Microvascular anatomy of the cerebellar parafloccular perforating space

Abstract

T he surgical anatomy of the cerebellopontine angle (CPA) is complex and challenging. The cerebellopontine cistern (CPC) lies in the CPA between the brainstem, cerebellum, and petrous portion of the temporal bone and is crossed by multiple delicate nerves and small vessels directed toward the cerebellum and highly eloquent portions of the brainstem. This region often witnesses vascular pathology and tumors, leading to lengthy cerebellar retraction, dissection, and the use of bipolar coagulation that jeopardizes the integrity of cranial nerves (CNs) and cerebellar and brainstem perfusion. The cisternal surface of the middle cerebellar peduncle lateral to the cerebellar flocculus-namely, the paraflocculus or parafloccular perforating space-is particularly susceptible to the abovementioned surgical manipulation from a retrosigmoid approach, which is the workhorse approach for CPA lesions. The importance of this small but key area in the cerebellopontine interface was recognized in a classic article by David and Askenasy in the 1930s, 14 and previously published articles have described its topographic relationship to the major branches of the anterior inferior cerebellar artery (AICA) and posterior inferior cerebellar abbreviatioNs AICA = anterior inferior cerebellar artery; CN = cranial nerve; CPA = cerebellopontine angle; CPC = cerebellopontine cistern; PICA = posterior inferior cerebellar artery; SCA = superior cerebellar artery. obJective The cerebellopontine angle is a common site for tumor growth and vascular pathologies requiring surgical manipulations that jeopardize cranial nerve integrity and cerebellar and brainstem perfusion. To date, a detailed study of vessels perforating the cisternal surface of the middle cerebellar peduncle-namely, the paraflocculus or parafloccular perforating space-has yet to be published. In this report, the perforating vessels of the anterior inferior cerebellar artery (AICA) in the parafloccular space, or on the cisternal surface of the middle cerebellar peduncle, are described to elucidate their relevance pertaining to microsurgery and the different pathologies that occur at the cerebellopontine angle. methods Fourteen cadaveric cerebellopontine cisterns (CPCs) were studied. Anatomical dissections and analysis of the perforating arteries of the AICA and posterior inferior cerebellar artery at the parafloccular space were recorded using direct visualization by surgical microscope, optical histology, and scanning electron microscope. A comprehensive review of the English-language and Spanish-language literature was also performed, and findings related to anatomy, histology, physiology, neurology, neuroradiology, microsurgery, and endovascular surgery pertaining to the cerebellar flocculus or parafloccular spaces are summarized. results A total of 298 perforating arteries were found in the dissected specimens, with a minimum of 15 to a maximum of 26 vessels per parafloccular perforating space. The average outer diameter of the cisternal portion of the perforating arteries was 0.1...

Neurosurgical and Clinical Relevance of Microsurgical Anatomy of Cerebellar Para Floccular Perforating Space

“…Before the entrance into the neural tissue, these vessels would send branches to the cisternal portion of the cranial nerves and provide vasa nervorum to the facial and vestibulocochlear nerves. These findings provide anatomical knowledge of the vascular structures that could explain the potential origin of ischemic insult during surgeries of the CPA [15].…”

Posterior vascular anatomy of the encephalon: a comprehensive review

“…This segment can be further subdivided into three parts: premeatal, meatal and postmeatal, depending on the proximity and relation with the internal acoustic meatus. It gives rise to several nerve-related branches including the labyrinth or labyrinthine artery, the recurrent perforating arteries (in the parafloccular space or on the cisternal surface of the middle cerebellar peduncle [ 42 ], and the subarcuate artery. Moreover, specific branches for the cranial nerves from VI to the XI can be found, overlapping with blood flow sources as diverse as those coming from the PICA or even the ascending pharyngeal artery [ 9 , 15 ].…”

Contributions of Near Infrared Light Emitting Diode in Neurosurgery

“…Endovascular injection of indocyanine green has been significantly helpful in distinguishing the vein of the arteriovenous cerebellopontine angle. Within the posterior fossa surgery the use of the ECG can be an important factor for safety, to not compromise the perforators from distal ICA and the vein of the cerebellpontine angle [50]. NIR Fluorescence has been used to assist in determining areas dense with VEGFR-1 and VEGFR-2 mRNA after incubation with VEGF/Cy5.5, potentially indicating carotid plaque instability [51].…”