The bony bridges of the atlas over the "groove of the vertebral artery" are commonly seen in plain radiographs of the cervical spine, and it is a subject of controversy whether they cause compression of the underneath lying vertebral artery. To clarify this we examined a total of 176 dried and complete atlas vertebrae and found the presence of a "canal for the vertebral artery" (CVA) in 10.23% and an incomplete "canal for the vertebral artery" in 24.43%. The CVA and incomplete CVA is more common in males (11.11% and 24.9%) than in females (9.3% and 24.42%). We found a higher incidence of CVA in laborers (37.5%) than in nonlaborers (4.16%). The incomplete CVA appeared to be more characteristic in the age group of 5-44 years. In the age group of 45-90 years the CVA was characteristic, which probably means that an incomplete CVA is the precursor of a CVA. The superoinferior diameter of the CVA canal ranged from 5.1 to 6.1 mm at the right side and from 4.6 to 5.8 mm at the left side, while the anteroposterior diameter was 5.6-6.9 mm at the right side and 6.1-7.2 mm at the left side. We also found a high incidence of coexistence of CVA and the "retrotransverse foramen" (72.22%) which means that because of possible compression of the vertebral veins the blood flow is directed into the small vein of the retrotransverse foramen. Finally, in 93.5% of unilateral CVA a deeply excavated contralateral "groove of the vertebral artery" was found.

The Dorello's canal, first described by Gruber, in 1859, as an osteofibrous canal at the apex of the petrous bone containing the abducens nerve and the inferior petrosal sinus.' Dorello, in 1905, and Vail, in 1922, also studied the anatomy of this area.2'3 Since then, the canal has been considered clinically important in interpreting sixth nerve palsy.Recently, the interest in this anatomic structure has been revived because of advances in skull base surgery, especially in the surgery of petroclival area.410The first microanatomic study of the Dorello's canal was performed by Umansky et al and reported in 1991.11 This study represents a significant contribution to our knowledge of this specific area. The authors used the operating microscope to present a series of measurements concerning the Dorello's canal's anatomic elements. They also defined its complex relationship to the cavernous, basilar, and inferior petrosal sinuses. Further, they noted the controversies surrounding the canal's definition and proposed their own opinion in this topic.In contrast to the surgical need for a detailed knowledge of the microanatomy of this area, only a few references to the Dorello's canal can be found in the literature. All the above studies disclosed several variations that emphasize the need for further dissections. Our study was performed to contribute further to the definition of the Dorello's canal microanatomy. MATERIALS AND METHODSTwenty cadaveric wet bone specimens of sphenoid bone and the petrous apex, with the dura mater, nerves, and soft tissue intact, were obtained from cadavers. The specimens were fixed in 10% formalin solution. After fixation, the specimens were examined and immobilized on a special base. The operating microscope was used for dissections and photographs. Microsurgical instruments were used, as well.During the first stage, the specimens were inspected for anatomic variations of the petroclival area. The abducens nerve was also examined at its entrance to the interdural space at the clivus.During the second stage, we performed dissections on the right side to expose the Dorello's canal. We began at the posterior petroclinoid fold, above the petrous apex, and dissected down to the endosteal dura of the petrous bone to reveal the petrous apex, the Meckel's cave, and the posterior third of the cavernous sinus. The abducens nerve was identified where it crosses the lateral wall of the cavernous internal carotid artery (ICA). Further dissections to the dorsum sellae and the clival dura exposed the confluence of cavernous, basilar, and inferior petrosal sinuses, the petrosphenoidal or Gruber's ligament, and the Dorello's canal.

Overall, high incidence of NBSI and considerable resistance of Gram-positive and particularly Gram-negative bacteria were noted in neurosurgical patients. Mortality was high with advanced age and stay in IMCU being the most important death-related factors.

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With increasing numbers of individuals being on long-term immuno-suppression, EBV-associated SMTs may be encountered more frequently in the future.

Invasive aspergillosis has long been recognized as one of the most significant and often fatal opportunistic fungal infections in liver transplant recipients. We report a case of a liver transplant recipient who developed an Aspergillus fumigatus brain abscess that produced significant neurologic symptoms. The patient was managed successfully with a combination of surgery and medical treatment with Voriconazole. To our knowledge, this is the second such case reported in the literature.

<b><i>Background and Purpose:</i></b> According to the classical hypothesis, the cerebrospinal fluid (CSF) is actively secreted inside the brain’s ventricular system, predominantly by the choroid plexuses, before flowing unidirectionally in a cranio-caudal orientation toward the arachnoid granulations (AGs), where it is reabsorbed into the dural venous sinuses. This concept has been accepted as a doctrine for more than 100 years and was subjected only to minor modifications. Its inability to provide an adequate explanation to questions arising from the everyday clinical practice, in addition to the ever growing pool of experimental data contradicting it, has led to the identification of its limitations. Literature includes an increasing number of studies suggesting a more complex mechanism than that previously described. This review article summarizes the proposed mechanisms of CSF regulation, referring to the key clinical and experimental developments supporting or defying them. <b><i>Methods:</i></b> A non-systematical literature search of the major databases was performed for studies on the mechanisms of CSF homeostasis. Gray literature was additionally assessed employing a hand-search technique. No restrictions were imposed regarding the time, language, or type of publication. <b><i>Conclusion:</i></b> CSF secretion and absorption are expected to take place throughout the entire brain’s capillaries network under the regulation of hydrostatic and osmotic gradients. The unidirectional flow is defied, highlighting the possibility of its complete absence. The importance of AGs is brought into question, potentiating the significance of the lymphatic system as the primary site of reabsorption. However, the definition of hydrocephalus and its treatment strategies remain strongly associated with the classical hypothesis.

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