The Posterior Inferior Cerebellar Artery (PICA): An Anatomical and Clinical Analysis.

AIM: To study the operative approaches for posterior inferior cerebellar artery (PICA) aneurysms or understanding the different pathologies that can affect this artery, and to present detailed knowledge of this artery?s anatomy. MATERIAL AND METHODS: The present study analyzed the different variations of the PICA?s first two segments, the anterior medullary and lateral medullary segments, regarding the number of trunks, their emergency site, and the presence or absence of hypoplasia of this artery, through microsurgical dissection of 23 fresh cadaver brains. RESULTS: Some striking variations were found, such as the absence of the left vertebral artery in one of the brains and the emergence of any PICA in another two brains studied. Moreover, variations such as hypoplastic arteries, missing trunks on one side and double or triple trunks, different emergence sites, significant PICA emergence from the superior part of the vertebral artery (59% of the trunks), and asymmetries between the right and left sides were recorded. The double origins of non-hypoplastic PICAs were found in 17% (n = 4) of patients. CONCLUSION: The results obtained in the present study indicated the great importance of the studies and reviews on the different topographies of PICA; these studies and reviews expand the knowledge and consensus on the characteristics and implications of PICA?s variations. The clinical implication of this knowledge and consensus is obtaining the best surgical strategies for clipping aneurysms and, in addition, the best choices for occlusion of the vessel affected if the territory of the main vessel has an adequate collateral circulation. From the results of the present study, it is evident that there was a significant PICA emergence from the superior part of the vertebral artery and that the double origin of non-hypoplastic trunks was also found in some patients; the latter is associated with a greater chance of aneurysms and other additional complications.

Arterial Supply of the Thalamus: A Comprehensive Review.

The thalamus is a deep cerebral structure that is crucial for proper neurological functioning as it transmits signals from nearly all pathways in the body. Insult to the thalamus can, therefore, result in complex syndromes involving sensation, cognition, executive function, fine motor control, emotion, and arousal, to name a few. Specific territories in the thalamus that are supplied by deep cerebral arteries have been shown to correlate with clinical symptoms. The aim of this review is to enhance our understanding of the arterial anatomy of the thalamus and the complications that can arise from lesions to it by considering the functions of known thalamic nuclei supplied by each vascular territory.

Microsurgical Approaches to the Ambient Cistern Region: An Anatomic and Qualitative Study.

OBJECTIVE: We used microscopy to conduct qualitative and quantitative analysis of 4 surgical approaches commonly used in the surgery of the ambient cistern: infratentorial supracerebellar (SC), occipital interhemispheric, subtemporal (ST), and transchoroidal (TC). In addition, we performed a parahippocampal gyrus resection in the ST context. METHODS: Each approach was performed in 3 cadaveric heads (6 sides). After the microscopic anatomic dissection, the parahippocampal gyrus was resected through an ST approach. The qualitative analysis was based on anatomic observation and the quantitative analysis was based on the linear exposure of vascular structures and the area of exposure of the ambient cistern region. RESULTS: The ST approach provided good exposure of the inferior portion of the cistern and of the proximal segments of the posterior cerebral artery. After the resection of the parahippocampal gyrus, the area of exposure improved in all components, especially the superior area. A TC approach provided the best exposure of the superior area compared with the other approaches. The posterolateral approaches (SC/occipital interhemispheric) to the ambient cistern region provided similar exposure of anatomic structures. There was a significant difference (P < 0.05) in linear exposure of the posterior cerebral artery when comparing the ST/TC and ST/SC approaches. CONCLUSIONS: This study has demonstrated that surgical approaches expose dissimilarly the different regions of the ambient cistern and an approach should be selected based on the specific need of anatomic exposure.

Anatomical variation of the superiorcerebelar artery: a case study

During routine dissection in the laboratory was observed the presence of a variation of the superior cerebellarartery in a brain of a young adult male. This artery belongs to the vertebral-basilar system and is branch ofthe basilar artery, prior to its bifurcation giving rise to the posterior cerebral arteries. This variation is clinicallyimportant due to cerebellar infarctions that affect a significant portion of the population, and records of thistype of variation become important especially for the few records that are found in literature.

