Surgical anatomy of the arteries of the posterior fossa

Abstract

The development of revascularization for vertebrobasilar ischemic events has created a need to identify the best sites at which to perform bypass procedures. Since the occlusive process may selectively affect various levels of the vertebrobasilar tree, sites in different vessels must be used to reestablish flow distal to the area of occlusion. Twenty-seven unfixed human brains were obtained 4 to 8 hours post mortem, and the vertebrobasilar system was injected with polyester resin. Under a surgical microscope the outer diameter, length, and site of origin of major branches were recorded for the following arteries: vertebral, basilar, posterior inferior cerebellar (PICA), anterior inferior cerebellar (AICA), superior cerebellar (SCA), and posterior cerebral (PCA). The ideal sites for an anastomosis were identified as the pretonsillar segment of the PICA, the second portion of the AICA, the perimesencephalic segment of the SCA, and the perimesencephalic part of the PCA. Based on the anatomical observations reported here, these were the best sites because of their outer diameter, degree of mobility, least number of branches, and frequency of occurrence. Use of two of these arteries, however, may pose potential problems: although the PCA has an ideal outer diameter, it also has numerous branches to the brain stem in its most accessible site in the perimesencephalic area; and the PICA is not consistently present, being found in only 75% of the 27 specimens studied.

Hemifacial spasm associated with Marfan's syndrome: A case report

“…These proliferative and atrophic changes may be due to alterations in blood flow at the greater and lesser curvatures. On the other hand, a neuroanatomic investigation showed that only a small number of perforating branches arise from the proximal half of the vertebral artery prior to the origin of the PICA [10]. This is an important finding in explaining the mobile tendency of this part of the VA, because fewer perforating branches allow greater mobilization.…”

“…Patients with Marfan's syndrome are often easily recognized by skeletal manifestations including tall stature, arachnodactyly, dolicostenomelia, kyphoscoliosis, pectum excavatum, and joint hypermobility [4]. In addition, patients with Marfan's syndrome can demonstrate tortuous and elongated intracranial arteries which may be related to dissection of the internal carotid artery [1 ] or to intracranial giant aneurysms [6,10]. Although these elongated intracranial vessels can theoretically cause neurovascular compression resulting in hemifacial spasm or trigeminal neuralgia, no prior report exists in the literature.…”

Microvascular anatomy of the cerebellar parafloccular perforating space

“…He commented that the basal cerebellar group extends into the horizontal cerebellar fissure, lateral to the cerebellar flocculus and paraflocculus, but he did not describe the characteristics of the perforating branches in the parafloccular region. 64 To the best of our knowledge, the only article in the literature that describes with some detail the perforating vessels arising from the AICA was published by Shrontz et al in 1986. 59 According to their description, as the AICA extends from the basilar artery in the lateral and caudal directions, the second segment of the AICA (a 2 , or the lateral pontine segment) courses laterally and comes in close proximity to CN VII at the lateral portion of the cerebellar flocculus.…”

“…64 To the best of our knowledge, the only article in the literature that describes with some detail the perforating vessels arising from the AICA was published by Shrontz et al in 1986. 59 According to their description, as the AICA extends from the basilar artery in the lateral and caudal directions, the second segment of the AICA (a 2 , or the lateral pontine segment) courses laterally and comes in close proximity to CN VII at the lateral portion of the cerebellar flocculus. The perforating branches in this segment originate from the initial 10 mm of the vessel after the CN VII crosses over the AICA.…”

A Rare Case of the Posterior Inferior Cerebellar Artery

“…Besides originating from the vertebral artery, the PICA may also originate from various arteries, such as the basilar artery, as a common trunk with the anterior inferior cerebel lar artery (AICA), and from the ascending pharyngeal artery (table 1). In other cases, however, the PICA was demonstrated to be totally absent [Shrontz, 1986;Fankhauser et al. 1979].…”