration of the posterior inferior cerebellar artery that was definitively identified as a cause of bleeding.

Cerebral arterial fenestrations

Arterial fenestrations are an anatomic variant with indeterminate significance. Given the controversy surrounding fenestrations we sought their prevalence within our practice along with their association with other cerebrovascular anomalies. We retrospectively reviewed 10,927 patients undergoing digital subtraction angiography between 1992 and 2011. Dictated reports were searched for the terms "fenestration" or "fenestrated" with images reviewed for relevance, yielding 228 unique cases. A Medline database search from February 1964 to January 2013 generated 304 citations, 127 cases of which were selected for analysis. Cerebral arterial fenestrations were identified in 228 patients (2.1%). At least one aneurysm was noted in 60.5% of patients, with an aneurysm arising from the fenestration in 19.6% of patients. Aneurysmal subarachnoid hemorrhage or non-aneurysmal subarachnoid hemorrhage were present in 60.1% and 15.8%, respectively. For the subset of patients with an aneurysm arising directly from a fenestration relative to those patients with an aneurysm not immediately associated with a fenestration, the prevalence of aneurysmal subarachnoid hemorrhage was 66.7% vs. 58.6% (p = 0.58). Fenestrations were more often within the posterior circulation (73.2%) than the anterior circulation (24.6%), though there was no difference in the prevalence of aneurysms within these groups (61.1% vs. 60.7%, p = 1.0). Cerebral arterial fenestrations are an anatomic variant more often manifesting at the anterior communicating arterial complex and basilar artery and with no definite pathological relationship with aneurysms.

Double origin of the posterior inferior cerebellar artery: association with intracranial aneurysm on catheter angiography

OBJECTIVE

Double origin of the posterior inferior cerebellar artery (PICA) is a congenital anomaly in which the PICA forms from two separate vessels arising from the vertebral artery. The prevalence of double origin of the PICA on catheter angiography is unknown because only four case reports have been published. Because some congenital intracranial vascular oddities are associated with an elevated incidence of aneurysm formation, we sought to determine the association between intracranial aneurysm and double origin of the PICA and to measure the prevalence of double origin of the PICA on catheter angiography.

MATERIALS AND METHODS

A retrospective review was done over a 27-month period to identify patients with double origin of the PICA. Patients were excluded if both PICAs were not adequately visualized on catheter angiography. The cohort was then divided into two groups consisting of patients with and those without intracranial aneurysm.

RESULTS

A total of 207 patients (101 males, 106 females) met the inclusion criteria. One or more cerebral aneurysms were found in 35.3% and double origin of the PICA in 1.45% of the patients. Double origin of the PICA was present in 4.1% of the patients with an aneurysm, and none of the patients without an aneurysm had double origin of the PICA (p = 0.043). A majority of the seven known cases of double origin of the PICA described by angiography in the peer-reviewed literature have associated intracranial aneurysm disease.

CONCLUSION

Our data show that double origin of the PICA is seen in 4.1% of patients with intracranial aneurysm and on 1.45% of catheter angiograms. Double origin of the PICA has an increased association with intracranial aneurysmal disease and may represent a risk factor for subsequent development of intracranial aneurysm.

Aneurysm originating from the fenestration of the posterior cerebral artery: case report

OBJECTIVE AND IMPORTANCE

A rare case of an aneurysm arising at the fenestration of the P2 segment of the posterior cerebral artery is reported.

CLINICAL PRESENTATION

A 37-year-old man presented with severe headache and disturbance of consciousness. Computed tomographic scanning showed diffuse subarachnoid hemorrhage. Cerebral angiography revealed an aneurysm at the fenestration of the P2 segment of the right posterior cerebral artery. The aneurysm was located at the middle portion of the lower trunk of the fenestration. An unruptured arteriovenous malformation was incidentally found in the right thalamus.

INTERVENTION

A right frontotemporal craniotomy with orbitozygomatic osteotomy was made, and the aneurysm was successfully clipped. One year after the operation, gamma knife surgery was performed for the right thalamic arteriovenous malformation.

CONCLUSION

This is the first reported case of an aneurysm originating from the middle portion of a fenestrated posterior cerebral artery.