Microsurgical anatomy of the posterior cerebral artery in three-dimensional images.

OBJECTIVE: To describe the microsurgical anatomy, branches, and anatomic relationships of the posterior cerebral artery (PCA) represented in three-dimensional images. METHODS: Seventy hemispheres of 35 brain specimens were studied. They were previously injected with red silicone and fixed in 10% formalin for at least 40 days. Four of the studied specimens were frozen at -10° to -15 °C for 14 days, and additional dissection was done with the Klingler's fiber dissection technique at ×6 to ×40 magnification. Each segment of the artery was measured and photographed to obtain three-dimensional stereoscopic images. RESULTS: The PCA origin was in the interpeduncular cistern at the pontomesencephalic junction level in 23 specimens (65.7%). The PCA was divided into four segments: P1 extends from the PCA origin to its junction with the posterior communicating artery with an average length of 7.7 mm; P2 was divided into an anterior and posterior segment. The P2A segment begins at the posterior communicating artery and ends at the most lateral aspect of the cerebral peduncle, with an average length of 23.6 mm, and the P2P segment extends from the most lateral aspect of the cerebral peduncle to the posterior edge of the lateral surface of the midbrain, with an average length of 16.4 mm; P3 extends from the posterior edge of the lateral surface of the midbrain and ends at the origin of the parieto-occipital sulcus along the calcarine fissure, with an average length of 19.8 mm; and the P4 segment corresponds to the parts of the PCA that run along or inside both the parieto-occipital sulcus and the distal part of the calcarine fissure. CONCLUSIONS: To standardize the neurosurgical practice and knowledge, surgical anatomic classifications should be used uniformly and further modified according to the neurosurgical experience gathered. The PCA classification proposed intends to correlate its anatomic segments with their required microneurosurgical approaches.

Modified abbreviated transcavernous approach to basilar artery aneurysms--case report.

BACKGROUND: Endovascular procedures and direct surgical clipping are the main therapeutic modalities for managing of BAAs. Furthermore, giant or wide-necked aneurysms and those that involve the PCA or perforators at its neck usually are not embolized. CASE DESCRIPTION: A 55-year-old man presented to the emergency room complaining of sudden and intense headache. Neurological examination evidenced meningismus. Computed tomography disclosed a subarachnoid hemorrhage (Fisher grade III). Arteriograms revealed BAA, whose neck was partially obscured by the PCP. A standard pterional craniotomy was performed, followed by extensive drilling of the greater sphenoid wing. The neck was partially hidden by the PCP, and no proximal control was obtained without drilling the PCP and opening the CS (modified TcA). Drilling of the PCP was begun by cutting the overlying dura and extended caudally as much as possible. Next, opening of the roof of the CS was performed by incising the dura in the oculomotor trigone medial and parallel to the oculomotor nerve and lateral to ICA; the incision progressed posteriorly toward the dorsum sellae. Further resection of the dorsum sellae and clivus was carried out. After performing these steps, proximal control was obtained, aneurysm was deflated, perforators were saved, and aneurysm was clipped. CONCLUSIONS: This study has demonstrated the clinical usefulness of an abbreviated form of the TcA, which led the "modified TcA," in approaching complex low-lying BAA. It provides additional surgical room by removing the PCP and partially opening the CS, which permits further bone removal and improves exposure.

Biometría de las Arterias Comunicantes Posteriores y Cerebrales Posteriores en su Segmento Precomunicante (P1) en el Círculo Arterial del Cerebro (Willis) / Biometrics of the Posterior Communicating Artery and the Posterior Cerebral Artery in its Precommunicating Segment (P1) of the Arterial Circle of Brain (Willis)

El conocimiento anatómico y clínico preciso del círculo arterial del cerebro, se hace cada vez más necesario, por la compleja relación neural que presentan las diversas arterias que entran en su formación y además por su gran variabilidad. Utilizamos 36 encéfalos humanos frescos, provenientes de especímenes autopsiados adultos, cuyos datos bioantropológicos fueron previamente registrados. El calibre de las aa. comunicantes posteriores fue, en promedio, de 1,08 mm (DE 0,45 ) en ambos lados y su longitud de 17,51 mm( DE 7,9) en el lado derecho y de 16,9 mm (DE 8,0 ) en el lado izquierdo. La ACP en el segmento P1 presentó un calibre de 2,56 mm (DE 077) en el lado derecho y de 2,32 mm (DE 0,64) en el lado izquierdo. La longitud de estas arterias correspondió a 9,43 mm (DE 8,92) en el lado derecho y de 8,82 mm (DE 7,33 ) en el lado izquierdo. Las dimensiones observadas demuestran variabilidad que consideramos interesante de considerar en la anatomía quirúrgica.

The anatomical and clinical anatomy of the arterial circle of brain knowledge , is each time more necessary by cause of the complex neural relation of its components and great variability. Thirty six unfixed brain were obtained at autopsy from adult individuals without signs of cerebrovascular disease and the specimens had registered bioanthropological data. The caliber of the posterior communicating arteries corresponds to 1.08 mm (S.D. 0.45) mean both sides and the longitude to 17.51 mm (S.D. 7.9 ) in the right side and 16.9 mm (S.D. 8.0) in the left side. The P1 segment of the posterior cerebral artery presented a caliber of 2.56 mm (S.D. 0.77) in the right side and of 2.32 mm (S.D. 0.64) in the left side. The length of these arteries corresponded to 9.43 mm (S.D.8.92) in the right side and of 8.82 mm (S.D. 7.33) in the left side. The observed dimensions present variability that we considered interesting to chirurgical anatomy.

Anatomia microquirurgica del segmento P1 de la arteria cerebral posterior / Microsurgical anatomy of the P1 posterior cerebral artery segment

Objective: This study was conducted to clarify the anatomy of the posterior cerebral artery P1 segment. Methods: Four formalin-fixed adults heads were examined using X6 to X40 magnification. The vessels were filled with colored silicon. Results: The branches arising from the P1 are: 1) the posterior thalamoperforating arteries; 2) the short and long circumflex branches; 3) the medial posterior choroidalartery; and 4)the meningeal branch of Davidoff and Schechter. Conclusion: the correct knowledge of the anatomy of the P1 segment of the posterior cerebral artery is very important in the treatment of lesions located in the interpeduncular cistern (AU)

Estudio anatómico sobre el polígono de Willis. Parte II: sector posterior / Anatomical study of the circle of Willis. Part II: posterior sector

Se estudió el polígono de Willis en 35 encéfalos de cadáveres adultos. Se hallaron variaciones en el 68,6 por ciento de los casos; el 22.9 por ciento presentó dos variaciones, el 20 por ciento tres. El sector posterior del polígono tuvo variaciones en el 57,1 por ciento de los casos. El calibre de la arteria vertebral fue mayor a izquierda en el 45 por ciento de los casos; en el 50 por ciento sus calibres fueron similares (promedio 2,7 mm a derecha y 3,4 mm a izquierda). La arteria comunicante posterior (AcomP) presentó variaciones en 20 casos. De ellos, 10 fueron disposiciones fetales (29 por ciento) y 9 casos codominancia con la cerebral posterior. El origen de la AcomP se ubicó entre 0 y 6 mm por debajo del origen de la coroidea anterior (promedio 2,9 mm). El calibre de la arteria cerebral posterior fue en promedio 2 mm. Se encontraron dos disposiciones poco frecuentes; en un caso había un círculo anastomótico complejo entre una cerebral posterior hipoplásica y la cerebelosa superior homolateral. En el otro, una arteria cerebral posterior filiforme se bifurcaba antes de alcanzar la AcomP. La arteria carótida interna izquierda fue dominante para la circulación anterior en 4 casos, en un caso lo fue para ambos sectores del polígono. Finalmente, se destaca la variabilidad del polígono de Willis y su importancia en la cirugía de aneurismas intracraneanos, presentación clínica de las obstrucciones vasculares o vasoespasmo (AU)